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Title: A History of Science, Volume 5 - Aspects Of Recent Science
Author: Williams, Henry Smith, 1863-1943, Williams, Edward Huntington, 1868-1944
Language: English
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A HISTORY OF SCIENCE

By Henry Smith Williams

Assisted By Edward H. Williams

In Five Volumes


VOLUME V.

Aspects Of Recent Science

New York And London

Harper And Brothers

Copyright, 1904, by Harper & Brothers.

Published November, 1904.



CONTENTS


  BOOK V


  CHAPTER I--THE BRITISH MUSEUM

  The founding of the British Museum, p. 4--Purchase of Sir Hans Sloane's
  collection of curios by the English government, p. 4--Collection of
  curios and library located in Montague Mansion, p. 5--Acquisition of
  the collection of Sir William Hamilton, p. 5--Capture of Egyptian
  antiquities by the English, p. 5--Construction of the present museum
  building, p. 6--The Mesopotamian department, p. 8--The Museum of Natural
  History in South Kensington, p. 8--Novel features in the structure of
  the building, p. 9--Arrangement of specimens to illustrate evolution,
  protective coloring, etc., p.-- --Exhibits of stuffed specimens amid
  their natural surroundings, p. 10--Interest taken by visitors in the
  institution, p. 12.

  CHAPTER II--THE ROYAL SOCIETY OP LONDON FOR IMPROVING NATURAL KNOWLEDGE

  The Royal Society, p. 14--Weekly meetings of the society, p. 15--The tea
  before the opening of the lecture, p. 15--Announcement of the beginning
  of the lecture by bringing in the great mace, p. 16--The lecture-room
  itself, p. 17--Comparison of the Royal Society and the Royal Academy
  of Sciences at Berlin, p. 18--The library and reading-room, p. 19--The
  busts of distinguished members, p. 20--Newton's telescope and Boyle's
  air-pump, p. 21.

  CHAPTER III--THE ROYAL INSTITUTION AND LOW-TEMPERATURE RESEARCHES

  The founding of the Royal Institution, p. 29--Count Rumford, p. 30--His
  plans for founding the Royal Institution, p. 32--Change in the spirit
  of the enterprise after Rumford's death, p. 33--Attitude of the
  earlier workers towards the question of heat as a form of motion,
  p. 34--Experiments upon gases by Davy and Faraday, p. 35--Faraday's
  experiments with low temperatures, p. 39--Other experiments to produce
  lower temperature, p. 39--Professor De-war begins low-temperature
  research, p. 39--His liquefaction of hydrogen, p. 43--Hampson's method
  of producing low temperatures, p. 44--Dewar's invention of the vacuum
  vessel, p. 53--Its use in retaining liquefied gases, p. 54--Changes in
  physical properties of substances at excessively low temperatures, p.
  56--Magnetic phenomena at low temperatures, p. 56--Changes in the color
  of substances at low temperatures, p. 57--Substances made luminous by
  low temperatures, p. 58--Effect of low temperatures upon the strength of
  materials, p. 59--Decrease of chemical activity at low temperatures, p.
  60--Olzewski's experiments with burning substances in liquid oxygen,
  p. 61--Approach to the absolute zero made by liquefying hydrogen, p.
  69--Probable form of all matter at the absolute zero, p. 70--Uncertain
  factors that enter into this determination, p. 71.

  CHAPTER IV--SOME PHYSICAL LABORATORIES AND PHYSICAL PROBLEMS

  Sir Norman Lockyer and Spectroscopic Studies of the Sun and Stars, p.
  73--Observations made at South Kensington by Sir Norman and his staff,
  p. 74--His theories as to the influence of sun-spots and terrestrial
  weather, p. 75--Spectroscopic studies of sun-spots, p. 76--Studies of
  the so-called reverse lines of the spectrum, p. 78--Discovery of the new
  star in the constellation of Perseus, p. 80--Spectroscopic studies
  of the new star, p. 81--Professor Ramsay and the new gases, p.
  82--University College in London, p. 83--Professor Ramsay's laboratory
  and its equipment, p. 84--The discovery of argon, p. 86--Professor
  Ramsay's work on krypton, neon, and zenon, p. 87--Discoveries of new
  constituents of the atmosphere, p. 88--Interesting questions raised
  by these discoveries, p. 89--Professor J. J. Thomson and the nature
  of electricity, p. 92--Study of gases in relation to the conduction
  of electricity, p. 93--Electricity regarded as a form of matter, p.
  97--Radio-activity, p. 97--The nature of emanations from radio-active
  bodies, p. 10a--The source of energy of radioactivity, p.
  106--Radio-activity and the structure of the atom, p. 108--Effect of
  radio-activity upon heat-giving life of the sun and the earth, p. 111.

  CHAPTER V--THE MARINE BIOLOGICAL LABORATORY

  The aquarium, p. 113--The arrangement of the tanks and exhibits, p.
  114--The submarine effect of this arrangement, p. 115--Appearance of the
  submarine dwellers in their natural surroundings, p. 116--The eels and
  cuttle-fishes, p. 116--The octopuses, p. 117--The technical department
  of the laboratory, p. 119--The work of Dr. Anton Dohrn, founder of the
  laboratory, p. 121--The associates of Dr. Dohrn, p. 122--The collecting
  of surface specimens, p. 123--Collecting specimens by dredging, p.
  124--Fauna of the Bay of Naples, p. 124--Abundance of the material for
  biological study, p. 125--Advantages offered by marine specimens for
  biological study, p. 126--Method of preserving jelly-fish and similar
  fragile creatures, p. 127--Uses made of the specimens in scientific
  study, p. 128--Different nationalities represented among the workers at
  the laboratory, p. 130--Methods of investigation, p. 131--Dr. Diesch's
  studies of heredity at the laboratory, p. 131--Other subjects under
  scientific investigation, p. 132--The study of chromosomes, p.
  133--Professor Weismann's theory of heredity based on these studies,
  p. 33--Experiments in the division of egg-cells, p. 134--Experiments
  tending to refute Weismann's theory, p. 136--Dr. Dohrn*s theory of
  the type of the invertebrate ancestor, p. 137--Publications of the
  laboratory, p. 139--Meetings of the investigators at Signor Bifulco's,
  p. 141--Marine laboratories of other countries, p. 142.

  CHAPTER VI--ERNST HAECKEL AND THE NEW ZOOLOGY

  The "dream city" of Jena, p. 145--The old market-place, p. 147--The
  old lecture-halls of the university, p. 148--Ernst Haeckel, p. 151--His
  discoveries of numerous species of radiolarians, p. 153--The part played
  in evolution by radiolarians, p. 156--Haeckel's work on morphology,
  and its aid to Darwinian philosophy, p. 156--Freedom of thought and
  expression in the University of Jena, p. 157--Haeckel's laboratory, p.
  160--His method of working, p. 161--His methods of teaching, p. 164--The
  import of the study of zoology, p. 166--Its bearing upon evolution, p.
  168--The present status of Haeckel's genealogical tree regarding the
  ancestry of man, p. 171--Dubois's discovery of the skull of the ape-man
  of Java, p. 173--Its close resemblance to the skull of the ape, p.
  173--Man's line of descent clearly traced by Haeckel, p. 175--The
  "missing link" no longer missing, p. 176.

  CHAPTER VII--SOME MEDICAL LABORATORIES AND MEDICAL PROBLEMS

  The Boulevard Pasteur, p. 179--The Pasteur Institute, p. 180--The tomb
  of Pasteur within the walls, p. 181--Aims and objects of the Pasteur
  Institute, p. 182--Antirabic treatment given, p. 183--Methods of
  teaching in the institute, p. 185--The director of the institute and his
  associates, p. 185--The Virchow Institute of Pathology, p. 186--Studies
  of the causes of diseases, p. 187--Organic action and studies of
  cellular activities, p. 188--The discoveries of Rudolph Virchow, p.
  188--His work in pathology, p. 189--Character of the man, his ways of
  living and working, p. 189--His methods of lecturing and teaching, p.
  191--The Berlin Institute of Hygiene, p. 193--Work of Professor Koch
  as carried on in the institute, p. 194--Work of his successors in the
  institute, p. 195--Investigations in hygiene, p. 196--Investigations
  of the functions of the human body in their relations to everyday
  environment, p. 197--The Museum of Hygiene, p. 198--Studies in methods
  of constructing sewerage systems in large cities, p. 199--Studies in
  problems of ventilation, p. 200.

  CHAPTER VIII--SOME UNSOLVED SCIENTIFIC PROBLEMS

  The ever-shifting ground of scientific progress, p. 203--Solar and
  telluric problems, p. 205--Mayer's explanation of the continued heat
  of the sun, p. 206--Helmholtz's suggestion as to the explanation, p.
  207--The estimate of the heat-giving life of the sun by Lord Kelvin
  and Professor Tait, p. 208--Lockyer's suggestion that the chemical
  combination of elements might account for the sun's heat, p.
  209--Computations as to the age of the earth's crust, p. 210--Lord
  Kelvin's computation of the rigidity of the telluric structure, p.
  211--Estimates of the future life of the earth, p. 212--Physical
  problems, p. 213--Attempts to explain the power of gravitation,
  p. 214--The theory of Le Sage, p. 214--Speculations based upon the
  hypothesis of the vortex atom, p. 216--Lord Kelvin's estimate of the
  vortex theory, p. 217--Attempted explanation of the affinity of
  atoms, p. 217--Solubility, as explained by Ostwald and Mendeleef, p.
  218--Professor Van 't Hoof's studies of the space relations of atoms, p.
  219--Life problems, p. 220--Question as to living forms on other worlds
  besides our own, p. 21 x--The question of the "spontaneous generation"
  of living protoplasm, p. 222--The question of the evolution from
  non-vital to vital matter, p. 223--The possibility of producing organic
  matter from inorganic in the laboratory, p. 224--Questions as to
  the structure of the cell, p. 225--Van Beneden's discovery of the
  centrosome, p. 226--Some problems of anthropology, p. 227.

  CHAPTER IX--RETROSPECT AND PROSPECT

  The scientific attitude of mind, p. 2 30--Natural versus supernatural,
  p. 233--Inductive versus deductive reasoning, p. 235--Logical induction
  versus hasty generalization, p. 239--The future of Darwinism, p. 241.

  APPENDIX

  A LIST OF SOURCES



A HISTORY OF SCIENCE--BOOK V



ASPECTS OF RECENT SCIENCE

STUDENTS of the classics will recall that the old Roman historians were
accustomed to detail the events of the remote past in what they were
pleased to call annals, and to elaborate contemporary events into
so-called histories. Actuated perhaps by the same motives, though with
no conscious thought of imitation, I have been led to conclude this
history of the development of natural science with a few chapters
somewhat different in scope and in manner from the ones that have gone
before.

These chapters have to do largely with recent conditions. Now and again,
to be sure, they hark back into the past, as when they tell of the
origin of such institutions as the British Museum, the Royal Society,
and the Royal Institution; or when the visitor in modern Jena imagines
himself transplanted into the Jena of the sixteenth century. But these
reminiscent moods are exceptional. Our chief concern is with strictly
contemporary events--with the deeds and personalities of scientific
investigators who are still in the full exercise of their varied powers.
I had thought that such outlines of the methods of contemporary workers,
such glimpses of the personalities of living celebrities, might form a
fitting conclusion to this record of progress. There is a stimulus in
contact with great men at first hand that is scarcely to be gained in
like degree in any other way. So I have thought that those who have not
been privileged to visit the great teachers in person might like to
meet some of them at second hand. I can only hope that something of
the enthusiasm which I have gained from contact with these men may make
itself felt in the succeeding pages.

It will be observed that these studies of contemporary workers are
supplemented with a chapter in which a hurried review is taken of the
field of cosmical, of physical, and of biological science, with
reference to a few of the problems that are still unsolved. As we have
noted the clearing up of mystery after mystery in the past, it may be
worth our while in conclusion thus to consider the hordes of mysteries
which the investigators of our own age are passing on to their
successors. For the unsolved problems of to-day beckon to the alluring
fields of to-morrow.



I. THE BRITISH MUSEUM

IN the year 1753 a remarkable lottery drawing took place in London.
It was authorized, through Parliament, by "his gracious Majesty" King
George the Second. Such notables as the archbishop of Canterbury and the
lord chancellor of the realm took official interest in its success. It
was advertised far and wide--as advertising went in those days--in the
_Gazette_, and it found a host of subscribers. Of the fifty thousand
tickets--each costing three pounds--more than four thousand were to
be of the class which the act of Parliament naively describes as
"fortunate tickets." The prizes aggregated a hundred thousand pounds.

To be sure, state lotteries were no unique feature in the England of
that day. They formed as common a method of raising revenue in the
island realm of King George II. as they still do in the alleged
continental portion of his realm, France, and in the land of his
nativity, Germany. Indeed, the particular lottery in question was to
be officered by the standing committee on lotteries, whose official
business was to "secure two and a half million pounds for his Majesty"
by this means. But the great lottery of 1754 had interest far beyond the
common run, for it aimed to meet a national need of an anomalous kind--a
purely intellectual need. The money which it was expected to bring was
to be used to purchase some collections of curiosities and of books that
had been offered the government, and to provide for their future care
and disposal as a public trust for the benefit and use of the people.
The lottery brought the desired money as a matter of course, for the
"fool's tax" is the one form of revenue that is paid without stint and
without grumbling. Almost fifty thousand pounds remained in the hands
of the archbishop of Canterbury and his fellow-trustees after the prizes
were paid. And with this sum the institution was founded which has been
increasingly famous ever since as the British Museum.

The idea which had this splendid result had originated with Sir Hans
Sloane, baronet, a highly respected practising physician of Chelsea,
who had accumulated a great store of curios, and who desired to see the
collection kept intact and made useful to the public after his death.
Dying in 1753, this gentleman had directed in his will that the
collection should be offered to the government for the sum of twenty
thousand pounds; it had cost him fifty thousand pounds. The government
promptly accepted the offer--as why should it not, since it had at hand
so easy a means of raising the necessary money? It was determined to
supplement the collection with a library of rare books, for which
ten thousand pounds was to be paid to the Right Honorable Henrietta
Cavendish Holies, Countess of Oxford and Countess Mortimer, Relict of
Edward, Earl of Oxford and Earl Mortimer, and the Most Noble Margaret
Cavendish, Duchess of Portland, their only daughter.

The purchases were made and joined with the Cottonian library, which
was already in hand. A home was found for the joint collection, along
with some minor ones, in Montague Mansion, on Great Russell Street, and
the British Museum came into being. Viewed retrospectively, it seems
a small affair; but it was a noble collection for its day; indeed,
the Sloane collection of birds and mammals had been the finest private
natural history collection in existence. But, oddly enough, the weak
feature of the museum at first was exactly that feature which has been
its strongest element in more recent years--namely, the department of
antiquities. This department was augmented from time to time, notably by
the acquisition of the treasures of Sir William Hamilton in 1773; but it
was not till the beginning of the nineteenth century that the windfall
came which laid the foundation for the future incomparable greatness of
the museum as a repository of archaeological treasures.

In that memorable year the British defeated the French at Alexandria,
and received as a part of the conqueror's spoils a collection of
Egyptian antiquities which the savants of Napoleon's expedition had
gathered and carefully packed, and even shipped preparatory to sending
them to the Louvre. The feelings of these savants may readily be
imagined when, through this sad prank of war, their invaluable treasures
were envoyed, not to their beloved France, but to the land of their
dearest enemies, there to be turned over to the trustees of the British
Museum.

The museum authorities were not slow to appreciate the value of the
treasures that had thus fallen into their hands, yet for the moment
it proved to them something of a white elephant. Montague Mansion was
already crowded; moreover, its floors had never been intended to hold
such heavy objects, so it became imperatively necessary to provide new
quarters for the collection. This was done in 1807 by the erection of
a new building on the old site. But the trustees of that day failed to
gauge properly the new impulse to growth that had come to the museum
with the Egyptian antiquities, for the new building was neither in
itself sufficient for the needs of the immediate future nor yet
so planned as to be susceptible of enlargement with reasonable
architectural effect. The mistakes were soon apparent, but, despite
various tentatives and "meditatings," fourteen years elapsed before
the present magnificent building was planned. The construction, wing by
wing, began in 1823, but it was not until 1846 that the last vestige
of the old museum buildings had vanished, and in their place, spreading
clear across the spacious site, stood a structure really worthy of the
splendid collection for which it was designed.

But no one who sees this building to-day would suspect its relative
youth. Half a century of London air can rival a cycle of Greece or Italy
in weathering effect, and the fine building of the British Museum
frowns out at the beholder to-day as grimy and ancient-seeming as if
its massive columns dated in fact from the old Grecian days which they
recall. Regardless of age, however, it is one of the finest and most
massive specimens of Ionic architecture in existence. Forty-four massive
columns, in double tiers, form its frontal colonnade, jutting forward
in a wing at either end. The flight of steps leading to the central
entrance is in itself one hundred and twenty-five feet in extent; the
front as a whole covers three hundred and seventy feet. Capping the
portico is a sculptured tympanum by Sir Richard Westmacott, representing
the "Progress of Civilization" not unworthily. As a whole, the building
is one of the few in London that are worth visiting for an inspection of
their exterior alone. It seems admirably designed to be, as it is, the
repository of one of the finest collections of Oriental and classical
antiquities in the world.

There is an air of repose about the _ensemble_ that is in itself
suggestive of the Orient; and the illusion is helped out by the pigeons
that flock everywhere undisturbed about the approaches to the building,
fluttering to be fed from the hand of some recognized friend, and
scarcely evading the feet of the casual wayfarer. With this scene before
him, if one will close his ears to the hum of the great city at his
back he can readily imagine himself on classical soil, and, dreaming of
Greece and Italy, he will enter the door quite prepared to find himself
in the midst of antique marbles and the atmosphere of by-gone ages.

I have already pointed out that the turning-point in the history of
the British Museum came just at the beginning of the century, with the
acquisition of the Egyptian antiquities. With this the institution threw
off its swaddling-clothes. Hitherto it had been largely a museum of
natural history; in future, without neglecting this department, it
was to become equally important as a museum of archaeology. The Elgin
marbles, including the wonderful Parthenon frieze, confirmed this
character, and it was given the final touch by the reception, about
the middle of the century, of the magnificent Assyrian collection just
exhumed at the seat of old Nineveh by Mr. (afterwards Sir Henry) Layard.
Since then these collections, with additions of similar character, have
formed by far the most important feature of the British Museum. But in
the mean time archaeology has become a science.

Within recent years the natural history collection has been removed _in
toto_ from the old building to a new site far out in South Kensington,
and the casual visitor is likely to think of it as a separate
institution. The building which it occupies is very modern in appearance
as in fact. It is a large and unquestionably striking structure, and one
that gives opportunity for very radical difference of opinion as to its
architectural beauty. By some it is much admired; by others it is almost
equally scoffed at. Certain it is that it will hardly bear comparison
with the parent building in Great Russell Street.

Interiorly, the building of the natural history museum is admirably
adapted for its purpose. Its galleries are for the most part well
lighted, and the main central hall is particularly well adapted for
an exhibition of specimens, to which I shall refer more at length in
a moment. For the rest there is no striking departure from the
conventional. Perhaps it is not desired that there should be, since long
experience seems to have settled fairly well the problem of greatest
economy of space, combined with best lighting facilities, which always
confronts the architect in founding a natural history museum.

There is, however, one striking novel feature in connection with the
structure of the natural history museum at Kensington which must not
be overlooked. This is the quite unprecedented use of terra-cotta
ornamentation. Without there is a striking display of half-decorative
and half-realistic forms; while within the walls and pillars everywhere
are covered with terracotta bas-reliefs representing the various forms
of life appropriate to the particular department of the museum which
they ornament. This very excellent feature might well be copied
elsewhere, and doubtless will be from time to time.

As to the exhibits proper within the museum, it may be stated in a word
that they cover the entire range of the faunas and floras of the
globe in a variety and abundance of specimens that are hardly excelled
anywhere, and only duplicated by one or two other collections in Europe
and two or three in America.

It would be but a reiteration of what the catalogues of all large
collections exhibit were one to enumerate the various forms here shown,
but there are two or three exhibits in this museum which are more novel
and which deserve special mention. One of these is to be found in a set
of cases in the main central hall. Here are exhibited, in a delightfully
popular form, some of the lessons that the evolutionist has taught us
during the last half-century. Appropriately enough, a fine marble statue
of Darwin, whose work is the fountain-head of all these lessons, is
placed on the stairway just beyond, as if to view with approval this
beautiful exemplification of his work.

One of these cases illustrates the variations of animals under
domestication, the particular specimens selected being chiefly the
familiar pigeon, in its various forms, and the jungle-fowl with its
multiform domesticated descendants.

Another case illustrates very strikingly the subject of protective
coloration of animals. Two companion cases are shown, each occupied by
specimens of the same species of birds and animals--in one case in their
summer plumage and pelage and in the other clad in the garb of winter.
The surroundings in the case have, of course, been carefully prepared
to represent the true environments of the creatures at the appropriate
seasons. The particular birds and animals exhibited are the
willow-grouse, the weasel, and a large species of hare. All of these,
in their summer garb, have a brown color, which harmonizes marvellously
with their surroundings, while in winter they are pure white, to match
the snow that for some months covers the ground in their habitat.

The other cases of this interesting exhibit show a large variety of
birds and animals under conditions of somewhat abnormal variation, in
the one case of albinism and the other of melanism. These cases are,
for the casual visitor, perhaps the most striking of all, although, of
course, they teach no such comprehensive lessons as the other exhibits
just referred to.

The second of the novel exhibits of the museum to which I wish to refer
is to be found in a series of alcoves close beside the central cases in
the main hallway.

Each of these alcoves is devoted to a class of animals--one to mammals,
one to birds, one to fishes, and so on. In each case very beautiful sets
of specimens have been prepared, illustrating the anatomy and physiology
of the group of animals in question. Here one may see, for example, in
the alcove devoted to birds, specimens showing not only details of
the skeleton and muscular system, but the more striking examples of
variation of form of such members as the bill, legs, wings, and tails.
Here are preparations also illustrating, very strikingly, the vocal
apparatus of birds. Here, again, are finely prepared wings, in which
the various sets of feathers have been outlined with different-colored
pigments, so that the student can name them at a glance. In fact, every
essential feature of the anatomy of the bird may be studied here as in
no other collection that I know of. And the same is true of each of the
other grand divisions of the animal kingdom. This exhibit alone gives an
opportunity for the student of natural history that is invaluable. It is
quite clear to any one who has seen it that every natural history museum
must prepare a similar educational exhibit before it can claim to do
full justice to its patrons.

A third feature that cannot be overlooked is shown in the numerous cases
of stuffed birds, in which the specimens are exhibited, not merely
by themselves on conventional perches, but amid natural surroundings,
usually associated with their nests and eggs or young. These exhibits
have high artistic value in addition to their striking scientific worth.
They teach ornithology as it should be taught, giving such clews to
the recognition of birds in the fields as are not at all to be found in
ordinary collections of stuffed specimens. This feature of the museum
has, to be sure, been imitated in the American Museum of Natural History
in New York, but the South Kensington Museum was the first in the field
and is still the leader.

A few words should be added as to the use made by the public of the
treasures offered for their free inspection by the British Museum. I
shall attempt nothing further than a few data regarding actual visits to
the museum. In the year 1899 the total number of such visits
aggregated 663,724; in 1900 the figures rise to 689,249--well towards
three-quarters of a million. The number of visits is smallest in the
winter months, but mounts rapidly in April and May; it recedes slightly
for June and July, and then comes forward to full tide in August, during
which month more than ninety-five thousand people visited the museum
in 1901, the largest attendance in a single day being more than nine
thousand. August, of course, is the month of tourists--particularly of
tourists from America--but it is interesting and suggestive to note
that it is not the tourist alone who visits the British Museum, for the
flood-tide days of attendance are always the Bank holidays, including
Christmas boxing-day and Easter Monday, when the working-people turn out
_en masse_. On these days the number of visits sometimes mounts above
ten thousand.

All this, it will be understood, refers exclusively to the main building
of the museum on Great Russell Street. But, meantime, out in Kensington,
at the natural history museum, more than half a million visits each year
are also made. In the aggregate, then, about a million and a quarter of
visits are paid to the British Museum yearly, and though the bulk of the
visitors may be mere sight-seers, yet even these must carry away many
ideas of value, and it hardly requires argument to show that, as a
whole, the educational influence of the British Museum must be enormous.
Of its more direct stimulus to scientific work through the trained
experts connected with the institution I shall perhaps speak in another
connection.



II. THE ROYAL SOCIETY OF LONDON FOR IMPROVING NATURAL KNOWLEDGE


A SESSION OF THE SOCIETY

THERE is one scientific institution in London more venerable and more
famous even than the British Museum. This, of course, is the Royal
Society, a world-famous body, whose charter dates from 1662, but whose
actual sessions began at Gresham College some twenty years earlier. One
can best gain a present-day idea of this famous institution by attending
one of its weekly meetings in Burlington House, Piccadilly--a great,
castle-like structure, which serves also as the abode of the Royal
Chemical Society and the Royal Academy of Arts. The formality of an
invitation from a fellow is required, but this is easily secured by any
scientific visitor who may desire to attend the meeting. The
programme of the meeting each week appears in that other great British
institution, the _Times_, on Tuesdays.

The weekly meeting itself is held on Thursday afternoon at half-past
four. As one enters the door leading off the great court of Burlington
House a liveried attendant motions one to the rack where great-coat
and hat may be left, and without further ceremony one steps into the
reception-room unannounced. It is a middle-sized, almost square room,
pillared and formal in itself, and almost without furniture, save for
a long temporary table on one side, over which cups of tea are being
handed out to the guests, who cluster there to receive it, and then
scatter about the room to sip it at their leisure. We had come to hear
a lecture and had expected to be ushered into an auditorium; but we had
quite forgotten that this is the hour when all England takes its tea,
the _élite_ of the scientific world, seemingly, quite as much as the
devotees of another kind of society. Indeed, had we come unawares into
this room we should never have suspected that we had about us other than
an ordinary group of cultured people gathered at a conventional
"tea," except, indeed, that suspicion might be aroused by the great
preponderance of men--there being only three or four women present--and
by the fact that here and there a guest appears in unconventional
dress--a short coat or even a velvet working-jacket. For the rest
there is the same gathering into clusters of three or four, the same
inarticulate clatter of many voices that mark the most commonplace of
gatherings.

But if one will withdraw to an inoffensive corner and take a critical
view of the assembly, he will presently discover that many of the faces
are familiar to him, although he supposed himself to be quite among
strangers. The tall figure, with the beautiful, kindly face set in
white hair and beard, has surely sat for the familiar portrait of Alfred
Russel Wallace. This short, thick-set, robust, business-like figure is
that of Sir Norman Lockyer. Yonder frail-seeming scholar, with white
beard, is surely Professor Crookes. And this other scholar, with tall,
rather angular frame and most kindly gleam of eye, is Sir Michael
Foster; and there beyond is the large-seeming though not tall figure,
and the round, rosy, youthful-seeming, beautifully benevolent face of
Lord Lister. "What! a real lord there?" said a little American girl to
whom I enumerated the company after my first visit to the Royal Society.
"Then how did he act? Was he very proud and haughty, as if he could not
speak to other people?" And I was happy to be able to reply that though
Lord Lister, perhaps of all men living, would be most excusable did he
carry in his manner the sense of his achievements and honors, yet in
point of fact no man could conceivably be more free from any apparent
self-consciousness. As one watches him now he is seen to pass from group
to group with cordial hand-shake and pleasant word, clearly the most
affable of men, lord though he be, and president of the Royal Society,
and foremost scientist of his time.

Presently an attendant passed through the tearoom bearing a tremendous
silver mace, perhaps five feet long, surmounted by a massive crown and
cross, and looking like nothing so much as a "gigantic war-club."
This is the mace which, when deposited on the president's desk in the
lecture-room beyond, will signify that the society is in session. "It is
the veritable mace," some one whispers at your elbow, "concerning which
Cromwell gave his classical command to 'Remove that bauble.'" But since
the mace was not made until 1663, some five years after Cromwell's
death, this account may lack scientific accuracy. Be that as it may,
this mace has held its own far more steadily than the fame of its
alleged detractor, and its transportation through the tea-room is the
only manner of announcement that the lecture is about to open in the
hall beyond. Indeed, so inconspicuous is the proceeding, and so quietly
do the members that choose to attend pass into the lecture-hall, leaving
perhaps half the company engaged as before, that the "stranger "--as
the non-member is here officially designated--might very readily fail
to understand that the séance proper had begun. In any event, he cannot
enter until permission has been formally voted by the society.

When he is allowed to enter he finds the meeting-room little different
from the one he has left, except that it is provided with a sort of
throne on a raised platform at one end and with cushioned benches for
seats. On the throne, if one may so term it, sits Lord Lister, scarcely
more than his head showing above what seems to be a great velvet cushion
which surmounts his desk, at the base of which, in full view of the
society, rests the mace, fixing the eye of the "stranger," as it is
alleged to have fixed that of Cromwell aforetime, with a peculiar
fascination. On a lower plane than the president, at his right and left,
sit Sir Michael Foster and Professor Arthur William Rucker, the two
permanent secretaries. At Sir Michael's right, and one stage nearer the
audience, stands the lecturer, on the raised platform and behind the
desk which extends clear across the front of the room. As it chances,
the lecturer this afternoon is Professor Ehrlich, of Berlin and
Frankfort-on-the-Main, who has been invited to deliver the Croonian
lecture. He is speaking in German, and hence most of the fellows are
assisting their ears by following the lecture in a printed translation,
copies of which, in proof, were to be secured at the door.

The subject of the lecture is "Artificial Immunization from Disease."
It is clear that the reader is followed with interested attention, which
now and again gives rise to a subdued shuffle of applause.

The fact that the lecturer is speaking German serves perhaps to suggest
even more vividly than might otherwise occur to one the contrast between
this meeting and a meeting of the corresponding German society--the
Royal Academy of Sciences at Berlin. Each is held in an old building
of palatial cast and dimensions, of which Burlington House, here
in Piccadilly, is much the older--dating from 1664--although its
steam-heating and electric-lighting apparatus, when contrasted with the
tile stoves and candles of the other, would not suggest this. For the
rest, the rooms are not very dissimilar in general appearance, except
for the platform and throne. But there the members of the society are
shut off from the audience both by the physical barrier of the table and
by the striking effect of their appearance in full dress, while here the
fellows chiefly compose the audience, there being only a small company
of "strangers" present, and these in no way to be distinguished by dress
or location from the fellows themselves. It may be added that the custom
of the French Academy of Sciences is intermediate between these two.
There the visitors occupy seats apart, at the side of the beautiful
hall, the main floor being reserved for members. But the members
themselves are not otherwise distinguishable, and they come and go and
converse together even during the reading of a paper almost as if this
were a mere social gathering. As it is thus the least formal, the
French meeting is also by far the most democratic of great scientific
gatherings. Its doors are open to whoever may choose to enter. The
number who avail themselves of this privilege is not large, but it
includes, on occasions, men of varied social status and of diverse races
and colors--none of whom, so far as I could ever discern, attracts the
slightest attention.

At the German meeting, again, absolute silence reigns. No one thinks
of leaving during the session, and to make any sound above a sigh would
seem almost a sacrilege. But at the Royal Society an occasional auditor
goes or comes, there are repeated audible signs of appreciation of the
speaker's words, and at the close of the discourse there is vigorous
and prolonged applause. There is also a debate, of the usual character,
announced by the president, in which "strangers" are invited to
participate, and to which the lecturer finally responds with a brief
_Nachwort_, all of which is quite anomalous from the German or French
stand-points. After that, however, the meeting is declared adjourned
with as little formality in one case as in the others, and the fellows
file leisurely out, while the attendant speedily removes the mace, in
official token that the séance of the Royal Society is over.


THE LIBRARY AND READING-ROOM

But the "stranger" must not leave the building without mounting to the
upper floor for an inspection of the library and reading-room. The rooms
below were rather bare and inornate, contrasting unfavorably with the
elegant meeting-room of the French institute. But this library makes
full amends for anything that the other rooms may lack. It is one of the
most charming--"enchanting" is the word that the Princess Christian is
said to have used when she visited it recently--and perhaps quite the
most inspiring room to be found in all London. It is not very large as
library rooms go, but high, and with a balcony supported by Corinthian
columns. The alcoves below are conventional enough, and the high
tables down the centre, strewn with scientific periodicals in engaging
disorder, are equally conventional. But the color-scheme of the
decorations--sage-green and tawny--is harmonious and pleasing, and the
effect of the whole is most reposeful and altogether delightful.

Chief distinction is given the room, however, by a row of busts on
either side and by certain pieces of apparatus on the centre tables.

The busts, as will readily be surmised, are portraits of distinguished
fellows of the Royal Society. There is, however, one exception to this,
for one bust is that of a woman--Mary Somerville, translator of the
_Mécanique Céleste_, and perhaps the most popular of the scientific
writers of her time. It is almost superfluous to state that the row of
busts begins with that of Newton. The place of honor opposite is held by
that of Faraday. Encircling the room to join these two one sees, among
others, the familiar visages of Dr. Gilbert; of Sir Joseph Banks, the
famous surgeon of the early nineteenth century, who had the honor of
being the only man that ever held the presidential chair of the
Royal Society longer than it was held by Newton; of James Watts, of
"steam-engine" fame; of Sabine, the astronomer, also a president of
the society; and of Dr. Falconer and Sir Charles Lyell, the famous
geologists.

There are numerous other busts in other rooms, some of them stowed away
in nooks and crannies, and the list of those selected for the library
does not, perhaps, suggest that this is the room of honor, unless,
indeed, the presence of Newton and Faraday gives it that stamp. But in
the presence of the images of these two, and of Lyell, to go no farther,
one feels a certain sacredness in the surroundings.

If this is true of the mere marble images, what shall we say of the
emblems on the centre table? That little tubular affair, mounted on a
globe, the whole cased in a glass frame perhaps two feet high, is the
first reflecting telescope ever made, and it was shaped by the hand of
Isaac Newton. The brass mechanism at the end of the next table is the
perfected air-pump of Robert Boyle, Newton's contemporary, one of the
founders of the Royal Society and one of the most acute scientific minds
of any time. And here between these two mementos is a higher apparatus,
with crank and wheel and a large glass bulb that make it conspicuous.
This is the electrical machine of Joseph Priestley. There are other
mementos of Newton--a stone graven with a sun-dial, which he carved as
a boy, on the paternal manor-house; a chair, said to have been his,
guarded here by a silk cord against profanation; bits of the famous
apple-tree which, as tradition will have it, aided so tangibly in
the greatest of discoveries; and the manuscript of the _Principia_
itself--done by the hand of an amanuensis, to be sure, but with
interlinear corrections in the small, clear script of the master-hand
itself. Here, too, is the famous death-mask, so much more interesting
than any sculptured portrait, and differing so strangely in its
broad-based nose and full, firm mouth from the over-refined lineaments
of the sculptured bust close at hand. In a room not far away, to reach
which one passes a score or two of portraits and as many busts of
celebrities--including, by-the-bye, both bust and portrait of Benjamin
Franklin--one finds a cabinet containing other mementos similar to those
on the library tables. Here is the first model of Davy's safety-lamp;
there a chronometer which aided Cook in his famous voyage round the
world. This is Wollaston's celebrated "Thimble Battery." It will slip
readily into the pocket, yet he jestingly showed it to a visitor as
"his entire laboratory." That is a model of the double-decked boat made
by Sir William Petty, and there beyond is a specimen of almost, if not
quite, the first radiometer devised by Sir William Crookes.

As one stands in the presence of all these priceless relics, so vividly
do the traditions of more than two centuries of science come to mind
that one seems almost to have lived through them. One recalls, as if it
were a personal recollection, the founding of the Royal Society itself
in 1662, and the extraordinary scenes which the society witnessed during
the years of its adolescence.

As one views the mementos of Boyle and Newton, one seems to be living in
the close of the seventeenth century. It is a troublous time in England.
Revolution has followed revolution. Commonwealth has supplanted monarchy
and monarchy commonwealth. At last the "glorious revolution" of 1688 has
placed a secure monarch on the throne. But now one external war follows
another, and the new king, William of Orange, is leading the "Grand
Alliance" against the French despot Louis XIV. There is war everywhere
in Europe, and the treaty of Ryswick, in 1697, is but the preparation
for the war of the Spanish Alliance, which will usher in the new
century. But amid all this political turmoil the march of scientific
discovery has gone serenely on; or, if not serenely, then steadily, and
perhaps as serenely as could be hoped. Boyle has discovered the law of
the elasticity of gases and a host of minor things. Robert Hooke is
on the track of many marvels. But all else pales before the fact that
Newton has just given to the world his marvellous law of gravitation,
which has been published, with authority of the Royal Society, through
the financial aid of Halley. The brilliant but erratic Hooke lias
contested the priority of discovery and strenuously claimed a share in
it. Halley eventually urges Newton to consider Hooke's claim in some of
the details, and Newton yields to the extent of admitting that the
great fact of gravitational force varying inversely as the square of
the distance had been independently discovered by Hooke; but he includes
also Halley himself and Sir Christopher Wren, along with Hooke,
as equally independent discoverers of the same principle. To the
twentieth-century consciousness it seems odd to hear Wren thus named as
a scientific discoverer; but in truth the builder of St. Paul's began
life as a professor of astronomy at Gresham College, and was the
immediate predecessor of Newton himself in the presidential chair of the
Royal Society. Now, at the very close of the seventeenth century, Boyle
is recently dead, but Hooke, Wren, Halley, and Newton still survive:
some of them are scarcely past their prime. It is a wonderful galaxy of
stars of the first magnitude, and even should no other such names come
in after-time, England's place among the scientific constellations is
secure.

But now as we turn to the souvenirs of Cooke and Wollaston and Davy
the scene shifts by a hundred years. We are standing now in the closing
epoch of the eighteenth century. These again are troublous times. The
great new colony in the West has just broken off from the parent swarm.
Now all Europe is in turmoil. The French war-cloud casts its ominous
shadow everywhere. Even in England mutterings of the French Revolution
are not without an echo. The spirit of war is in the air. And yet, as
before, the spirit of science also is in the air. The strain of the
political relations does not prevent a perpetual exchange of courtesy
between scientific men and scientific bodies of various nations. Davy's
dictum that "science knows no country" is perpetually exemplified in
practice. And at the Royal Society, to match the great figures that were
upon the scene a century before, there are such men as the eccentric
Cavendish, the profound Wollaston, the marvellously versatile Priestley,
and the equally versatile and even keener-visioned Rumford. Here, too,
are Herschel, who is giving the world a marvellous insight into the
constitution of the universe; and Hutton, who for the first time gains a
clear view of the architecture of our earth's crust; and Jenner, who is
rescuing his fellow-men from the clutches of the most deadly of plagues;
to say nothing of such titanic striplings as Young and Davy, who are
just entering the scientific lists. With such a company about us we are
surely justified in feeling that the glory of England as a scientific
centre has not dimmed in these first hundred and thirty years of the
Royal Society's existence.

And now, as we view the radiometer, the scene shifts by yet another
century, and we come out of cloud-land and into our own proper age. We
are at the close of the nineteenth century--no, I forget, we are fairly
entering upon the twentieth. Need I say that these again are troublous
times? Man still wages warfare on his fellow-man as he has done time
out of mind; as he will do--who shall say how long? But meantime, as
of yore, the men of science have kept steadily on their course. But
recently here at the Royal Society were seen the familiar figures of
Darwin and Lyell and Huxley and Tyndall. Nor need we shun any comparison
with the past while the present lists can show such names as Wallace,
Kelvin, Lister, Crookes, Foster, Evans, Rayleigh, Ramsay, and Lock-yer.
What revolutionary advances these names connote! How little did those
great men of the closing decades of the seventeenth and eighteenth
centuries know of the momentous truths of organic evolution for which
the names of Darwin and Wallace and Huxley stand! How little did
they know a century ago, despite Hutton's clear prevision, of these
marvellous slow revolutions through which, as Lyell taught us, the
earth's crust had been built up! Not even Jen-ner could foresee a
century ago the revolution in surgery which has been effected in our
generation through the teachings of Lister.

And what did Rumford and Davy know of energy in its various
manifestations as compared with the knowledge of to-day, of Crookes
and Rayleigh and Ramsay and Kelvin? What would Joseph Priestley, the
discoverer of oxygen, and Cavendish, the discoverer of nitrogen,
think could they step into the laboratory of Professor Ramsay and see
test-tubes containing argon and helium and krypton and neon and zenon?
Could they more than vaguely understand the papers contributed in recent
years to the Royal Society, in which Professor Ramsay explains how these
new constituents of the atmosphere are obtained by experiments on liquid
air. "Here," says Professor Ramsay, in effect, in a late paper to the
society, "is the apparatus with which we liquefy hydrogen in order to
separate neon from helium by liquefying the former while the helium
still remains gaseous." Neon, helium, liquid air, liquid hydrogen--these
would seem strange terms to the men who on discovering oxygen and
nitrogen named them "dephlogisticated air" and "phlogisti-cated air"
respectively.

Again, how elementary seems the teaching of Her-schel, wonderful though
it was in its day, when compared with our present knowledge of the
sidereal system as outlined in the theories of Sir Norman Lock-yer.
Herschel studied the sun-spots, for example, with assiduity, and even
suggested a possible connection between sun-spots and terrestrial
weather. So far, then, he would not be surprised on hearing the
announcement of Professor Lockyer's recent paper before the Royal
Society on the connection between sun-spots and the rainfall in India.
But when the paper goes on to speak of the actual chemical nature of the
sun-spots, as tested by a spectroscope; to tell of a "cool" stage when
the vapor of iron furnishes chief spectrum lines, and of a "hot" stage
when the iron has presumably been dissociated into unknown "proto-iron"
constituents--then indeed does it go far beyond the comprehension of the
keenest eighteenth-century intellect, though keeping within the range of
understanding of the mere scientific tyro of to-day.

Or yet again, consider a recent paper contributed by Professor Lockyer
to the Royal Society, entitled "The New Star in Perseus: Preliminary
Note"--referring to the new star that flashed suddenly on the vision of
the terrestrial observers at more than first magnitude on February 22,
1901. This "star," the paper tells us, when studied by its spectrum,
is seen to be due to the impact of two swarms of meteors out in
space--swarms moving in different directions "with a differential
velocity of something like seven hundred miles a second." Every
astronomer of to-day understands how such a record is read from the
displacement of lines on the spectrum, as recorded on the photographic
negative. But imagine Sir William Herschel, roused from a century's
slumber, listening to this paper, which involves a subject of which he
was the first great master. "Ebulae," he might say; "yes, they were a
specialty of mine; but swarms of meteors--I know nothing of these. And
'spectroscopes,' 'photographs'--what, pray, are these? In my day there
were no such words or things as spectroscope and photograph; to my mind
these words convey no meaning."

But why go farther? These imaginings suffice to point a moral that he
who runs may read. Of a truth the march of science still goes on as it
has gone on with steady tread throughout the long generations of the
Royal Society's existence. If the society had giants among its members
in the days of its childhood and adolescence, no less are there giants
still to keep up its fame in the time of its maturity. The place of
England among the scientific constellations is secure through tradition,
but not through tradition alone.



III. THE ROYAL INSTITUTION AND THE LOW-TEMPERATURE RESEARCHES


FOUNDATION AND FOUNDER

"GEORGE THE THIRD, by the Grace of God King of Great Britain, France,
and Ireland, Defender of the Faith, etc., to all to whom these presents
shall come, greeting. Whereas several of our loving subjects are
desirous of forming a Public Institution for diffusing the knowledge and
facilitating the general introduction of Useful Mechanical Inventions
and Improvements; and for teaching, by Courses of Philosophical Lectures
and Experiments, the Application of Science to the Common Purposes of
Life, we do hereby give and grant"--multifarious things which need not
here be quoted. Such are the opening words of the charter with which, a
little more than a century ago, the Royal Institution of Great Britain
came into existence and received its legal christening. If one reads on
he finds that the things thus graciously "given and granted," despite
all the official verbiage, amount to nothing more than royal sanction
and approval, but doubtless that meant more in the way of assuring
popular approval than might at first glimpse appear. So, too, of the
list of earls, baronets, and the like, who appear as officers and
managers of the undertaking, and who are described in the charter as
"our right trusty and right well-beloved cousins," "our right trusty
and well-beloved counsellors," and so on, in the skilfully graduated
language of diplomacy. The institution that had the King for patron and
such notables for officers seemed assured a bright career from the very
beginning. In name and in personnel it had the flavor of aristocracy,
a flavor that never palls on British palate. And right well the
institution has fulfilled its promise, though in a far different way
from what its originator and founder anticipated.

Its originator and founder, I say, and say advisedly; for, of course,
here, as always, there is one man who is the true heart and soul of the
movement, one name that stands, in truth, for the whole project, and to
which all the other names are mere appendages. You would never suspect
which name it is, in the present case, from a study of the charter,
for it appears well down the file of graded titles, after "cousins" and
"counsellors" have had their day, and is noted simply as "our trusty
and well-beloved Benjamin, Count of Rumford, of the Holy Roman Empire."
Little as there is to signalize it in the charter, this is the name of
the sole projector of the enterprise in its incipiency, of the
projector of every detail, of the writer of the charter itself even. The
establishment thus launched with royal title might with full propriety
have been called, as indeed it sometimes is called, the Rumford
Institution.

The man who thus became the founder of this remarkable institution was
in many ways a most extraordinary person. He was an American by birth,
and if not the most remarkable of Americans, he surely was destined to
a more picturesque career than ever fell to the lot of any of his
countrymen of like eminence. Born on a Massachusetts farm, he was a
typical "down-east Yankee," with genius added to the usual shrewd,
inquiring mind and native resourcefulness. He was self-educated and
self-made in the fullest sense in which those terms can be applied. At
fourteen he was an unschooled grocer-lad--Benjamin Thompson by name--in
a little New England village; at forty he was a world-famous savant,
as facile with French, Italian, Spanish, and German as with his native
tongue; he had become vice-president and medallist of the Royal
Society, member of the Berlin National Academy of Science, of the French
Institute, of the American Academy of Science, and I know not what other
learned bodies; he had been knighted in Great Britain after serving
there as under-secretary of state and as an officer; and he had risen
in Bavaria to be more than half a king in power, with the titles, among
others, of privy councillor of state, and head of the war department,
lieutenant-general of the Bavarian armies, holder of the Polish order of
St. Stanislas and the Bavarian order of the White Eagle, ambassador to
England and to France, and, finally, count of the Holy Roman Empire.
Once, in a time of crisis, Rumford was actually left at the head of
a council of regency, in full charge of Bavarian affairs, the elector
having fled. The Yankee grocer-boy had become more than half a king.

Never, perhaps, did a man of equal scientific attainments enjoy a
corresponding political power. Never was political power wielded more
justly by any man.

For in the midst of all his political and military triumphs, Rumford
remained at heart to the very end the scientist and humanitarian. He
wielded power for the good of mankind; he was not merely a ruler but
a public educator. He taught the people of Bavaria economy and Yankee
thrift. He established kitchens for feeding the poor on a plan that was
adopted all over Europe; but, better yet, he created also workshops for
their employment and pleasure-gardens for their recreation. He actually
banished beggary from the principality.

It was in the hope of doing in some measure for London what he had done
for Munich that this large-brained and large-hearted man was led to the
project of the Royal Institution. He first discussed his plans with a
committee of the Society for Alleviating the Condition of the Poor, for
it was the poor, the lower ranks of society, whom he wished chiefly to
benefit. But he knew that to accomplish his object, he must work through
the aristocratic channels; hence the name of the establishment and the
charter with its list of notables. The word institution was selected
by Rumford, after much deliberation, as, on the whole, the least
objectionable title for the establishment, as having a general
inclusiveness not possessed by such words as school or college. Yet in
effect it was a school which Rumford intended to found--a school for
the general diffusion of useful knowledge. There were to be classes
for mechanics, and workshops, kitchens, and model-rooms, where the
"application of science to the useful purposes of life" might be
directly and practically taught; also a laboratory for more technical
investigations, with a "professor" in charge, who should also deliver
popular lectures on science. Finally, there was to be a scientific
library.

All these aims were put into effect almost from the beginning. The
necessary funds were supplied solely by popular subscription and by the
sale of lecture tickets (as all funds of the institution have been ever
since), and before the close of the year 1800 Rumford's dream had become
an actuality--as this practical man's dreams nearly always did. The new
machine did not move altogether without friction, of course, but on the
whole all went well for the first few years. The institution had found
a local habitation in a large building in Albemarle Street, the same
building which it still occupies, and for a time Rumford lived there and
gave the enterprise his undivided attention. He appointed the brilliant
young Humphry Davy to the professorship of chemistry, and the even
more wonderful Thomas Young to that of natural philosophy. He saw the
workshops and kitchens and model-rooms in running order--the entire
enterprise fully launched. Then other affairs, particularly an
attachment for a French lady, the widow of the famous chemist Lavoisier
(whom he subsequently married, to his sorrow), called him away from
England never to return. And the first chapter in the history of the
Royal Institution was finished.


METHOD AND RESULT

Rumford, the humanitarian, gone, a curious change came over the spirit
of the enterprise he had founded. The aristocrats who at first were
merely ballast for the enterprise now made their influence felt. With
true British reserve, they announced their belief that the education of
the masses involved a dangerous political tendency. Hence the mechanics'
school was suspended and the workshops and kitchens abolished; in
a word, the chief ends for which the institution was founded were
annulled. The library and the lectures remained, to be sure, but they
were for the amusement of the rich, not for the betterment of the poor.
It was the West End that made a fad of the institution and a society
function of the lectures of Sydney Smith and of the charming youth Davy.
Thus the institution came to justify its aristocratic title and its
regal patronage; and the poor seemed quite forgotten.

But indeed the institution itself was poor enough in these days, after
the first flush of enthusiasm died away, and it is but fair to remember
that without the support of its popular lectures its very existence
would have been threatened. Nor in any event are regrets much in order
over the possible might-have-beens of an institution whose laboratories
were the seat of the physical investigations of Thomas Young, through
which the wave theory of light first gained a footing, and of the
brilliant chemical researches of Davy, which practically founded the
science of electro-chemistry and gave the chemical world first knowledge
of a galaxy of hitherto unknown elements. Through the labors of
these men, and through the popular lecture-courses delivered at the
institution by such other notables of science as Wollaston, Dalton, and
Rum-ford, the enterprise had become world-famous before the close of the
first decade of its existence.

From that day till this the character of the Royal Institution has
not greatly changed. The enterprise shifted around during its earliest
years, while it was gaining its place in the scheme of things; but once
that was found, like a true British institution it held its course with
an inertia that a mere century of time could not be expected to alter.
Rumford was the sole founder of the enterprise, but it was Davy who
gave it the final and definitive cast. He it was who established the
tradition that the Royal Institution was to be essentially a laboratory
for brilliant original investigations, the investigator to deliver
a yearly course of lectures, but to be otherwise untrammelled. It
occupied, and has continued to occupy, the anomalous position of a
school to which pupils are on no account admitted, and whose professors
teach nothing except by a brief course of lectures to which whoever
cares to pay the admission price may freely enter.

But the marvellous results achieved at the Royal Institution have more
than justified the existence of so anomalous an enterprise. Superlatives
are always dangerous, but it may well be doubted whether there is
another single institution in the world where so many novel original
discoveries in physical science have been made as have been brought to
light in the laboratories of the building on Albemarle Street during
this first century of its occupancy; for practically all that is to
be credited to Thomas Young, Humphry Davy, Michael Faraday, and John
Tyndall, not to mention living investigators, is to be credited also to
the Royal Institution, whose professorial chairs these great men have
successively occupied. Davy spent here the best years of his youth
and prime. Faraday, his direct successor, came to the institution in a
subordinate capacity as a mere boy, and was the life of the institution
for half a century. Tyndall gave it forty years of service. What wonder,
then, that the Briton speaks of the institution as the "Pantheon of
Science"?

If you visit the Royal Institution to-day you will find it in most
exterior respects not unlike what it presumably was a century ago. Its
long, stone front, dinged with age, with its somewhat Pantheon-like
colonnade, has an appearance of dignity rather than of striking
impressiveness. The main entrance, jutting full on the sidewalk, is at
the street level, and the glass door gives hospitable glimpses of the
interior. Entering, one finds himself in a main central hall, at the
foot of the main central staircase. The air of eminent respectability
so characteristic of the British institution is over all; likewise
the pervasive hush of British reserve. But you will not miss also the
atmosphere of sincere if uneffusive British courtesy.

At your right, as you mount the stairway, is a large statue of Faraday;
on the wall right ahead is a bronze medallion of Tyndall, placed beneath
a large portrait of Davy. At the turn of the stairs is a marble bust of
Wollaston. Farther on, in hall and library, you will find other busts of
Faraday, other portraits of Davy; portraits of Faraday everywhere,
and various other busts of notables who have had connection with the
institution. You will be shown the lecture-hall where Davy, Faraday,
and Tyndall pronounced their marvellous discourses; the arrangement, the
seats, the cushions even if appearances speak truly, and certainly the
lecture-desk itself, unchanged within the century. You may see the crude
balance, clumsy indeed to modern eyes, with which Davy performed his
wonders. The names and the memories of three great men--Davy,
Faraday, and Tyndall--will be incessantly before you, and the least
impressionable person could not well escape a certain sense of
consecration of his surroundings. The hush that is over everything seems
but fitting.

All that is as it should be. But there are other memories connected with
these surroundings which are not so tangibly presented to the senses.
For where, amid all these busts and portraits, is the image of that
other great man, the founder of the institution, the sole originator
of the enterprise which has made possible the aggregation of all
these names and these memories? Where are the remembrances of
that extraordinary man whom the original charter describes as "our
well-beloved Benjamin, Count of Rumford?" Well, you will find a portrait
of him, it is true, if you search far enough, hung high above a doorway
in a room with other portraits. But one finds it hard to escape the
feeling that there has been just a trifling miscarriage of justice in
the disposal. Doubtless there was no such intention, but the truth seems
to be that the glamour of the newer fame of Faraday has dazzled a little
the eyes of the rulers of the institution of the present generation.
But that, after all, is a small matter about which to quibble. There is
glory enough for all in the Royal Institution, and the disposal of busts
and portraits is unworthy to be mentioned in connection with the lasting
fame of the great men who are here in question. It would matter little
if there were no portrait at all of Rumford here, for all the world
knows that the Royal Institution itself is in effect his monument. His
name will always be linked in scientific annals with the names of Young,
Davy, Faraday, and Tyndall. And it is worthy such association, for
neither in native genius nor in realized accomplishments was Rumford
inferior to these successors.


FROM LIQUID CHLORINE TO LIQUID HYDROGEN

Nor is it merely by mutual association with the history of the Royal
Institution that these great names are linked. There was a curious
and even more lasting bond between them in the character of their
scientific discoveries. They were all pioneers in the study of those
manifestations of molecular activity which we now, following Young
himself, term energy. Thus Rumford, Davy, and Young stood almost alone
among the prominent scientists of the world at the beginning of the
century in upholding the idea that heat is not a material substance--a
chemical element--but merely a manifestation of the activities of
particles of matter. Rumford's papers on this thesis, communicated to
the Royal Society, were almost the first widely heralded claims for this
then novel idea. Then Davy came forward in support of Rumford, with
his famous experiment of melting ice by friction. It was perhaps
this intellectual affinity that led Rumford to select Davy for
the professorship at the Royal Institution, and thus in a sense to
predetermine the character of the scientific work that should be
accomplished there--the impulse which Davy himself received from
Rum-ford being passed on to his pupil Faraday. There is, then, an
intangible but none the less potent web of association between the
scientific work of Rumford and some of the most important researches
that were conducted at the Royal Institution long years after his death;
and one is led to feel that it was not merely a coincidence that some
of Faraday's most important labors should have served to place on a firm
footing the thesis for which Rumford battled; and that Tyndall should
have been the first in his "beautiful book" called _Heat, a Mode of
Motion_, to give wide popular announcement to the fact that at last the
scientific world had accepted the proposition which Rumford had vainly
demonstrated three-quarters of a century before.

This same web of association extends just as clearly to the most
important work which has been done at the Royal Institution in the
present generation, and which is still being prosecuted there--the
work, namely, of Professor James Dewar on the properties of matter at
excessively low temperatures. Indeed, this work is in the clearest sense
a direct continuation of researches which Davy and Faraday inaugurated
in 1823 and which Faraday continued in 1844. In the former year Faraday,
acting on a suggestion of Davy's, performed an experiment which resulted
in the production of a "clear yellow oil" which was presently proved to
be liquid chlorine. Now chlorine, in its pure state, had previously been
known (except in a forgotten experiment of Northmore's) only as a gas.
Its transmutation into liquid form was therefore regarded as a very
startling phenomenon. But the clew thus gained, other gases were
subjected to similar conditions by Davy, and particularly by Faraday,
with the result that several of them, including sulphurous, carbonic,
and hydrochloric acids were liquefied. The method employed, stated in
familiar terms, was the application of cold and of pressure. The results
went far towards justifying an extraordinary prediction made by that
extraordinary man, John Dalton, as long ago as 1801, to the effect that
by sufficient cooling and compressing all gases might be transformed
into liquids--a conclusion to which Dalton had vaulted, with the
sureness of supreme genius, from his famous studies of the properties of
aqueous vapor.

Between Dalton's theoretical conclusion, however, and experimental
demonstration there was a tremendous gap, which the means at the
disposal of the scientific world in 1823 did not enable Davy and Faraday
more than partially to bridge. A long list of gases, including the
familiar oxygen, hydrogen, and nitrogen, resisted all their efforts
utterly--notwithstanding the facility with which hydrogen and oxygen
are liquefied when combined in the form of water-vapor, and the relative
ease with which nitrogen and hydrogen, combined to form ammonia, could
also be liquefied. Davy and Faraday were well satisfied of the truth of
Dalton's proposition, but they saw the futility of further efforts
to put it into effect until new means of producing, on the one hand,
greater pressures, and, on the other, more extreme degrees of cold,
should be practically available. So the experiments of 1823 were
abandoned.

But in 1844 Faraday returned to them, armed now with new weapons, in the
way of better air-pumps and colder freezing mixtures, which the labors
of other workers, chiefly Thilorier, Mitchell, and Natterer, had made
available. With these new means, and without the application of any
principle other than the use of cold and pressure as before, Faraday now
succeeded in reducing to the liquid form all the gases then known with
the exception of six; while a large number of these substances were
still further reduced, by the application of the extreme degrees of
cold now attained, to the condition of solids. The six gases which still
proved intractable, and which hence came to be spoken of as "permanent
gases," were nitrous oxide, marsh gas, carbonic oxide, oxygen, nitrogen,
and hydrogen.

These six refractory gases now became a target for the experiments of a
host of workers in all parts of the world. The resources of mechanical
ingenuity of the time were exhausted in the effort to produce low
temperatures on the one hand and high pressures on the other. Thus
Andrews, in England, using the bath of solid carbonic acid and ether
which Thilorier had discovered, and which produces a degree of cold
of--80° Centigrade, applied a pressure of five hundred atmospheres, or
nearly four tons to the square inch, without producing any change of
state. Natterer increased this pressure to two thousand seven hundred
atmospheres, or twenty-one tons to the square inch, with the same
negative results. The result of Andrews' experiments in particular was
the final proof of what Cagniard de la Tour had early suspected
and Faraday had firmly believed, that pressure alone, regardless of
temperature, is not sufficient to reduce a gas to the liquid state. In
other words, the fact of a so-called "critical temperature," varying
for different substances, above which a given substance is always a gas,
regardless of pressure, was definitively discovered. It became clear,
then, that before the resistant gases would be liquefied means of
reaching extremely low temperatures must be discovered. And for this,
what was needed was not so much new principles as elaborate and
costly machinery for the application of a principle long familiar--the
principle, namely, that an evaporating liquid reduces the temperature of
its immediate surroundings, including its own substance.

Ingenious means of applying this principle, in connection with the means
previously employed, were developed independently by Pictet in Geneva
and Cailletet in Paris, and a little later by the Cracow professors
Wroblewski and Olzewski, also working independently. Pictet, working on
a commercial scale, employed a series of liquefied gases to gain lower
and lower temperatures by successive stages. Evaporating sulphurous acid
liquefied carbonic acid, and this in evaporating brought oxygen under
pressure to near its liquefaction point; and, the pressure being
suddenly released (a method employed in Faraday's earliest experiments),
the rapid expansion of the compressed oxygen liquefies a portion of
its substance. This result was obtained in 1877 by Pictet and Cailletet
almost simultaneously. Cailletet had also liquefied the newly discovered
acetylene gas. Five years later Wroblewski liquefied marsh gas, and the
following year nitrogen; while carbonic oxide and nitrous oxide yielded
to Olzewski in 1884. Thus forty years of effort had been required to
conquer five of Faraday's refractory gases, and the sixth, hydrogen,
still remains resistant. Hydrogen had, indeed, been seen to assume the
form of visible vapor, but it had not been reduced to the so-called
static state--that is, the droplets had not been collected in an
appreciable quantity, as water is collected in a cup. Until this should
be done, the final problem of the liquefaction of hydrogen could not be
regarded as satisfactorily solved.

More than another decade was required to make this final step in the
completion, of Faraday's work. And, oddly enough, yet very fittingly,
it was reserved for Faraday's successor in the chair at the Royal
Institution to effect this culmination. Since 1884 Professor Dewar's
work has made the Royal Institution again the centre of low-temperature
research. By means of improved machinery and of ingenious devices for
shielding the substance operated on from the accession of heat, to which
reference will be made more in detail presently, Professor Dewar was
able to liquefy the gas fluorine, recently isolated by Moussan, and the
recently discovered gas helium in 1897. And in May, 1898, he was able to
announce that hydrogen also had yielded, and for the first time in
the history of science that* elusive substance, hitherto "permanently"
gaseous, was held as a tangible liquid in a cuplike receptacle; and this
closing scene of the long struggle was enacted in the same laboratory in
which Faraday performed the first liquefaction experiment with chlorine
just three-quarters of a century before.

It must be noted, however, that this final stage in the liquefaction
struggle was not effected through the use of the principle of
evaporating liquids which has just been referred to, but by the
application of a quite different principle and its elaboration into a
perfectly novel method. This principle is the one established long ago
by Joule and Thomson (Lord Kelvin), that compressed gases when allowed
to expand freely are lowered in temperature. In this well-known
principle the means was at hand greatly to simplify and improve the
method of liquefaction of gases, only for a long time no one recognized
the fact. Finally, however, the idea had occurred to two men almost
simultaneously and quite independently. One of these was Professor
Linde, the well-known German experimenter with refrigeration processes;
the other, Dr. William Hampson, a young English physician. Each of these
men conceived the idea--and ultimately elaborated it in practice--of
accumulating the cooling effect of an expanding gas by allowing the
expansion to take place through a small orifice into a chamber in which
the coil containing the compressed gas was held. In Dr. Hampson's words:

"The method consists in directing all the gas immediately after its
expansion over the coils which contain the compressed gas that is on its
way to the expansion-point. The cold developed by expansion in the first
expanded gas is thus communicated to the oncoming compressed gas, which
consequently expands from, and therefore to, a lower temperature
than the preceding portion. It communicates in the same way its own
intensified cold to the succeeding portion of compressed gas, which, in
its turn, is made colder, both before and after expansion, than any
that had gone before. This intensification of cooling goes on until the
expansion-temperature is far lower than it was at starting; and if
the apparatus be well arranged the effect is so powerful that even the
smaller amount of cooling due to the free expansion of gas through a
throttle-valve, though pronounced by Siemens and Coleman incapable
of being utilized, may be made to liquefy air without using other
refrigerants."

So well is this principle carried out in Dr. Hamp-son's apparatus for
liquefying air that compressed air passing into the coil at ordinary
temperature without other means of refrigeration begins to liquefy in
about six minutes--a result that seems almost miraculous when it is
understood that the essential mechanism by which this is brought about
is contained in a cylinder only eighteen inches long and seven inches in
diameter.

As has been said, it was by adopting this principle of self-intensive
refrigeration that Professor Dewar was able to liquefy hydrogen. More
recently the same result has been attained through use of the same
principle by Professor Ramsay and Dr. Travers at University College,
London, who are to be credited also with first publishing a detailed
account of the various stages of the process. It appears that the use of
the self-intensification principle alone is not sufficient with hydrogen
as it is with the less volatile gases, including air, for the reason
that at all ordinary temperatures hydrogen does not cool in expanding,
but actually becomes warmer. It is only after the compressed hydrogen
has been cooled by immersion in refrigerating media of very low
temperature that this gas becomes amenable to the law of cooling on
expansion. In the apparatus used at University College the coil of
compressed hydrogen is passed successively through (1) a jar containing
alcohol and solid carbonic acid at a temperature of--80° Centigrade; (2)
a chamber containing liquid air at atmospheric pressure, and (3)
liquid air boiling in a vacuum bringing the temperature to perhaps 2050
Centigrade before entering the Hampson coil, in which expansion and
the self-intensive refrigeration lead to actual liquefaction. With this
apparatus Dr. Travers succeeded in producing an abundant quantity of
liquid hydrogen for use in the experiments on the new gases that were
first discovered in the same laboratory through the experiments on
liquid air--gases about which I shall have something more to say in
another chapter.


PRINCIPLES AND EXPERIMENTS

At first blush it seems a very marvellous thing, this liquefaction
of substances that under all ordinary conditions are gaseous. It is
certainly a little startling to have a cup of clear, water-like liquid
offered one, with the assurance that it is nothing but air; still more
so to have the same air presented in the form of a white "avalanche
snow." In a certain sense it is marvellous, because the mechanical
difficulties that have been overcome in reducing the air to these
unusual conditions are great. Yet, in another and broader view, there
is nothing more wonderful about liquid air than about liquid water, or
liquid mercury, or liquid iron. Long before air was actually liquefied,
it was perfectly understood by men of science that under certain
conditions it could be liquefied just as surely as water, mercury, iron,
and every other substance could be brought to a similar state. This
being known, and the principles involved understood, had there been
nothing more involved than the bare effort to realize these conditions
all the recent low-temperature work would have been mere scientific
child's-play, and liquid air would be but a toy of science. But in point
of fact there are many other things than this involved; new principles
were being searched for and found in the course of the application of
the old ones; new light was being thrown into many dark corners; new
fields of research, some of them as yet barely entered, were being
thrown open to the investigator; new applications of energy, of vast
importance not merely in pure science but in commercial life as well,
were being made available. That is why the low-temperature work must be
regarded as one of the most important scientific accomplishments of our
century.

At the very outset it was this work in large measure which gave the
final answer to the long-mooted question as to the nature of heat,
demonstrating the correctness of Count Rumford's view that heat is
only a condition not itself a substance. Since about the middle of the
century this view, known as the mechanical theory of heat, has been the
constant guide of the physicists in all their experiments, and any
one who would understand the low-temperature phenomena must keep this
conception of the nature of heat clearly and constantly in mind. To
understand the theory, one must think of all matter as composed
of minute isolated particles or molecules, which are always in
motion--vibrating, if you will. He must mentally magnify and
visualize these particles till he sees them quivering before him,
like tuning-forks held in the hand. Remember, then, that, like the
tuning-fork, each molecule would, if left to itself, quiver less and
less violently, until it ran down altogether, but that the motion thus
lessening is not really lost. It is sent out in the form of ether waves,
which can set up like motion in any other particles which they reach, be
they near or remote; or it is transmitted as a direct push--a kick,
if you will--to any other particle with which the molecule comes in
physical contact.

But note now, further, that our molecule, while incessantly giving out
its energy of motion in ether waves and in direct pushes, is at the same
time just as ceaslessly receiving motion from the ether waves made by
other atoms, and by the return push of the molecules against which it
pushes. In a word, then, every molecule of matter is at once a centre
for the distribution of motion (sending out impulses which affect,
sooner or later, every other atom of matter in the universe), and, from
the other point of view, also a centre for the reception of motion from
every direction and from every other particle of matter in the universe.
Whether any given molecule will on the whole gain motion or lose it
depends clearly on the simple mechanical principles of give and take.

From equally familiar mechanical principles, it is clear that our
vibrating molecule, in virtue of its vibrations, is elastic, tending to
be thrown back from every other molecule with which it comes in contact,
just as a vibrating tuning-fork kicks itself away from anything it
touches. And of course the vigor of the recoil will depend upon the
vigor of the vibration and the previous movements. But since these
movements constitute temperature, this is another way of saying that
the higher the temperature of a body the more its molecules will tend to
spring asunder, such separation in the aggregate constituting expansion
of the mass as a whole. Thus the familiar fact of expansion of a body
under increased temperature is explained.

But now, since all molecules are vibrating, and so tending to separate,
it is clear that no unconfined mass of molecules would long remain in
contiguity unless some counter influence tended to draw them together.
Such a counter influence in fact exists, and is termed the "force" of
cohesion. This force is a veritable gravitation influence, drawing every
molecule towards every other molecule. Possibly it is identical with
gravitation. It seems subject to some law of decreasing in power with
the square of the distance; or, at any rate, it clearly becomes less
potent as the distance through which it operates increases.

Now, between this force of cohesion which tends to draw the molecules
together, and the heat vibrations which tend to throw the molecules
farther asunder, there seems to be an incessant battle. If cohesion
prevails, the molecules are held for the time into à relatively fixed
system, which we term the solid state. If the two forces about balance
each other, the molecules move among themselves more freely but maintain
an average distance, and we term the condition the liquid state. But if
the heat impulse preponderates, the molecules (unless restrained from
without) fly farther and farther asunder, moving so actively that when
they collide the recoil is too great to be checked by cohesion, and this
condition we term the gaseous state.

Now after this statement, it is clear that what the low-temperature
worker does when he would liquefy a gas is to become the champion of the
force of cohesion. He cannot directly aid it, for so far as is known it
is an unalterable quantity, like gravitation. But he can accomplish the
same thing indirectly by weakening the power of the rival force. Thus,
if he encloses a portion of gas in a cylinder and drives a piston down
against it, he is virtually aiding cohesion by forcing the molecules
closer together, so that the hold of cohesion, acting through a less
distance, is stronger. What he accomplishes here is not all gain,
however, for the bounding molecules, thus jammed together, come in
collision with one another more and more frequently, and thus their
average activity of vibration is increased and not diminished; in
other words, the temperature of the gas has risen in virtue of the
compression. Compression alone, then, will not avail to enable cohesion
to win the battle.

But the physicist has another resource. He may place the cylinder of gas
in a cold medium, so that the heat vibrations sent into it will be less
vigorous than those it sends out. That is a blow the molecule cannot
withstand. It is quite impotent to cease sending out the impulses
however little comes in return; hence the aggregate motion becomes less
and less active, until finally the molecule is moving so sluggishly
that when it collides with its fellow cohesion is able to hold it there.
Cohesion, then, has won the battle, and the gas has become a liquid.

Such, stated in terms of the mechanical theory of heat, is what is
brought to pass when a gas is liquefied in the laboratory of the
physicist. It remains only to note that different chemical substances
show the widest diversity as to the exact point of temperature at which
this balance of the expansive and cohesive tendencies is affected, but
that the point, under uniform conditions of pressure, is always the same
for the same substance. This diversity has to do pretty clearly with the
size of the individual molecules involved; but its exact explanation is
not yet forthcoming, and, except in a general way, the physicist
would not be able to predict the "critical temperature" of any new gas
presented to him. But once this has been determined by experiment, he
always knows just what to expect of any given substance. He knows, for
example, that in a mixture of gases hydrogen would still remain gaseous
after all the others had assumed the liquid state, and most of them the
solid state as well.

These mechanical conceptions well in mind, it is clear that what the
would-be liquefier of gases has all along sought to attain is merely
the insulation of the portion of matter with which he worked against the
access of heat-impulse from its environment. It is clear that were any
texture known which would permit a heat-impulse to pass through it in
one direction only, nothing more would be necessary than to place a
portion of gas in such a receptacle of this substance, so faced as to
permit egress but not entrance of the heat, and the gas thus enclosed,
were it hydrogen itself, would very soon become liquid and solid,
through spontaneous giving off of its energy, without any manipulation
whatever. Contrariwise, were the faces of the receptacle reversed, a
piece of iron placed within it would be made red-hot and melted though
the receptacle were kept packed in salt and ice and no heat applied
except such as came from this freezing mixture. One could cook a
beefsteak with a cake of ice had he but such a material as this with
which to make his stove. Not even Rumford or our modern Edward Atkinson
ever dreamed of such economy of fuel as that.

But, unfortunately, no such substance as this is known, nor, indeed, any
substance that will fully prevent the passage of heat-impulses in either
direction. Hence one of the greatest tasks of the experimenters has
been to find a receptacle that would insulate a cooled substance even
partially from the incessant bombardment of heat-impulses from without.
It is obvious that unless such an insulating receptacle could be
provided none of the more resistent gases, such as oxygen, could be
long kept liquid, even when once brought to that condition, since an
environment of requisite frigidity could not practicably be provided.

But now another phase of the problem presents itself to the
experimenter. Oxygen has assumed the quiescent liquid state, to be
sure, but in so doing it has fallen below the temperature of its cooling
medium; hence it is now receiving from that medium more energy of
vibration than it gives, and unless this is prevented very soon its
particles will again have power to kick themselves apart and resume the
gaseous state. Something, then, must be done to insulate the liquefied
gas, else it will retain the liquid state for too short a time to be
much experimented with. How might such insulation be accomplished?

The most successful attack upon this important problem has been made by
Professor Dewar. He invented a receptacle for holding liquefied gases
which, while not fulfilling the ideal conditions referred to above, yet
accomplishes a very remarkable degree of heat insulation. In consists of
a glass vessel with double walls, the space between which is rendered
a vacuum of the highest practicable degree. This vacuum, containing
practically no particles of matter, cannot, of course, convey
heat-impulses to or from the matter in the receptacle with any degree
of rapidity. Thus one of the two possible means of heat transfer is shut
off and a degree of insulation afforded the liquefied substance. But
of course the other channel, ether radiation, remains. Even this may be
blocked to a large extent, however, by leaving a trace of mercury vapor
in the vacuum space, which will be deposited as a fine mirror on
the inner surface of the chamber. This mirror serves as an admirable
reflector of the heat-rays that traverse the vacuum, sending more
than half of them back again. So, by the combined action of vacuum and
mirror, the amount of heat that can penetrate to the interior of the
receptacle is reduced to about one-thirtieth of what would enter an
ordinary vessel. In other words, a quantity of liquefied gas which would
evaporate in one minute from an ordinary vessel will last half an hour
in one of Professor Dewar's best vacuum vessels. Thus in one of these
vessels a quantity of liquefied air, for example, can be kept for a
considerable time in an atmosphere at ordinary temperature, and will
only volatilize at the surface, like water under the same conditions,
though of course more rapidly; whereas the same liquid in an ordinary
vessel would boil briskly away, like water over a fire. Only, be it
remembered, the air in "boiling" is at a temperature of about one
hundred and eighty degrees below zero, so that it would instantly freeze
almost any substance placed into it. A portion of alcohol poured on its
surface will be changed quickly into a globule of ice, which will
rattle about the sides of the vessel like a marble. That is not what one
ordinarily thinks of as a "boiling" temperature.

If the vacuum vessel containing a liquefied gas be kept in a cold
medium, and particularly if two vacuum tubes be placed together, so that
no exposed surface of liquid remains, a portion of liquefied air, for
example, may be kept almost indefinitely. Thus it becomes possible
to utilize the liquefied gas for experimental investigation of the
properties of matter at low temperatures that otherwise would be quite
impracticable. Great numbers of such experiments have been performed in
the past decade or so by all the workers with low temperatures already
mentioned, and by various others, including, fittingly enough, the
holder of the Rumford professorship of experimental physics at Harvard,
Professor Trowbridge. The work of Professor Dewar has perhaps been the
most comprehensive and varied, but the researches of Pictet, Wroblewski,
and Olzewski have also been important, and it is not always possible
to apportion credit for the various discoveries accurately, since
the authorities themselves are in unfortunate disagreement in several
questions of priority. But in any event, such questions of exact
priority have no great interest for any one but the persons directly
involved. We may quite disregard them here, confining attention to the
results themselves, which are full of interest.

The questions investigated have to do with the physical properties,
such as electrical conductivity, magnetic condition, light-absorption,
cohesion, and chemical affinities of matter at excessively low
temperatures. It is found that in all these regards most substances are
profoundly modified when excessively cooled. Thus if a piece of any pure
metal is placed in an electric circuit and plunged into liquid air, its
resistance to the passage of the electricity steadily decreases as the
metal cools, until at the temperature of the liquid it is very trifling
indeed. The conclusion seems to be justified that if the metal could be
still further cooled until it reached the theoretical "absolute zero,"
or absolutely heatless condition, the electrical resistance would also
be nil. So it appears that the heat vibrations of the molecules of a
pure metal interfere with the electrical current. The thought suggests
itself that this may be because the ether waves set up by the vibrating
molecules conflict with the ether strain which is regarded by some
theorists as constituting the electrical "current." But this simple
explanation falters before further experiments which show, paradoxically
enough, that the electrical resistance of carbon exactly reverses what
has just been said of pure metals, becoming greater and greater as the
carbon is cooled. If an hypothesis were invented to cover this case
there would still remain a puzzle in the fact that alloys of metals
do not act at all like the pure metals themselves, the electrical
resistance of such alloys being, for the most part, unaffected by
changed temperature. On the whole, then, the facts of electrical
conduction at low temperatures are quite beyond the reach of present
explanation. They must await a fuller knowledge of molecular conditions
in general than is at present available--a knowledge to which the
low-temperature work itself seems one of the surest channels.

Even further beyond the reach of present explanation are the facts as to
magnetic conditions at low temperatures. Even as to the facts themselves
different experimenters have differed somewhat, but the final conclusion
of Professor Dewar is that, after a period of fluctuation, the power of
a magnet repeatedly subjected to a liquid-air bath becomes permanently
increased. Various substances not markedly magnetic at ordinary
temperatures become so when cooled. Among these, as Professor Dewar
discovered, is liquid oxygen itself. Thus if a portion of liquid air be
further cooled until it assumes a semi-solid condition, the oxygen may
be drawn from the mass by a magnet, leaving a pure nitrogen jelly. These
facts are curious enough, and full of suggestion, but like all other
questions having to do with magnetism, they hold for the present
generation the double fascination of insoluble mystery. To be sure, one
may readily enough suggest that if magnetism be really a whirl in the
ether, this whirl is apparently interfered with by the waves of radiant
heat; or, again, that magnetism is presumably due to molecular motions
which are apparently interfered with by another kind of molecular
motions which we call heat vibrations; but there is a vagueness about
the terms of such guesses that leaves them clearly within the category
of explanations that do not explain.

When it comes to the phenomena of light, we can, as is fitting, see
our way a little more clearly, since, thanks to Thomas Young and his
successors, we know pretty definitely what light really is. So when
we learn that many substances change their color utterly at low
temperatures--red things becoming yellow and yellow things white,
for example--we can step easily and surely to at least a partial
explanation. We know that the color of any object depends simply
upon the particular ether waves of the spectrum which that particular
substance absorbs; and it does not seem anomalous that molecules packed
close together at--180° of temperature should treat the ether waves
differently than when relatively wide apart at an ordinary temperature.
Yet, after all, that may not be the clew to the explanation. The packing
of the molecules may have nothing to do with it. The real explanation
may lie in the change of the ether waves sent out by the vibrating
molecule; indeed, the fact that the waves of radiant heat and those of
light differ only in amplitude lends color to this latter supposition.
So the explanation of the changed color of the cooled substance is at
best a dubious one.

Another interesting light phenomenon is found in the observed fact that
very many substances become markedly phosphorescent at low temperatures.
Thus, according to Professor Dewar, "gelatine, celluloid, paraffine,
ivory, horn, and india-rubber become distinctly luminous, with a bluish
or greenish phosphorescence, after cooling to--180° and being stimulated
by the electric light." The same thing is true, in varying degrees,
of alcohol, nitric acid, glycerine, and of paper, leather, linen,
tortoise-shell, and sponge. Pure water is but slightly luminous, whereas
impure water glows brightly. On the other hand, alcohol loses its
phosphorescence when a trace of iodine is added to it. In general,
colored things are but little phosphorescent. Thus the white of egg is
very brilliant but the yolk much less so. Milk is much brighter than
water, and such objects as a white flower, a feather, and egg-shell
glow brilliantly. The most remarkable substances of all, says Professor
Dewar, whom I am all along quoting, are "the platinocyanides among
inorganic compounds and the ketonic compounds among organic. Ammonium
platinocyanide, cooled while stimulated by arc light, glows fully
at--180°; but on warming it glows like a lamp. It seems clear,"
Professor Dewar adds, "that the substance at this low temperature must
have acquired increased power of absorption, and it may be that at
the same time the factor of molecular friction or damping may have
diminished." The cautious terms in which this partial explanation is
couched suggest how far we still are from a full understanding of the
interesting phenomena of phosphorescence. That a molecule should be
able to vibrate in such a way as to produce the short waves of light,
dissevered from the usual linking with the vibrations represented by
high temperature, is one of the standing puzzles of physics. And the
demonstrated increase of this capacity at very low temperatures only
adds to the mystery.

There are at least two of the low-temperature phenomena, however,
that seem a little less puzzling--the facts, namely, that cohesion and
rigidity of structure are increased when a substance is cooled and that
chemical activity is very greatly reduced, in fact almost abolished.
This is quite what one would expect _a priori_--though no wise man would
dwell on his expectation in advance of the experiments--since the whole
question of liquids and solids _versus_ gases appears to be simply a
contest between cohesive forces that are tending to draw the molecules
together and the heat vibration which is tending to throw them apart.
As a substance changes from gas to liquid, and from liquid to solid,
contracting meantime, simply through the lessening of the heat
vibrations of its molecules, we might naturally expect that the solid
would become more and more tenacious in structure as its molecules came
closer and closer together, and at the same time became less and less
active, as happens when the solid is further cooled. And for once
experiment justifies the expectation. Professor De-war found that the
breaking stress of an iron wire is more than doubled when the wire
is cooled to the temperature of liquid air, and all other metals are
largely strengthened, though none other to quite the same degree.
He found that a spiral spring of fusible metal, which at ordinary
temperature was quickly drawn out into a straight wire by a weight
of one ounce, would, when cooled to -182 deg, support a weight of two
pounds, and would vibrate like a steel spring so long as it was cool.
A bell of fusible metal has a distinct metallic ring at this low
temperature; and balls of iron, tin, lead, or ivory cooled to -182
deg and dropped from a height, "in all cases have the rebound greatly
increased. The flattened surface of the lead is only one-third what it
would be at ordinary temperature." "These conditions are due solely to
the cooling, and persist only while the low temperature lasts."

If this increased strength and hardness of a contracted metal are
what one would expect on molecular principles, the decreased chemical
activity at low temperatures is no less natural-seeming, when one
reflects how generally chemical phenomena are facilitated by the
application of heat. In point of fact, it has been found that at the
temperature of liquid hydrogen practically all chemical activity
is abolished, the unruly fluorine making the only exception. The
explanation hinges on the fact that every atom, of any kind, has
power to unite with only a limited number of other atoms. When the
"affinities" of an atom are satisfied, no more atoms can enter into the
union unless some atoms already there be displaced. Such displacement
takes place constantly, under ordinary conditions of temperature,
because the vibrating atoms tend to throw themselves apart, and other
atoms may spring in to take the places just vacated--such interchange,
in fact, constituting the essence of chemical activity. But when the
temperature is reduced the heat-vibration becomes insufficient to
throw the atoms apart, hence any unions they chance to have made are
permanent, so long as the low temperature is maintained. Thus it is that
substances which attack one another eagerly at ordinary temperatures
will lie side by side, utterly inert, at the temperature of liquid air.

Under certain conditions, however, most interesting chemical experiments
have been made in which the liquefied gases, particularly oxygen, are
utilized. Thus Olzewski found that a bit of wood lighted and thrust into
liquid oxygen burns as it would in gaseous oxygen, and a red-hot iron
wire thrust into the liquid burns and spreads sparks of iron. But more
novel still was Dewar's experiment of inserting a small jet of ignited
hydrogen into the vessel of liquid oxygen; for the jet continued to
burn, forming water, of course, which was carried away as snow. The idea
of a gas-jet burning within a liquid, and having snow for smoke, is
not the least anomalous of the many strange conceptions that the
low-temperature work has made familiar.


PRACTICAL RESULTS AND ANTICIPATIONS

Such are some of the strictly scientific results of the low-temperature
work. But there are other results of a more directly practical
kind--neither more important nor more interesting on that account, to
be sure, but more directly appealing to the generality of the
non-scientific public. Of these applications, the most patent and the
first to be made available was the one forecast by Davy from the very
first--namely, the use of liquefied gases in the refrigeration of
foods. Long before the more resistant gases had been liquefied, the more
manageable ones, such as ammonia and sulphurous acid, had been utilized
on a commercial scale for refrigerating purposes. To-day every
brewery and every large cold-storage warehouse is supplied with such
a refrigerator plant, the temperature being thus regulated as is not
otherwise practicable. Many large halls are cooled in a similar manner,
and thus made comfortable in the summer. Ships carrying perishables
have the safety of their cargoes insured by a refrigerator plant. In all
large cities there are ice manufactories using the same method, and of
late even relatively small establishments, hotels, and apartment houses
have their ice-machine. It seems probable that before long all such
buildings and many private dwellings will be provided with a cooling
apparatus as regularly as they are now equipped with a heating
apparatus.

The exact details of the various refrigerator machines of course vary,
but all of them utilize the principles that the laboratory workers first
established. Indeed, the entire refrigerator industry, now assuming
significant proportions, may be said to be a direct outgrowth of that
technical work which Davy and Faraday inaugurated and prosecuted at the
Royal Institution--a result which would have been most gratifying to the
founder of the institution could he have forecast it. The usual means
of distributing the cooling fluids in the commercial plants is by
the familiar iron pipes, not dissimilar in appearance (when not in
operation) to the familiar gas, water, and steam pipes. When operating,
however, the pipes themselves are soon hidden from view by the thick
coating of frost which forms over them. In a moist beer-cellar
this coating is often several inches in thickness, giving a very
characteristic and unmistakable appearance.

Another commercial use to which refrigerator machines are now put is in
the manufacture of various drugs, where absolute purity is desirable.
As different substances congeal at different temperatures, but the same
substances at uniform pressure always at the same temperature, a
means is afforded of freeing a drug from impurities by freezing, where
sometimes the same result cannot be accomplished with like thoroughness
by any other practicable means. Indeed, by this means impurities have
been detected where not previously suspected. And Professor Ramsay has
detected some new elementary substances even, as constituents of the
air, which had previously not been dissociated from the nitrogen with
which they are usually mixed.

Such applications of the refrigerator principles as these, however,
though of vast commercial importance, are held by many enthusiasts to
be but a bagatelle compared with other uses to which liquefied gases
may some time be put. Their expectations are based upon the enormous
potentialities that are demonstrably stored in even a tiny portion of,
say, liquefied air. These are, indeed, truly appalling. Consider, for
example, a portion of air at a temperature above its critical point, to
which, as in Thilorier's experiments, a pressure of thirty-one tons to
the square inch of the encompassing wall is being applied. Recall that
action and reaction are equal, and it is apparent that the gas itself is
pushing back--struggling against being compressed, if you will--with an
equal power. Suppose the bulk of the gas is such that at this pressure
it occupies a cubical space six inches on a side--something like the
bulk of a child's toy balloon, let us say. Then the total outward
pressure which that tiny bulk of gas exerts, in its desperate molecular
struggle, is little less than five thousand tons. It would support an
enormous building without budging a hair's-breadth. If the building
weighed less than five thousand tons it would be lifted by the gas; if
much less it would be thrown high into the air as the gas expanded. It
gives one a new sense of the power of numbers to feel that infinitesimal
atoms, merely by vibrating in unison, could accomplish such a result.

But now suppose our portion of gas, instead of being placed under our
hypothetical building, is plunged into a cold medium, which will permit
its heat-vibrations to exhaust themselves without being correspondingly
restored. Then, presently, the temperature is lowered below the critical
point, and, presto! the mad struggle ceases, the atoms lie amicably
together, and the gas has become a liquid. What a transformed thing
it is now. Instead of pressing out with that enormous force, it has
voluntarily contracted as the five thousand tons pressure could not
make it do; and it lies there now, limpid and harmless-seeming, in the
receptacle, for all the world like so much water.

And, indeed, the comparison with water is more than superficial, for
in a cup of water also there are wonderful potentialities, as every
steam-engine attests. But an enormous difference, not in principle but
in practical applications, exists in the fact that the potentialities
of the water cannot be utilized until relatively high temperatures are
reached. Costly fuel must be burned and the heat applied to the water
before it can avail to do its work. But suppose we were to place our
portion of liquid air, limpid and water-like, in the cylinder of a
locomotive, where the steam of water ordinarily enters. Then, though no
fuel were burned--though the entire engine stood embedded in the snow
of an arctic winter--it would be but a few moments before the liquid air
would absorb even from this cold medium heat enough to bring it above
its critical temperature; and, its atoms now dancing apart once more and
re-exerting that enormous pressure, the piston of the engine would be
driven back and then the entire cylinder burst into fragments as the
gas sought exit. In a word, then, a portion of liquid air has a store
of potential energy which can be made kinetic merely by drawing upon
the boundless and free supply of heat which is everywhere stored in the
atmosphere we breathe and in every substance about us. The difficulty
is, not to find fuel with which to vaporize it, as in case of water,
but to keep the fuel from finding it whether or no. Were liquid air in
sufficient quantities available, the fuel problem would cease to
have any significance. But of course liquid air is not indefinitely
available, and exactly here comes the difficulty with the calculations
of many enthusiasts who hail liquefied gas as the motive power of the
near future. For of course in liquefying the air power has been applied,
for the moment wasted, and unless we can get out of the liquid more
energy than we have applied to it, there is no economy of power in
the transaction. Now the simplest study of the conditions, with the
mechanical theory of matter in mind, makes it clear that this is
precisely what one can never hope to accomplish. Action and reaction are
equal and in opposite directions at all stages of the manipulation, and
hence, under the most ideal conditions, we must expect to waste as much
work in condensing a gas (in actual practice more) as the condensed
substance can do in expanding to the original volume. Those enthusiasts
who have thought otherwise, and who have been on the point of perfecting
an apparatus which will readily and cheaply produce liquid air after
the first portion is produced, are really but following the old
perpetual-motion-machine will-o'-the-wisp.

It does not at all follow from this, however, that the energies of
liquefied air may not be utilized with enormous advantage. It is not
always the cheapest form of power-transformer that is the best for all
purposes, as the use of the electrical storage battery shows. And so it
is quite within the possibilities that a multitude of uses may be
found for the employment of liquid air as a motive power, in which its
condensed form, its transportability or other properties will give
it precedence over steam or electricity. It has been suggested, for
example, that liquefied gas would seem to afford the motive power par
excellence for the flying-machine, once that elusive vehicle is well in
harness, since one of the greatest problems here is to reduce the weight
of the motor apparatus. In a less degree the same problem enters into
the calculations of ships, particularly ships of war; and with them also
it may come to pass that a store of liquid air (or other gas) may come
to take the place of a far heavier store of coal. It is even within the
possibilities that the explosive powers of the same liquid may take the
place of the great magazines of powder now carried on war-ships; for,
under certain conditions, the liquefied gas will expand with explosive
suddenness and violence, an "explosion" being in any case only a very
sudden expansion of a confined gas. The use of the compressed air in the
dynamite guns, as demonstrated in the Cuban campaign, is a step in this
direction. And, indeed, the use of compressed air in many commercial
fields already competing with steam and electricity is a step towards
the use of air still further compressed, and cooled, meantime, to a
condition of liquidity. The enormous advantages of the air actually
liquefied, and so for the moment quiescent, over the air merely
compressed, and hence requiring a powerful retort to hold it, are patent
at a glance. But, on the other hand, the difficulty of keeping it liquid
is a disadvantage that is equally patent. How the balance will be struck
between these contending advantages and disadvantages it remains for
the practical engineering inventors of the future--the near future,
probably--to demonstrate.

Meantime there is another line of application of the ideas which the
low-temperature work has brought into prominence which has a peculiar
interest in the present connection because of its singularly Rumfordian
cast, so to speak, I mean the idea of the insulation of cooled or heated
objects in the ordinary affairs of life, as, for example, in cooking.
The subject was a veritable hobby with the founder of the Royal
Institution all his life. He studied the heat-transmitting and
heat-reflecting properties of various substances, including such
directly practical applications as rough surfaces _versus_ smooth
surfaces for stoves, the best color for clothing in summer and in
winter, and the like. He promulgated his ideas far and wide, and
demonstrated all over Europe the extreme wastefulness of current methods
of using fuel. To a certain extent his ideas were adopted everywhere,
yet on the whole the public proved singularly apathetic; and, especially
in America, an astounding wastefulness in the use of fuel is the general
custom now as it was a century ago. A French cook will prepare an
entire dinner with a splinter of wood, a handful of charcoal, and a
half-shovelful of coke, while the same fuel would barely suffice to
kindle the fire in an American cook-stove. Even more wonderful is the
German stove, with its great bulk of brick and mortar and its glazed
tile surface, in which, by keeping the heat in the room instead of
sending it up the chimney, a few bits of compressed coal do the work of
a hodful.

It is one merit of the low-temperature work, I repeat, to have called
attention to the possibilities of heat insulation in application to "the
useful purposes of life." If Professor Dewar's vacuum vessel can reduce
the heat-transmitting capacity of a vessel by almost ninety-seven per
cent., why should not the same principle, in modified form, be applied
to various household appliances--to ice-boxes, for example, and
to cooking utensils, even to ovens and cook-stoves? Even in the
construction of the walls of houses the principles of heat insulation
might advantageously be given far more attention than is usual at
present; and no doubt will be so soon as the European sense of economy
shall be brought home to the people of the land of progress and
inventions. The principles to be applied are already clearly to hand,
thanks largely to the technical workers with low temperatures. It
remains now for the practical inventors to make the "application to the
useful purposes of life." The technical scientists, ignoring the example
which Rumford and a few others have set, have usually no concern with
such uninteresting concerns.

For the technical scientists themselves, however, the low-temperature
field is still full of inviting possibilities of a strictly technical
kind. The last gas has indeed been liquefied, but that by no means
implies the last stage of discovery. With the successive conquest of
this gas and of that, lower and lower levels of temperature have been
reached, but the final goal still lies well beyond. This is the north
pole of the physicist's world, the absolute zero of temperature--the
point at which the heat-vibrations of matter are supposed to be
absolutely stilled. Theoretically this point lies 2720 below the
Centigrade zero. With the liquefaction of hydrogen, a temperature of
about -253 deg or -254 deg Centigrade has been reached. So the gap
seems not so very great. But like the gap that separated Nansen from the
geographical pole, it is a very hard road to travel. How to compass it
will be the study of all the low-temperature explorers in the immediate
future. Who will first reach it, and when, and how, are questions for
the future to decide.

And when the goal is reached, what will be revealed? That is a question
as full of fascination for the physicist as the north-pole mystery
has ever been for the generality of mankind. In the one case as in
the other, any attempt to answer it to-day must partake largely of the
nature of a guess, yet certain forecasts may be made with reasonable
probability. Thus it can hardly be doubted that at the absolute zero all
matter will have the form which we term solid; and, moreover, a degree
of solidity, of tenacity and compactness greater than ever otherwise
attained. All chemical activity will presumably have ceased, and any
existing compound will retain unaltered its chemical composition so
long as absolute zero pertains; though in many, if not in all cases,
the tangible properties of the substance--its color, for example, and
perhaps its crystalline texture--will be so altered as to be no longer
recognizable by ordinary standards, any more than one would ordinarily
recognize a mass of snowlike crystals as air.

It has, indeed, been suggested that at absolute zero all matter may take
the form of an impalpable powder, the forces of cohesion being destroyed
with the vibrations of heat. But experiment seems to give no warrant to
this forecast, since cohesion seems to increase exactly in proportion
to the decrease of the heat-vibrations. The solidity of the meteorites
which come to the earth out of the depths of space, where something
approaching the zero temperature is supposed to prevail, also
contradicts this assumption. Still less warrant is there for a visionary
forecast at one time entertained that at absolute zero matter will
utterly disappear. This idea was suggested by the observation, which
first gave a clew to the existence of the absolute zero, that a gas at
ordinary temperatures and at uniform pressure contracts by 1-27 2d of
its own bulk with each successive degree of lowered temperature. If this
law held true for all temperatures, the gas would apparently contract to
nothingness when the last degree of temperature was reached, or at least
to a bulk so insignificant that it would be inappreciable by standards
of sense. But it was soon found by the low-temperature experimenters
that the law does not hold exactly at extreme temperatures, nor does it
apply at all to the rate of contraction which the substance shows after
it assumes the liquid and solid conditions. So the conception of the
disappearance of matter at zero falls quite to the ground.

But one cannot answer with so much confidence the suggestion that at
zero matter may take on properties hitherto quite unknown, and making
it, perhaps, differ as much from the conventional solid as the solid
differs from the liquid, or this from the gas. The form of vibration
which produces the phenomena of temperature has, clearly, a determining
share in the disposal of molecular relations which records itself to our
senses as a condition of gaseousness, liquidity, or solidity; hence it
would be rash to predict just what inter-molecular relations may not
become possible when the heat-vibration is altogether in abeyance. That
certain other forms of activity may be able to assert themselves in
unwonted measure seems clearly forecast in the phenomena of increased
magnetism, and of phosphorescence at low temperatures above outlined.
Whether still more novel phenomena may put in an appearance at the
absolute zero, and if so, what may be their nature, are questions that
must await the verdict of experiment. But the possibility that this may
occur, together with the utter novelty of the entire subject, gives
the low-temperature work precedence over almost every other subject
now before the world for investigation (possible exceptions being
radio-activity and bacteriology). The quest of the geographical pole is
but a child's pursuit compared with the quest of the absolute zero. In
vital interest the one falls as far short of the other as the cold of
frozen water falls short of the cold of frozen air.

Where, when, and by whom the absolute zero will be first reached are
questions that may be answered from the most unexpected quarter. But it
is interesting to know that great preparations are being made today in
the laboratories of the Royal Institution for a further attack upon the
problem. Already the research equipment there is the best in the world
in this field, and recently this has been completely overhauled and
still further perfected. It would not be strange, then, in view of past
triumphs, if the final goal of the low-temperature workers should be
first reached in the same laboratory where the outer territories of
the unknown land were first penetrated three-quarters of a century ago.
There would seem to be a poetic fitness in the trend of events should it
so transpire. But of course poetic fitness does not always rule in the
land of science.



IV. SOME PHYSICAL LABORATORIES AND PHYSICAL PROBLEMS


SIR NORMAN LOCKYER AND SOLAR CHEMISTRY

SIR NORMAN LOCKYER is professor of astronomical physics and director
of the solar observatory at the Royal College of Science in South
Kensington. Here it is that his chief work has been done for some thirty
years past. The foundation-stone of that work is spectroscopic study of
the sun and stars. In this study Professor Lockyer was a pioneer, and he
has for years been recognized as the leader. But he is no mere observer;
he is a generalizer as well; and he long since evolved revolutionary
ideas as to the origin of the sidereal and solar systems.

For a man whose chief occupation is the study of the sun and stars,
smoky, foggy, cloudy London may seem a strange location. I asked
Professor Lockyer about this, and his reply was most characteristic.
"The fact is," he said, "the weather here is too fine from one point of
view: my working staff is so small, and the number of working nights so
large, that most of the time there is no one about to do anything during
the day. Then, another thing, here at South Kensington I am in touch
with my colleagues in the other departments--physics, chemistry, and so
forth--and can at once draw upon their special knowledge for aid on any
obscure point in their lines that may crop up. If we were out in the
country this would not be so. You see, then, that it is a choice between
weather and brains. I prefer the brains."

Professor Lockyer went on to state, however, that he is by no means
altogether dependent upon the observations made at South Kensington. For
certain purposes the Royal Observatory at Greenwich is in requisition,
and there are three observatories at different places in India at which
photographs of the sun-spots and solar spectra are taken regularly.
From these combined sources photographs of the sun are forthcoming
practically every day of the year; to be accurate, on three hundred and
sixty days out of the three hundred and sixty-five. It was far
otherwise when Professor Lockyer first began his studies of the sun, as
observations were then made and recorded on only about one-third of the
days in each year.

Exteriorly the observatory at South Kensington is not at all such a
place as one might expect to find. It is, in Professor Lockyer's own
words, "little more than a collection of sheds," but within these
alleged sheds may be found an excellent equipment of telescopes, both
refracting and reflecting, and of all other things requisite to the
peculiar study which forms the subject of special research here.

I have had occasion again and again to call attention to this relatively
meagre equipment of the European institutions, but in no case, perhaps,
is the contrast more striking between the exterior appearance of a
famous scientific institution and the work that is being accomplished
within it than is shown in the case of the South Kensington observatory.
It should be added that this remark does not apply to the chief building
of the Royal College of Science itself.

The theories for which Professor Lockyer has so long been famous are
well known to every one who takes much interest in the progress of
scientific ideas. They are notably the theory that there is a direct
causal association between the prevalence of sun-spots and terrestrial
weather; the theory of the meteoritic origin of all members of the
sidereal family; and the dissociation theory of the elements, according
to which our so-called elements are really compounds, capable of being
dissociated into simpler forms when subjected to extreme temperatures,
such as pertain in many stars. As I have said, these theories are by no
means new. Professor Lockyer has made them familiar by expounding them
for a full quarter of a century or more. But if not new, these theories
are much too important to have been accepted at once without a protest
from the scientific world. In point of fact, each of them has been met
with most ardent opposition, and it would, perhaps, not be too much to
say that not one of them is, as yet, fully established. It is of the
highest interest to note, however, that the multitudinous observations
bearing upon each of these topics during the past decade have tended, in
Professor Lockyer's opinion, strongly to corroborate each one of these
opinions.

Two or three years ago Sir Norman Lockyer, in association with his son,
communicated to the Royal Society a paper in which the data recently
obtained as to the relation between sun-spots and the weather
in India--the field of observations having been confined to that
territory--are fully elaborated. A remarkable feature of the recent
work in that connection has been the proof, or seeming proof, that the
temperature of the sun fluctuates from year to year. At times when the
sun-spots are numerous and vigorous in their action, the spectrum of
the elements in these spots becomes changed. During the times of minimum
sun-spot activity the spectrum shows, for example, the presence of large
quantities of iron in these spots--of course in a state of vapor. But in
times of activity this iron disappears, and the lines which previously
vouched for it are replaced by other lines spoken of as the enhanced
lines of iron--that is to say, the lines which are believed to represent
the unknown substance or substances into which the iron has been
decomposed; and what is true of iron is true of various other elements
that are detected in the sun-spots. The explanation of this phenomena,
if Professor Lockyer reads the signs aright, is that during times of
minimum sun-spot activity the temperature of the sun-spots is relatively
cool, and that in times of activity the temperature becomes greatly
increased. One must come, therefore, to speaking of hot spots and cool
spots on the sun; although the cool spots, it will be understood,
would hardly be considered cool in the terrestrial sense, since their
temperature is sufficient to vaporize iron.

Now the point of the recent observations is that the fluctuations in
the sun's heat, due to the periodic increase and subsidence of sun-spot
disturbances--such fluctuations having been long recognized as having
regular cyclic intervals of about eleven years--are instrumental in
effecting changes in the terrestrial weather. According to the paper
just mentioned, it would appear to be demonstrated that the periods
of decreased rainfall in India have a direct and relatively unvarying
relationship to the prevalence of the sun-spots, and that, therefore, it
has now become possible, within reasonable limits, to predict some years
in advance the times of famine in India. So important a conclusion as
this is certainly not to be passed over lightly, and all the world,
scientific and unscientific alike, will certainly watch with acute
interest for the verification of this seemingly startling practical
result of so occult a science as solar spectroscopy.

The theory of the decomposition of the elements is closely bound up with
the meteoritic theory. In a word, it may be said of each that Professor
Lockyer is firmly convinced that all the evidence that has accumulated
in recent years is so strongly in favor as to bring these theories
almost to a demonstration. The essence of the meteoritic theory, it
will be recalled, is that all stars have their origin in nebulae which
consist essentially of clouds of relatively small meteorites. It will be
recalled further that Professor Lockyer long ago pointed out that
stars pass through a regular series of changes as to temperature, with
corresponding changes of structure, becoming for a time hotter and
hotter until a maximum is reached, and then passing through gradual
stages of cooling until their light dies out altogether. Very recently
Professor Lockyer has been enabled, through utilization of the multiform
records accumulated during years of study, to define the various typical
stages of the sidereal evolution; and not merely to define them but
to illustrate them practically by citing stars which belong to each
of these stages, and to give them yet clearer definition by naming the
various elements which the spectroscope reveals as present in each.

His studies have shown that the elements do not always give the same
spectrum under all conditions; a result quite at variance with the
earlier ideas on the subject. Even in the terrestrial laboratory it
is possible to subject various metals, including iron, to temperatures
attained with the electric spark at which the spectrum becomes different
from that, for example, which was attained with the lower temperature
of the electric arc. Through these studies so-called series-spectra
have been attained for various elements, and a comparison of these
series-spectra with the spectra of various stars has led to the
conclusion that many of the unknown lines previously traced in the
spectra of such stars are due to the decomposition products of familiar
elements; all of which, of course, is directly in line of proof of the
dissociation hypothesis.

Another important result of Professor Lockyer's very recent studies has
come about through observation of the sun in eclipse. A very interesting
point at issue all along has been the question as to what layers of the
sun's atmosphere are efficient in producing the so-called reverse lines
of the spectrum. It is now shown that the effect is not produced, as
formerly supposed, by the layers of the atmosphere lying just above the
region which Professor Lockyer long ago named the chromosphere, but by
the gases of higher regions. Reasoning from analogy, it may be supposed
that a corresponding layer of the atmosphere of other stars is the
one which gives us the reverse spectrum of those stars. The exact
composition of this layer of the sidereal atmosphere must, of course,
vary with the temperature of the different stars, but in no case can
we expect to receive from the spectroscope a full record of all the
substances that may be present in other layers of the atmosphere or in
the body of the star itself. Thus, for example, the ordinary Freuenhofer
spectrum of the sun shows us no trace of the element helium, though
through other observations at the time of eclipse Professor Lockyer had
discovered that element there, as we have seen, some thirty years before
anything was known of it on the earth.

In a recent eclipse photographs were taken of the spectra of the lower
part of the sun's atmosphere by itself, and it was found that the
spectrum of this restricted area taken by itself gave the lines which
specialize the spectra of so different a star as Procyon. "I recognize
in the result," says Professor Lockyer, "a veritable Rosetta Stone which
will enable us to read the celestial hieroglyphics presented to us in
stellar spectra, and help us to study the spectra and to get at results
much more distinctly and certainly than ever before."

But the most striking confirmation which the meteoritic hypothesis has
received has come to hand through study of the spectrum of the new star
which appeared in the constellation Perseus in February, 1901, and which
was so widely heralded everywhere in the public press. This star was
discovered on the morning of February 22d by star-gazers in Scotland,
and in America almost simultaneously. It had certainly not been
visible a few hours before, and it had blazed up suddenly to a greater
brilliancy than that of a first-magnitude star. At first it was
bluish-white in color, indicating an extremely high temperature, but
it rapidly subsided in brilliancy and assumed a red color as it cooled,
passing thus, in the course of a few days, through stages for which
ordinary stars require periods of many millions of years.

The most interesting feature of the spectrum of this new star was the
fact that it showed both light and dark lines for the same substances,
the two lying somewhat apart. This means, being interpreted, that some
portions of a given substance are giving out light, thus producing
the bright lines of the spectrum, and that other portions of the same
substance are stopping certain rays of transmitted light, thus producing
the dark lines. The space between the bright and dark lines, being
measured, indicated that there was a differential motion between the
two portions of substance thus recorded of something like seven hundred
miles a second. This means, according to theory--and it seems hardly
possible to explain it otherwise--that two sidereal masses, one at least
of which was moving at an enormous rate of speed, had collided, such
collision, of course, being the cause of the incandescence that made the
mass suddenly visible from the earth as a new star.

New stars are by no means every-day affairs, there having been but
thirty-two of them recorded in the world's history, and of these only
two have exceeded the present one in brilliancy. As a mere spectacle,
therefore, this new star was of great interest; but a far greater
importance attaches to it through the fact that it conforms so admirably
to the course that meteoritic hypothesis would predict for it. "That is
what confounds my opponents," said Professor Lockyer, in talking to me
about the new star. "Most of those who oppose my theory have not taken
the trouble to make observations for themselves, but have contented
themselves with falling back apparently on the postulate that because
a theory is new it must be wrong. Then, outside the scientific world,
comparatively few people appreciate the extreme parsimony of nature.
They expect, therefore, that when such a phenomenon as the appearance of
a new star occurs, the new-comer will establish new rules for itself and
bring chaos into the scientific world. But in point of fact nature never
does things in two ways if she can possibly do them in one, and the
most striking thing about the new stars is that all the phenomena they
present conform so admirably to the laws built up through observation of
the old familiar stars. As to our particular theories, we here at South
Kensington"--it will be understood that this use of the editorial "we"
is merely a modest subterfuge on the part of Professor Lockyer--"have
no regard for them at all simply as ours. Like all scientists worthy the
name, we seek only the truth, and should new facts come along that seem
to antagonize our theory we should welcome them as eagerly as we welcome
all new facts of whatever bearing. But the truth is that no such new
facts have appeared in all these years, but that, on the contrary, the
meteoritic hypothesis has received ever-increasing support from most
unexpected sources, from none more brilliantly or more convincingly than
from this new star in Perseus." And I suspect that as much as this at
least--if not indeed a good deal more--will be freely admitted by every
candid investigator of Sir Norman Lockyer's theory.


SIR WILLIAM RAMSAY AND THE NEW GASES

The seat of Sir William Ramsay's labors is the University College,
London. The college building itself, which is located on Gower Street,
is, like the British Museum, reminiscent or rather frankly duplicatory
in its columned architecture of the classical. Interiorly it is like
so many other European institutions in its relative simplicity of
equipment. One finds, for example, Professor Ramsay and Dr. Travers
generating the hydrogen for their wonderful experiments in an old
beer-cask. Professor Ramsay himself is a tall, rather spare man, just
entering the gray stage of life, with the earnest visage of the scholar,
the keen, piercing eye of the investigator--yet not without a twinkle
that justifies the lineage of the "canny Scot." He is approachable,
affable, genial, full of enthusiasm for his work, yet not taking it with
such undue seriousness as to rob him of human interest--in a word, the
type of a man of science as one would picture him in imagination, and
would hope, with confident expectation, to find him in reality.

I have said that the equipment of the college is somewhat primitive, but
this must not be taken too comprehensively. Such instances as that
of the beer-cask show, to be sure, an adaptation of means to ends on
economical lines; yet, on the other hand, it should not be forgotten
that the beer-cask serves its purpose admirably; and, in a word, it may
be said that Professor Ramsay's laboratory contains everything that
is needed to equip it fully for the special work to which it has been
dedicated for some years past. In general, it looks like any other
laboratory--glass tubes, Bunsen burners, retorts and jars being in
more or less meaningless tangles; but there are two or three bits of
apparatus pretty sure to attract the eye of the casual visitor which
deserve special mention. One of these is a long, wooden, troughlike
box which extends across the room near the ceiling and is accessible by
means of steps and a platform at one end. Through this boxlike tube the
chief expert in spectroscopy (Dr. Bay-ley) spies on the spectrum of
the gas, and learns some of its innermost secrets. But an even more
mystifying apparatus is an elaborate array of long glass tubes, some of
them carried to the height of several feet, interspersed with cups of
mercury and with thermometers of various sizes and shapes. The technical
scientist would not make much of this description, but neither would an
untechnical observer make much of the apparatus; yet to Dr. Travers, its
inventor, it is capable of revealing such extraordinary things as the
temperature of liquid hydrogen--a temperature far below that at which
the contents of even an alcoholic thermometer are solidified; at which,
indeed, the prime constituents of the air suffer a like fate. The
responsible substance which plays the part of the familiar mercury, or
alcohol, in Dr. Travers's marvellous thermometer is hydrogen gas.
The principle by which it is utilized does not differ, in its rough
essentials, from that of ordinary thermometers, but the details of its
construction are much too intricate to be elaborated here.

But if you would see the most wonderful things in this laboratory--or
rather, to be quite accurate, I should say, if you would stand in the
presence of the most wonderful things--you must go with Professor
Ramsay to his own private laboratory, and be introduced to some little
test-tubes that stand inverted in cups of mercury decorating a shelf at
one end. You would never notice these tubes of your own accord were
you to browse ever so long about the room. Even when your attention
is called to them you still see nothing remarkable. These are ordinary
test-tubes inverted over ordinary mercury. They contain something, since
the mercury does not rise in them completely, but if that something be
other than ordinary air there is nothing about its appearance, or rather
lack of appearance, to demonstrate it. But your interest will hardly
fail to be arrested when Professor Ramsay, indicating one and another of
these little tubes, says: "Here you see, or fail to see, all the krypton
that has ever been in isolated existence in the world, and here all the
neon, and here, again, all the zenon."

You will understand, of course, that krypton, neon, and zenon are the
new gases of the atmosphere whose existence no one suspected until
Professor Ramsay ferreted them out a few years ago and isolated them. In
one sense there should be nothing mysterious about substances that every
air-breathing creature on the globe has been imbibing pretty constantly
ever since lungs came into fashion. But in another view the universal
presence of these gases in the air makes it seem all the more wonderful
that they could so long have evaded detection, considering that
chemistry has been a precise science for more than a century. During
that time thousands of chemists have made millions of experiments in the
very midst of these atmospheric gases, yet not one of the experimenters,
until recently, suspected their existence. This proves that these gases
are no ordinary substances--common though they be. Personally I have
examined many scientific exhibits in many lands, but nowhere have I seen
anything that filled my imagination with so many scientific visions as
these little harmless test-tubes at the back of Professor Ramsay's desk.
Perhaps I shall attempt to visualize some of these imaginings before
finishing this paper, but for the moment I wish to speak of the _modus
operandi_ of the discovery of these additions to the list of elements.

The discovery of argon came about in a rather singular way. Lord
Rayleigh, of the Royal Institution, had noticed in experiments with
nitrogen that when samples of this element were obtained from chemicals,
such samples were uniformly about one per cent, lighter in weight
than similar quantities of nitrogen obtained from the atmosphere.
This discrepancy led him to believe that the atmospheric nitrogen must
contain some impurity.

Curiously enough, the experiments of Cavendish, the discoverer of
nitrogen--experiments made more than a century ago--had seemed to show
quite conclusively that some gaseous substance different from nitrogen
was to be found mixed with the samples of this gas as he obtained it
from the atmosphere. This conclusion of Cavendish, put forward indeed
but tentatively, had been quite ignored by his successors. Now,
however, it transpired, by experiments made jointly by Lord Rayleigh
and Professor Ramsay, that the conclusion was quite justified, it being
shown presently that there actually exists in every portion of nitrogen,
as extracted from the atmosphere, a certain quantity of another gas,
hitherto unknown, and which now received the name of argon. It will
be recalled with what astonishment the scientific and the unscientific
world alike received the announcement made to the Royal Society in 1895
of the discovery of argon, and the proof that this hitherto unsuspected
constituent of the atmosphere really constitutes about one per cent, of
the bulk of atmospheric nitrogen, as previously estimated.

The discovery here on the earth of a substance which Professor Lockyer
had detected as early as 1868 in the sun, and which he had provisionally
named helium, excited almost equal interest; but this element was found
in certain minerals, and not as a constituent of the atmosphere.

Having discovered so interesting a substance as argon, Professor
Ramsay and his assistants naturally devoted much time and attention to
elucidating the peculiarities of the new substance. In the course of
these studies it became evident to them that the presence of argon alone
did not fully account for all the phenomena they observed in handling
liquefied air, and in 1898 Professor Ramsay was again able to electrify
his audience at the Royal Society by the announcement of the discovery,
in pretty rapid succession, of three other elementary substances as
constituents of the atmosphere, these three being the ones just referred
to--krypton, neon, and zenon.

It is a really thrilling experience, standing in the presence of the
only portions of these new substances that have been isolated, to hear
Professor Ramsay and Dr. Travers, his chief assistant, tell the story
of the discovery--how they worked more and more eagerly as they found
themselves, so to say, on a "warmer scent," following out this clew
and that until the right one at last brought the chase to a successful
issue. "It was on a Sabbath morning in June, if I remember rightly,
when we finally ran zenon down," says Dr. Travers, with a half smile;
and Professor Ramsay, his eyes twinkling at the recollection of this
very unorthodox procedure, nods assent. "And have you got them all
now?" I queried, after hearing the story. "Yes; we think so," replied
Professor Ramsay. "And I am rather glad of it," he adds, with a half
sigh, "for it was wearisome even though fascinating work." Just how
wearisome it must have been only a professional scientific investigator
can fully comprehend; but the fascination of it all may be comprehended
in some measure by every one who has ever attempted creative work of
whatever grade or in whatever field.

I have just said that the little test-tubes contain the only bit of
each of the substances named that has ever been isolated. This statement
might lead the untechnical reader to suppose that these substances, once
isolated, have been carefully stored away and jealously guarded, each
in its imprisoning test-tubes. Jealously guarded they have been, to be
sure, but there has not been, by any means, the solitary confinement
that the words might seem to imply. On the contrary, each little whiff
of gas has been subjected to a variety of experiments--made to pass
through torturing-tubes under varying conditions of temperature, and
brought purposely in contact with various other substances, that its
physical and chemical properties might be tested. But in each case the
experiment ended with the return of the substance, as pure as before, to
its proper tube. The precise results of all these experiments have been
communicated to the Royal Society by Professor Ramsay. Most of these
results are of a technical character, hardly appealing to the average
reader. There is one very salient point, however, in regard to which all
the new substances, including argon and helium, agree; and it is that
each of them seems to be, so far as present experiments go, absolutely
devoid of that fundamental chemical property, the power to combine with
other elements. All of them are believed to be monatomic--that is
to say, each of their molecules is composed of a single atom. This,
however, is not an absolutely novel feature as compared with other
terrestrial elements, for the same thing is true, for example, of such a
familiar substance as mercury. But the incapacity to enter into chemical
combinations seems very paradoxical; indeed it is almost like saying
that these are chemical elements which lack the most fundamental of
chemical properties.

It is this lack of combining power, of course, that explains the
non-discovery of these elements during all these years, for the
usual way of testing an element is to bring it in contact with other
substances under conditions that permit its atoms to combine with
other atoms to the formation of new substances. But in the case of new
elements such experiments as this have not proved possible under any
conditions as yet attained, and reliance must be had upon other physical
tests--such as variation of the bulk of the gas under pressure, and
under varying temperatures, and a study of the critical temperatures
and pressures under which each gas becomes a liquid. The chief reliance,
however, is the spectroscope--the instrument which revealed the presence
of helium in the sun and the stars more than a quarter of a century
before Professor Ramsay ferreted it out as a terrestrial element.
Each whiff of colorless gas in its test-tube interferes with the light
passing through it in such a way that when viewed through a prism it
gives a spectrum of altogether unique lines, which stamp it as krypton,
neon, or zenon as definitely as certain familiar and more tangible
properties stamp the liquid which imprisons it as mercury.


QUERIES SUGGESTED BY THE NEW GASES

Suppose that a few years ago you had asked some chemist, "What are the
constituents of the atmosphere?" He would have responded, with entire
confidence, "Oxygen and nitrogen chiefly, with a certain amount of
water-vapor and of carbonic-acid gas and a trace of ammonia." If
questioned as to the chief properties of these constituents, he would
have replied, with equal facility, that these are among the most
important elements; that oxygen might almost be said to be the
life-giving principle, inasmuch as no air-breathing creature could get
along without it for many moments together; and that nitrogen is equally
important to the organism, though in a different way, inasmuch as it is
not taken up through the lungs. As to the water-vapor, that, of course,
is a compound of oxygen and hydrogen, and no one need be told of its
importance, as every one knows that water makes up the chief bulk of
protoplasm; carbonic-acid gas is also a compound of oxygen, the other
element this time being carbon, and it plays a quite different rôle in
the economy of the living organism, inasmuch as it is produced by the
breaking down of tissues, and must be constantly exhaled from the lungs
to prevent the poisoning of the organism by its accumulation; while
ammonia, which exists only in infinitesimal quantities in the air, is a
compound of nitrogen and hydrogen, introducing, therefore, no new
element.

If one studies somewhat attentively the relation which these elements
composing the atmosphere bear to the living organism he cannot fail to
be struck with it; and it would seem a safe inductive reasoning from the
stand-point of the evolutionist that the constituents of the atmosphere
have come to be all-essential to the living organism, precisely because
all their components are universally present. But, on the other hand,
if we consider the matter in the light of these researches regarding the
new gases, it becomes clear that perhaps the last word has not been said
on this subject; for here are four or five other elementary substances
which, if far less abundant than oxygen and nitrogen, are no less widely
distributed and universally present in the atmosphere, yet no one of
which apparently takes any chemical share whatever in ministering to the
needs of the living organism. This surely is an enigma.

Taking another point of view, let us try to imagine the real status of
these new gases of the air. We think of argon as connected with nitrogen
because in isolation experiments it remains after the oxygen has been
exhausted, but in point of fact there is no such connection between
argon and nitrogen in nature. The argon atom is just as closely in
contact with the oxygen in the atmosphere as with the nitrogen; it
simply repels each indiscriminately. But consider a little further;
the argon atom not only repels all advance on the part of oxygen and
nitrogen, but it equally holds itself aloof from its own particular
kindred atoms. The oxygen or nitrogen atom never rests until it has
sought out a fellow, but the argon atom declines all fellowship. When
the chemist has played his tricks upon it, it finds itself crowded
together with other atoms of the same kind; but lift up the little
test-tube and these scurry off from one another in every direction, each
losing its fellows forever as quickly as possible.

As one ponders this one is almost disposed to suggest that the atom of
argon (or of krypton, helium, neon, or zenon, for the same thing applies
to each and all of these) seems the most perfect thing known to us in
the world, for it needs no companionship, it is self-sufficing. There
is something sublime about this magnificient isolation, this splendid
self-reliance, this undaunted and undauntable self-sufficiency--these
are traits which the world is wont to ascribe to beings more than
mortal. But let us pause lest we push too far into the old, discredited
territory of metaphysics.


PROFESSOR J. J. THOMPSON AND THE NATURE OP ELECTRICITY

Many fascinating questions suggest themselves in connection with these
strange, new elements--new, of course, only in the sense of human
knowledge--which all these centuries have been about us, yet which have
managed until now to keep themselves as invisible and as intangible as
spirits. Have these celibate atoms remained thus always isolated, taking
no part in world-building? Are they destined throughout the sweep of
time to keep up this celibate existence? And why do these elements alone
refuse all fellowship, while the atoms of all the other seventy-odd
known elements seek out mates under proper conditions with unvarying
avidity?

It is perhaps not possible fully to answer these questions as yet, but
recent studies in somewhat divergent fields give us suggestive clews to
some of them. I refer in particular to the studies in reference to the
passage of electricity through liquids and gases and to the observations
on radioactivity. The most conspicuous worker in the field of
electricity is Professor J. J. Thompson, who for many years has had
charge of the Cavendish laboratory at Cambridge. In briefly reviewing
certain phases of his work we shall find ourselves brought into contact
with some of the same problems raised by workers in the other fields of
physics, and shall secure some very interesting bits of testimony as to
the solution of questions already outlined.

The line of observation which has led to the most striking results has
to do, as already suggested, with the conduction of electricity through
liquids and gases. It has long been known that many liquids conduct
electricity with relative facility. More recently it has been observed
that a charge of electricity carried by any liquid bears a curious
relation to the atomic composition of that liquid. If the atom in
question is one of the sort that can combine with only a single other
atom (that is to say, a monovalent atom), each atom conveys a unit
charge, which is spoken of as an ion of electricity. But if a divalent
atom is in question the charge carried is double, and, similarly, a
trivalent atom carries a triple charge. As there are no intermediate
charges it is obvious that here a very close relation is suggested
between electrical units and the atomic units of matter.

This, however, is only a beginning. Far more interesting are the results
obtained by the study of gases in their relation to the conduction
of electricity. As is well known, gases under ordinary conditions are
nonconductors. But there are various ways in which a gas may be changed
so as to become a conductor; for example, by contact with incandescent
metals or with flame, or by treating with ultra-violet light, with
Rôntgen rays, or with the rays of a radio-active substance. Now the
all-important question is as to just what change has taken place in the
gas so treated to make it a conductor of electricity. I cannot go into
details here as to the studies that have been addressed to the answer
of this question, but I will briefly epitomize what, for our present
purpose, are the important results. First and foremost of these is the
fact that a gas thus rendered conductive contains particles that can
be filtered out of it by passing the gas through wool or through water.
These particles are the actual agents of conduction of electricity,
since the gas when filtered ceases to be conductive. But there is
another way in which the particles may be removed--namely, by action
of electricity itself. If the gas be caused to pass between two metal
plates, one of them insulated and attached to an electrometer, a charge
of positive electricity at high potential sent through the other plate
will drive part of the particles against the insulated plate. This
proves that the particles in question are positively electrified.
The amount of the charge which they carry may be measured by the
electrometer.

The aggregate amount of the electrical charge carried by these minute
particles in the gas being known, it is obvious that could we know the
number of particles involved the simplest calculation would determine
the charge of each particle. Professor Thompson devised a singularly
ingenious method of determining this number. The method was based on
the fact discovered by C. T. R. Wilson that charged particles acted as
nuclei round which small drops of water condense much as dust particles
serve the same purpose. "In dust-free air," says Professor Thompson,
"as Aitken showed, it is very difficult to get a fog when damp air is
cooled, since there are no nuclei for the drops to condense round. If
there are charged particles in dust-free air, however, the fog will be
deposited round these by super-saturation far less than that required to
produce any appreciable fog when no charged particles are present.

"Thus, in sufficiently supersaturated damp air a cloud is deposited on
these charged particles and they are thus rendered visible. This is the
first step towards counting them. The drops are, however, far too small
and too numerous to be counted directly. We can, however, get their
number indirectly as follows: suppose we have a number of these
particles in dust-free air in a closed vessel, the air being saturated
with water-vapor; suppose now that we produce a sudden expansion of the
air in the vessel; this will cool the air, it will be supersaturated
with vapor, and drops will be deposited round the charged particles. Now
if we know the amount of expansion produced we can calculate the cooling
of the gas, and, therefore, the amount of water deposited. Thus we know
the volume of water in the form of drops, so that if we know the volume
of one drop we can deduce the number of drops. To find the size of a
drop, we make use of the investigations made by Sir George Stokes on the
rate at which small spheres fall through the air. In consequence of
the viscosity of the air small bodies fall exceedingly slowly, and the
smaller they are the slower they fall." *

Professor Thompson gives us the formula by which Stokes made his
calculation. It is a relatively simple algebraic one, but need not be
repeated here. For us it suffices that with the aid of this formula,
by merely measuring the actual descent of the top of a vapor cloud,
Professor Thompson was able to find the volume of the drops and thence
the number of particles. The number of particles being known, the
charge of electricity carried by each could be determined, as already
suggested. Experiments were made with air, hydrogen, and carbonic acid,
and it was found that the particles had the same charge in all of these
gases. "A strong argument," says Professor Thompson, "in favor of
the atomic character of electricity." When we add that the charge in
question was found to be the same as the unit charge of an ion in a
liquid, it will be seen that the experiment has other points of interest
and suggestiveness.

Even more interesting in some regards were the results of computation
as to the actual masses of the charged particles in question. Professor
Thompson found that the carrier of a negative charge could have only
about one-thousandth part of the mass of a hydrogen atom, which latter
had been regarded as the smallest mass able to have an independent
existence. Professor Thompson gave the name corpuscle to these units
of negative electricity; they are now more generally termed electrons.
"These corpuscles," he says, "are the same however the electrification
may have risen or wherever they may be found. Negative electricity in a
gas at a low pressure has thus a structure analogous to that of a gas,
the corpuscles taking the place of the molecules. The 'negative electric
fluid,' to use the old notation, resembles the gaseous fluid with a
corpuscular instead of a molecular structure.'" Professor Thompson does
not hesitate to declare that we now "know more about 'electric fluid'
than we know about such fluids as air or water."*3* The results of his
studies lead him, he declares, "to a view of electrification which
has a striking resemblance to that of Franklin's _One Fluid Theory of
Electricity_. Instead of taking, as Franklin did, the electric fluid
to be positive electricity," he says, "we take it to be negative. The
'electric fluid' of Franklin corresponds to an assemblage of corpuscles,
negative electrification being a collection of these corpuscles. The
transference of electrification from one place to another is effected
by the motion of corpuscles from the place where there is a gain of
positive electrification to the place where there is a gain of
negative. A positively electrified body is one that has lost some of its
corpuscles."*4* According to this view, then, electricity is not a form
of energy but a form of matter; or, to be more precise, the electrical
corpuscle is the fundamental structure out of which the atom of matter
is built. This is a quite different view from that scarcely less recent
one which regards electricity as the manifestation of ether strain,
but it must be admitted that the corpuscular theory is supported by a
marvellous array of experimental evidence, though it can perhaps hardly
be claimed that this brings the theory to the plane of demonstration.
But all roads of physical science of late years have seemed to lead
towards the electron, as will be made further manifest when we consider
the phenomena of radio-activity, to which we now turn.


RADIO-ACTIVITY

In 1896, something like a year after the discovery of the X-ray,
Niewenglowski reported to the French Academy of Sciences that the
well-known chemical compound calcium sulphide, when exposed to sunlight,
gave off rays that penetrated black paper. He had made his examinations
of this substance, since, like several others, it was known to exhibit
strong fluorescent or phosphorescent effects when exposed to the cathode
rays, which are known to be closely connected with the X-rays. This
discovery was followed very shortly by confirmatory experiments made by
Becquerel, Troost, and Arnold, and these were followed in turn by the
discovery of Le Bon, made almost simultaneously, that certain bodies
when acted upon by sunlight give out radiations which act upon a
photographic plate. These manifestations, however, are not the effect of
radio-activity, but are probably the effects of short ultra-violet
light waves, and are not produced spontaneously by the substances. The
radiations, or emanations, of the radio-active substances, on the other
hand, are given out spontaneously, pass through substances opaque to
ordinary light, such as metal plates, act upon photographic plates, and
discharge electrified bodies. The substances uranium, thorium, polonium,
radium, and their compounds are radioactive, radium being by far the
most active.

The first definite discovery of such a radio-active substance was made
by M. Henri Becquerel, in 1896, while making some experiments upon
the peculiar ore pitch-blende. Pitch-blende is a heavy, black,
pitchy-looking mineral, found principally at present in some parts of
Saxony and Bohemia on the Continent, in Cornwall in Great Britain, and
in Colorado in America. It is by no means a recently discovered mineral,
having been for some years the source of uranium and its compounds,
which, on account of their brilliant colors, have been used in
dye-stuffs and some kinds of stained glass. It is a complex mineral,
containing at least eight or ten elements, which can be separated from
it only with great difficulty and by complicated chemical processes.

Becquerers discovery was brought about by a lucky accident, although,
like so many other apparently accidental scientific discoveries, it was
the outcome of a long series of scientific experiments all trending in
the same direction. He had found that uranium, when exposed to the sun's
rays, appeared to possess the property of absorbing them and of then
acting upon a photographic plate. Since pitch-blende contained uranium,
or uranium salts, he surmised that a somewhat similar result might be
obtained with the ore itself. He therefore prepared a photographic plate
wrapped in black paper, intending to attempt making an impression on the
plate of some metal body interposed between it and the pitch-blende. For
this purpose he had selected a key; but as the day proved to be cloudy
he put the plate, with the key and pitch-blende resting upon it, in
a dark drawer in his desk, and did not return to the experiment for
several days. Upon doing so, however, he developed the plate without
further exposure, when to his astonishment he found that the developed
negative showed a distinct impression of the key. Clearly this was the
manifestation of a property heretofore unknown in any natural substance,
and was strikingly similar to the action of the Roentgen rays. Further
investigations by Lord Kelvin, Beattie, Smolan, and Rutherford confirmed
the fact that, like the Roentgen rays, the uranium rays not only acted
upon the photographic plate but discharged electrified bodies. And what
seemed the more wonderful was the fact that these "Becquerel rays," as
they were now called, emanated spontaneously from the pitch-blende.
But although this action is analogous to the Roentgen rays, at least as
regards its action upon the photographic plate and its influence on
the electric field, its action is extremely feeble in comparison, the
Roentgen rays producing effects in minutes, or even seconds, which
require days of exposure to uranium rays. The discovery of the
radio-active properties of uranium was followed about two years later by
the discovery that thorium, and the minerals containing thorium,
possess properties similar to those of uranium. This discovery was
made independently and at about the same time by Schmidt and Madame
Skaldowska Curie. But the importance of this discovery was soon
completely overshadowed by the discovery of radium by Madame Curie,
working with her husband, Professor Pierre Curie, at the École
Polytechnique in Paris. Madame Curie, stimulated by her own discoveries
and those of the other scientists just referred to, began a series of
examinations upon various substances by numerous complicated methods
to try and find a possible new element, as certain peculiarities of the
substances found in the pitch-blende seemed to indicate the presence of
some hitherto unknown body. The search proved a most difficult one
on account of the peculiar nature of the object in question, but the
tireless enthusiasm of Madame Curie knew nothing of insurmountable
obstacles, and soon drew her husband into the search with her. Her first
discovery was that of the substance polonium--so named by Madame Curie
after her native country, Poland. This proved to be another of the
radio-active substances, differing from any other yet discovered, but
still not the sought-for element. In a short time, however, the two
Curies made the great discovery of the element radium--a substance
which, according to their estimate, is some one million eight hundred
thousand times more radioactive than uranium. The name for this element,
_radium_, was proposed by Madame Curie, who had also suggested the term
"radio-activity."

The bearing of the discovery of radium and radioactivity upon theories
of the atom and matter will be considered in a moment; first the more
tangible qualities of this wonderful substance may be briefly referred
to. The fact that radio-active emanations traverse all forms of matter
to greater or less depth--that is, pass through wood and iron with
something the same ease that light passes through a window-glass--makes
the subject one of greatest interest; and particularly so as the
demonstration of this fact is so tangible. While the rays given out by
radium cannot, of course, be seen by the unaided eye, the effects of
these rays upon certain substances, which they cause to phosphoresce,
are strikingly shown. One of such substances is the diamond, and a
most striking illustration of the power of radium in penetrating opaque
substances has been made by Mr. George F. Kunz, of the American Museum
of Natural History. Mr. Kunz describes this experiment as follows:

"Radium bromide of three hundred thousand activity was placed in a
sealed glass tube inside a rubber thermometer-holder, which was tightly
screwed to prevent any emanation of any kind from passing through the
joints. This was placed under a heavy silver tureen fully one-sixteenth
of an inch in thickness; upon this were placed four copper plates, such
as are used for engraving; upon these a heavy graduated measuring-glass
10 cm. in diameter; this was filled with water to a depth of six inches.
A diamond was suspended in the water and immediately phosphoresced.
Whenever the tube of radium was drawn away more than two or three feet
the phosphoresce ceased; whenever it was placed under the tureen the
diamond immediately phosphoresced again. This experiment proves that the
active power of the radium penetrated the following substances:

"Glass in the form of a tube, sealed at both ends; the rubber
thermometer-holder; silver tureen; four copper plates; a glass vase or
measuring-glass one-quarter of an inch in thickness; three inches of
water. There is no previously known substance or agent, whether it be
even light or electricity, that possesses such wonderfully penetrative
powers."*5*


THE NATURE OF EMANATIONS FROM RADIO-ACTIVE BODIES

What, then, is the nature of these radiations? Are they actually
material particles hurled through the ether? Or are they like light--and
possibly the Roentgen rays--simply undulations in the ether? As yet this
question is an open one, although several of the leading investigators
have postulated tentative hypotheses which at least serve as a working
basis until they are either confirmed or supplanted. On one point,
however, there seems to be unanimity of opinion--there seems to be
little question that there are at least three different kinds of rays
produced by radio-active substances. According to Sir William Crookes,
the first of these are free electrons, or matter in an ultra-gaseous
state, as shown in the cathode stream. These particles are extremely
minute. They carry a negative charge of electricity, and are identified
with the electric corpuscles of Thompson. Rays of the second kind are
comparable in size to the hydrogen atom, and are positively electrified.
These are easily checked by material obstructions, although they render
the air a conductor and affect photographic plates. The third are very
penetrating rays, which are not deflected by electricity and which are
seemingly identical with Roentgen rays. Professor E. Rutherford has
named these rays beta (B), alpha (a), and gamma (v) rays respectively.
Of these the beta rays are deviated strongly by the magnetic field, the
alpha much less so--very slightly, in fact--while the gamma rays are not
affected at all. The action of these three different sets of rays upon
certain substances is not the same, the beta and gamma rays acting
strongly upon barium platinocyanide, but feebly on Sidot's blende,
while the alpha rays act exactly the reverse of this, acting strongly on
Sidot's blende.

If a surface is coated with Sidot's blende and held near a piece of
radium nitrate, the coated surface begins to glow. If now it is examined
with a lens, brilliant sparks or points can be seen. As the radium is
brought closer and closer these sparks increase in number, until, as Sir
William Crookes says, we seem to be witnessing a bombardment of flying
atoms hurled from the radium against the surface of the blende. A little
instrument called a spinthariscope, devised by Dr. Crookes and on sale
at the instrument and optical-goods shops, may be had for a trifling
sum. It is fitted with a lens focused upon a bit of Sidot's blende and
radium nitrate, and in a dark room shows these beautiful scintillations
"like a shower of stars." A still less expensive but similar device
is now made in the form of a microscopic slide, to be used with the
ordinary lens.

As we said a moment ago, radium appears to be an elementary substance,
as shown by its spark-spectrum being different from that of any other
known substance--the determinative test as fixed by the International
Chemical Congress. A particle of radium free from impurities should,
therefore, according to the conventional conception of an element,
remain unchanged and unchangeable. If any such change did actually take
place it would mean that the conception of the Daltonian atom as
the ultimate particle of matter is definitively challenged from a new
direction. This is precisely what has taken place. In July of 1903 Sir
William Ramsay and Mr. Soddy, in making some experiments with radium,
saw produced, apparently from radium emanations, another quite different
and distinct substance, the element helium. The report of such a
revolutionary phenomenon was naturally made with scientific caution.
Though the observation seemed to prove the actual transformation of one
element into another, Professor Ramsay himself was by no means ready to
declare the absolute certainty of this. Yet the presumption in favor
of this interpretation of the observed phenomena is very strong; and so
cautious a reasoner as Professor Rutherford has declared recently that
"there can be no doubt that helium is derived from the emanations of
radium in consequence of changes of some kind occurring in it."*6*

"In order to explain the presence of helium in radium on ordinary
chemical lines," says Professor Rutherford, "it has been suggested that
radium is not a true element, but a molecular compound of helium with
some substance known or unknown. The helium compound gradually breaks
down, giving rise to the helium observed. It is at once obvious that
this postulated helium compound is of an entirely different character to
any other compound previously observed in chemistry. Weight for weight,
it emits during its change an amount of energy at least one million
times greater than any molecular compound known. In addition, it must
be supposed that the rate of breaking up of the helium compound is
independent of great ranges of temperature--a result never before
observed in any molecular change. The helium compound in its breaking
up must give rise to the peculiar radiations and also pass through the
successive radio-active change observed in radium.... On the other
hand, radium, as far as it has been examined, has fulfilled every
test required of an element. It has a well-marked and characteristic
spectrum, and there is no reason to suppose that it is not an element in
the ordinarily accepted sense of the term."*7*


THE SOURCE OF ENERGY OF RADIO-ACTIVITY

In 1903 Messrs. Curie and Laborde*8* made the remarkable announcement
that a crystal of radium is persistently warmer than its surrounding
medium; in other words, that it is perpetually giving out heat without
apparently becoming cooler. At first blush this seemed to contradict the
great physical law of the conservation of energy, but physicists were
soon agreed that a less revolutionary explanation of the phenomenon is
perfectly tenable. The giving off of heat is indeed only an additional
evidence of the dissipation of energy to which the radio-active atom
is subjected. And no one now believes that radio-activity can persist
indefinitely without actually exhausting the substance of the atom. Even
so, the evidence of so great a capacity to give out energy is startling,
and has given rise to various theories (all as yet tentative) in
explanation. Thus J. Perrin*9* has suggested that atoms may consist of
parts not unlike a miniature planetary system, and in the atoms of the
radio-elements the parts more distant from the centre are continually
escaping from the central attraction, thus giving rise to the
radiations. Monsieur and Madame Curie have suggested that the energy may
be borrowed from the surrounding air in some way, the energy lost by
the atom being instantly regained. Pilipo Re,*10* in 1903, advanced the
theory that the various parts of the atom might at first have been free
particles constituting an extremely tenuous nebula.

These parts gradually becoming collected around condensed centres have
formed what we know as the atoms of elements, the atom thus becoming
like an extinct sun of the solar system. From this point of view the
radio-active atoms represent an intermediate stage between nebulae
and chemical atoms, the process of contraction giving rise to the heat
emissions.

Lord Kelvin has called attention to the fact that when two pieces of
paper, one white and the other black, are placed in exactly similar
glass vessels of water and exposed to light, the temperature of the
vessel containing the black paper is raised slightly higher than the
other. This suggests the idea that in a similar manner radium may keep
its temperature higher than the surrounding air by the absorption of
other radiations as yet unknown.

Professor J. J. Thompson believes that the source of energy is in the
atom itself and not external to it. "The reason," he says, "which
induces me to think that the source of the energy is in the atom of
radium itself and not external to it is that the radio-activity of
substances is in all cases in which we have been able to localize it a
transient property. No substance goes on being radio-active very long.
It may be asked, how can this statement be reconciled with the fact
that thorium and radium keep up their activity without any appreciable
falling off with time. The answer to this is that, as Rutherford and
Soddy have shown in the case of thorium, it is only an exceedingly small
fraction of the mass which is at any one time radio-active, and that
this radio-active portion loses its activity in a few hours, and has to
be replaced by a fresh supply from the non-radio-active thorium."*11*

If Professor Thompson's view be correct, the amount of potential energy
inherent in the atom must be enormous.


RADIO-ACTIVITY AND THE STRUCTURE OF THE ATOM

But whatever the source of the energy displayed by the radio-active
substances, it is pretty generally agreed that the radio-activity of
the radio-elements results in the disruption of their atoms. Since all
substances appear to be radio-active in a greater or less degree,
it would seem that, unless there be a very general distribution
of radio-active atoms throughout all substances, all atoms must be
undergoing disruption. Since the distribution of radio-active matter
throughout the earth is so great, however, it is as yet impossible to
determine whether this may not account for the radio-activity of all
substances.

As we have just seen, recent evidence seems to point to the cause of the
disruption of radio-active atoms as lying in the atoms themselves. This
view is quite in accord with modern ideas of the instability of certain
atoms. It has been suggested that some atoms may undergo a slower
disintegration without necessarily throwing off part of their systems
with great velocity. It is even possible that all matter may be
undergoing transformation, this transformation tending to simplify
and render more stable the constituents of the earth. The radio-active
bodies, however, are the only ones that have afforded an opportunity for
studying this transformation. In these the rapidity of the change would
be directly proportionate to their radioactivity. Radium, according
to the recent estimate of the Curies, would be disintegrating over
a million times more rapidly than uranium. Since the amount of
transformation occurring in radium in a year amounts to from 1-2000
to 1-10,000 of the total amount, the time required for the complete
transformation of an atom of uranium would be somewhere between two
billion and ten billion years--figures quite beyond the range of human
comprehension.

Various hypotheses have been postulated to account for the instability
of the atom. Perhaps the most thinkable of these to persons not
specially trained in dealing with abstruse subjects is that of Professor
Thompson. It has the additional merit, also, of coming from one of the
best-known investigators in this particular field. According to this
hypothesis the atom may be considered as a mass of positively and
negatively charged particles, all in rapid motion, their mutual forces
holding them in equilibrium. In case of a very complex structure of
this kind it is possible to conceive of certain particles acquiring
sufficient kinetic energy to be projected from the system. Or the
constraining forces may be neutralized momentarily, so that the particle
is thrown off at the same velocity that it had acquired at the instant
it is released. The primary cause of this disintegration of the atom
may be due to electro-magnetic radiation causing loss of energy of the
atomic system.

Sir Oliver Lodge suggests that this instability of the atom may be the
result of the atom's radiation of energy. "Lodge considered the simple
case of a negatively charged electron revolving round an atom of
mass relatively large but having an equal positive charge and held in
equilibrium by electrical forces. This system will radiate energy, and
since the radiation of energy is equivalent to motion in a resisting
medium, the particle tends to move towards the centre and its speed
consequently increases. The rate of radiation of energy will increase
rapidly with the speed of the electron. When the speed of the electron
becomes very nearly equal to the velocity of light, according to Lodge,
the system is unstable. It has been shown that the apparent mass of an
electron increases very rapidly as the speed of light is approached, and
is theoretically infinite at the speed of light. There will be at this
stage a sudden increase of the mass of the revolving atom, and, on the
supposition that this stage can be reached, a consequent disturbance of
the balance of forces holding the system together. Lodge considers it
probable that under these conditions the parts of the system will break
asunder and escape from the sphere of one another's influence.

"It is probable," adds Rutherford, "that the primary cause of the
disintegration of the atom must be looked for in the 1 ss of energy of
the atomic system due to electro-magnetic radiation."*12*

Several methods have been devised for testing the amount of heat given
off by radium and its compounds, and for determining its actual rise
in temperature above that of the surrounding atmosphere. One of these
methods is to place some substance, such as barium chloride, in a
calorimeter, noting at what point the mercury remains stationary. Radium
is then introduced, whereupon the mercury in the tube gradually rises,
falling again when the radium is removed. By careful tests it has
been determined that a gram of radium emits about twenty-four hundred
gram-calories in twenty-four hours. On this basis a gram of radium in a
year emits enough energy to dissociate about two hundred and twenty-five
grams of water.

What seems most remarkable about this constant emission of heat by the
radium atom is that it does not apparently draw upon external sources
for it, but maintains it by the internal energy of the atom itself. This
latent energy must be enormous, but is only manifested when the atom
is breaking up. In this process of disruption many of the particles are
thrown off; but the greater part seem to be stopped in their flight in
the radium itself, so that their energy of motion is manifested in the
form of heat. Thus, if this explanation is correct, the temperature of
the radium is maintained above that of surrounding substances by the
bombardment of its own particles. Since the earth and the atmosphere
contain appreciable quantities of radio-active matter, this must play
a very important part in determining the temperature of the globe--so
important a part, indeed, that all former estimates as to the probable
length of time during which the earth and sun will continue to radiate
heat are invalidated. Such estimates, for example, as that of Lord
Kelvin as to the probable heat-giving life of the sun must now be
multiplied from fifty to five hundred times.

In like manner the length of time that the earth has been sufficiently
cool to support animal and vegetable life must be re-estimated. Until
the discovery of radium it seemed definitely determined that the earth
was gradually cooling, and would continue to cool, un til, like the
moon, it would become too cold to support any kind of vegetable or
animal life whatever. But recent estimates of the amount of radio-active
matter in the earth and atmosphere, and the amount of heat constantly
given off from this source, seem to indicate that the loss of heat
is (for the moment) about evenly balanced by the heat given out by
radio-active matter. Thus at the beginning of the new century we see
the phenomenon of a single discovery in science completely overturning
certain carefully worked out calculations, although not changing the
great principles involved. It is but the repetition of the revolutionary
changes that occur at intervals in the history of science, a simple
discovery setting at naught some of the most careful calculations of a
generation.



V. THE MARINE BIOLOGICAL LABORATORY AT NAPLES


THE AQUARIUM

MANY tourists who have gone to Naples within recent years will recall
their visit to the aquarium there among their most pleasant experiences.
It is, indeed, a place worth seeing. Any Neapolitan will direct you to
the beautiful white building which it occupies in the public park close
by the water's side. The park itself, statue-guarded and palm-studded,
is one of the show-places of the city; and the aquarium building,
standing isolated near its centre, is worthy of its surroundings. As
seen from the bay, it gleams white amid the half-tropical foliage,
with the circling rampart of hills, flanked by Vesuvius itself, for
background. And near at hand the picturesque cactus growth scrambling
over the walls gives precisely the necessary finish to the otherwise
rather severe type of the architecture. The ensemble prepares one to be
pleased with whatever the structure may have to show within.

It prepares one also, though in quite another way, for a surprise; for
when one has crossed the threshold and narrow vestibule, while the gleam
of the outside brightness still glows before his eyes, he is plunged
suddenly into what seems at first glimpse a cavern of Egyptian darkness,
and the contrast is nothing less than startling. To add to the effect,
one sees all about him, near the walls of the cavern, weird forms of
moving creatures, which seem to be floating about lazily in the air, in
grottos which glow with a dim light or sparkle with varied colors. One
is really looking through glass walls into tanks of water filled with
marine life; but both glass and water are so transparent that it is
difficult at first glimpse to realize their presence, unless a stream of
water, with its attendant bubbles, is playing into the tanks. And even
then the effect is most elusive; for the surface of the water, which
you are looking up to from below, mirrors the contents of the tanks so
perfectly that it is difficult to tell where the reality ends and the
image begins, were it not that the duplicated creatures move about with
their backs downward in a scene all topsy-turvy. The effect is most
fantastic.

More than that, it is most beautiful as well. You are, in effect, at the
bottom of the ocean--or rather, at the bottom of many oceans in one. No
light comes to you except through the grottos about you--grottos haunted
by weird forms of the deep, from graceful to grotesque, from almost
colorless to gaudy-hued. To your dilated pupils the light itself has
the weird glow of unreality. It is all like the wonders of the Arabian
Nights made tangible or like a strange spectacular dream. If one were in
a great diving-bell at the bottom of the veritable ocean he could hardly
feel more detached from the ordinary aerial world of fact.

As one recovers his senses and begins to take definite note of things
about him he sees that each one of the many grottos has a different set
of occupants, and that not all of the creatures there are as unfamiliar
as at first they seemed. Many of the fishes, for example, and the
lobsters, crabs, and the like, are familiar enough under other
conditions, but even these old acquaintances look strange under these
changed circumstances. But for the rest there are multitudes of forms
that one had never seen or imagined, for the sea hides a myriad of
wonders which we who sail over its surface, and at most glance dimly
a few feet into its depths, hardly dream of. Even though one has seen
these strange creatures "preserved" in museums, he does not know
them, for the alleged preservation there has retained little enough of
essential faciès of the real creature, which the dead shell can no more
than vaguely suggest.

Here, however, we see the real thing. Each creature lives and moves in a
habitat as nearly as may be like that which it haunted when at
liberty, save that tribes that live at enmity with one another are here
separated, so that the active struggle for existence, which plays
so large a part in the wild life of sea as well as land, is not
represented. For the rest the creatures of the deep are at home in these
artificial grottos, and disport themselves as if they desired no other
residence. For the most part they pay no heed whatever to the human
inspectors without their homelike prisons, so one may watch their
activities under the most favorable conditions.

It is odd to notice how curiously sinuous are all the movements, not
alone of the fish, but of a large proportion of the other forms of
moving life of the waters. The curve, the line of beauty, is the symbol
of their every act; there are no angles in their world. They glide
hither and yon, seemingly without an effort, and always with wavy,
oscillating gracefulness. The acme of this sinuosity of movement is
reached with those long-drawn-out fishes the eels. Of these there are
two gigantic species represented here--the conger, a dark-skinned,
rather ill-favored fellow, and the beautiful Italian eel, with a
velvety, leopard-spotted skin. These creatures are gracefulness itself.
They are ribbon-like in tenuousness, and to casual glance they give the
impression of long, narrow pennants softly waving in a gentle breeze.
The great conger--five or six feet in length--has, indeed, a certain
propensity to extend himself rigidly in a fishlike line and lie
immovable, but the other species is always true to his colors, so to
say--his form is always outlined in curves.

The eels attract their full share of attention from the visitors, but
there is one family of creatures which easily holds the palm over all
the others in this regard. These are the various representatives of the
great cult of squids and cuttle-fishes. The cuttle-fish proper--who,
of course, is no fish at all--is shaped strangely like a diminutive
elephant, with a filmy, waving membrane along its sides in lieu of legs.
Like the other members of his clan, he can change his color variously.
Sometimes he is of a dull brown, again prettily mottled; then, with
almost kaleidoscopic suddenness, he will assume a garb beautifully
striped in black and white, rivalled by nothing but the coat of the
zebra. The cuttle-fish is a sluggish creature, seeking out the darker
corners of his grotto, and often lying motionless for long periods
together. But not so the little squid. He does not thrive in captivity,
and incessantly wings his way back and forth, with slow, wavy
flappings of his filmy appendages, until he wears himself out and dies
unreconciled.

In marked contrast with both cuttle-fish and squid is their cousin the
octopus--a creepy, crawly creature, like eight serpents in one--at once
the oddest and the most fascinating creature in the entire aquarium. You
will find a crowd almost always before his grotto watching his curious
antics. Usually slow and deliberate in movement, he yet has capacity
for a certain agility. Now and again he dives off suddenly, head first,
through the water, with the directness if not quite with the speed of an
arrow. A moment later, tired of his flight, he sprawls his eight webbed
legs out in every direction, breaking them seemingly into a thousand
joints, and settles back like an animated parachute awreck. Then
perchance he perches on a rock knowingly, with the appearance of
owl-like wisdom, albeit his head looks surprisingly like a frog's. Anon
he holds his head erect and stretches out his long arms in what is most
palpably a yawn. Then, for pure diversion, he may hold himself
half erect on his umbrella frame of legs and sidle along a sort of
quadrille--a veritable "eight hands in round."

But all the while he conveys distinctly the impression of a creature to
the last degree blasé. Even when a crab is let down into his grotto by
an attendant for the edification of the visitors the octopus seems to
regard it with only lukewarm interest. If he deigns to go in pursuit,
it is with the air of one who says, "Anything to oblige," rather than
of eagerness for a morsel of food. Yet withal, even though unhurried,
he usually falls upon the victim with surprising sureness of aim,
encompassing it in his multiform net. Or perhaps, thinking the game
hardly worth so much effort, he merely reaches out suddenly with one
of his eight arms--each of which is a long-drawn-out hand as well--and
grasps the victim and conveys it to his distensible maw without so much
as changing his attitude.

All this of the giant octopus--brown and warty and wrinkled and blasé.
But the diminutive cousin in the grotto with the jellyfishes is a bird
of quite another feather. Physically he is constructed on the same model
as the other, but his mentality is utterly opposed. No grand rôles for
him; his part is comedy. He finds life full of interest. He is satisfied
with himself and with the world. He assumes an aspect of positive
rakishness, and intelligence, so to say, beams from his every limb. All
day long he must be up and doing. For want of better business he will
pursue a shrimp for hours at a time with the zest of a true sportsman.
Now he darts after his intended prey like a fox-hound. Again he resorts
to finesse, and sidles off, with eyes fixed in another direction, like
a master of stratagem. To be sure, he never catches the shrimp--but what
of that? The true sportsman is far removed from the necessity for mere
material profit. I half suspect that little octopus would release the
shrimp if once he caught him, as the true fisherman throws back the
excess of his catch. It is sport, not game, that he covets.


THE LABORATORY AND ITS FOUNDER

When one has made the circuit of the aquarium he will have seen and
marvelled at some hundreds of curious creatures utterly unlike anything
to be found above water. Brightly colored starfishes, beautiful
sea-urchins, strange stationary ascidians, and flower-like sea-anemones,
quaint sea-horses, and filmy, fragile jellyfishes and their multiform
kin--all seem novel and wonderful as one sees them in their native
element. Things that appear to be parts of the rocky or sandy bed of the
grottos startle one by moving about, and thus discovering themselves
as living creatures, simulating their environment for purposes of
protection. Or perhaps what seems to be a giant snail suddenly unfurls
wings from its seeming shell, and goes waving through the water, to the
utter bewilderment of the beholder. Such freaks as this are quite
the rule among the strange tribes of the deep, for the crowding of
population there makes the struggle for existence keen, and necessitates
all manner of subterfuges for the preservation of species.

Each and every one of the thirty-odd grottos will repay long
observation, even on the part of the most casual visitor, and when one
has seen them all, he will know more at first hand of the method of life
of the creatures of the sea than all the books could teach him. He will
depart fully satisfied, and probably, if he be the usual sight-seer,
he will never suspect that what he has seen is really but an incidental
part of the institution whose building he has entered. Even though he
note casually the inscription "Stazione Zoôlogica" above the entrance,
he may never suspect that the aquarium he has just visited is only an
adjunct--the popular exhibit, so to speak--of the famous institution
of technical science known to the English-speaking world as the Marine
Biological Laboratory at Naples. Yet such is the fact. The aquarium
seems worthy enough to exist by and for itself. It is a great popular
educator as well as amuser, yet its importance is utterly insignificant
compared with the technical features of the institution of which it is
an adjunct.

This technical department, the biological laboratory proper, has its
local habitation in the parts of the building not occupied by the
aquarium--parts of which the general public, as a rule, sees nothing.
There is, indeed, little to see that would greatly interest the casual
inspector, for in its outward aspects one laboratory is much like
another, a seeming hodgepodge of water-tanks, glass jars of specimens,
and tables for microscopes. The real status of a laboratory is not
determined by the equipment.

And yet it will not do to press this assertion too far, for in one sense
it is the equipment of the Naples laboratory that has made it what it
is. Not, however, the equipment in the sense of microscopes and other
working paraphernalia. These, of course, are the best of their kind, but
machinery alone does not make a great institution, any more than
clothes make the man. The all-essential and distinctive equipment of
the laboratory reveals itself in its personnel. In the present case, as
always in a truly great institution of any kind, there is one dominating
personality, one moving spirit. This is Dr. Anton Dohrn, founder of the
laboratory, and still its controller and director, in name and in fact.

More than twenty-five years ago Dr. Dohrn, then a young man fresh from
the universities of his native Germany, discovered what he felt to be
a real need in the biological world. He was struck with the fact that
nowhere in the world could be found an establishment affording good
opportunities for the study of marine life. Water covers three-fifths of
the earth's surface, as everybody knows, and everywhere this water teems
with life, so that a vast preponderance of the living things of the
globe find their habitat there. Yet the student who might desire to make
special studies of this life would find himself balked at the threshold
for want of opportunity.

It was no great thing to discover this paucity, which, indeed, fairly
beckoned the discoverer. The great thing was to supply the deficiency,
and this was what Dr. Dohrn determined to do. He selected Naples as the
best location for the laboratory he proposed to found, because of its
climate and its location beside the teeming waters of the Mediterranean.
He organized a laboratory; he called about him a corps of able
assistants; he made the Marine Biological Laboratory at Naples famous,
the Mecca of all biological eyes throughout the world. It was not all
done in a day. It was far enough from being done without opposition and
discouragement; but these are matters of history which Dr. Dohrn now
prefers not to dwell upon. Suffice it that the result aimed at was
finally achieved, and in far greater measure than could at first be
hoped for.

And from that day till this Naples has been the centre of that branch
of biological inquiry which has for its object the investigation of
problems best studied with material gathered from the sea. And this,
let me hasten to add, includes far more than a mere study of the life
histories of marine animals and plants as such. It includes problems of
cell activity, problems of heredity, life problems of many kinds, having
far wider horizons than the mere question as to how a certain fish or
crustacean lives and moves and has its being.

Dr. Dohrn's chief technical associates are all Germans, like their
leader, but, like him also, all gifted with a polyglot mastery of
tongues that has stood them in good stead in their intercourse with the
biologists of many nationalities who came to work at the laboratory. I
must not pause to dwell upon the personnel of the staff in general,
but there is one other member who cannot be overlooked even in the most
casual survey of the work of the institution. One might almost as well
forget Dr. Dohrn himself as to overlook Signor Lo Bianco, chief of the
collecting department. Signor Bianco it is who, having expert knowledge
of the haunts and habits of every manner of marine creature, can direct
his fishermen where to find and how to secure whatever rare specimen any
worker at the laboratory may desire. He it is, too, who, by studying old
methods and inventing new ones, has learned how to preserve the delicate
forms for subsequent study in lifelike ensemble that no one else can
quite equal. Signor Bianco it is, in short, who is the indispensable
right-hand man of the institution in all that pertains to its practical
working outside the range of the microscope. Each night Signor Lo Bianco
directs his band of fishermen as to what particular specimens are most
to be sought after next day to meet the needs of the workers in the
laboratory. Before sunrise each day, weather permitting, the little
scattered fleet of boats is far out on the Bay of Naples; for the
surface collecting, which furnishes a large share of the best material,
can be done only at dawn, as the greater part of the creatures thus
secured sink into the retirement of the depths during the day, coming
to the surface to feed only at night. You are not likely to see the
collecting party start out, therefore, but if you choose you may see
them return about nine or ten o'clock by going to the dock not far
from the laboratory. The boats come in singly at about this hour, their
occupants standing up to row, and pushing forward with the oars, after
the awkward Neapolitan fashion. Many of the fishermen are quaint
enough in appearance; some of them have grown old in the service of the
laboratory. The morning's catch is contained in glass jars placed
in baskets especially constructed for the purpose. The baskets have
handles, but these are quite superfluous except to lift them from the
boats, for in the transit to the laboratory the baskets are carried,
as almost everything else is carried in Naples, on the head. To the
novitiate it seems a striking risk to pile baskets of fragile glass and
even more fragile specimens one above another, and attempt to balance
the whole on the head, but nothing could be easier, or seemingly more
secure, for these experts. Arrived at the laboratory, the jars are
turned over to Signer Lo Bianco and his assistants, who sort the
material, and send to each investigator in the workrooms whatever he may
have asked for.

Of course surface-skimming is not the only method of securing material
for the laboratory. The institution owns a steam-launch named the
_Johannes Müller_, in honor of the great physiologist, which operates
a powerful dredge for securing all manner of specimens from the
sea-bottom. Then ordinary lines and nets are more or less in requisition
for capturing fish. And in addition to the regular corps of collectors,
every fisherman of the neighborhood has long since learned to bring
to the laboratory all rare specimens of any kind that he may chance to
capture. So in one way and another the institution makes sure of having
in tribute all that the richly peopled waters of the Mediterranean can
offer. And this well-regulated system of collecting, combined with the
richness of the fauna and flora of the Bay of Naples, has no small share
in the success of the marine laboratory. But these, of course, were
factors that Dr. Dohrn took into account from the beginning.

Indeed, it was precisely with an eye to these important factors that
Naples was selected as the site of the future laboratory in the days
when the project was forming.

The Bay of Naples is most happily located for the needs of the
zoologist. It is not too far south to exclude the fauna of the temperate
zone, yet far enough south to furnish a habitat for many forms of
life almost tropical in character. It has, in short, a most varied and
abundant fauna. And, on the other hand, the large colony of Neapolitan
fishermen made it certain that skilled collectors would always be at
hand to make available the wealth of material. It requires no technical
education to appreciate the value of this to the original investigator,
particularly to the student of life problems. A skilful worker may do
much with a single specimen, as, for example, Johannes Mûller did half a
century ago with the one available specimen of amphioxus, the lowest of
vertebrates, then recently discovered. What Mûller learned from that one
specimen seems almost miraculous. But what if he had had a bucketful of
the little boneless creatures at his disposal, as the worker at Naples
now may have any day for the asking?

When it comes to problems of development, of heredity, a profusion
of material is almost a necessity. But here the creatures of the sea
respond to the call with amazing proficiency. Most of them are, of
course, oviparous, and it is quite the rule for them to deposit their
eggs by hundreds of thousands, by millions even. Everybody knows, since
Darwin taught us, that the average number of offspring of any given
species of animal or plant bears an inverse proportion to the liability
of that species to juvenile fatalities. When, therefore, we find a fish
or a lobster or other pelagic creature depositing innumerable eggs, we
may feel perfectly sure that the vast majority of the eggs themselves,
or the callow creatures that come out of them, will furnish food for
their neighbors at an early day. It is an unkind world into which
the resident of the deep is born. But his adversity is his human
contemporary's gain, and the biologist will hardly be blamed, even by
the most tender-hearted anti-vivisectionist, for availing himself freely
of material which otherwise would probably serve no better purpose than
to appease the appetite of some rapacious fish.

Their abundance is not the only merit, however, of the eggs of pelagic
creatures, in the eyes of the biologist. By equal good-fortune it
chances that colorless things are at a premium in the sea, since to
escape the eye of your enemy is a prime consideration. So the eggs in
question are usually transparent, and thus, shielded from the vision
of marine enemies, are beautifully adapted for the observation of the
biologist. As a final merit, they are mostly of convenient size for
manipulation under the microscope. For many reasons, then, the marine
egg offers incomparable advantages to the student of cell life, an egg
being the typical cell. And since nowadays the cell is the very focus of
attention in the biological world, the importance of marine laboratories
has been enhanced proportionately.

But of course not all the work can be done with eggs or with living
specimens of any kind. It is equally important on occasion to examine
the tissues of adult specimens, and for this, as a rule, the tissues
must first be subjected to some preserving and hardening process
preliminary to the cutting of sections for microscopical examination.
This is done simply enough in the case of some organisms, but there is
a large class of filmy, tenuous, fragile creatures in the sea population
of which the jellyfish may be mentioned as familiar examples. Such
creatures, when treated in an ordinary way, by dropping them into
alcohol, shrivel up, coming to resemble nothing in particular, and
ceasing to have any value for the study of normal structures. How to
overcome this difficulty was one of the problems attacked from the
beginning at the Naples laboratory. The chief part of the practical work
of these experiments fell to the share of Signor Lo Bianco. The success
that attended his efforts is remarkable. To-day you may see at the
laboratory all manner of filmy, diaphanous creatures preserved in
alcohol, retaining every jot of their natural contour, and thus offering
unexampled opportunities for study _en masse_, or for being sectioned
for the microscope. The methods by which this surprising result has been
accomplished are naturally different for different creatures; Signor Lo
Bianco has written a book telling how it all has been done. Perhaps the
most important principle involved with a majority of the more tenuous
forms is to stupefy the animal by gradually adding small quantities of
a drug, such as chloral, to the water in which the creature is detained.
When by this means the animal has been rendered so insensible that
it responds very sluggishly to stimuli, it is plunged into a toxic
solution, usually formaline, which kills it so suddenly that its muscles
in their benumbed state have not time to contract.

Any one who has ever tried to preserve a jellyfish, for example, by
ordinary methods will recall the sorry result, and be prepared to
appreciate Signor Lo Bianco's wonderfully beautiful specimens.
Naturalists have come from all over the world to Naples to learn "just
how" the miracle is accomplished, for it must be understood that the
mere citation of the _modus operandi_ by no means enables the
novitiate to apply it successfully at once. In the case of some of the
long-drawn-out forms of clustered ascidians and the like, the delicacy
of manipulation required to make successful preservations raises the
method as practised at Naples almost to the level of a fine art. It is
a boon to naturalists everywhere that the institution here is able
sometimes to supply other laboratories less favorably situated with
duplicates from its wealth of beautifully preserved specimens.


METHODS AND RESULTS

These, then, are some of the material conditions that have contributed
to make the results of the scientific investigations at the Naples
laboratory notable. But of course, even with a superabundance of
material, discoveries do not make themselves. "Who uses this material?"
is, after all, the vital question. And in this regard the laboratory
at Naples presents, for any one who gets at its heart, so to speak, an
ensemble that is distinctive enough; for the men who work in the light
and airy rooms of the laboratory proper have come for the purpose from
all corners of the civilized globe, and not a few of them are men of
the highest distinction in their various lines of biological science.
A large proportion are professors in colleges and universities of their
various countries; and for the rest there is scarcely one who is not
in some sense master of the biological craft. For it must be understood
that this laboratory at Naples is not intended as a training-school for
the apprentice. It offers in the widest sense a university course in
biology, and that alone. There is no instructor here who shows the
new-comer how to use the microscope, how to utilize the material, how
to go about the business of discovery. The worker who comes to Naples
is supposed to have learned all these things long before. He is
merely asked, then, what class of material he desires, and, this being
furnished him, he is permitted to go his own way unmolested. He may work
much or little, or not at all; he may make epochal discoveries or no
discoveries of any sort, and it will be all one to the management. No
one will ask him, in any event, what he has done or why he has not done
otherwise. In a word, the worker in the laboratory here, while being
supplied with opportunities for study such as he could hardly find
elsewhere, retains all the freedom of his own private laboratory.

Little wonder, then, that it is regarded as a rare privilege to be
allowed to work in this laboratory. Fortunately, however, it is a
privilege that may be obtained by almost any earnest worker who, having
learned the technique of the craft elsewhere, desires now to prosecute
special original studies in biology. Most of the tables here are leased
in perpetuity, for a fixed sum per annum, by various public or private
institutions of different countries. Thus, for example, America has the
right of use of several tables, the Smithsonian Institution leasing one,
Columbia University another, a woman's league a third, and so on. Any
American desiring to work at Naples should make application to one of
these various sources, stating the exact time when he would like to
go, and if there be a vacancy for that time the properly accredited
applicant is almost sure to receive the privilege he asks for. Failing
in this, however, there is still a court of last appeal in Dr. Dohrn
himself, who may have a few unoccupied tables at his disposal, and who
will surely extend the courtesy of their occupancy, for a reasonable
period, to any proper applicant, come he whence he may.

Thus it chances that one finds men of all nations working in the Naples
laboratory--biologists from all over Europe, including Russia, from
America, from Australia, from Japan. One finds women also, but these,
I believe, are usually from America. Biologists who at home are at the
head of fully equipped laboratories come here to profit by the wealth
of material, as well as to keep an eye upon the newest methods of their
craft, and to gain the inspiration of contact with other workers in
allied fields. Many of the German university teachers, for example, make
regular pilgrimages to Naples during their vacations, and more than one
of them have made the original investigations here that have given them
an international reputation.

As to the exact methods of study employed by the individual workers
here, little need be said. In this regard, as in regard to instrumental
equipment, one biological laboratory is necessarily much like another,
and the general conditions of original scientific experiment are pretty
much the same everywhere. What is needed is, first, an appreciation of
the logical bearings of the problem to be solved; and, secondly, the
skill and patience to carry out long lines of experiments, many of which
necessarily lead to no tangible result. The selection of material for
the experiments planned, the watching and cultivating of the living
forms in the laboratory tanks, the cutting of numberless filmy sections
for microscopical examination--these things, variously modified for each
case, make up the work of the laboratory student of general biology.
And just in proportion as the experiments are logically planned and
carefully executed will the results be valuable, even though they be but
negative. Just in proportion as the worker, by inclusion and exclusion,
attains authentic results--results that will bear the test of
repetition--does his reputation as a dependable working biologist become
established.

The subjects attacked in the marine laboratory first and last are
practically coextensive with the range of general biology, bacteriology
excepted. Naturally enough, the life histories of marine forms of
animals and plants have come in for a full share of attention. But, as I
have already intimated, this zoological work forms only a small part of
the investigations undertaken here, for in the main the workers prefer
to attack those general biological problems which in their broader
outlines apply to all forms of living beings, from highest to lowest.
For example, Dr. Driesch, the well-known Leipzig biologist, spends
several months of each year at the laboratory, and has made here most of
those studies of cell activities with which his name is associated.
The past season he has studied an interesting and important problem of
heredity, endeavoring to ascertain the respective shares of the male and
female parents in the development of the offspring. The subjects of his
experiments have been various species of sea-urchins, but the principles
discovered will doubtless be found to apply to most, or perhaps all,
forms of vertebrate life as well.

While these studies were under way another developmental problem was
being attacked in a neighboring room of the laboratory by Professor
Kitasato, of the University of Tokio, Japan. The subjects this time were
the embryos of certain fishes, and the investigation had to do with
the development of instructive monstrosities through carefully designed
series of injuries inflicted upon the embryo at various stages of its
development. Meantime another stage of the developmental history of
organic things--this time a microscopical detail regarding the cell
divisions of certain plants--has been studied by Professor Mottier,
of Indiana; while another American botanist, Professor Swingle, of
the Smithsonian Institution, has been going so far afield from
marine subjects as to investigate the very practical subject of the
fertilization of figs as practised by the agriculturists about Naples.

Even from these few citations it will appear how varied are the lines of
attack of a single biological problem; for here we see, at the hands
of a few workers, a great variety of forms of life--radiates, insects,
vertebrates, low marine plants and high terrestrial ones--made to
contribute to the elucidation of various phases of one general topic,
the all-important subject of heredity. All these studies are conducted
in absolute independence, and to casual inspection they might seem to
have little affinity with one another; yet in reality they all trench
upon the same territory, and each in its own way tends to throw light
upon a topic which, in some of its phases, is of the utmost practical
importance to the human family. It is a long vault from the embryo of
an obscure sea-weed to the well-being of man, yet it may well happen--so
wide in their application are the general life principles--that study of
the one may point a practical moral for the other.

Indeed, it constantly happens that the student of biology, while
gazing through his microscope, hits upon discoveries that have the most
far-removed implications. Thus a few years ago it was discovered that
when a cell is about to bisect itself and become two cells, its nucleus
undergoes a curious transformation. Within the nuclear substance little
bodies are developed, usually threadlike in form, which take on a deep
stain, and which the biologist calls chromosomes. These chromosomes vary
in number in the cells of different animals, but the number is always
the same for any given species of animal. If one were to group animate
beings in classes according to this very fundamental quality of the
cells he would have some very curious relations established. Thus, under
the heading "creatures whose cells have twenty-four chromosomes," one
would find beings so different as "the mouse, the salamander, the trout,
and the lily," while the sixteen-chromosome group would introduce the
very startling association of the ox, the guinea-pig, the onion, and man
himself. But whatever their number, the chromosomes are always exactly
bisected before the cell divides, one-half being apportioned to each of
the two cells resulting from the division.

Now the application is this: It was the study of these odd nuclear
structures and their peculiar manouvrings that, in large measure, led
Professor Weismann to his well-known theory of heredity, according
to which the acquired traits of any being are not transmissible to the
offspring. Professor Weismann came to believe that the apportionment
of the nuclear substance, though quantitatively impartial, is sometimes
radically uneven in quality; in particular, that the first bisection
of the egg-cell, which marks the beginning of embryonic development,
produces two cells utterly different in potentiality, the one containing
the "body plasm," which is to develop the main animal structures, the
other encompassing the "germ plasm," by which the racial integrity is
[to be preserved. Throughout the life of the individual, he believed,
this isolation continued; hence the assumed lack of influence of
acquired bodily traits upon the germ plasm and its engendered offspring.
Hence, also, the application of the microscopical discovery to the
deepest questions of human social evolution.

Every one will recall that this theory, born of the laboratory, made
a tremendous commotion in the outside world. Its application to the
welfare and progress of humanity gave it supreme interest, and polemics
unnumbered were launched in its favor and in its condemnation. Eager
search was made throughout the fields of botany and zoology for new
evidence pro or con. But the definitive answer came finally from the
same field of exploration in which the theory had been originated--the
world of the cell--and the Marine Biological Laboratory was the seat of
the new series of experiments which demonstrated the untenability of the
Weismannian position. Most curious experiments they were, for in effect
they consisted of the making of two or more living creatures out of one,
in the case of beings so highly organized as the sea-urchins, the
little fishlike vertebrate, amphioxus, and even the lower orders of true
fishes. Of course the division of one being to form two is perfectly
familiar in the case of those lowly, single-celled creatures such as the
protozoa and the bacteria, but it seems quite another matter when one
thinks of cutting a fish in two and having two complete living fish
remaining. Yet this is virtually what the biologists did.

Let me hasten to add that the miraculous feat was not accomplished
with an adult fish. On the contrary, it is found necessary to take the
subject quite at the beginning of its career, when it consists of an
egg-cell in the earliest stages of proliferation. Yet the principle is
quite the same, for the adult organism is, after all, nothing more
than an aggregation of cells resulting from repeated divisions (growth
accompanying) and redivisions of that original egg-cell. Considering
its potentialities, the egg-cell, seemingly, is as much entitled to be
considered an individual as is the developed organism. Yet it transpires
that the biologist has been able so to manipulate a developing egg-cell,
after its bisection, that the two halves fall apart, and that each half
(now become an independent cell) develops into a complete individual,
instead of the half-individual for which it seemed destined. A
strange trick, that, to play with an individual _Ego_, is it not?
The traditional hydra with its reanimating heads was nothing to this
scientific hydra, which, when bisected bodily, rises up calmly as two
whole bodies.

But even this is not the full measure of the achievement, for it has
been found that in some cases the experiment may be delayed until the
developing egg has made a second bisection, thus reaching the four-cell
stage, when four completely formed individuals emerge from the
dismembered egg. And in the case of certain medusae, success has
attended experiments made at the eight-cell and even at the sixteen-cell
stage of development, the creature which had got thus far on its career
in single blessedness becoming eight or sixteen individuals at the wave
of the enchanted wand--that is to say, the dissecting-needle--of
the biologist. All of which savors of conjury, but is really only
matter-of-fact biological experiment--experiment, however, of which
the implications by no means confine themselves to matters of fact
biological. For clearly the fact that the separated egg-cells grow into
complete individuals shows that Weismann's theory, according to which
one of the cells contained only body plasm, the other only germ plasm,
is quite untenable. Thus the theory of the non-transmissibility of
acquired characters is deprived of its supposed anatomical support and
left quite in the air, to the imminent peril of a school of sociologists
who had built thereon new theories of human progress. Also the question
of the multiplied personalities clearly extends far beyond the field
of the biologist, and must be turned over to the consideration of the
psychologist--if, indeed, it does not fall rather within the scope of
the moralist.

But though it thus often chances that the biologist, while gazing
stoically through his microscope, may discover things in his microcosm
that bear very closely upon the practical interests of the most
unscientific members of the human family, it would be a mistake to
suppose that it is this class of facts that the worker is particularly
seeking. The truth is that, as a rule, the pure biologist is engaged in
work for the love of it, and nothing is further from his thoughts than
the "practical" bearings or remote implications of what he may discover.
Indeed, many of his most hotly pursued problems seem utterly divorced
from what an outsider would call practical bearings, though, to be
sure, one can never tell just what any new path may lead to. Such, for
example, is the problem which, next to questions of cell activities,
comes in for perhaps as large a share of attention nowadays as any other
one biological topic;--namely, the question as to just which of
the various orders of invertebrate creatures is the type from which
vertebrates were evolved in the past ages--in other words, what
invertebrate creature was the direct ancestor of the vertebrates,
including man. Clearly it can be of very little practical importance to
man of to-day as to just who was his ancestor of several million years
ago. But just as clearly the question has interest, and even the layman
can understand something of the enthusiasm with which the specialist
attacks it.

As yet, it must be admitted, the question is not decisively answered,
several rival theories contending for supremacy in the case. One of
the most important of these theories had its origin at the Naples
laboratory; indeed, Dr. Dohrn himself is its author. This is the view
that the type of the invertebrate ancestor is the annelid--a form whose
most familiar representative is the earth-worm. The many arguments for
and against accepting the credentials of this unaristocratic ancestor
cannot be dwelt upon here. But it may be consolatory, in view of the
very plebeian character of the earth-worm, to know that various of the
annelids of the sea have a much more aristocratic bearing. Thus the
filmy and delicately beautiful structures that decorate the pleasant
home of the quaint little seahorse in the aquarium--structures having
more the appearance of miniature palm-trees than of animals--are really
annelids. One can view Dr. Dohrn's theory with a certain added measure
of equanimity after he learns this, for the marine annelids are seen,
some of them, to be very beautiful creatures, quite fitted to grace
their distinguished offspring should they make good their ancestral
claims.

These glimpses will suffice, perhaps, to give at least a general idea of
the manner of thing which the worker at the marine laboratory is seeking
to discover when he interrogates the material that the sea has given
him. In regard to the publication of the results of work done at the
Naples laboratory, the same liberal spirit prevails that actuates the
conduct of the institution from first to last. What the investigator
dis* covers is regarded as his own intellectual property, and he
is absolutely free, so far as the management of this institution is
concerned, to choose his own medium in giving it to the world. He may,
and often does, prefer to make his announcements in periodicals or books
issued in his own country and having no connection whatever with the
Naples laboratory. But, on the other hand, his work being sufficiently
important, he may, if he so desire, find a publisher in the institution
itself, which issues three different series of important publications,
under the editorship of Professor Mayer.

One of these, entitled _Mittheilungen aus der Zoologische Station
zu Neapel_, permits the author to take his choice among four
languages--German, English, French, or Italian. It is issued
intermittently, as occasion requires. The second set of publications
consists of ponderous monographs upon the fauna and flora of the Gulf
of Naples. These are beautifully illustrated in color, and sometimes a
single volume costs as much as seventeen thousand dollars to issue. Of
course only a fraction of that sum is ever recovered through sale of the
book. The third publication, called _Zoologischen Jahresbericht_, is a
valuable résumé of biological literature of all languages, keeping the
worker at the laboratory in touch with the discoveries of investigators
elsewhere.

The latter end is attained further by the library of the institution,
which is supplied with all the periodicals of interest to the biologist
and with a fine assortment of technical books. The library-room, aside
from its printed contents, is of interest because of its appropriate
mural decorations, and because of the bronze portrait busts of the two
patron saints of the institution, Von Baer and Darwin, which look down
inspiringly upon the reader.

All in all, then, it would be hard to find a deficiency in the Stazione
Zoologica as an instruement of biological discovery. A long list might be
cited of the revelations first brought to light within its walls. And
yet, as it seems to me, the greatest value of this institution as an
educational factor in science--as a biological lever of progress--does
not depend so much upon the tangible revelations of fact that have come
out of its laboratories as upon other of its influences. Scientific
ideas, like all other forms of human thought, move more or less in
shoals. Very rarely does a great discovery emanate from an isolated
observer. The man who cannot come in contact with other workers in
kindred lines becomes more or less insular, narrow, and unfitted for
progress. Nowadays, of course, the free communication between different
quarters of the globe takes away somewhat from the insularity of any
quarter, and each scientist everywhere knows something of what the
others are doing, through wide-spread publications. But this can never
altogether take the place of personal contact and the inspirational
communication from man to man. Hence it is that a rendezvous, where all
the men of a craft go from time to time and meet their fellows from all
over the world, has an influence for the advancement of the guild
which is enormous and unequivocal, even though difficult of direct
demonstration.

This feature, then, it seems to me, gives Dr. Dohrn's laboratory its
greatest value as an educational factor, as a moving force in the
biological world. It is true that the new-comer there is likely to be
struck at first with a sense of isolation, and to wonder at the seeming
exclusiveness of the workers, the self-absorption of each and every
one. Outside the management, whom he meets necessarily, no one pays
the slightest attention to him at first, or seems to be aware of his
existence. He is simply assigned to a room or table, told to ask for
what he wants, and left to his own devices. As he walks along the
hallways he sees tacked on the doors the cards of biologists from all
over the world, exposing names with which he has long been familiar.
He understands that the bearers of the names are at work within the
designated rooms, but no one offers to introduce him to them, and
for some time, perhaps, he does not so much as see them, nor would he
recognize them if he did. He feels strange and isolated in the midst of
this stronghold of his profession.

But soon this feeling leaves him. He begins to meet his fellow-workers
casually here and there--in the hallways, at the distributing-tanks, in
the library. There are no formal gatherings, and there are some workers
who never seem to affiliate at all with the others; but in the long-run,
here as elsewhere, kindred spirits find one another out; and even the
unsocial ones take their share, whether or no, in the indefinable but
very sensible influence of massed numbers. Presently some one suggests
to the new-comer that he join some of the others of a Wednesday or
Saturday evening, at a rendezvous where a number of them meet regularly.
He goes, under escort of his sponsor, and is guided through one of those
narrow, dark, hill-side streets of Naples where he would hardly feel
secure to go alone, to a little wine-shop in what seems a veritable
dungeon--a place which, if a stranger in Naples, he would never even
remotely think of entering. But there he finds his confrères of the
laboratory gathered about a long table, with the most conglomerate
groups of Neapolitans of a seemingly doubtful class at their elbows.
Each biologist has a caraffa of light wine on the table before him,
and all are smoking. And, staid men of science that they are, they are
chattering away on trivial topics with the animation of a company of
school-boys. The stock language is probably German, for this bohemian
gathering is essentially a German institution; but the Germans are
polyglots, and you will hardly find yourself lost in their company,
whatever your native tongue.

Your companions will tell you that for years the laboratory fraternity
have met twice a week at this homely but hospitable establishment. The
host, honest Dominico Vincenzo Bifulco, will gladly corroborate the
statement by bringing out for inspection a great blank-book in which
successive companies of his guests from the laboratory have scrawled
their names, written epigrams, or made clever sketches. That book will
some day be treasured in the library of a bibliophile, but that will not
be until Bifulco is dead, for while he lives he will never part with it.

One comes to look upon this bohemian wine-shop as an adjunct of the
laboratory, and to feel that the free-and-easy meetings there are
in their way as important for the progress of science as the private
séances of the individual workers in the laboratory itself. Not because
scientific topics are discussed here, though doubtless that sometimes
happens, but because of that vitalizing influence of the contact of
kindred spirits of which I am speaking, and because this is the one
place where a considerable number of the workers at the laboratory meet
together with regularity.

The men who enter into such associations go out from them revitalized,
full of the spirit of propaganda. Returned to their own homes, they
agitate the question of organizing marine laboratories there; and it is
largely through the efforts of the graduates, so to say, of the Naples
laboratory that similar institutions have been established all over the
world.

Thanks largely to the original efforts of Dr. Dohrn, nearly
all civilized countries with a coast-line now have their marine
laboratories. France has half a dozen, two of them under government
control. Russia has two on the Black Sea and one on the French
Mediterranean coast. Great Britain has important stations at St.
Andrews, at Liverpool, and at Plymouth. The Scandinavian peninsula has
also three important stations. Germany shows a paucity by comparison,
which, however, is easily understood when one reflects that the
mother-laboratory at Naples is essentially a German institution despite
its location.

The American stations are located at Woods' Holl and at Cold Spring
Harbor, on opposite coasts of Long Island Sound. The Japanese station is
an adjunct of Tokio University. For the rest, the minor offspring of
the Naples laboratory are too numerous to be cited here. Nor can I enter
into any details regarding even the more important ones. Each in its way
enters into the same general line of work, varying the details according
to the bent of mind of individual directors and the limitations of
individual resources. But in the broader outlines the aim of all is the
same, and what we have seen at Naples is typical of what is best in all
the others.



VI. ERNST HAECKEL AND THE NEW ZOOLOGY


THE DREAM CITY

THE train crept on its tortuous way down the picturesque valley of the
little Saale. At last we saw, high above us, on a jutting crag, three
quaint old castles, in one of which, as we knew from our _Baedeker_;
Goethe at one time lived. We were entering the region of traditions.
Soon we knew we should be passing that famous battle-field on which
Napoleon, in 1806, sealed the fate of Germany for a generation. But this
spot, as seen from the car window, bore no emblem to distinguish it, and
before we were quite sure that we had reached it we had in point of fact
passed on, and the train was coming to a stop. "Jena!" called the guard,
and the scramble for "luggage" began, leaving us for the moment no place
for other thoughts than to make sure that all our various parcels were
properly dragged out along with ourselves. For a wonder no Dienstman
appeared to give us aid--showing how unexpected is the arrival of any
wayfarer at this untoward season--and for a moment one seemed in danger
of being reduced to the unheard-of expedient of carrying one's own
satchel. But, fortunately, one is rescued from this most un-German
predicament by the porter of a waiting hotel omnibus, and so at last we
have time to look about us, and to awaken to a realizing sense that we
have reached the land of traditions; that we have come to Mecca; that we
are in the quondam home of Guericke, Fichte, Goethe, Schiller, Oken, and
Gagenbaur; in the present home of Haeckel.

The first glimpse of a mountain beaming down at us from across the way
was in admirable conformity with our expectations, but for the rest, the
vicinage of the depot presented a most distressing air of modernity. A
cluster of new buildings--some of them yet unfinished--stared back at us
and the mountain with the most barefaced aspect of cosmopolitanism. Was
this, then, Jena, the home of traditions? Or were we entering some Iowa
village, where the first settlers still live who but yesterday banished
the prairie-dog and the buffalo?

But this disappointment and its ironical promptings were but fleeting.
Five minutes' drive and we were in the true Jena with the real flavor of
mediaeval-ism about us. Here is the hostelry where Luther met the Swiss
students in 1522. There is nothing in that date to suggest our Iowa
village, nor in the aspect of the hostelry itself, thank fortune. And
there rises the spire of the city church, up the hill yonder, which was
aging, as were most of the buildings that still flank it, when Luther
made that memorable visit. America was not discovered, let alone Iowa,
when these structures were erected. Now, sure enough, we are in the
dream city.

A dream city it truly seems, when one comes to wander through its
narrow, tortuous streets, between time-stained walls, amid its rustic
population. Coming from Berlin, from Dresden, from Leipzig--not to
mention America--one feels as if he had stepped suddenly back two or
three centuries into the past. There are some evidences of modernity
that mar the illusion, to be sure; but the preponderance of the
old-time emblems is sufficient to leave the mind in a delightful glow
of reminiscences. As a whole, the aspect of the central portion of the
village--of the true Jena--cannot greatly have changed since the days
when Luther stopped here on his way to Wittenberg; surely not since
1662, when the mighty young Leibnitz, the Aristotle of Germany, came to
Jena to study under Weigel, the most famous of German mathematicians
of that century. Here and there an old house has been demolished, to be
sure; even now you may see the work of destruction going on, as a
new street is being cut through a time-honored block close to the old
church. But in the main the old thoroughfares run hither and thither,
seemingly at random, as of old, disclosing everywhere at their limits
a sky-line of picturesque gables, and shut in by walls that often are
almost canon-like in narrowness; while the heavy, buttressed doors and
the small, high-placed windows speak of a time when every house partook
of the nature of the fortress.

The footway of the thoroughfares has no doubt vastly changed, for it is
for the most part paved now--badly enough, to be sure, yet, after
all, paved as no city was in the good old days when garbage filled
the streets and cleanliness was an unknown virtue. The Jena streets of
to-day are very modern in their cleanliness; yet a touch of medievalism
is retained in that the main work of cleaning is done by women. But, for
that matter, it seems to the casual observer as if the bulk of all the
work here were performed by the supposedly weaker sex. Certainly woman
is here the chief beast of burden. In every direction she may be seen,
in rustic garb, struggling cheerily along under the burden of a gigantic
basket strapped at her back. You may see the like anywhere else in
Germany, to be sure, but not often elsewhere in such preponderant
numbers. And scarcely elsewhere does the sight jar so little on one's
New-World sensibilities as in the midst of this mediaeval setting. One
is even able to watch the old women sawing and splitting wood in the
streets here, with no thought of anything but the picturesque-ness of
the incident.

If one follows a band of basket-laden women, he will find that their
goal is that focal-point of every old-time city, the market-place. There
arrived, he will witness a scene common enough in Europe but hardly to
be duplicated anywhere in America. Hundreds of venders of meat, fish,
vegetables, cloths, and household utensils have their open-air booths
scattered all across the wide space, and other hundreds of purchasers
are there as well. Quaint garbs and quainter faces are everywhere,
and the whole seems quite in keeping with the background of
fifteenth-century houses that hedges it in on every side. Could John the
Magnanimous, who rises up in bronze in the midst of the assembly, come
to life, he would never guess that three and a half centuries have
passed since he fell into his last sleep.

This same John the Magnanimous it was who founded the institution which
gives Jena its fame and distinguishes it from all the other quaint
hypnotic clusters of houses that nestle similarly here and there in
other picturesque valleys of the Fatherland--I mean, of course, its
world-renowned university. It is but a few minutes' walk from the
market-place, past the home where Schiller once lived and through the
"street" scarcely more than arms'-breadth wide beyond, to the site of
the older buildings of the university. Inornate, prosaic buildings they
are, unrelieved even by the dominant note of picturesqueness; rescued,
however, from all suggestion of the commonplace by the rugged ruins of
the famed "powder-tower" jutting out from the crest of the hill just
above, by the spire of the old church which seems to rise from the
oldest university building itself, and by the mountain peaks that jut up
into view far beyond.

If you would enter one of the old buildings there is naught to hinder.
Go into one of the lecture-halls which chances at the moment to be
unoccupied, and you will see an array of crude old benches for seats
that look as if they might have been placed there at the very inaugural
of the institution. The boards that serve for desks, if you scan them
closer, you will find scarred all over with the marks of knives, showing
how some hundreds of successive classes of listeners have whiled away
the weary lecture-hours. Not a square inch can you find of the entire
desk surface that is un-scarred. If one would woo a new sensation, he
has but to seat himself on one of these puritanical old benches and
conjure up in imagination the long series of professors that may have
occupied the raised platform in front, recalling the manner of thought
and dogma that each laid down as verity. He of the first series appears
in the garb of the sixteenth century, with mind just eagerly striving to
peer a little way out of the penumbra of the Renaissance. The students
who carve the first gashes in the new desks will learn, if perchance
they listen in intervals of whittling, that this World on which they
live is perhaps not flat, but actually round, like a ball. It is
debatable doctrine, to be sure, but we must not forget that Signor
Columbus, recently dead, found land off to the west which is probably a
part of the Asiatic continent. If the earth be indeed a ball, then the
sun and stars whirl clear around it in twenty-four hours, travelling
thus at an astonishing speed, for the sphere in which they are fastened
is situated hundreds of miles away. The sun must be a really great ball
of fire--perhaps a mile even in diameter. The moon, as is plain to see,
is nearly as large. The stars, of course, are only sparks, though of
great brilliancy. They are fixed in a different sphere from that of the
sun. In still other spheres are the moon, and a small set of large stars
called planets, of which latter there are four, in order that, with the
sun, the moon, and the other stars, there may be made seven orders of
heavenly bodies--seven being, of course, the magic number in accordance
with which the universe is planned.

This is, in substance, the whole subject of astronomy, as that first
professor must have taught it, even were he the wisest man of his time.
Of the other sciences, except an elementary mathematics, there was
hardly so much as an inkling taught that first class of students. You
will find it appalling, as you muse, to reflect upon the amazing mixture
of utter ignorance and false knowledge which the learned professor of
that day brought to the class-room, and which the "educated" student
carried away along with his degree. The one and the other knew Greek,
Latin, and Bible history and doctrine. Beyond that their minds were
as the minds of babes. Yet no doubt the student who went out from the
University of Jena in the year 1550 thought himself upon the pinnacles
of learning. So he was in his day and age, but could he come to life
to-day, in the full flush of his scholarship, yonder wood-vender, plying
her saw out here in front of the university building, would laugh in
derision at his simplicity and ignorance. So it seems that, after all,
the subjects of John the Magnanimous have changed more than a little
during the three hundred and odd years that John himself, done in
bronze, has been standing out there in the market-place.


THE CAREER OF A ZOOLOGIST

Had one time for it, there would be real interest in noting the steps
by which the mental change in question has been brought about; in
particular to note the share which the successive generations of Jena
professors have taken in the great upward struggle. But we must
not pause for that here. Our real concern, despite the haunting
reminiscences, is not with the Jena of the past, but with the Jena of
to-day; not with ghosts, but with the living personality who has made
the Jena of our generation one of the greatest centres of progress in
human thought in all the world. Jena is Jena to-day not so much because
Guericke and Fichte and Hegel and Schiller and Oken taught here in the
past, as because it has for thirty-eight years been the seat of the
labors of Germany's greatest naturalist, one of the most philosophical
zoologists of any country or any age, Professor Ernst Haeckel. It is of
Professor Haeckel and his work that I chiefly mean to write, and if I
have dwelt somewhat upon Jena itself, it is because this quaint, retired
village has been the theatre of Haeckel's activities all the mature
years of his life, and because the work he has here accomplished could
hardly have been done so well elsewhere; some of it, for reasons I shall
presently mention, could hardly have been done elsewhere at all--at
least in another university.

It was in 1861 that young Dr. Haeckel came first to Jena as a teacher.
He had made a tentative effort at the practice of medicine in Berlin,
then very gladly had turned from a distasteful pursuit to the field of
pure science. His first love, before he took up the study of medicine,
had been botany, though pictorial art, then as later, competed with
science for his favorable attention. But the influence of his great
teacher, Johannes Müller, together with his medical studies, had turned
his attention more directly to the animal rather than vegetable life,
and when he left medicine it was to turn explicitly to zoology as a life
study. Here he believed he should find a wider field than in art, which
he loved almost as well, and which, it may be added, he has followed all
his life as a dilettante of much more than amateurish skill. Had he so
elected, Haeckel might have made his mark in art quite as definitely
as he has made it in science. Indeed, even as the case stands, his
draughtsman's skill has been more than a mere recreation to him, for
without his beautiful drawings, often made and reproduced in color, his
classical monographs on various orders of living creatures would have
lacked much of their present value.

Moreover, quite aside from these merely technical drawings, Professor
Haeckel has made hundreds of paintings purely for recreation and the
love of it, illustrating--and that too often with true artistic feeling
for both form and color--the various lands to which his zoological
quests have carried him, such as Sicily, the Canaries, Egypt, and India.
From India alone, after a four-months' visit, Professor Haeckel brought
back two hundred fair-sized water-colors, a feat which speaks at once
for his love of art and his amazing industry.

I dwell upon this phase of Professor Haeckel's character and temperament
from the very outset because I wish it constantly to be borne in mind,
in connection with some of the doctrines to be mentioned presently, that
here we have to do with no dry-as-dust scientist, cold and soulless, but
with a broad, versatile, imaginative mind, one that links the scientific
and the artistic temperaments in rarest measure. Charles Darwin, with
whose name the name of Haeckel will always be linked, told with regret
that in his later years he had become so steeped in scientific facts
that he had lost all love for or appreciation of art or music. There has
been no such mental warping and atrophy in the mind of Ernst Haeckel.
Yet there is probably no man living to-day whose mind contains a larger
store of technical scientific facts than his, nor a man who has enriched
zoology with a larger number of new data, the result of direct personal
observation in field or laboratory.

How large Haeckel's contribution in this last regard has been can be
but vaguely appreciated by running over the long list of his important
publications, though the list includes more than one hundred titles,
unless it is understood that some single titles stand for monographs
of gigantic proportions, which have involved years of labor in the
production. Thus the text alone of the monograph on the radiolarians,
a form of microscopic sea-animalcule (to say nothing of the volume of
plates), is a work of three gigantic volumes, weighing, as Professor
Haeckel laughingly remarks, some thirty pounds, and representing twelve
years of hard labor. This particular monograph, by-the-bye, is written
in English (of which, as of several other languages, Professor Haeckel
is perfect master), and has a history of more than ordinary interest. It
appears that the radiolarians were discovered about a half-century
ago by Johannes Müller, who made an especial-study of them, which was
uncompleted at the time of his death in 1858. His monograph, describing
the fifty species then known, was published posthumously. Haeckel,
on whom the mantle of the great teacher was to fall, and who had been
Müller's last pupil, took up the work his revered master had left
unfinished as his own first great original _Arbeit_. He went to Messina
and was delighted to find the sea there replete with radiolarians, of
which he was able to discover one or two new species almost every day,
until he had added one hundred and fifty all told to Müller's list, or
more than triple the whole number previously known. The description of
these one hundred and fifty new radiolarians constituted Haeckel's first
great contribution to zoology, and won him his place as teacher at Jena
in 1861.

Henceforth Haeckel was, of course, known as the greatest authority
on this particular order of creatures. For this reason it was that
Professor Murray, the naturalist of the famous expedition which the
British government sent around the world in the ship _Challenger_,
asked Haeckel to work up the radiolarian material that had been gathered
during that voyage. Murray showed Haeckel a little bottle containing
water, with a deposit of seeming clay or mud in the bottom. "That
mud," he said, "was dredged up from the bottom of the ocean, and every
particle of it is the shell of a radiolarian." "Impossible," said
Haeckel. "Yet true," replied Murray, "as the microscope will soon prove
to you."

So it did, and Professor Haeckel spent twelve years examining that mud
under the microscope, with the result that, before he had done, he had
discovered no fewer than four thousand new species of radiolarians, all
of which, of course, had to be figured, described, and christened.
Think of baptizing four thousand creatures, finding a new, distinct, and
appropriate Latin name for each and every one, and that, too, when the
creatures themselves are of microscopic size, and the difference between
them often so slight that only the expert eye could detect it. Think,
too, of the deadly tedium of labor in detecting these differences,
in sketching them, and in writing out, to the length of three monster
volumes, technical dissertations upon them.

To the untechnical reader that must seem a deadly, a veritably
mind-sapping task. And such, indeed, it would prove to the average
zoologist. But with the mind of a Haeckel it is far otherwise. To him a
radiolarian, or any other creature, is of interest, not so much on its
own account as for its associations. He sees it not as an individual
but as a link in the scale of organic things, as the bearer of a certain
message of world-history. Thus the radiolarians, insignificant creatures
though they seem, have really taken an extraordinary share in building
up the crust of the earth. The ooze at the bottom of the sea,
which finally becomes metamorphosed into chalk or stone, is but the
aggregation of the shells of dead radiolarians. In the light of such a
rôle the animalcule takes on a new interest.

But even greater is the interest that attaches to every creature in
regard to the question of its place in the organic scale of evolution.
What are the homologies of this form and that? What its probable
ancestry? What gaps does it bridge? What can it tell us of the story of
animal creation? These and such like are the questions that have been
ceaselessly before Haeckel's mind in all his studies of zoology. Hence
the rich fountain of philosophical knowledge that has welled up from
what otherwise might have been the most barren of laboratory borings.
Thus from a careful investigation of the sponge Haeckel was led to
his famous gastrula theory, according to which the pouchlike
sponge-animalcule--virtually a stomach without members--is the type of
organism on which all high organisms are built, so to speak--that is,
out of which all have evolved.

This gastrula theory, now generally accepted, is one of Haeckel's two
great fundamental contributions to the evolution philosophy with the
history of which his life work is so intimately linked. The other
contribution is the theory, even more famous and now equally undisputed,
that every individual organism, in its em-bryological development,
rehearses in slurred but unmistakable epitome the steps of evolution by
which the ancestors of that individual came into racial being. That is
to say, every mammal, for example, originating in an egg stage, when it
is comparable to a protozoon, passes through successive stages when it
is virtually in succession a gastrula, a fish, and an amphibian before
it attains the mammalian status, because its direct ancestors were in
succession, through the long geological ages, protozoons, gastrulae,
fishes, amphibians before the true mammal was evolved. This theory cast
a flood of light into many dark places of the Darwinian philosophy. It
was propounded in 1866 in Professor Haeckel's great work on morphology,
and it has ever since been a guiding principle in his important
philosophical studies.

It was through this same work on morphology that Haeckel first came
to be universally recognized as the great continental champion of
Darwinism--the Huxley of Germany. Like Huxley, Haeckel had at once made
the logical application of the Darwinian theory to man himself, and he
sought now to trace the exact lineage of the human family as no one had
hitherto attempted to fathom it. Utilizing his wide range of zoological
and anatomical knowledge, he constructed a hypothetical tree of
descent--or, if you prefer, ascent--from the root in a protozoon to
the topmost twig or most recent offshoot, man. From that day till this
Haeckel's persistent labors have been directed towards the perfection of
that genealogical tree.

This work on morphology was much too technical to reach the general
public, but in 1868 Haeckel prepared, at the instigation of his friend
and confrère Gagenbaur, what was practically a popular abridgment of
the technical work, which was published under the title of _The Natural
History of Creation_. This work created a furor at once. It has been
translated into a dozen languages, and has passed through nine editions
in the original German. Through it the name of Haeckel became almost
a household word the world over, and subject for mingled applause
and opprobrium--applause from the unprejudiced for its great merit;
opprobrium from the bigoted because of the unprecedented candor with
which it followed the Darwinian hypothesis to its logical goal.

The same complete candor of expression has marked every stage of the
unfolding of Professor Haeckel's philosophical pronouncements. This
fact is the more remarkable because Professor Haeckel is, so far as I am
aware, the only scientist of our generation who has felt at liberty to
announce, absolutely without reserve, the full conclusions to which his
philosophy has carried him, when these conclusions ran counter to the
prevalent prejudices of his time. Some one has said that the German
universities are oases of freedom. The remark is absolutely true of
Jena. It is not true, I believe, in anything like the same degree of any
other German university, or of any other university in the world. One
thing before others that has endeared Jena to Haeckel, and kept him
there in the face of repeated flattering calls to other universities, is
that full liberty of spirit has been accorded him there, as he knew it
would not be accorded elsewhere. "When a man comes into the atmosphere
of Jena," says Professor Haeckel, "he perforce begins to think--there
is no escape from it. And he is free to let his thoughts carry
him whithersoever they honestly may. My beliefs," he added, "are
substantially the beliefs of my colleagues in science everywhere, as I
know from private conversations; but they, unlike myself, are not free
to speak the full truth as they see it. I myself would not be tolerated
elsewhere, as I am well aware. Had I desired to remain in Berlin, for
example, I must have kept silent. But here in Jena one is free."

And he smiles benignly as he says it. The controversies through which he
has passed and the calumnies of which he has been the target have left
no scars upon this broad, calm spirit.


HAECKEL AS MAN AND TEACHER

It is indeed a delightful experience to meet Professor Haeckel in the
midst of his charming oasis of freedom, his beloved Jena. To reach his
laboratory you walk down a narrow lane, past Schiller's house, and
the garden where Schiller and Goethe used to sit and where now the
new observatory stands. Haeckel's laboratory itself is a simple oblong
building of yellowish brick, standing on a jutting point of land high
above the street-level. Entering it, your eye is first caught by a set
of simple panels in the wall opposite the door bearing six illustrious
names: Aristotle, Linne, Lamarck, Cuvier, Müller, Darwin--a Greek,
a Swede, two Frenchmen, a German, and an Englishman. Such a list is
significant; it tells of the cosmopolitan spirit that here holds sway.

The ground-floor of the building is occupied by a lecture-room and by
the zoological collection. The latter is a good working-collection, and
purports to be nothing else. Of course it does not for a moment compare
with the collections of the museums in any large city of Europe or
America, nor indeed is it numerically comparable with many private
collections, or collections of lesser colleges in America. Similarly,
when one mounts the stairs and enters the laboratory proper, he finds a
room of no great dimensions and nowise startling in its appointments. It
is admirably lighted, to be sure, and in all respects suitably equipped
for its purpose, but it is by no means so large or so luxurious as the
average college laboratory of America. Indeed, it is not to be mentioned
in the same breath with the laboratories of a score or two of our
larger colleges. Yet, with Haeckel here, it is unquestionably the finest
laboratory in which to study zoology that exists in the world to-day, or
has existed for the last third of a century.

Haeckel himself is domiciled, when not instructing his classes, in a
comfortable but plain room across the hall--a room whose windows look
out across the valley of the Saale on an exquisite mountain landscape,
with the clear-cut mountain that Schiller's lines made famous at its
focus. As you enter the room a big, robust man steps quickly forward to
grasp your hand. Six feet or more in height, compactly built, without
corpulence; erect, vigorous, even athletic; with florid complexion and
clear, laughing, light-blue eyes that belie the white hair and whitening
beard; the ensemble personifying at once kindliness and virility,
simplicity and depth, above all, frank, fearless honesty, without a
trace of pose or affectation--such is Ernst Haeckel. There is something
about his simple, frank, earnest, sympathetic, yet robust, masculine
personality that reminds one instinctively, as does his facial contour
also, of Walt Whitman.

A glance about the room shows you at once that it is a place for study,
and also that it is the room of the most methodical of students.
There are books and papers everywhere, yet not the slightest trace of
disorder. Clearly every book and every parcel of papers has a place,
and is kept in that place. The owner can at any moment lay his hand upon
anything he desires among all these documents. This habit of orderliness
has had no small share, I take it, in contributing to Professor
Haeckel's success in carrying forward many lines of research at the same
time, and carrying all to successful terminations. Then there goes with
it, as a natural accompaniment, a methodical habit of working,
without which no single man could have put behind him the multifarious
accomplishments that stand to Professor Haeckers credit.

Orderliness is not a more pronounced innate gift with Professor Haeckel
than is the gift of initial energy to undertake and carry on work which
leads to accomplishment--a trait regarding which men, even active men,
so widely differ. But Professor Haeckel holds that whatever his normal
bent in this direction, it was enormously strengthened in boyhood by the
precepts of his mother--from whom, by-the-bye, he chiefly inherits his
talents. "My mother," he says, "would never permit me to be idle for a
moment. If I stood at a window day-dreaming, she would always urge me
to be up and doing. 'Work or play,' she would urge, 'but do not stand
idle.' Through this reiterated admonition, physical activity became a
life-long habit with me, and work almost a necessity of my being. If
I have been able to accomplish my full share of labors, this is the
reason. I am never idle, and I scarcely know the meaning of _ennui_."

This must not be interpreted as meaning, however, that Professor Haeckel
takes up a task and works at it all day long unceasingly. That is not
the German method of working, and in this regard Professor Haeckel is
a thorough German. "When I was a young man," he says, "I at one time,
thanks to the persuasions of some English friends, became a convert to
the English method of working, and even attempted to introduce it into
Germany. But I soon relinquished it, and lapsed back into our German
method, which I am convinced will produce better results for the average
worker. The essential of this method is the long midday rest, which
enables one late in the afternoon to begin what is virtually a new
day's-work, and carry it out with vigor and without undue fatigue.
Thus I, who am an early riser, begin work at five in summer and six in
winter, after the customary light breakfast of coffee and rolls. I do
not take a second breakfast at ten or eleven, as many Germans do, but
work continuously until one o'clock, when I have dinner. This, with
me, as with all Germans, is the hearty meal of the day. After dinner I
perhaps take a half-hour's nap; then read the newspaper, or chat with my
family for an hour, and perhaps go for a long walk. At about four, like
all Germans, I take my cup of coffee, but without cake or other food.
Then, at four, having had three full hours of brain-rest and diversion,
I am ready to go to work again, and can accomplish four hours more of
work without undue fatigue. At eight I have my rather light supper, and
after that I attempt no further work, giving the evening to reading,
conversation, or other recreation. I do not retire till rather late, as
I require only five or six hours' sleep."

Such is the method of labor division that enables not Professor Haeckel
only, but a host of other German brain-workers to accomplish enormous
labors, yet to thrive on the accomplishment and to carry the ruggedness
and health of youth far into the decades that are too often with our own
workers given over to decrepitude. Haeckel at sixty-five looks as if he
were good for at least a score of years of further effort. And should he
fulfil the promise of his present rugged-ness, he will do no more than
numbers of his colleagues in German universities have done and are
doing. When one runs over the list of octogenarians, and considers at
the same time the amount of the individual output of the best German
workers, he is led to feel that Professor Haeckel was probably right in
giving up the continuous-day method of labor and reverting to the German
method.

In addition to the original researches that Professor Haeckel has
carried out, to which I have already made some reference, there has,
of course, been all along another large item of time-consumption to be
charged up to his duties as a teacher. These, to be sure, are somewhat
less exacting in the case of a German university professor than they
are in corresponding positions in England or America. Thus, outside the
hours of teaching, Professor Haeckel has all along been able to find
about eight hours a day for personal, original research. When he told
Professor Huxley so in the days of their early friendship, Huxley
exclaimed: "Then you ought to be the happiest man alive. Why, I can find
at most but two hours a day to use for myself."

So much for the difference between German methods of teaching, where the
university professor usually confines his contact with the pupils to an
hour's lecture each day, and the English system, according to which the
lecturer is a teacher in other ways as well. Yet it must be added that
in this regard Professor Haeckel is not an orthodox German, for his
contact with his students is by no means confined to the lecture-hour.
Indeed, if one would see him at his best, he must go, not to the
lecture-hall, but to the laboratory proper during the hours when
Professor Haeckel personally presides there, and brings knowledge and
inspiration to the eager band of young dissectors who gather there. It
will perhaps seem strange to the reader to be told that the hours on
which this occurs are from nine till one o'clock of a day which is
perhaps not devoted to class-room exercises in any other school of
Christendom whatever--namely, the Sabbath. It is interesting to reflect
what would be the comment on such a procedure in London, for example,
where the underground railway trains even must stop running during the
hours of morning service. But Jena is not London, and, as Professor
Haeckel says, "In Jena one is free. It pleases us to have our Sabbath
service in our tabernacle of science."

All questions of time aside, it is a favored body of young men who
occupy the benches in the laboratory during Professor Haeckel's unique
Sunday-morning service. Each student has before him a microscope and a
specimen of the particular animal that is the subject of the morning's
lesson. Let us say that the subject this morning is the crawfish. Then
in addition to the specimens with which the students are provided, and
which each will dissect for himself under the professor's guidance,
there are scattered about the room, on the various tables, all manner
of specimens of allied creatures, such as crabs, lobsters, and the like.
There are dissected specimens also of the crawfish, each preparation
showing a different set of organs, exhibited in preserving fluids. Then
there are charts hung all about the room illustrating on a magnified
scale, by diagram and picture, all phases of the anatomy of the subjects
under discussion. The entire atmosphere of the place this morning smacks
of the crawfish and his allies.

The session begins with a brief off-hand discussion of the general
characteristics and affinities of the group of arthropoda, of which the
crawfish is a member. Then, perhaps, the professor calls the students
about him and gives a demonstration of the curious phenomena of
hypnotism as applied to the crawfish, through which a living specimen,
when held for a few moments in a constrained attitude, will pass into
a rigid "trance," and remain standing on its head or in any other
grotesque position for an indefinite period, until aroused by a blow
on the table or other shock. Such are some of the little asides, so to
speak, with which the virile teacher enlivens his subject and gives it
broad, human interest. Now each student turns to his microscope and his
individual dissection, and the professor passes from one investigator
to another with comment, suggestion, and criticism; answering questions,
propounding anatomical enigmas for solution--enlivening, vivifying,
inspiring the entire situation.

As the work proceeds, Professor Haeckel now and again calls the
attention of the entire class to some particular phase of the subject
just passing under their individual observation, and in the most
informal of talks, illustrated on blackboard and chart, clears up
any lurking mysteries of the anatomy, or enlivens the subject with an
incursion into physiology, embryology, or comparative morphology of the
parts under observation. Thus by the close of the session the student
has something far more than a mere first-hand knowledge of the anatomy
of the crawfish--though that in itself were much. He has an insight
also into a half-dozen allied subjects. He has learned to look on the
crawfish as a link in a living chain--a creature with physiological,
psychological, ontological affinities that give it a human interest not
hitherto suspected by the novitiate. And when the entire series of
Sunday-morning "services" has been carried through, one order after
another of the animal kingdom being similarly made tribute, the favored
student has gone far towards the goal of a truly philosophical zoology,
as different from the old-time dry-bones anatomy as the living crawfish
is different from the dead shell which it casts off in its annual
moulting time.


THE NEW ZOOLOGY

What, then, is the essence of this "philosophical zoology" of which
Haeckel is the greatest living exponent and teacher and of which his
pupils are among the most active promoters? In other words, what is the
real status, and the import and meaning, the _raison d'être_, if you
will, of the science of zoology to-day?

To clear the ground for an answer to that question, one must glance
backward, say half a century, and note the status of the zoology of that
day, that one may see how utterly the point of view has changed since
then; what a different thing zoology has become in our generation from
what it was, for example, when young Haeckel was a student at Jena back
in the fifties. At that time the science of zoology was a conglomeration
of facts and observations about living things, grouped about a set of
specious and sadly mistaken principles. It was held, following Cuvier,
that the beings of the animal kingdom had been created in accordance
with five preconceived types: the vertebrate, with a spinal column;
the articulate, with jointed body and members, as represented by the
familiar crustaceans and insects; the mollusk, of which the oyster and
the snail are familiar examples; the radiate, with its axially
disposed members, as seen in the starfish; and the low, almost formless
protozoon, most of whose representatives are of microscopic size. Each
of these so-called classes was supposed to stand utterly isolated from
the others, as the embodiment of a distinct and tangible idea. So, too,
of the lesser groups or orders within each class, and of the still more
subordinate groups, named technically families, genera; and, finally,
the individual species. That the grouping of species into these groups
was more or less arbitrary was of course to some extent understood, yet
it was not questioned by the general run of zoologists that a genus,
for example, represented a truly natural group of species that had been
created as variations upon one idea or plan, much as an architect
might make a variety of houses, no one exactly like any other, yet all
conforming to a particular type or genus of architecture--for example,
the Gothic or the Romanesque. That each of the groups defined by the
classifiers had such status as this was the stock doctrine of zoology,
as also that the individual species making up the groups, and hence
the groups themselves, maintained their individual identity absolutely
unaltered from the moment of their creation, throughout all successive
generations, to the end of their racial existence.

Such being the fundamental conception of zoology, it remained only for
the investigator to study each individual species with an eye to
its affinities with other species, that each might be assigned by a
scientific classification to the particular place in the original scheme
of creation which it was destined to occupy. Once such affinities
had been correctly determined and interpreted for all species, the
zoological classification would be complete for all time. A survey of
the completed schedule of classification would then show at a glance the
details of the preconceived system in accordance with which the members
of the animal kingdom were created, and zoology would be a "finished"
science.

In the application of this relatively simple scheme, to be sure, no end
of difficulties were encountered. Each higher animal is composed of so
many members and organs, of such diverse variations, that naturalists
could never agree among themselves as to just where a balance of
affinities between resemblances and differences should be struck;
whether, for example, a given species varied so much from the type
species of a genus--say the genus Gothic house--as to belong properly
to an independent genus--say Romanesque house; or whether, on the other
hand, its divergencies were still so outweighed by its resemblances as
to permit of its retention as an aberrant member of genus number one.
Perpetual quibbling over these matters was quite the order of the day,
no two authorities ever agreeing as to details of classification. The
sole point of agreement was that preconceived types were in question--if
only the zoologists could ever determine just what these types were.
Meantime, the student who supposed classifications to be matters of
moment, and who laboriously learned to label the animals and birds
of his acquaintance with an authoritative Latin name, was perpetually
obliged to unlearn what he had acquired, as a new classifier brought new
resources of hair-splitting pursuit of a supposed type or ideal to bear
on the subject. Where, for example, our great ornithologists of the
early part of the century, such as Wilson and Audubon, had classed all
our numerous hawks in a genus falco, later students split the group up
into numerous genera--just how many it is impossible to say, as no two
authorities agreed on that point. Wilson, could he have come back a
generation after his death, would have found himself quite at a loss to
converse with his successors about the birds he knew and loved so
well, using their technical names--though the birds themselves had not
changed.

Notwithstanding all the differences of opinion about matters of detail,
however, there was, nevertheless, substantial agreement about the
broader outlines of classifications, and it might fairly enough
have been hoped that some day, when longer study had led to finer
discrimination, the mysteries of all the types of creation would
be fathomed. But then, while this hope still seemed far enough from
realization, Charles Darwin came forward with his revolutionizing
doctrine--and the whole time-honored myth of "types" of creation
vanished in thin air. It became clear that the zoologists had been
attempting a task utterly Sisyphean. They had sought to establish
"natural groups" where groups do not exist in nature. They were eagerly
peering after an ideal that had no existence outside their imagination.
Their barriers of words could not be made to conform to barriers of
nature, because in nature there are no barriers.

What, then, was to be done? Should the whole fabric of classification
be abandoned? Clearly not, since there can be no science without
classification of facts about labelled groupings, however arbitrary.
Classifications then must be retained, perfected; only in future it must
be remembered that any classification must be more or less arbitrary,
and in a sense false; that it is at best only a verbal convenience, not
the embodiment of a final ideal. If, for example, we consider the very
"natural" group of birds commonly called hawks, we are quite justified
in dividing this group into several genera or minor groups, each
composed of several species more like one another than like the members
of other groups of species--that is, of other genera. But in so doing we
must remember that if we could trace the ancestry of our various species
of hawks we should find that in the remote past the differences that now
separate the groups had been less and less marked, and originally
quite non-existent, all the various species having sprung from a common
ancestor. The genera of to-day are cousin-groups, let us say; but the
parents of the existing species were of one brood, brothers and sisters.
And what applies to the minor groups called genera applies also, going
farther into the past, to all larger groups as well, so that in the last
analysis, all existing creatures being really the evolved and modified
descendants of one primordial type, it may be said that all animate
creation is but a single kind. In this broadened view the details of
classification ceased to have the importance once ascribed to them, and
the quibblings of the classifiers seem amusing rather than serious.
Yet the changed point of view left the subject by no means barren of
interest. For if the multitudinous creatures of the living world are
but diversified twig-lets of a great tree of ascent, spread by branching
from a common root, at least it is worth knowing what larger branches
each group of twiglets--representing a genus, let us say--has sprung
from. In particular, since the topmost twig of the tree is represented
by man himself and his nearest relatives, is it of human interest to
inquire just what branches and main stems will be come upon in tracing
back the lineage of this particular offshoot. This attempt had, perhaps,
no vast, vital importance in the utilitarian sense in which these terms
are oftenest used, but at least it had human interest. Important or
otherwise, it was the task that lay open to zoology, and apparently its
only task, so soon as the Darwinian hypothesis had made good its status.
The man who first took this task in hand, and who has most persistently
and wisely followed it, and hence the man who became the recognized
leader in the field of the new zoology, was, as I have already
intimated, Professor Haeckel. His hypothetical tree of man's lineage,
tracing the ancestry of the human family back to the earliest geological
times and the lowest orders of beings, has been familiar now for just
a third of a century. It was at first confessedly only a tentative
genealogy, with many weak limbs and untraced branches. It was perfected
from time to time, as new data came to hand, through studies of
paleontology, of embryology, and of comparative anatomy. It will be of
interest, then, to inquire just what is its status today and to examine
briefly Professor Haeckel's own most recent pronouncement regarding it.

Perhaps it is not worth our while here to go too far down towards the
root of the genealogical tree to begin our inquiry. So long as it is
admitted that the remote ancestry is grounded in the lowest forms of
organisms, it perhaps does not greatly matter to the average reader that
there are dark places in the lineage during the period when our ancestor
had not yet developed a spinal column--when, in other words, he had not
attained the dignity of the lowest fish. Neither, perhaps, need we
mourn greatly that the exact branch by which our reptilian or amphibian
non-mammalian ancestor became the first and most primitive of mammals is
still hidden in unexplored recesses of early strata. The most patrician
monarch of to-day would not be greatly disturbed as to just who were his
ancestors of the days of the cave-dweller. It is when we come a little
nearer home that the question begins to take on its seemingly personal
significance. Questions of grandparents and great-grandparents concern
the patrician very closely. And so all along, the question that has
interested the average casual investigator of the Darwinian theory
has been the question as to man's immediate ancestor--the parents and
grandparents of our race, so to speak. Hence the linking of the word
"monkey" with the phrase "Darwinian theory" in the popular mind; and
hence, also, the interpretation of the phrase "missing link" in relation
to man's ancestry, as applying only to our ancestor and not to any other
of the gaps in the genealogical chain.

What, then, is the present status of Haeckel's genealogical tree
regarding man's most direct ancestor? Prom what non-human parent did the
human race directly spring? That is a question that has proved itself of
lasting, vital human interest. It is a question that long was answered
only with an hypothesis, but which Professor Haeckel to-day professes
to be able to answer with a decisive and affirmative citation not of
theories but of facts. In a word, it is claimed that man's immediate
ancestor is now actually upon record, that the much-heralded "missing
link" is missing no longer. The principal single document, so to
speak, on which this claim is based consists of the now famous skull and
thigh-bone which the Dutch surgeon, Dr. Eugene Dubois, discovered in the
year 1891 in the tertiary strata of the island of Java. Tertiary strata,
it should be explained, had never hitherto yielded any fossils bordering
on the human type, but this now famous skeleton was unmistakably akin
to the human. The thigh in particular, taken by itself, would have
been pronounced by any competent anatomist to be of human origin.
Unquestionably the individual who bore it had been accustomed to take
an erect attitude in walking. And yet the skull was far inferior in size
and shape to that of any existing tribe of man--was, indeed, rather of
a simian type, though, on the other hand, of about twice the capacity
of any existing ape. In a word, it seemed clear that the creature whose
part skeleton had been found by Dr. Dubois was of a type intermediate
between the lowest existing man and the highest existing man-apes. It
was, in short, the actual prototype of that hypothetical creature which
Haeckel, in his genealogical tree, had christened _pithecanthropus_, the
ape-man. As such it was christened _Pithecanthropus erectus_, the erect
ape-man.

Now the discovery of this remarkable form did not make Professor Haeckel
any more certain that some such form had existed than he was thirty
years before when he christened a hypothetical subject with the title
now taken by a tangible claimant. But, after all, there is something
very taking about a prophecy fulfilled, and so the appearance of
_Pithecanthropus erectus_ created no small sensation in the zoological
world. He was hailed by Haeckel and his followers as the veritable
"missing link," and as such gained immediate notoriety. But, on the
other hand, a reactionary party at once attacked him with the most
bitter animadversions, denouncing him as no true ancestor of man with
a bitterness that is hard to understand, considering that the origin of
man from _some_ lower form has long ceased to be matter of controversy.
"_Pithecanthropus_ is at least half an ape," they cried, with the clear
implication of "anything but an ape for an ancestor!"

I confess I have always found it hard to understand just why this
peculiar aversion should always be held against the unoffending ape
tribe. Why it would not be quite as satisfactory to find one's ancestor
in an ape as in the alternative lines of, for example, the cow, or the
hippopotamus, or the whale, or the dog has always been a mystery. Yet
the fact of this prejudice holds. Probably we dislike the ape because
of the very patency of his human affinities. The poor relation is
objectionable not so much because he is poor as because he is a
relation. So, perhaps, it is not the apeness, so to speak, of the ape
that is objectionable, but rather the human-ness. In any event, the
aversion has been matter of common notoriety ever since the Darwinian
theory became fully accepted; it showed itself now with renewed force
against poor _pithecanthropus_. A half-score of objections were launched
against him. It is needless to rehearse them now, since they were all
met valiantly, and the final verdict saw the new-comer triumphantly
ensconced in man's ancestral halls as the oldest sojourner there who
has any title to be spoken of as "human." He is only half human, to be
sure--a veritable ape-man, as his name implies--but exactly therein lies
his altogether unique distinction. He is the embodiment of that "missing
link" whose nonappearance had hitherto given so much comfort to the
sceptical.

Perhaps some crumbs of comfort may be found by the reactionists in the
fact that it is not held by Professor Haeckel, or by any other competent
authority, that the link which _pithecanthropus_ supplies welds man
directly with any existing man-ape--with gorilla, chimpanzee, or orang.
It is held that these highest existing apes are side branches, so
to say, of the ancestral tree, who developed, in their several ways,
contemporaneously with our direct ancestors, but are not themselves
directly of the royal line. The existing ape that has clung closest to
the direct ancestral type of our own race, it appears, is the gibbon--a
creature far less objectionable in that rôle because of the very paucity
of his human characteristics, as revealed to the casual observer.
Gibbon-like fossil apes are known, in strata representing a time some
millions of years antecedent to the epoch of _pithecanthropus_
even, which are held to be directly of the royal line through which
_pithecanthropus_, and the hypothetical _Homo stupidus_, and the known
_Homo neanderthalensis_, and, lastly, proud _Homo sapiens_ himself have
descended. Thus Professor Haeckel is able to make the affirmation, as he
did recently before the International Zoological Congress in Cambridge,
that man's line of descent is now clearly traced, from a stage back in
the Eocene time when our ancestor was not yet more than half arrived to
the ape's estate, down to the time of true human development. "There no
longer exists," he says, "a 'missing link.' The phyletic continuity
of the primate stem, from the oldest lemurs down to man himself, is an
historical fact."

It should, perhaps, be added that the force of this rather startling
conclusion rests by no means exclusively upon the finding of
_pithecanthropus_ and the other fossils, nor indeed upon any
paleontological evidence whatever. These, of course, furnish data of
a very tangible and convincing kind; but the evidence in its totality
includes also a host of data from the realms of embryology and
comparative anatomy--data which, as already suggested, enabled Professor
Haeckel to predicate the existence of _pithecanthropus_ long in advance
of his actual discovery. Whether the more remote gaps in the chain of
man's ancestry will be bridged in a manner similarly in accord with
Professor Haeckel's predications, it remains for future discoveries
of zoologist and paleontologist to determine. In any event, the recent
findings have added an increment of glory to that philosophical zoology
of which Professor Haeckel is the greatest living exponent.

This tracing of genealogies is doubtless the most spectacular feature of
the new zoology, yet it must be clear that the establishment of lines
of evolution is at best merely a preparation for the all-important
question, Why have these creatures, man included, evolved at all? That
question goes to the heart of the new zoological philosophy. A partial
answer was, of course, given by Darwin in his great doctrine of natural
selection. But this doctrine, while explaining the preservation of
favorable variations, made no attempt to account for the variations
themselves. Professor Haeckel's contribution to the subject consisted in
the revival of the doctrine of Lamarck, that individual variations, in
response to environmental influences, are transmitted to the offspring,
and thus furnish the material upon which, applying Darwin's principle,
evolution may proceed. This Lamarck-Haeckel doctrine was under a cloud
for a recent decade, during the brief passing of the Weismannian myth,
but it has now emerged, and stands as the one recognized factor in the
origin of those variations whose cumulative preservation through natural
selection has resulted in the evolution of organic forms.

But may there not be other factors, as yet unrecognized, that supplement
the Lamarckian and Darwinian principles in bringing about this
marvellous evolution of beings? That, it would seem, is the most vital
question that the philosophical zoology of our generation must hand on
to the twentieth century. For today not even Professor Haeckel himself
can give it answer.



VII. SOME MEDICAL LABORATORIES AND MEDICAL PROBLEMS


THE PASTEUR INSTITUTE

THE national egotism that characterizes the French mind is not without
its compensations. It leads, for example, to the tangible recognition
of the merits of the great men of the nation and to the promulgation
of their names in many public ways. Thus it would be hard to mention a
truly distinguished Frenchman of the older generations whose name has
not been given to a street in Paris. Of the men of science thus
honored, one recalls off-hand the names of Buffon, Cuvier, Geoffroy
Saint-Hilaire, Pinel, Esquirol, Lamarck, Laplace, Lavoisier, Arago,
Claude Bernard, Broca--indeed, one could readily extend the list
to tiresome dimensions. Moreover, it is a list that is periodically
increased by the addition of new names, as occasion offers, for the
Parisian authorities never hesitate to rechristen a street or a portion
of a street, regardless of former associations.

One of the most recent additions to this roll of fame is the name of
Pasteur. The boulevard that bears that famous name is situated in a
somewhat out-of-the-way corner of the city, though to reach it one has
but to traverse the relatively short course of the Avenue de Breteuil
from so central a position as the tomb of Napoleon. The Boulevard
Pasteur itself is a not long but very spacious thoroughfare, which
will some day be very beautiful, when the character of its environing
buildings has somewhat changed and its quadruple rows of trees have had
time for development. At present its chief distinction, in the eyes
of most observers, would probably be found in the fact that it is the
location of the famous _fête forain_ at one of the annually recurring
stages of the endless itinerary of that noted function. During the
period of this distinction, which falls in the month of May, the
boulevard becomes transformed into a veritable Coney Island of
merry-go-rounds, shooting-galleries, ginger-bread booths, and clap-trap
side-shows, to the endless delight of throngs of pleasure-seekers. There
is no sight in all Paris worthier inspection for the foreigner than the
Boulevard Pasteur offers at this season, for one gains a deep insight
into the psychology of a people through observation of the infantile
delight with which the adult population here throws itself into the
spirit of amusements which with other nations are for the most part
reserved for school-children. Only a race either in childhood or
senescence, it would seem, could thus give itself over with undisguised
delight to the enchantments of wooden horses, cattle, cats, and pigs; to
the catching of wooden fish with hooks; to the shooting at targets that
one could almost touch with the gun-muzzle, and to the grave observation
of sideshow performances that would excite the risibilities of the most
unsophisticated audience that could be found in the Mississippi Valley.

As we move among this light-hearted and lightheaded throng we shall
scarcely escape a feeling of good-humored contempt for what seems an
inferior race. It will be wholesome, therefore, for us to turn aside
from the boulevard into the Rue Dotot, which leads from it near its
centre, and walk a few hundred yards away from the pleasure-seekers,
where an evidence of a quite different and a no less characteristic
phase of the national psychology will be before us. For here, within
easy sound of the jangling discords of the organs that keep time for the
march of the _cheveaux de bois_, rises up a building that is in a sense
the monument of a man who was brother in blood and in sentiment to the
revellers we have just left in the boulevard, yet whose career stamped
him as one of the greatest men of genius of any race or any time. That
man was Louis Pasteur. The building before us is the famous institute
that bears his name.

In itself this building is a simple and unimposing structure, yet of
pleasing contour. It is as well placed as the surroundings permit, on a
grassed terrace, a little back from the street, where a high iron fence
guards it and gives it a degree of seclusion. There are other buildings
visible in the rear, which, as one learns on entering, are laboratories
and the like, where the rabbits and guinea-pigs and dogs that are so
essential to the work of the laboratory are kept. On the terrace
in front is a bronze statue of a boy struggling with a rabid dog--a
reminder of the particular labor of the master-worker which led directly
to the foundation of the institution. It will be remembered that it
was primarily to give Pasteur a wider opportunity to apply his newly
discovered treatment for the prevention of rabies that the subscription
was undertaken which led finally to the erection of the buildings before
us and brought the Pasteur Institute in its present form into being.
Of the other aims and objects of the institution I shall speak more at
length in a moment.

I have just said that the building before us is in effect the monument
of the great savant. This is true in a somewhat more literal sense than
might be supposed, for the body of Pasteur rests in a crypt at its base.
The personal labors of the great discoverer were practically ended at
the time when the institute was opened in 1888, on which occasion,
as will be remembered, the scientific representatives of all nations
gathered in Paris to do honor to the greatest Frenchman of his
generation. He was spared to the world, however, for seven years more,
during which time he fully organized the work of the institution along
the lines it has since followed, and was, of course, the animating
spirit of all the labors undertaken there by his devoted students and
assistants. He is the animating spirit of the institution still, and it
is fitting that his body should rest in the worthy mausoleum within the
walls of that building whose erection was the tangible culmination
of his life labors. The sarcophagus is a shrine within this temple of
science which will serve to stimulate generations of workers here to
walk worthily in the footsteps of the great founder of the institution.
For he must be an unimaginative person indeed who, passing beneath that
arch bearing the simple inscription "Ici Repose Pasteur," could descend
into the simple but impressive mausoleum and stand beside the massive
granite sarcophagus without feeling the same kind of mental uplift which
comes from contact with a great and noble personality. The pretentious
tomb of Galileo in the nave of Santa Croce at Florence, and the crowded
resting-place of Newton and Darwin in Westminster Abbey, have no such
impressiveness as this solitary vault where rests the body of Pasteur,
isolated in death as the mightier spirits must always be in life.


AIMS AND OBJECTS OF THE PASTEUR INSTITUTE

If one chances to come to the institute in the later hours of the
morning he will perhaps be surprised to find a motley company of men,
women, and children, apparently of many nationalities and from varied
walks of life, gathered about one of the entrances or sauntering near
by. These are the most direct beneficiaries of the institution, the
unfortunate victims of the bites of rabid dogs, who have come here to
take the treatment which alone can give them immunity from the terrible
consequences of that mishap. Rabies, or hydrophobia as it is more
commonly termed with us, is well known to be an absolutely fatal malady,
there being no case on record of recovery from the disease once fully
established. Even the treatment which Pasteur developed and which is
here carried out cannot avail to save the victim in whom the active
symptoms of the malady are actually present. But, fortunately, the
disease is peculiarly slow in its onset, sometimes not manifesting
itself for weeks or months after the inoculation; and this delay, which
formerly was to the patient a period of fearful doubt and anxiety, now
suffices, happily, for the application of the protective inoculations
which enable the person otherwise doomed to resist the poison and go
unscathed. Thus it is that the persons who gather here each day to the
number of fifty, or even one hundred, have the appearance of and the
feelings of average health, though a large proportion of them bear in
their systems, on arrival, the germs of a disease that would bring them
speedily to a terrible end were it not that the genius of Pasteur had
found a way to give them immunity. The number of persons who have been
given the anti-rabic treatment here is more than twenty-five thousand.
To have given safety to such an army of unfortunates is, indeed, enough
merit for any single institution; but it must not be supposed that this
record is by any manner of means the full measure of the benefits which
the Institut Pasteur has conferred upon humanity. In point of fact, the
preparation and use of the anti-rabic serum is only one of many aims
of the institution, whose full scope is as wide as the entire domain of
contagious diseases. Pasteur's personal discoveries had demonstrated
the relation of certain lower organisms, notably the bacteria, to the
contagious diseases, and had shown the possibility of giving immunity
from certain of these diseases through the use of cultures of the
noxious bacteria themselves. He believed that these methods could be
extended and developed until all the contagious diseases, which hitherto
have accounted for so startling a proportion of all deaths, were brought
within the control of medical science. His deepest thought in founding
the institute was to supply a tangible seat of operations for this
attempted conquest, where the brilliant assistants he had gathered about
him, and their successors in turn, might take a share in this great
struggle, unhampered by the material drawbacks which so often confront
the would-be worker in science.

He desired also that the institution should be a centre of education
along the lines of its work, adding thus an indirect influence to the
score of its direct achievements. In both these regards the institution
has been and continues to be worthy of its founder. The Pasteur
Institute is in effect a school of bacteriology, where each of the
professors is at once a teacher and a brilliant investigator. The chief
courses of instruction consist of two series each year of lectures and
laboratory demonstrations on topics within the field of bacteriology.
These courses, at which all the regular staff of the institution assist
more or less, are open to physicians and other competent students
regardless of nationality, and they suffice to inculcate the principles
of bacteriology to a large band of seekers each year.

But more important, perhaps, than this form of educational influence is
the impetus given by the institute to the researches of a small, select
band of investigators who have taken up bacteriology for a life work,
and who come here to perfect themselves in the final niceties of the
technique of a most difficult profession. Thus such men as Calmette,
the discoverer of the serum treatment of serpent-poisoning, and Yersin,
famous for his researches in the prevention and cure of cholera by
inoculation, are "graduates" of the Pasteur Institute. Indeed, almost
all the chief laborers in this field in the world to-day, including the
directors of practically all the daughter institutes bearing the same
name that are now scattered all over the world, have had at least a
share of their training in the mother institute here in Paris.

Of the work of the men who form the regular staff of the Pasteur
Institute only a few words need be said here. Doctors Roux, Grancher,
Metchnikoff, and Chamberland all had the privilege of sharing Pasteur's
labors during the later years of the master's life, and each of them is
a worthy follower of the beloved leader and at the same time a brilliant
original investigator.*1* Roux is known everywhere in connection with
the serum treatment of diphtheria, which he was so largely instrumental
in developing. Grancher directs the anti-rabic department and allied
fields. Metchnikoff, a Russian by birth and Parisian by adoption, is
famous as the author of the theory that the white blood-corpuscles of
the blood are the efficient agents in combating bacteria. Chamberland
directs the field of practical bacteriology in its applications to
hygiene, including the department in which protective serums are
developed for the prevention of various diseases of domesticated
animals, notably swine fever and anthrax. About one million sheep and
half as many cattle are annually given immunity from anthrax by the
serum here produced.

Of the patient and unremitting toil demanded of the investigator in
this realm of the infinitely little; of the skill in manipulation, the
fertility of resource, the scrupulous exactness of experiment that
are absolutely prerequisite to success; of the dangers that attend
investigations which deal with noxious germs, every one who knows
anything of the subject has some conception, but those alone can have
full comprehension who have themselves attempted to follow the devious
and delicate pathways of bacteriology. But the goals to which these
pathways lead have a tangibility that give them a vital interest for all
the world. The hopes and expectations of bacteriology halt at nothing
short of the ultimate extirpation of contagious diseases. The way to
that goal is long and hard, yet in time it will be made passable. And
in our generation there is no company of men who are doing more
towards that end than the staff of that most famous of bacteriological
laboratories the Pasteur Institute.


THE VIRCHOW INSTITUTE OF PATHOLOGY

Even were the contagious diseases well in hand, there would still
remain a sufficient coterie of maladies whose origin is not due to the
influence of living germs. There are, for example, many diseases of the
digestive, nutritive, and excretory systems, of the heart and arteries,
of the brain and nerves, and various less clearly localized abnormal
conditions, that owe their origin to inherent defects of the
organism, or to various indiscretions of food or drink, to unhygienic
surroundings, to material injuries, or to other forms of environmental
stress quite dissociated from the action of bacteria. It is true that
one would need to use extreme care nowadays in defining more exactly the
diseases that thus lie without the field of the bacteriologist, as that
prying individual seems prone to claim almost everything within sight,
and to justify his claim with the microscope; but after that instrument
has done its best or worst, there will still remain a fair contingent
of maladies that cannot fairly be brought within the domain of the
ever-present "germ." On the other hand, all germ diseases have of course
their particular effects upon the system, bringing their results within
the scope of the pathologist. Thus while the bacteriologist has no
concern directly with any disease that is not of bacterial origin, the
pathologist has a direct interest in every form of disease whatever;
in other words, bacteriology, properly considered, is only a special
department of pathology, just as pathology itself is only a special
department of general medicine.

Whichever way one turns in science, subjects are always found thus
dovetailing into one another and refusing to be sharply outlined.
Nevertheless, here as elsewhere, there are theoretical bounds that
suffice for purposes of definition, if not very rigidly lived up to in
practice; and we are justified in thinking of the pathologist (perhaps
I should say the pathological anatomist) as the investigator of disease
who is directly concerned with effects rather than with causes, who aims
directly at the diseased tissue itself and reasons only secondarily
to the causes. His problem is: given a certain disease (if I may be
permitted this personified form of expression), to find what tissues of
the body are changed by it from the normal and in what manner changed.

It requires but a moment's reflection to make it clear that a certain
crude insight into the solution of this problem, as regards all common
diseases, must have been the common knowledge of medical men since
the earliest times. Thus not even medical knowledge was needed to
demonstrate that the tissues of an in: flamed part become red and
swollen; and numerous other changes of diseased tissues are almost
equally patent. But this species of knowledge, based on microscopic
inspection, was very vague and untrustworthy, and it was only after the
advent of the perfected microscope, some three-quarters of a century
ago, that pathological anatomy began to have any proper claim to
scientific rank. Indeed, it was not until about the year 1865 that the
real clew was discovered which gave the same impetus to pathology that
the demonstration of the germ theory of disease gave at about the same
time to etiology, or the study of causes of disease. This clew consisted
of the final demonstration that all organic action is in the last resort
a question of cellular activities, and, specifically, that all abnormal
changes in any tissues of the body, due to whatever disease, can consist
of nothing more than the destruction, or the proliferation, or the
alteration of the cells that compose that tissue.

That seems a simple enough proposition nowadays, but it was at once
revolutionary and inspiring in the day of its original enunciation some
forty years ago. The man who had made the discovery was a young German
physician, professor in the University of Freiburg, by name Rudolph
Virchow. The discovery made him famous, and from that day to this the
name of Virchow has held somewhat the same position in the world
of pathology that the name of Pasteur occupied in the realm of
bacteriology. Virchow was called presently to a professorship in the
University of Berlin. In connection with this chair he established his
famous Institute of Pathology, which has been the Mecca of all students
of pathology ever since. He did a host of other notable things as well,
among others, entering the field of politics, and becoming a recognized
leader there no less than in science. Indeed, it seemed during the later
decades of his life as if one encountered Virchow in whatever direction
one turned in Berlin, and one feels that it was not without reason that
his compatriots spoke of him as "the man who knows everything." To the
end he retained all the alertness of intellect and the energy of body
that had made him what he was. One found him at an early hour in the
morning attending to the routine of his hospital duties, his lectures,
and clinical demonstrations. These finished, he rushed off, perhaps
to his parliamentary duties; thence to a meeting of the Academy of
Sciences, or to preside at the Academy of Medicine or at some other
scientific gathering. And in intervals of these diversified pursuits he
was besieged ever by a host of private callers, who sought his opinion,
his advice, his influence in some matter of practical politics, of
statecraft, or of science, or who, perhaps, had merely come the length
of the continent that they might grasp the hand of the "father of
pathology."

In whatever capacity one sought him out, provided the seeking were not
too presumptuous, one was sure to find the great savant approachable,
courteous, even cordial. A man of multifarious affairs, he impressed
one as having abundance of time for them all, and to spare. There is a
leisureliness about the seeming habit of existence on the Continent that
does not pertain in America, and one felt the flavor of it quite as much
in the presence of this great worker as among those people who from
our stand-point seem never really to work at all. This is to a certain
extent explained if one visited Virchow in his home, and found to his
astonishment that the world-renowned physician, statesman, pathologist,
anthropologist was domiciled in a little apartment of the most modest
equipment, up two flights, in a house of most unpretentious character.
Everything was entirely respectable, altogether comfortable, to be sure;
but it was a grade of living which a man of corresponding position in
America could not hold to without finding himself quite out of step with
his confrères and the subject of endless comment. But in this city
of universal apartment-house occupancy and relatively low average of
display in living it is quite otherwise. Virchow lived on the same
plane, generally speaking, with the other scientists of Europe; it is
only from the American standpoint that there is any seeming disparity
between his fame and his material station in life; nor do I claim this
as a merit of the American stand-point.

Be that as it may, however, our present concern lies not with these
matters, but with Virchow the pathologist and teacher. To see the
great scientist at his best in this rôle, it was necessary to visit the
Institute of Pathology on a Thursday morning at the hour of nine. On
the morning of our visit we found the students already assembled and
gathered in clusters all about the room, examining specimens of morbid
anatomy, under guidance of various laboratory assistants. This was
to give them a general familiarity with the appearances of the
disease-products that would be described to them in the ensuing lecture.
But what is most striking about the room was the very unique method of
arrangement of the desk or table on which the specimens rested. It
was virtually a long-drawn-out series of desks winding back and forth
throughout the entire room, but all united into one, so that a specimen
passed along the table from end to end will make a zigzag tour of the
room, passing finally before each person in the entire audience. To
facilitate such transit, there was a little iron railway all along the
centre of the table, with miniature turn-tables at the corners, along
which microscopes, with adjusted specimens for examination, might be
conveyed without danger of maladjustment or injury. This may seem a
small detail, but it is really an important auxiliary in the teaching
by demonstration with specimens for which this room was peculiarly
intended. The ordinary lectures of Professor Virchow were held in a
neighboring amphitheatre of conventional type.

Of a sudden there was a hush in the hum of voices, as a little, thin,
frail-seeming man entered and stepped briskly to the front of the
room and upon the low platform before the blackboard in the corner. A
moment's pause for the students to take their places, and the lecturer,
who of course was Virchow himself, began, in a clear, conversational
voice, to discourse on the topic of the day, which chanced to be the
formation of clots in blood-vessels. There was no particular attempt at
oratory; rather the lecturer proceeded as if talking man to man, with
no thought but to make his meaning perfectly clear. He began at once
putting specimens in circulation, as supplied on his demand by his
assistants from a rather grewsome-looking collection before him. Now
he paused to chaff the assistant who was making the labels, poking
good-humored jokes at his awkwardness, but with no trace of sting. Again
he became animated, his voice raised a little, his speech more vehement,
as he advanced his own views on some contested theory or refuted the
objections that some opponent had urged against him, always, however,
with a smile lurking about his eyes or openly showing on his lips.

Constantly the lecturer turned to the blackboard to illustrate with
colored, crayons such points of his discourse as the actual specimens in
circulation might leave obscure. Everything must be made plain to every
hearer or he would not be satisfied. One can but contrast such teaching
as this with the lectures of the average German professor, who seems not
to concern himself in the least as to whether anything is understood by
any one. But Virchow had the spirit of the true teacher. He had the air
of loving his task, old story as it was to him. Most of his auditors
were mere students, yet he appealed to them as earnestly as if they
were associates and equals. He seemed to try to put himself on their
level--to make his thought near to them. Physically he was near to them
as he talked, the platform on which he stood being but a few inches
in height, and such physical nearness conduces to a familiarity of
discourse that is best fitted for placing lecturer and hearers _en
rapport_. All in all, appealing as it does almost equally to ear and
eye, it is a type of what a lecturer should be. Not a student there but
went away with an added fund of information, which is far more than can
be said of most of the lectures in a German university.

Needless to say, there are other departments to the Institute of
Pathology. There are collections of beautifully preserved specimens for
examination; rooms for practical experimentation in all phases of the
subject, the chemical side included; but these are not very different
from the similar departments of similar institutions everywhere. What
was unique and characteristic about this institution was the personality
of the director. Now he is gone, but his influence will not soon be
forgotten. The pupils of a great teacher are sure to carry forward the
work somewhat in the spirit of the master for at least a generation.


THE BERLIN INSTITUTE OP HYGIENE

I purposely refrain from entering into any details as to the character
of the technical work done at the Virchow Institute, because the subject
of pathology, despite its directly practical bearings, is in itself
necessarily somewhat removed from the knowledge of the general reader.
One cannot well understand the details of changes in tissues under
abnormal conditions unless one first understands the normal conditions
of the tissues themselves, and such knowledge is reserved for the
special students of anatomy. For the nonprofessional observer the
interest of the Virchow Institute must lie in its general scope rather
than in the details of the subjects there brought under investigation,
which latter have, indeed, of necessity, a somewhat grewsome character
despite the beneficent results that spring from them. It is quite
otherwise, however, with the work of the allied institution of which I
now come to speak. The Institute of Hygiene deals with topics not very
remote from those studied in the Virchow Institute, part of its work,
indeed, falling clearly within the scope of pathology; but it differs in
being clearly comprehensible to the general public and of immediate
and tangible interest from the most strictly utilitarian stand-point,
hygiene being, in effect, the tangible link between the more abstract
medical sciences and the affairs of every-day life.

The Institute of Hygiene has also the interest that always attaches to
association with a famous name, for it was here that Professor Koch made
the greater part of those investigations which made his name the best
known, next to that of Pasteur, of any in the field of bacteriology.
In particular, the researches on the cholera germ, and those even more
widely heralded researches that led to the discovery of the bacillus of
tuberculosis, and the development of the remedy tuberculin, of which
so much was at first expected, were made by Professor Koch in the
laboratories of the antiquated building which was then and is still
the seat of the Institute of Hygiene. More recently Professor Koch has
severed his connection with the institution after presiding over it for
many years, having now a semi-private laboratory just across from the
Virchow Institute, in connection with the Charité Hospital; but one
still thinks of the Institute of Hygiene as peculiarly the "Koch
Institute" without injustice, so fully does its work follow the lines
laid out for it by the great leader.

But however much the stamp of any individual personality may rest upon
the institute, it is officially a department of the university, just as
is the Virchow Institute. Like the latter, also, its local habitation
is an antiquated building, strangely at variance, according to American
ideas, with its reputation, though by no means noteworthy in this regard
in the case of a German institution. It is situated in a part of the
city distant from any other department of the university, and there is
nothing about it exteriorly to distinguish it from other houses of the
solid block in which it stands. Interiorly, it reminds one rather of a
converted dwelling than a laboratory proper. Its rooms are well
enough adapted to their purpose, but they give one the impression of
a makeshift. The smallest American college would be ill-satisfied with
such an equipment for any department of its work. Yet in these dingy
quarters has been accomplished some of the best work in the new science
of bacteriology that our century will have to boast.

The actual equipment of the bacteriological laboratory here is not,
indeed, quite as meagre as it seems at first, there being numerous
rooms, scattered here and there, which in the aggregate give opportunity
for work to a large number of investigators, though no single room makes
an impressive appearance. There is one room, however, large enough to
give audience to a considerable class, and here lectures were given by
Professor Koch and continue to be given by his successors to the special
students of bacteriology who come from all over the world, as well as to
the university students who take the course as a part of their regular
medical curriculum. In regard to this feature of its work, the Institute
of Hygiene differs in no essential respect from the Pasteur Institute
and other laboratories of bacteriology. The same general routine of work
pertains: the patient cultivation of the minute organisms in various
mediums, their careful staining by special processes, and their
investigation under the microscope mark the work of the bacteriologist
everywhere. Many details of the special methods of culture or treatment
originated here with Professor Koch, but such matters are never kept
secret in science, so one may see them practised quite as generally
and as efficiently in other laboratories as in this one. Indeed, it may
frankly be admitted that, aside from its historical associations with
the pioneer work in bacteriology, which will always make it memorable,
there is nothing about the bacteriological laboratory here to give it
distinction over hundreds of similar ones elsewhere; while in point of
technical equipment, as already noted, it is remarkable rather for what
it lacks than for what it presents.

The department of bacteriology, however, is only one of several
important features of the institute. One has but to ascend another
flight of stairs to pass out of the sphere of the microbe and enter a
department where attention is directed to quite another field. We have
now come to what may be considered the laboratory of hygiene proper,
since here the investigations have to do directly with the functionings
of the human body in their relations to the every-day environment.
Here again one is struck with the meagre equipment with which important
results may be attained by patient and skilled investigators. In only
one room does one find a really elaborate piece of apparatus. This
exceptional mechanism consists essentially of a cabinet large enough to
give comfortable lodgment to a human subject--a cabinet with walls of
peculiar structure, partly of glass, and connected by various pipes with
sundry mysterious-seeming retorts. This single apparatus, however, is
susceptible of being employed for the investigation of an almost endless
variety of questions pertaining to the functionings of the human body
considered as a working mechanism.

Thus, for example, a human subject to be experimented upon may remain
for an indefinite period within this cabinet, occupied in various ways,
taking physical exercise, reading, engaged in creative mental labor,
or sleeping. Meantime, air is supplied for respiration in measured
quantities, and of a precisely determined composition, as regards
chemical impurities, moisture, and temperature. The air after passing
through the chamber being again analyzed, the exact constituents added
to it as waste products of the human machine in action under varying
conditions are determined. It will readily be seen that by indefinitely
varying the conditions of such experiments a great variety of data
may be secured as to the exact physiological accompaniments of various
bodily and mental activities. Such data are of manifest importance to
the physiologist and pathologist on the one hand, while at the same
time having a direct bearing on such eminently practical topics as the
construction of shops, auditoriums, and dwellings in reference to light,
heat, and ventilation. It remains only for practical architecture to
take advantage of the unequivocal data thus placed at its disposal--an
opportunity of which practical architecture, in Germany as elsewhere on
the Continent, has hitherto been very slow to avail itself.


THE MUSEUM OF HYGIENE

The practical lessons thus given in the laboratory are supplemented in
an even more tangible manner, because in a way more accessible to
the public, in another department of the institution which occupies a
contiguous building, and is known as the Museum of Hygiene. This, unlike
the other departments of the institute, is open to the general public
on certain days of each week, and it offers a variety of exhibits of
distinctly novel character and of high educational value. The general
character of the exhibits may be inferred from the name, but perhaps the
scope is even wider than might be expected. In a word, it may be said
that scarcely anything having to do with practical hygiene has been
overlooked. Thus one finds here numberless models of dwelling-houses,
showing details of lighting, heating, and ventilation; models not
merely of individual dwellings, but also of school-buildings, hospitals,
asylums, and even prisons. Sometimes the models represent merely
ideal buildings, but more generally they reproduce in miniature actual
habitations. In the case of the public buildings, the model
usually includes not merely the structures themselves but the
surroundings--lawns, drives, trees, out-buildings--so that one can get a
very good idea of the more important hospitals, asylums, and prisons of
Germany by making a tour of the Museum of Hygiene. Regarding the details
of structure, one can actually gain a fuller knowledge in many cases
than he could obtain by actual visits to the original institutions
themselves.

The same thing is true of various other features of the subjects
represented. Thus there is a very elaborate model here exhibited of the
famous Berlin system of sewage-disposal. As is well known, the essential
features of this system consist of the drainage of sewage into local
reservoirs, from which it is forced by pumps, natural drainage not
sufficing, to distant fields, where it is distributed through tile pipes
laid in a network about a yard beneath the surface of the soil. The
fields themselves, thus rendered fertile by the waste products of the
city, are cultivated, and yield a rich harvest of vegetables and grains
of every variety suitable to the climate. The visitor to this field
sees only rich farms and market-gardens under ordinary process of
cultivation. The system of pipes by which the land is fertilized is
as fully hidden from his view as are, for example, the tributary
sewage-pipes beneath the city pavements. The average visitor to Berlin
knows nothing, of course, about one or the other, and goes away, as he
came, ignorant of the important fact that Berlin has reached a better
solution of the great sewage problem than has been attained by any
other large city. Such, at least, is likely to be the case unless the
sight-seer chance to pay a visit to the Museum of Hygiene, in which
case a few minutes' inspection of the model there will make the matter
entirely clear to him. It is to be regretted that the authorities
of other large cities do not make special visits to Berlin for this
purpose; though it should be added that some of them have done so, and
that the Berlin system of "canalization" has been adopted in various
places in America. But many others might wisely follow their example,
notably the Parisians, whose sewerage system, despite the boasted
exhibition canal-sewer, is, like so many other things Parisian, of the
most primitive character and a reproach to present-day civilization.

It may be added that there are plenty of things exhibited in this museum
which the Germans themselves might study to advantage, for it must be
understood that the other hygienic conditions pertaining to Berlin are
by no means all on a par with the high modern standard of the sewerage
system. In the matter of ventilation, for example, one may find
admirable models in the museum, showing just how the dwelling and shop
and school-room should make provision for a proper supply of pure air
for their occupants. But if one goes out from the museum and searches in
the actual dwelling or shop or school-room for the counterparts of
these models, one will be sorely puzzled where to find them. The general
impression which a casual inspection will leave in his mind is that the
word ventilation must be as meaningless to the German mind as it is, for
example, to the mind of a Frenchman or an Italian. This probably is not
quite just, since the German has at least reached the stage of having
museum models of ventilated houses, thus proving that the idea does
exist, even though latent, in his mental equipment, whereas the other
continental nationalities seem not to have reached even this incipient
stage of progress. All over Europe the people fear a current of air as
if veritable miasm must lurk in it. They seem quite oblivious to any
systematic necessity for replenishing the oxygen supply among large
assemblies, as any one can testify who has, for example, visited their
theatres or schools. And as to the private dwellings, after making
them as nearly air-tight as practicable, they endeavor to preserve the
_status quo_ as regards air supply seemingly from season to season. They
even seem to have passed beyond a mere negative regard for the subject
of fresh air, inasmuch as they will bravely assure you that to sleep
in a room with an open window will surely subject you to the penalty of
inflamed eyes.

In a country like France, where the open fireplace is the usual means
employed to modify the temperature (I will not say warm the room),
the dwellings do of necessity get a certain amount of ventilation,
particularly since the windows are not usually of the best construction.
But the German, with his nearly air-tight double windows and his even
more nearly sealed tile stove, spends the winter in an atmosphere
suggestive of the descriptions that arctic travellers give us of the
air in the hut of an Eskimo. It is clear, then, that the models in the
Museum of Hygiene have thus far failed of the proselyting purpose
for which they were presumably intended. How it has chanced that the
inhabitants of the country maintain so high an average of robust health
after this open defiance is a subject which the physiological department
of the Institute of Hygiene might well investigate.

Even though the implied precepts of the Museum of Hygiene are so largely
disregarded, however, it must be admitted that the existence of the
museum is a hopeful sign. It is a valuable educational institution,
and if its salutary lessons are but slowly accepted by the people, they
cannot be altogether without effect. At least the museum proves that
there are leaders in science here who have got beyond the range of
eighteenth-century thought in matters of practical living, and the
sign is hopeful for the future, though its promise will perhaps not be
fulfilled in our generation.



VII. SOME UNSOLVED SCIENTIFIC PROBLEMS


IN recent chapters we have witnessed a marvellous development in many
branches of pure science. In viewing so wonderfully diversified a field,
it has of course been impossible to dwell upon details, or even to
glance at every minor discovery. At best one could but summarize the
broad sweep of progress somewhat as a battle might be described by a
distant eye-witness, telling of the general direction of action, of
the movements of large masses, the names of leaders of brigades and
divisions, but necessarily ignoring the lesser fluctuations of advance
or recession and the individual gallantry of the rank and file. In
particular, interest has centred upon the storming of the various
special strongholds of ignorant or prejudiced opposition, which at last
have been triumphantly occupied by the band of progress. In each case
where such a stronghold has fallen, the victory has been achieved solely
through the destructive agency of newly discovered or newly marshalled
facts--the only weapons which the warrior of science seeks or cares for.
Facts must be marshalled, of course, about the guidon of a hypothesis,
but that guidon can lead on to victory only when the facts themselves
support it. Once planted victoriously on the conquered ramparts the
hypothesis becomes a theory--a generalization of science--marking a
fresh coign of vantage, which can never be successfully assailed unless
by a new host of antagonistic facts. Such generalizations, with the
events leading directly up to them, have chiefly occupied our attention.

But a moment's reflection makes it clear that the battle of science,
thus considered, is ever shifting ground and never ended. Thus at
any given period there are many unsettled skirmishes under way; many
hypotheses are yet only struggling towards the stronghold of theory,
perhaps never to attain it; in many directions the hosts of antagonistic
facts seem so evenly matched that the hazard of war appears uncertain;
or, again, so few facts are available that as yet no attack worthy the
name is possible. Such unsettled controversies as these have, for the
most part, been ignored in our survey of the field. But it would not be
fair to conclude our story without adverting to them, at least in brief;
for some of them have to do with the most comprehensive and important
questions with which science deals, and the aggregate number of facts
involved in these unfinished battles is often great, even though as yet
the marshalling has not led to final victory for any faction. In some
cases, doubtless, the right hypothesis is actually in the field, but its
supremacy not yet conclusively proved--perhaps not to be proved for many
years or decades to come. Some of the chief scientific results of the
nineteenth century have been but the gaining of supremacy for hypotheses
that were mere forlorn hopes, looked on with general contempt, if at
all heeded, when the eighteenth century came to a close--witness the
doctrines of the great age of the earth, of the immateriality of heat,
of the undulatory character of light, of chemical atomicity, of
organic evolution. Contrariwise, the opposite ideas to all of these
had seemingly a safe supremacy until the new facts drove them from the
field. Who shall say, then, what forlorn hope of to-day's science may
not be the conquering host of to-morrow? All that one dare attempt is
to cite the pretensions of a few hypotheses that are struggling over the
still contested ground.


SOLAR AND TELLURIC PROBLEMS

Our sun being only a minor atom of the stellar pebble, solar problems
in general are of course stellar problems also. But there are certain
special questions regarding which we are able to interrogate the sun
because of his proximity, and which have, furthermore, a peculiar
interest for the residents of our little globe because of our dependence
upon this particular star. One of the most far-reaching of these is
as to where the sun gets the heat that he gives off in such
liberal quantities. We have already seen that Dr. Mayer, of
conservation-of-energy fame, was the first to ask this question. As
soon as the doctrine of the persistence and convertibility of energy was
grasped, about the middle of the century, it became clear that this
was one of the most puzzling of questions. It did not at all suffice to
answer that the sun is a ball of fire, for computation showed that, at
the present rate of heat-giving, if the sun were a solid mass of coal,
he would be totally consumed in about five thousand years. As no such
decrease in size as this implies had taken place within historic times,
it was clear that some other explanation must be sought.

Dr. Mayer himself hit upon what seemed a tenable solution at the very
outset. Starting from the observed fact that myriads of tiny meteorites
are hurled into the earth's atmosphere daily, he argued that the sun
must receive these visitants in really enormous quantities--sufficient,
probably, to maintain his temperature at the observed limits. There was
nothing at all unreasonable about this assumption, for the amount of
energy in a swiftly moving body capable of being transformed into heat
if the body be arrested is relatively enormous. Thus it is calculated
that a pound of coal dropped into the sun from the mathematician's
favorite starting-point, infinity, would produce some six thousand times
the heat it could engender if merely burned at the sun's surface. In
other words, if a little over two pounds of material from infinity
were to fall into each square yard of the sun's surface each hour, his
observed heat would be accounted for; whereas almost seven tons per
square yard of stationary fuel would be required each hour to produce
the same effect.

In view of the pelting which our little earth receives, it seemed not
an excessive requisition upon the meteoric supply to suppose that the
requisite amount of matter may fall into the sun, and for a time this
explanation of his incandescence was pretty generally accepted. But soon
astronomers began to make calculations as to the amount of matter which
this assumption added to our solar system, particularly as it aggregated
near the sun in the converging radii, and then it was clear that no such
mass of matter could be there without interfering demonstrably with the
observed course of the interior planets. So another source of the sun's
energy had to be sought. It was found forthwith by that other great
German, Helmholtz, who pointed out that the falling matter through which
heat may be generated might just as well be within the substance of the
sun as without--in other words, that contraction of the sun's heated
body is quite sufficient to account for a long-sustained heat-supply
which the mere burning of any known substance could not approach.
Moreover the amount of matter thus falling towards the sun's centre
being enormous--namely, the total substance of the sun--a relatively
small amount of contraction would be theoretically sufficient to keep
the sun's furnace at par, so to speak.

At first sight this explanation seemed a little puzzling to many laymen
and some experts, for it seemed to imply, as Lord Kelvin pointed out,
that the sun contracts because it is getting cooler, and gains heat
because it contracts. But this feat is not really as paradoxical as it
seems, for it is not implied that there is any real gain of heat in the
sun's mass as a whole, but quite the reverse. All that is sought is
an explanation of a maintenance of heat-giving capacity relatively
unchanged for a long, but not an interminable, period. Indeed,
exactly here comes in the novel and startling feature of. Helmholtz's
calculation. According to Mayer's meteoric hypothesis, there were no
data at hand for any estimate whatever as to the sun's permanency, since
no one could surmise what might be the limits of the meteoric supply.
But Helmholtz's estimate implied an incandescent body cooling--keeping
up a somewhat equable temperature through contraction for a time, but
for a limited time only; destined ultimately to become liquid, solid; to
cool below the temperature of incandescence--to die. Not only so, but
it became possible to calculate the limits of time within which this
culmination would probably occur. It was only necessary to calculate the
total amount of heat which could be generated by the total mass of our
solar system in falling together to the sun's centre from "infinity" to
find the total heat-supply to be drawn upon. Assuming, then, that the
present observed rate of heat-giving has been the average maintained
in the past, a simple division gives the number of years for which the
original supply is adequate. The supply will be exhausted, it will be
observed, when the mass comes into stable equilibrium as a solid body,
no longer subject to contraction, about the sun's centre--such a body,
in short, as our earth is at present.

This calculation was made by Lord Kelvin, Professor Tait, and others,
and the result was one of the most truly dynamitic surprises of the
century. For it transpired that, according to mathematics, the entire
limit of the sun's heat-giving life could not exceed something like
twenty-five millions of years. The publication of that estimate, with
the appearance of authority, brought a veritable storm about the heads
of the physicists. The entire geological and biological worlds were
up in arms in a trice. Two or three generations before, they hurled
brickbats at any one who even hinted that the solar system might be more
than six thousand years old; now they jeered in derision at the attempt
to limit the life-bearing period of our globe to a paltry fifteen or
twenty millions.

The controversy as to solar time thus raised proved one of the most
curious and interesting scientific disputations of the century. The
scene soon shifted from the sun to the earth; for a little reflection
made it clear that the data regarding the sun alone were not
sufficiently definite. Thus Dr. Croll contended that if the parent
bodies of the sun had chanced to be "flying stars" before collision,
a vastly greater supply of heat would have been engendered than if the
matter merely fell together. Again, it could not be overlooked that
a host of meteors are falling into the sun, and that this source of
energy, though not in itself sufficient to account for all the heat in
question, might be sufficient to vitiate utterly any exact calculations.
Yet again, Professor Lockyer called attention to another source of
variation, in the fact that the chemical combination of elements
hitherto existing separately must produce large quantities of heat, it
being even suggested that this source alone might possibly account for
all the present output. On the whole, then, it became clear that the
contraction theory of the sun's heat must itself await the demonstration
of observed shrinkage of the solar disk, as viewed by future generations
of observers, before taking rank as an incontestable theory, and that
computations as to time based solely on this hypothesis must in the mean
time be viewed askance.

But the time controversy having taken root, new methods were naturally
found for testing it. The geologists sought to estimate the period of
time that must have been required for the deposit of the sedimentary
rocks now observed to make up the outer crust of the earth. The amount
of sediment carried through the mouth of a great river furnishes a clew
to the rate of denudation of the area drained by that river. Thus the
studies of Messrs. Humphreys and Abbot, made for a different purpose,
show that the average level of the territory drained by the Mississippi
is being reduced by about one foot in six thousand years. The sediment
is, of course, being piled up out in the Gulf at a proportionate rate.
If, then, this be assumed to be an average rate of denudation and
deposit in the past, and if the total thickness of sedimentary deposits
of past ages were known, a simple calculation would show the age of the
earth's crust since the first continents were formed. But unfortunately
these "ifs" stand mountain-high here, all the essential factors being
indeterminate. Nevertheless, the geologists contended that they could
easily make out a case proving that the constructive and destructive
work still in evidence, to say nothing of anterior revolutions, could
not have been accomplished in less than from twenty-five to fifty
millions of years.

This computation would have carried little weight with the physicists
had it not chanced that another computation of their own was soon made
which had even more startling results. This computation, made by Lord
Kelvin, was based on the rate of loss of heat by the earth. It thus
resembled the previous solar estimate in method. But the result was very
different, for the new estimate seemed to prove that a period of from
one hundred to two hundred millions of years has elapsed since the final
crust of the earth formed.

With this all controversy ceased, for the most grasping geologist or
biologist would content himself with a fraction of that time. But the
case for the geologist was to receive yet another prop from the studies
of radio-activity, which seem to prove that the atom of matter has in
store a tremendous, supply of potential energy which may be drawn on
in a way to vitiate utterly all the computations to which I have just
referred. Thus a particle of radium is giving out heat incessantly
in sufficient quantity to raise its own weight of water to the
boiling-point in an hour. The demonstrated wide distribution of
radio-active matter--making it at least an open question whether all
matter does not possess this property in some degree--has led to the
suggestion that the total heat of the sun may be due to radio-active
matter in its substance. Obviously, then, all estimates of the sun's age
based on the heat-supply must for the present be held quite in abeyance.
What is more to the point, however, is the fact, which these varying
estimates have made patent, that computations of the age of the earth
based on any data at hand are little better than rough guesses. Long
before the definite estimates were undertaken, geologists had proved
that the earth is very, very old, and it can hardly be said that
the attempted computations have added much of definiteness to that
proposition. They have, indeed, proved that the period of time to be
drawn upon is not infinite; but the nebular hypothesis, to say nothing
of common-sense, carried us as far as that long ago.

If the computations in question have failed of their direct purpose,
however, they have been by no means lacking in important collateral
results. To mention but one of these, Lord Kelvin was led by this
controversy over the earth's age to make his famous computation in which
he proved that the telluric structure, as a whole, must have at least
the rigidity of steel in order to resist the moon's tidal pull as it
does. Hopkins had, indeed, made a somewhat similar estimate as early as
1839, proving that the earth's crust must be at least eight hundred or
a thousand miles in thickness; but geologists had utterly ignored
this computation, and the idea of a thin crust on a fluid interior had
continued to be the orthodox geological doctrine. Since Lord Kelvin's
estimate was made, his claim that the final crust of the earth could
not have formed until the mass was solid throughout, or at least until
a honeycomb of solid matter had been bridged up from centre to
circumference, has gained pretty general acceptance. It still remains
an open question, however, as to what proportion the lacunas of molten
matter bear at the present day to the solidified portions, and therefore
to what extent the earth will be subject to further shrinkage and
attendant surface contortions. That some such lacunae do exist is
demonstrated daily by the phenomena of volcanoes. So, after all, the
crust theory has been supplanted by a compromise theory rather than
completely overthrown, and our knowledge of the condition of the
telluric depths is still far from definite. If so much uncertainty
attends these fundamental questions as to the earth's past and present,
it is not strange that open problems as to her future are still
more numerous. We have seen how, according to Professor Darwin's
computations, the moon threatens to come back to earth with destructive
force some day. Yet Professor Darwin himself urges that there are
elements of fallibility in the data involved that rob the computation of
all certainty. Much the same thing is true of perhaps all the estimates
that have been made as to the earth's ultimate fate. Thus it has been
suggested that, even should the sun's heat not forsake us, our day will
become month-long, and then year-long; that all the water of the globe
must ultimately filter into its depths, and all the air fly off into
space, leaving our earth as dry and as devoid of atmosphere as the moon;
and, finally, that ether-friction, if it exist, or, in default of that,
meteoric friction, must ultimately bring the earth back to the sun. But
in all these prognostications there are possible compensating factors
that vitiate the estimates and leave the exact results in doubt. The
last word of the cosmic science of our generation is a prophecy of
evil--if annihilation be an evil. But it is left for the science of
another generation to point out more clearly the exact terms in which
the prophecy is most likely to be fulfilled.


PHYSICAL PROBLEMS

In regard to all these cosmic and telluric problems, it will be seen,
there is always the same appeal to one central rule of action--the law
of gravitation. When we turn from macrocosm to microcosm it would
appear as if new forces of interaction were introduced in the powers of
cohesion and of chemical action of molecules and atoms. But Lord Kelvin
has argued that it is possible to form such a conception of the forms
and space relations of the ultimate particles of matter that their
mutual attractions may be explained by invoking that same law of
gravitation which holds the stars and planets in their course. What,
then, is this all-compassing power of gravitation which occupies so
central a position in the scheme of mechanical things?

The simple answer is that no man knows. The wisest physicist of
to-day will assure you that he knows absolutely nothing of the why of
gravitation--that he can no more explain why a stone tossed into the
air falls back to earth than can the boy who tosses the stone. But while
this statement puts in a nutshell the scientific status of explanations
of gravitation, yet it is not in human nature that speculative
scientists should refrain from the effort to explain it. Such efforts
have been made; yet, on the whole, they are surprisingly few in number;
indeed, there are but two that need claim our attention here, and one
of these has hardly more than historical interest. One of these is the
so-called ultramundane-corpuscle hypothesis of Le Sage; the other is
based on the vortex theory of matter.

The theory of Le Sage assumes that the entire universe is filled with
infinitely minute particles flying in right lines in every direction
with inconceivable rapidity. Every mass of tangible matter in the
universe is incessantly bombarded by these particles, but any two
non-contiguous masses (whether separated by an infinitesimal space or by
the limits of the universe) are mutually shielded by one another from a
certain number of the particles, and thus impelled towards one another
by the excess of bombardment on their opposite sides. What applies to
two masses applies also, of course, to any number of masses--in short,
to all the matter in the universe. To make the hypothesis workable, so
to say, it is necessary to assume that the "ultramundane" particles are
possessed of absolute elasticity, so that they rebound from one another
on collision without loss of speed. It is also necessary to assume that
all tangible matter has to an almost unthinkable degree a sievelike
texture, so that the vast proportion of the coercive particles pass
entirely through the body of any mass they encounter--a star or world,
for example--without really touching any part of its actual substance.
This assumption is necessary because gravitation takes no account of
mere corporeal bulk, but only of mass or ultimate solidarity. Thus a
very bulky object may be so closely meshed that it retards
relatively few of the corpuscles, and hence gravitates with relative
feebleness--or, to adopt a more familiar mode of expression, is light in
weight.

This is certainly heaping hypotheses together in a reckless way, and
it is perhaps not surprising that Le Sage's conception did not at first
arouse any very great amount of interest. It was put forward about
a century ago, but for two or three generations remained practically
unnoticed. The philosophers of the first half of our century seem
to have despaired of explaining gravitation, though Faraday long
experimented in the hope of establishing a relation between gravitation
and electricity or magnetism. But not long after the middle of
the century, when a new science of dynamics was claiming paramount
importance, and physicists were striving to express all tangible
phenomena intenus of matter in motion, the theory of Le Sage was
revived and given a large measure of attention. It seemed to have at
least the merit of explaining the facts without conflicting with any
known mechanical law, which was more than could be said of any other
guess at the question that had ever been made.

More recently, however, another explanation has been found which also
meets this condition. It is a conception based, like most other physical
speculations of the last generation, upon the hypothesis of the vortex
atom, and was suggested, no doubt, by those speculations which consider
electricity and magnetism to be conditions of strain or twist in
the substance of the universal ether. In a word, it supposes that
gravitation also is a form of strain in this ether--a strain that may be
likened to a suction which the vortex atom is supposed to exert on the
ether in which it lies. According to this view, gravitation is not
a push from without, but a pull from within; not due to exterior
influences, but an inherent and indissoluble property of matter itself.
The conception has the further merit of correlating gravitation with
electricity, magnetism, and light, as a condition of that strange
ethereal ocean of which modern physics takes so much account. But
here, again, clearly, we are but heaping hypothesis upon hypothesis,
as before. Still, an hypothesis that violates no known law and has the
warrant of philosophical probability is always worthy of a hearing. But
we must not forget that it is hypothesis only, not conclusive theory.

The same caution applies, manifestly, to all the other speculations
which have the vortex atom, so to say, for their foundation-stone. Thus
Professors Stewart and Tait's inferences as to the destructibility
of matter, based on the supposition that the ether is not quite
frictionless; Professor Dolbear's suggestions as to the creation of
matter through the development of new ether ripples, and the same
thinker's speculations as to an upper limit of temperature, based on the
mechanical conception of a limit to the possible vibrations of a vortex
ring, not to mention other more or less fascinating speculations based
on the vortex hypothesis, must be regarded, whatever their intrinsic
interest, as insecurely grounded, until such time as new experimental
methods shall give them another footing. Lord Kelvin himself holds all
such speculations utterly in abeyance. "The vortex theory," he says,
"is only a dream. Itself unproven, it can prove nothing, and any
speculations founded upon it are mere dreams about a dream."*1*

That certainly must be considered an unduly modest pronouncement
regarding the only workable hypothesis of the constitution of matter
that has ever been imagined; yet the fact certainly holds that the
vortex theory, the great contribution of the nineteenth century towards
the solution of a world-old problem, has not been carried beyond
the stage of hypothesis, and must be passed on, with its burden of
interesting corollaries, to another generation for the experimental
evidence that will lead to its acceptance or its refutation. Our century
has given experimental proof of the existence of the atom, but has not
been able to fathom in the same way the exact form or nature of this
ultimate particle of matter.

Equally in the dark are we as to the explanation of that strange
affinity for its neighbors which every atom manifests in some degree.
If we assume that the power which holds one atom to another is the same
which in the case of larger bodies we term gravitation, that answer
carries us but a little way, since, as we have seen, gravitation itself
is the greatest of mysteries. But again, how chances it that different
atoms attract one another in such varying degrees, so that, for example,
fluorine unites with everything it touches, argon with nothing? And how
is it that different kinds of atoms can hold to themselves such varying
numbers of fellow-atoms--oxygen one, hydrogen two, and so on? These
are questions for the future. The wisest chemist does not know why the
simplest chemical experiment results as it does. Take, for example, a
water-like solution of nitrate of silver, and let fall into it a few
drops of another water-like solution of hydrochloric acid; a white
insoluble precipitate of chloride of silver is formed. Any tyro in
chemistry could have predicted the result with absolute certainty. But
the prediction would have been based purely upon previous empirical
knowledge--solely upon the fact that the thing had been done before
over and over, always with the same result. Why the silver forsook the
nitrogen atom and grappled the atom of oxygen no one knows. Nor can any
one as yet explain just why it is that the new compound is an insoluble,
colored, opaque substance, whereas the antecedent ones were soluble,
colorless, and transparent. More than that, no one can explain with
certainty just what is meant by the familiar word soluble itself. That
is to say, no one knows just what happens when one drops a lump of salt
or sugar into a bowl of water. We may believe with Professor Ostwald
and his followers that the molecules of sugar merely glide everywhere
between the molecules of water, without chemical action; or, on the
other hand, dismissing this mechanical explanation, we may say with
Mendeleef that the process of solution is the most active of chemical
phenomena, involving that incessant interplay of atoms known as
dissociation. But these two explanations are mutually exclusive, and
nobody can say positively which one, if either, is right. Nor is either
theory at best more than a half explanation, for the why of the strange
mechanical or chemical activities postulated is quite ignored. How is
it, for example, that the molecules of water are able to loosen the
intermolecular bonds of the sugar particles, enabling them to scamper
apart?

But, for that matter, what is the nature of these intermolecular bonds
in any case? And why, at the same temperature, are some substances held
together with such enormous rigidity, others so loosely? Why does not
a lump of iron dissolve as readily as the lump of sugar in our bowl
of water? Guesses may be made to-day at these riddles, to be sure, but
anything like tenable solutions will only be possible when we know much
more than at present of the nature of intermolecular forces and of the
mechanism of molecular structures. As to this last, studies are
under way that are full of promise. For the past ten or fifteen years
Professor Van 't Hoof of Amsterdam (now of Berlin), with a company of
followers, has made the space relations of atoms a special study, with
the result that so-called stereo-chemistry has attained a firm position.
A truly amazing insight has been gained into the space relations of the
molecules of carbon compounds in particular, and other compounds are
under investigation. But these results, wonderful though they seem
when the intricacy of the subject is considered, are, after all, only
tentative. It is demonstrated that some molecules have their atoms
arranged in perfectly definite and unalterable schemes, but just how
these systems are to be mechanically pictured--whether as miniature
planetary systems or what not--remains for the investigators of the
future to determine.

It appears, then, that whichever way one turns in the realm of the atom
and molecule, one finds it a land of mysteries. In no field of science
have more startling discoveries been made in the past century than here;
yet nowhere else do there seem to lie wider realms yet unfathomed.


LIFE PROBLEMS

In the life history of at least one of the myriad star systems there
has come a time when, on the surface of one of the minor members of the
group, atoms of matter have been aggregated into such associations as
to constitute what is called living matter. A question that at once
suggests itself to any one who conceives even vaguely the relative
uniformity of conditions in the different star groups is as to whether
other worlds than ours have also their complement of living forms.
The question has interested speculative science more perhaps in our
generation than ever before, but it can hardly be said that much
progress has been made towards a definite answer. At first blush the
demonstration that all the worlds known to us are composed of the same
matter, subject to the same general laws, and probably passing through
kindred stages of evolution and decay, would seem to carry with it the
reasonable presumption that to all primary planets, such as ours, a
similar life-bearing stage must come. But a moment's reflection shows
that scientific probabilities do not carry one safely so far as
this. Living matter, as we know it, notwithstanding its capacity for
variation, is conditioned within very narrow limits as to physical
surroundings. Now it is easily to be conceived that these peculiar
conditions have never been duplicated on any other of all the myriad
worlds. If not, then those more complex aggregations of atoms which we
must suppose to have been built up in some degree on all cooling globes
must be of a character so different from what we term living matter that
we should not recognize them as such. Some of them may be infinitely
more complex, more diversified in their capacities, more widely
responsive to the influences about them, than any living thing on earth,
and yet not respond at all to the conditions which we apply as tests of
the existence of life.

This is but another way of saying that the peculiar limitations of
specialized aggregations of matter which characterize what we term
living matter may be mere incidental details of the evolution of our
particular star group, our particular planet even--having some such
relative magnitude in the cosmic order, as, for example, the exact
detail of outline of some particular leaf of a tree bears to the
entire subject of vegetable life. But, on the other hand, it is also
conceivable that the conditions on all planets comparable in position to
ours, though never absolutely identical, yet pass at some stage
through so similar an epoch that on each and every one of them there is
developed something measurably comparable, in human terms, to what
we here know as living matter; differing widely, perhaps, from any
particular form of living being here, yet still conforming broadly to
a definition of living things. In that case the life-bearing stage of
a planet must be considered as having far more general significance;
perhaps even as constituting the time of fruitage of the cosmic
organism, though nothing but human egotism gives warrant to this
particular presumption.

Between these two opposing views every one is free to choose according
to his preconceptions, for as yet science is unable to give a deciding
vote. Equally open to discussion is that other question, as to whether
the evolution of universal atoms into a "vital" association mass from
which all the diversified forms evolved, or whether such shifting from
the so-called non-vital to the vital was many times repeated--perhaps
still goes on incessantly. It is quite true that the testimony of our
century, so far as it goes, is all against the idea of "spontaneous
generation" under existing conditions. It has been clearly enough
demonstrated that the bacteria and other low forms of familiar life
which formerly were supposed to originate "spontaneously" had a quite
different origin. But the solution of this special case leaves the
general problem still far from solved. Who knows what are the conditions
necessary to the evolution of the ever-present atoms into "vital"
associations? Perhaps extreme pressure may be one of these conditions;
and, for aught any man knows to the contrary, the "spontaneous
generation" of living protoplasms may be taking place incessantly at the
bottom of every ocean of the globe.

This of course is a mere bald statement of possibilities. It may be met
by another statement of possibilities, to the effect that perhaps the
conditions necessary to the evolution of living matter here may have
been fulfilled but once, since which time the entire current of life on
our globe has been a diversified stream from that one source. Observe,
please, that this assumption does not fall within that category which
I mention above as contraband of science in speaking of the origin of
worlds. The existence of life on our globe is only an incident limited
to a relatively insignificant period of time, and whether the exact
conditions necessary to its evolution pertained but one second or a
hundred million years does not in the least matter in a philosophical
analysis. It is merely a question of fact, just as the particular
temperature of the earth's surface at any given epoch is a question of
fact, the one condition, like the other, being temporary and incidental.
But, as I have said, the question of fact as to the exact time of origin
of life on our globe is a question that science as yet cannot answer.

But, in any event, what is vastly more important than this question
as to the duration of time in which living matter was evolved is a
comprehension of the philosophical status of this evolution from the
"non-vital" to the "vital." If one assumes that this evolution was
brought about by an interruption of the play of forces hitherto working
in the universe--that the correlation of forces involved was unique,
acting then and then only--by that assumption he removes the question
of the origin of life utterly from the domain of science--exactly as the
assumption of an initial push would remove the question of the origin
of worlds from the domain of science. But the science of to-day most
emphatically demurs to any such assumption. Every scientist with a wide
grasp of facts, who can think clearly and without prejudice over the
field of what is known of cosmic evolution, must be driven to believe
that the alleged wide gap between vital and non-vital matter is largely
a figment of prejudiced human understanding. In the broader view
there seem no gaps in the scheme of cosmic evolution--no break in the
incessant reciprocity of atomic actions, whether those atoms be floating
as a "fire mist" out in one part of space, or aggregated into the
brain of a man in another part. And it seems well within the range of
scientific expectation that the laboratory worker of the future will
learn how so to duplicate telluric conditions that the universal forces
will build living matter out of the inorganic in the laboratory, as they
have done, and perhaps still are doing, in the terrestrial oceans.

To the timid reasoner that assumption of possibilities may seem
startling. But assuredly it is no more so than seemed, a century ago,
the assumption that man has evolved, through the agency of "natural
laws" only, from the lowest organism. Yet the timidity of that elder
day has been obliged by the progress of the past century to adapt its
conceptions to that assured sequence of events. And some day, in all
probability, the timidity of to-day will be obliged to take that final
logical step which to-day's knowledge foreshadows as a future if not a
present necessity.


THE MECHANISM OF THE CELL

Whatever future science may be able to accomplish in this direction,
however, it must be admitted that present science finds its hands quite
full, without going farther afield than to observe the succession of
generations among existing forms of life. Since the establishment of
the doctrine of organic evolution, questions of heredity, always
sufficiently interesting, have been at the very focus of attention of
the biological world. These questions, under modern treatment, have
resolved themselves, since the mechanism of such transmission has been
proximately understood, into problems of cellular activity. And much
as has been learned about the cell of late, that interesting microcosm
still offers a multitude of intricacies for solution.

Thus, at the very threshold, some of the most elementary principles of
mechanical construction of the cell are still matters of controversy. On
the one hand, it is held by Professor O. Butschli and his followers that
the substance of the typical cell is essentially alveolar, or foamlike,
comparable to an emulsion, and that the observed reticular structure of
the cell is due to the intersections of the walls of the minute ultimate
globules. But another equally authoritative school of workers holds to
the view, first expressed by Frommann and Arnold, that the reticulum is
really a system of threads, which constitute the most important basis of
the cell structure. It is even held that these fibres penetrate the cell
walls and connect adjoining cells, so that the entire body is a
reticulum. For the moment there is no final decision between these
opposing views. Professor Wilson of Columbia has suggested that both may
contain a measure of truth.

Again, it is a question whether the finer granules seen within the cell
are or are not typical structures, "capable of assimilation, growth,
and division, and hence to be regarded as elementary units of structure
standing between the cell and the ultimate molecules of living matter."
The more philosophical thinkers, like Spencer, Darwin, Haeckel,
Michael Foster, August Weismann, and many others, believe that such
"intermediate units must exist, whether or not the microscope reveals
them to view." Weismann, who has most fully elaborated a hypothetical
scheme of the relations of the intracellular units, identifies the
larger of these units not with the ordinary granules of the cell, but
with a remarkable structure called chromatin, which becomes aggregated
within the cell nucleus at the time of cellular division--a structure
which divides into definite parts and goes through some most suggestive
manoeuvres in the process of cell multiplication. All these are puzzling
structures; and there is another minute body within the cell, called the
centro-some, that is quite as much so. This structure, discovered by
Van Beneden, has been regarded as essential to cell division, yet some
recent botanical studies seem to show that sometimes it is altogether
wanting in a dividing cell.

In a word, the architecture of the cell has been shown by modern
researches to be wonderfully complicated, but the accumulating
researches are just at a point where much is obscure about many of
the observed phenomena. The immediate future seems full of promise
of advances upon present understanding of cell processes. But for the
moment it remains for us, as for preceding generations, about the most
incomprehensible, scientifically speaking, of observed phenomena, that a
single microscopic egg cell should contain within its substance all the
potentialities of a highly differentiated adult being. The fact that
it does contain such potentialities is the most familiar of every-day
biological observations, but not even a proximal explanation of the fact
is as yet attainable.


THE ANCESTRY OF THE MAMMALS

Turning from the cell as an individual to the mature organism which
the cell composes when aggregated with its fellows, one finds the
usual complement of open questions, of greater or less significance,
focalizing the attention of working biologists. Thus the evolutionist,
secure as is his general position, is yet in doubt when it comes to
tracing the exact lineage of various forms. He does not know, for
example, exactly which order of invertebrates contains the type from
which vertebrates sprang, though several hotly contested opinions,
each exclusive of the rest, are in the field. Again, there is like
uncertainty and difference of opinion as to just which order of lower
vertebrates formed the direct ancestry of the mammals. Among the mammals
themselves there are several orders, such as the whales, the elephants,
and even man himself, whose exact lines of more immediate ancestry are
not as fully revealed by present paleontology as is to be desired.


THE NEW SCIENCE OF ANTHROPOLOGY

All these, however, are details that hardly take rank with the general
problems that we are noticing. There are other questions, however,
concerning the history and present evolution of man himself that are
of wider scope, or at least seemingly greater importance from a human
stand-point, which within recent decades have come for the first time
within the scope of truly inductive science. These are the problems of
anthropology--a science of such wide scope, such far-reaching collateral
implications, that as yet its specific field and functions are not as
clearly defined or as generally recognized as they are probably destined
to be in the near future. The province of this new science is
to correlate the discoveries of a wide range of collateral
sciences--paleontology, biology, medicine, and so on--from the point
of view of human history and human welfare. To this end all observable
races of men are studied as to their physical characteristics, their
mental and moral traits, their manners, customs, languages, and
religions. A mass of data is already at hand, and in process of sorting
and correlating. Out of this effort will probably come all manner of
useful generalizations, perhaps in time bringing sociology, or the study
of human social relations, to the rank of a veritable science. But great
as is the promise of anthropology, it can hardly be denied that the
broader questions with which it has to deal--questions of race, of
government, of social evolution--are still this side the fixed plane
of assured generalization. No small part of its interest and importance
depends upon the fact that the great problems that engage it are as yet
unsolved problems. In a word, anthropology is perhaps the most important
science in the entire hierarchy to-day, precisely because it is an
immature science. Its position to-day is perhaps not unlike that of
paleontology at the close of the eighteenth century. May its promise
find as full fruition!



IX. RETROSPECT AND PROSPECT


THE SCIENTIFIC ATTITUDE OF MIND

ANY one who has not had a rigid training in science may advantageously
reflect at some length upon the meaning of true scientific induction.
Various illustrations in our text are meant to convey the idea that
logical thinking consists simply in drawing correct conclusions as to
the probable sequence of events in nature. It will soon be evident to
any one who carefully considers the subject that we know very little
indeed about cause and effect in a rigid acceptance of these words. We
observe that certain phenomena always follow certain other phenomena,
and these observations fix the idea in our mind that such phenomena bear
to one another the relation of effect and cause. The conclusion is a
perfectly valid one so long as we remember that in the last analysis the
words "cause" and "effect" have scarcely greater force than the terms
"invariable antecedent" and "invariable consequent"--that is to say,
they express an observed sequence which our experience has never
contradicted.

Now the whole structure of science would be hopelessly undermined
had not scientific men come to have the fullest confidence in the
invariability of certain of these sequences of events. Let us, for
example, take the familiar and fundamental observation that any
unsupported object, having what we term weight, invariably falls
directly towards the centre of the earth. We express this fact in
terms of a so-called law of gravitation, and every one, consciously or
unconsciously, gives full deference to this law. So firmly convinced
are we that the gravitation pull is a cause that works with absolute,
unvarying uniformity that we should regard it as a miracle were any
heavy body to disregard the law of gravitation and rise into the air
when not impelled by some other force of which we have knowledge. Thanks
to Newton, we know that this force of gravitation is not at all confined
to the earth, but affects the whole universe, so that every two bits
of matter, regardless of location, pull at each other with a force
proportionate to their mass and inversely as the square of their
distance.

Were this so-called law of gravitation to cease to operate, the entire
plan of our universe would be sadly disarranged. The earth, for example,
and the other planets would leave their elliptical orbits and hurtle
away on a tangential course. We should soon be beyond the reach of the
sun's beneficent influence; an arctic chill would pervade polar and
tropical regions alike, and the term of man's existence would
come suddenly to a close. Here, then, is a force at once the most
comprehensible and most important from a human stand-point that can be
conceived; yet it cannot be too often repeated, we know nothing whatever
as to the nature of this force. We do not know that there may not be
other starlike clusters beyond our universe where this force does not
prevail. We do not know that there may not come a period when this force
will cease to operate in our universe, and when, for example, it will be
superseded by the universal domination of a force of mutual repulsion.
For aught we know to the contrary, our universe may be a pulsing
organism, or portion of an organism, all the particles of which are at
one moment pulled together and the next moment hurled apart--the moments
of this computation being, of course, myriads of years as we human
pygmies compute time.

To us it would be a miracle if a heavy body, unsupported, should fly off
into space instead of dropping towards the centre of the earth; yet the
time may come when all such heavy objects will thus fly off into space,
and when the observer, could there be such, must marvel at the miracle
of seeing a heavy object fall towards the earth. Such thoughts as these
should command the attention of every student of science who would
really understand the meaning of what are termed natural laws. But, on
the other hand, such suggestions must be held carefully in check by the
observation that scientific imagining as to what may come to pass at
some remote future time must in no wise influence our practical faith
in the universality of certain natural laws in the present epoch. We may
imagine a time when terrestrial gravitation no longer exerts its power,
but we dare not challenge that power in the present. There could be no
science did we not accept certain constantly observed phenomena as the
effect of certain causes. The whole body of science is made up solely of
such observations and inferences. Natural science is so called because
it has to do with observed phenomena of nature.


NATURAL VERSUS SUPERNATURAL

A further word must be said as to this word "natural," and its
complementary word "supernatural." I have said in an early chapter that
prehistoric man came, through a use of false inductions, to the belief
in supernatural powers. Let us examine this statement in some detail,
for it will throw much light on our later studies. The thing to get
clearly in mind is the idea that when we say "natural" phenomena we
mean merely phenomena that have been observed to occur. From a truly
scientific stand-point there is no preconception as to what manner
of phenomenon may, or may not, occur. All manner of things do occur
constantly that would seem improbable were they not matters of
familiar knowledge. The simplest facts in regard to gravitation involve
difficulties that were stumbling-blocks to many generations of thinkers,
and which continue stumbling-blocks to the minds of each generation of
present-day children.

Thus most of us can recall a time when we first learned with
astonishment that the earth is "round like a ball"; that there are
people walking about on the other side of the world with their feet
towards ours, and that the world itself is rushing through space
and spinning rapidly about as it goes. Then we learn, further, that
numberless familiar phenomena would be quite different could we be
transported to other globes. That, for example, a man who can spring two
or three feet into the air here would be able, with the same muscular
exertion, to vault almost to the house-tops if he lived on a small
planet like the moon; but, on the other hand, would be held prone by his
own weight if transported to a great planet like Jupiter.

When, further, we reflect that with all our capacity to measure
and estimate this strange force of gravitation we, after all, know
absolutely nothing as to its real nature; that we cannot even imagine
how one portion of matter can act on another across an infinite abysm
(or, for that matter, across the smallest space), we see at once that
our most elementary scientific studies bring us into the presence of
inscrutable mysteries. In whatever direction we turn this view is
but emphasized. Electricity, magnetism, the hypothetical ether, the
inscrutable forces manifested everywhere in the biological field--all
these are, as regard their ultimate nature, altogether mysterious.

In a word, the student of nature is dealing everywhere with the
wonderful, the incomprehensible. Yet all the manifestations that he
observes are found to repeat themselves in certain unvarying sequences.
Certain applications of energy will produce certain movements of matter.
We may not know the nature of the so-called cause, but we learn to
measure the result, and in other allied cases we learn to reason back
or infer the cause from observation of results. The latter indeed is
the essence of scientific inquiry. When certain series of phenomena have
been classified together as obviously occurring under the domination
of the same or similar causes, we speak of having determined a law of
nature. For example, the fact that any body in motion tends to go on at
the same rate of speed in a direct line forever, expresses such a law.
The fact that the gravitation pull is directly as the mass and inversely
as the square of the distance of the bodies it involves, expresses
another such law. The fact that the planetary bodies of the solar system
revolve in elliptical orbits under the joint influence of the two laws
just named, expresses yet another law. In a word, then, these so-called
"laws" are nothing more than convenient formulae to express the
classification of observed facts.


INDUCTIVE VERSUS DEDUCTIVE REASONING

The ancient thinkers indulged constantly in what we now speak of
as deductive reasoning. They gave heed to what we term metaphysical
preconceptions as to laws governing natural phenomena. The Greeks, for
example, conceived that the circle is the perfect body, and that the
universe is perfect; therefore, sun and moon must be perfect spheres
or disks, and all the orbits of the heavenly bodies must be exactly
circular. We have seen that this metaphysical conception, dominating the
world for many centuries, exerted a constantly hampering influence upon
the progress of science. There were numerous other instances of the same
retarding influence of deductive reasoning. Modern science tries to cast
aside all such preconceptions. It does not always quite succeed, but
it makes a strenuous effort to draw conclusions logically from observed
phenomena instead of trying to force observations into harmony with
a preconeived idea. Herein lies the essential difference between the
primitive method and the perfected modern method. Neither the one nor
the other is intended to transcend the bounds of the natural. That is
to say, both are concerned with the sequence of actual events, with the
observation of actual phenomena; but the modern observer has the almost
infinite advantage of being able to draw upon an immense store of
careful and accurate observations. A knowledge of the mistakes of
his predecessors has taught him the value of caution in interpreting
phenomena that seem to fall outside the range of such laws of nature
as experience has seemed to demonstrate. Again and again the old
metaphysical laws have been forced aside by observation; as, for
example, when Kepler showed that the planetary orbits are not circular,
and Galileo's telescope proved that the spot-bearing sun cannot be a
perfect body in the old Aristotelian sense.

New means of observation have from time to time opened up new fields,
yet with all the extensions of our knowledge we come, paradoxically
enough, to realize but the more fully the limitations of that knowledge.
We seem scarcely nearer to-day to a true understanding of the real
nature of the "forces" whose operation we see manifested about us than
were our most primitive ancestors. But in one great essential we have
surely progressed. We have learned that the one true school is the
school of experience; that metaphysical causes are of absolutely no
consequence unless they can gain support through tangible observations.
Even so late as the beginning of the nineteenth century, the great
thinker, Hegel, retaining essentially the Greek cast of thought, could
make the metaphysical declaration that, since seven planets were known,
and since seven is the perfect number, it would be futile to search for
other planets. But even as he made this declaration another planet was
found. It would be safe to say that no thinker of the present day would
challenge defeat in quite the Aristotelian or Hegelian manner; but,
on the other hand, it is equally little open to doubt that, in matters
slightly less susceptible of tangible demonstration, metaphysical
conceptions still hold sway; and as regards the average minds of our
time, it is perhaps not an unfair estimate to say they surely have not
advanced a jot beyond the Aristotelian stand-point. Untrained through
actual experience in any field of inductive science, they remain easy
victims of metaphysical reasoning. Indeed, since the conditions of
civilization throw a protecting influence about us, and make the
civilized man less amenable to results of illogical action than was the
barbarian, it may almost be questioned whether the average person of
to-day is the equal, as a scientific reasoner, of the average man of the
Stone Age.

A few of the more tangible superstitions of primitive man have been
banished from even the popular mind by the clear demonstration of
science, but a host remains. I venture to question whether, if the test
could be made in the case of ten thousand average persons throughout
Christendom, it would not be found that a majority of these persons
entertain more utterly mistaken metaphysical ideas regarding natural
phenomena than they do truly scientific conceptions. We pride ourselves
on the enlightenment of our age, but our pride is largely based on an
illusion. Mankind at large is still in the dark age. The historian
of the remote future will see no radical distinction between the
superstitions of the thirteenth century and the superstitions of the
nineteenth century. But he will probably admit that a greater change
took place in the world of thought between the year 1859 and the close
of the nineteenth century than had occurred in the lapse of two thousand
years before If this estimate be correct, it is indeed a privilege to
be living in this generation, for we are on the eve of great things,
and beyond question the revolution that is going on about us denotes the
triumph of science and its inductive method. Just in proportion as we
get away from the old metaphysical preconceptions, substituting for them
the new inductive method, just in that proportion do we progress. The
essence of the new method is to have no preconceptions as to the
bounds of nature; to regard no phenomenon, no sequence of phenomena, as
impossible; but, on the other hand, to accept no alleged law, no theory,
no hypothesis, that has not the warrant of observed phenomena in its
favor.

The great error of the untrained mind of the primitive man was that he
did not know the value of scientific evidence. He made wide leaps from
observed phenomena to imagined causes, quite overlooking the proximal
causes that were near to hand. The untrained observer of to-day makes
the same mistake; hence the continued prevalence of those superstitious
misconceptions which primitive man foisted upon our race. But each new
generation of to-day is coming upon the field better trained in at least
the rudiments of scientific method than the preceding generation, and
this is perhaps the most hopeful feature of present-day education. Some
day every one will understand that there is no valid distinction between
the natural and the supernatural; in fact, that no such thing as a
supernatural phenomenon, in the present-day acceptance of the word, can
conceivably exist.

All conceivable manifestations of nature are natural, nor can we
doubt that all are reducible to law--that is to say, that they can be
classified and reduced to systems. But the scientific imagination, as
already pointed out, must admit that any and every scientific law of
our present epoch may be negatived in some future epoch. It is always
possible, also, that a seeming law of to-day may be proved false
to-morrow, which is another way of saying that man's classification
improves from generation to generation. For a "natural law," let it
be repeated, is not nature's method, but man's interpretation of that
method.


LOGICAL INDUCTION VERSUS HASTY GENERALIZATION

A great difficulty is found in the fact that men are forever making
generalizations--that is, formulating laws too hastily. A few phenomena
are observed and at once the hypothesis-constructing mind makes a guess
as to the proximal causes of these phenomena. The guess, once formulated
and accepted, has a certain influence in prejudicing the minds of future
observers; indeed, where the phenomena involve obscure principles the
true explanation of which is long deferred, a false generalization
may impress itself upon mankind with such force as to remain a
stumbling-block for an indefinite period. Thus the Ptolemaic conception
of the universe dominated the thought of Europe for a thousand years,
and could not be substituted by the true theory without a fierce
struggle; and, to cite an even more striking illustration, the early
generalizations of primitive man which explain numberless phenomena of
nature as due to an influence of unseen anthropomorphic beings remain
to this day one of the most powerful influences that affect our race--an
influence from which we shall never shake ourselves altogether free
until the average man--and particularly the average woman--learns to be
a good observer and a logical reasoner.

Something towards this end is being accomplished by the introduction of
experimental research and scientific study in general in our schools
and colleges. It is hoped that something towards the same end may be
accomplished through study of the history of the development of science.
Scarcely anything is more illuminative than to observe critically the
mistakes of our predecessors, noting how natural the mistakes were and
how tenaciously they were held to, how strenuously defended. Most of
all it would be of value to note that the false inductions which
have everywhere hampered the progress of science have been, from the
stand-point of the generation in which they originated, for the most
part logical inductions. We have seen that the Ptolemaic scheme of the
universe, false though it was in its very essentials, yet explained
in what may be termed a thoroughly scientific fashion the observed
phenomena. It is one way of expressing a fact to say that the sun moves
across the heavens from the eastern to the western horizon; and for most
practical purposes this assumption answers perfectly. It is only when
we endeavor to extend the range of theoretical astronomy, and to gain a
correct conception of the mechanism of the universe as a whole, that
the essentially faulty character of the geocentric conception becomes
apparent.

And so it is in many another field; the false generalizations and hasty
inductions serve a temporary purpose. Our only quarrel with them is that
they tend through a sort of inertia to go forever unchanged. It requires
a powerful thrust to divert the aggregate mind of our race from a given
course, nor is the effect of a new impulse immediately appreciable; that
is why the masses of the people always lag a generation or two
behind the advanced thinkers. A few receptive minds, cognizant of new
observations that refute an old generalization, accept new laws, and,
from the vantage-ground thus gained, reach out after yet other truths.
But, for the most part, the new laws thus accepted by the leaders remain
unknown to the people at large for at least one or two generations. It
required about a century for the heliocentric doctrine of Copernicus to
begin to make its way.

In this age of steam and electricity, progress is more rapid, and the
greatest scientific conception of the nineteenth century, the Darwinian
theory, may be said to have made something that approaches an absolute
conquest within less than half a century. This seems a marvellously
sudden conquest, but it must be understood that it is only the crude and
more tangible bearings of the theory that have thus made their way. The
remoter consequences of the theory are not even suspected by the great
majority of those who call themselves Darwinians to-day. It will require
at least another century for these ideas to produce their full effect.
Then, in all probability, it will appear that the nineteenth century
was the most revolutionary epoch by far that the history of thought has
known. And it owes this proud position to the fact that it was the epoch
in all history most fully subject to the dominant influence of inductive
science. Thanks to this influence, we of the new generation are able to
start out on a course widely divergent from the path of our
ancestors. Our leaders of thought have struggled free from the bogs
of superstition, and are pressing forward calmly yet with exultation
towards the heights.



APPENDIX


   (p. 95). J. J. Thompson, D.Sc., LL.D., Ph.D., F.R.S.,etc., Electricity
   and Matter, p. 75 ff., New York, 1904. The Silli-man Lectures, delivered
   at Yale University, May, 1903.

   (p. 96). Ibid., pp. 88, 89. 3 (p- 97)- Ibid., p. 89.

   (p. 97). Ibid., p. 87.

   (p. 102). George F. Kunz, "Radium and its Wonders," in the Review of
   Reviews for November, 1903, p. 589.

   (p. 105). E. Rutherford, Radio-Activity, p. 330, Cambridge, 1904.

   (p. 106). Ibid., p. 330.

   (p. 106). Compte Rendu, pp. 136, 673, Paris, 1903.

   (p. 106). Revue Scientifique, April 13, 1901. 10 (p. 106). Compte Rendu,
   p. 136, Paris, 1903.


   (p. 108). J. J. Thompson, Electricity and Matter, p. 162, New York,
   1904.

   (p. --). E. Rutherford, Radio-Activity, p. 340, Cambridge, 1904.

   (p. 185). Dr. Duclaux, who was one of Pasteur's chief assistants, and
   who succeeded him in the directorship of the Institute, died in 1903. He
   held a professorship in the University of Paris during the later years
   of his life, and his special studies had to do largely with the chemical
   side of bacteriology.

   (p. 217). Lord Kelvin's estimate as quoted was expressed to the writer
   verbally. I do not know whether he has anywhere given a similar written
   verdict.



A LIST OF SOURCES


I.--PERIOD COVERED BY VOLUME I.

An ax agoras. See vol. i., p. 240.

Archimedes. See vol. i., p. 196.

Many of the works of Archimedes are lost, but the following have come
down to us: (1) On the Sphere and Cylinder; (2) The Measure of the
Circle; (3) Conoids and Spheroids; (4) On Spirals; (5) Equiponderants
and Centres of Gravity; (6) The Quadrature of the Parabola; (7) On
Bodies Floating in Liquids; (8) The Psammites; (9) A Collection of
Lemmas.

Aristarchus. See vol. i., p. 212.

Magnitudes and Distances of the Sun and Moon is the only surviving work.
In the Armarius of Archimedes another work of Aristarchus is quoted--the
one in which he anticipates the discovery of Copernicus. Delambre, in
his Histoire de Vastronomie ancienne, treats fully the discoveries of
Aristarchus.

Aristotle. See vol. i., p. 82.

An edition of Aristotle was published by Aldus, Venice, 1495-1498, 5
vols. During the following eighty years seven editions of the Greek text
of the entire works were published, and many Latin translations.

Berosus. See vol. i., p. 58.

The fragments of Berosus have been trans, by I. P. Cory, and included
in his Ancient Fragments of Phoenician, Chaldean, Egyptian, and Other
Writers, London, 1826; second edition, 1832.

Democritus. See vol. i., p. 161.

Fragments only of the numerous works ascribed to Democritus have been
preserved. Democriii Abdereo operum fragmenta, Berlin, 1843, edited by
F. G. A. Mullach. Diodorus Siculus. See vol. i., p. 77.

The Historical Library. Perhaps the best available editions of Diodorus
are Wesseling's, 2 vols.; Amstel, 1745; and Dindorf's, 5 vols., Leipzig,
1828-1831. English trans, by Booth, London, 1700. Diogenes Laertius. See
vol. i., p. 121.

The Lives and Opinions of Eminent Philosophers (trans. by C. D. Yonge),
London, 1853.

Eratosthenes. See vol. i., p. 225.

The fragments of his philosophical works were published at Berlin, 1822,
under the title Eratosthenica. His poetical works were published at
Leipzig, 1872. Euclid. See vol. i., p. 193.

His Elements of Geometry is still available as an English school
text-book.

Galen (Claudius Galenus). See vol. i., p. 272.

Galen's preserved works are exceedingly bulky. The best-known edition is
that of C. G. Kuhn, in 21 volumes.

Hero. See vol. i., p. 242.

The Pneumatics of Hero of Alexandria, from the original Greek. Trans, by
B. Woodcroft, London, 1851. Herodotus. See vol. i.t p. 103.

History. English trans, by Beloe, 1791 and 1806. Trans, by Canon
Rawlinson, London, 1858-1860. Hipparchus. See vol. i., p. 233.

The only work of Hipparchus which has survived was published first by
Vittorius at Florence, 1567. Hippocrates. See vol. i., p. 170.

Numerous editions have been published of the Hippo-cratic writings,
including many works not written by the master himself. One of the best
editions is that of Littré, Paris, 1839, etc.

Khamurabi, Codb op. See vol. i., p. 76.

This famous inscription is on a block of black diorite nearly eight feet
in height. It was discovered at Susa by the French expedition under M.
de Morgan in December, 1901.

Leucippus. See vol. i., p. 161.

Pliny (Caius Plinius Secundus). See vol. i., p. 265.

His Natural History is available in several English editions and
reprints. Perhaps the best edition of the original text is the one
published by Julius Sillig, 5 vols., Leipzig, 1854-1859. Plutarch. See
vol. i., p. 198.

Life of Marcellus, in Parallel Lives. In this the mechanical inventions
of Archimedes are described. Polybius. See vol. i., p. 201.

In his Histories Polybius describes the mechanical contrivances and
war-engines of Archimedes, and also gives an account of his death.
Ptolbmy (Claudius Ptolemaeus). See vol. i., p. 269.

Geographia (or Almagest of the Arabs). The edition published by Nobbe,
in 3 vols., Leipzig, 1842, was one of the best complete editions of the
Greek text. The edition published in Didot's Bibliotheca Classicorum
Grocorum, Paris, 1883, is excellent. Earlier editions contain many
errors.

Strabo. See vol. i., p. 255.

The Geography of Strabo. Trans, by H. C. Hamilton and W. Falconer, 3
vols., London, 1857. There are several other editions of Strabo's work
available in English.

Tertullian. See vol. i., p. 195.

Apologeticus. Theophrastus. See vol. i., p. 188.

Utpivlaroplas, On the History of Plants. Written in 10 books.
This is one of the earliest works on botany which have come to us.
It was largely used by Pliny. In complete works, Schneider, Leipzig,
1818-1821, 5 vols. On Plants, edited by Wimmer, Breslau, 247

1842-1862. On Plants, edited by Slackhouse, Oxford, 1814.
atria, On the Causes of Plants, This was originally in 8 books, of
which 6 are now existant. Bibliog. vid. History of Plants.



II.--PERIOD COVERED BY VOLUME II.

Albategnius, Mohammed bbn Jabir. See vol. ii., p. 15.

The original MS. of his principal work, Zidje Sabt, is in the Vatican. A
Latin translation was first published by Plato Tiburtinus at Nuremberg,
in 1537, under the title De scientia stellarunt. Various reprints of
this have been made. Albertus Magnus. See vol. ii., p. 127.

Philosophic* Naturalis Isagoge, Vienna, 1514. Alhazen (full name, Abu
Ali al-Hasan Ibn Alhasan). See vol. ii., p. 18.

Only two of his works have been printed, his Treatise on Twilight
and his Thesaurus opticae, these being available in Michael Casiri's
Bibliotheca Arabico-Hispana Escuri-alensis, 2 vols., Madrid, 1760-1770.

Bacon, Francis. See vol. ii., p. 192.

Novum Organum was published in London, 1620. The Letters and Life of
Lard Bacon, in 7 vols., by James Spedding, appeared in 1862-1874. Bacon,
Roger. See vol. ii., p. 44.

Only an approximate estimate of the number of Bacon's works can be given
even now, although an infinite amount of time and labor has been
spent in collecting them. His great work is the Opus ma jus, "the
Encyclopaedia and the Organum of the Thirteenth Century." A partial list
of some of his other works is the following: Speculum alchemio, 1541
(trans, into English); De mirabili potestate artis et naturo, 1542
(trans, into English, 1659); Libellus de retardants se-nectutis
accidentibus, 1590 (trans, as "The Cure of Old. Age," 1683); and
Sanioris medicino Magistri d. Rogeri Baconis Anglici de arte chymio
scripta, 1603. 248

Boyle, Robert. See vol. ii., p. 205.

Philosophical Works, 3 vols., London, 1738.

Copernicus, Nicolaus. See vol. ii., p. 54.

Ad clar. v. d. Schonerum de libris revolutionism eruditiss. viri et
mathemattci excellentiss. Rev. Doctoris Nicolai Copernici Torunnaei,
Canonici Warmiensis, per quemdam juvenem mathematico studio sum,
Narratio prima, Dantzic, 1540. This was the first published statement
of the doctrine of Copernicus, and was a letter published by Rheticus.
Three years afterwards Copernicus's De orbium colestium revolutionibus,
Libri VI., was published at Nuremberg (1543).

Descartes, René. See vol. ii., p. 193.

Traité de Vhomme (Cousins's edition, in 11 vols., Paris, 1824).

Galilei, Galileo. See vol. ii., p. 91.

Dialogo dei due massimi sistemi del mondo, Florence, 1632. Discorsi e
dimostrazioni matematiche intorno a due nuove scienze, Leyden, 1638.
Gilbert, William (1540-1603). See vol. ii., p. 113.

De magnete, magneticisque corporibus, et de magno magnete tellure,
London, 1600. De magnete was trans. by P. Fleury Motteley, London, 1893.
Guericke, Otto von (1620-1686). See vol. ii., p. 213.

Expérimenta nova, ut vocant, Magdeburgica de vacuo spatio, Amsterdam,
1672. In the Phil. Trans, of the Royal Society of London, No. 88, for
1672.

Hales, Stephen (1677-1761). See vol. ii., p. 298.

Statical Essays, comprising Vegetable Staticks, London, 1727, and
Homostatics, London, 1733. Harvey, William. See vol. ii., p. 169.

Exercitatio anatomica de motu cordis et sanguinis, Frankfort-on-Main,
1628. The Works of, trans, by Robert Willis, London, 1847. Hauksbeb,
Francis. See vol. ii., p. 259.

Physico-Mechanical Experiments on Various Subjects, London, 1709. This
contains descriptions of his various discoveries in electricity, many of
which are given in the Phil. Trans.

Hooee, Robert. See vol. ii., p. 215.

Micrographia, or Some Philosophical Descriptions of Some Minute Bodies,
London, 1665. An Attempt to Prove the Motion of the Earth, London, 1674.
Microscopical Observations, London, 1780. Most of Hooke's important
discoveries were contributed as papers to the Royal Society and are
available in the Phil. Trans.

Huygens, Christian (1629-1695). See vol. ii., p. 218.

Traite de la lumière, Leyden, 1690. Complete works were published at
The Hague in 1888, under thetit le Ouvres complètes, by the Société
Hollandaise des Sciences. These books have not been translated into
English. Huygens's famous paper on the laws governing the collision of
elastic bodies appeared in the Phil. Trans, of the Royal Society for
1669.

Kepler, Johann. See vol. ii., p. 70.

Astronomia nova de motibus Stella Mortis, Leipzig, 1609, contains
Kepler's two first laws; and Harmonices mundi, 1619, contains the third
law, Phomomenon singulare, seu Mercurius in sole, Leipzig, 1609. Joannis
KepUri opera omnia, in 8 vols., Frankfort, 1858-1871.

Leeuwenhoek, Anthony van. See vol. ii., p. 179.

His discoveries are mostly recorded in the Phil. Trans. of the Royal
Society, between the years 1673 and 1723--one hundred and twelve papers
in all. His discovery of bacteria is recorded in Phil. Trans, for 1683;
and that of the discovery of the capillary circulation of the blood in
Phil. Trans, for 1790.

LiNNiEus, Carolus (1707-1778). See vol. ii., p. 299.

His Systema natures was published in 1735. Tro years later (1737)
he published Genera plantarum, which is generally considered as the
starting-point of modern botany. His published works amount to more than
one hundred and eighty.

Mariotte, Edme (died 1684). See vol. ii., p. 210.

Essais de physique (four essays), Paris, 1676-1679. 250

His De la nature de l'air, containing his statement of the law
connecting the volume and pressure of a gas, is contained in the second
essay.

Newton, Sir Isaac. See vol. ii., p. 241.

Philosophies naturalis principia mathematica, completed in July of
1687. The first edition was exhausted in a few months. There are several
translations, among others one by Andrew Motte, New York, 1848.

Paracelsus. See vol. ii., p. 159.

The Hermetic and Alchemical Writings of Paracelsus, trans, by A. E.
Waite, 2 vols., London, 1894. Pascal, Blaise. See vol. ii., p. 122.

Récit de la grande expérience de Vêquilibre de liqueurs, Paris, 1648.

Sawtree, John. See vol. ii., p. 124 ff.

Of the Philosopher's Stone, London, 1652. Swammerdam, John. See vol.
ii., p. 297.

Bibel der Natur, trans, into German, Leipzig, 1752. Sydenham, Thomas.
See vol. ii., p. 189.

His first work, Methodus curandi febres, was published in 1666. His last
work, Processus integri, appeared in 1692. His complete works, in Latin,
were published by the Sydenham Society, London, 1844, which published
also an English translation by Pr. R. G. Latham in 1848. There are
several other English translations.

Torricelli, Evanoelista. See vol. ii., p. 120.

Opera geometrica, Florence, 1644. Tycho Brahe. See vol. ii., p. 65.

De mundi aetherei recentioribus phonomenis, Prague, 1603. This has been
trans, into German by M. Bruns, Karlsruhe, 1894.

Vinci, Leonardo da. See vol. ii., p. 47.

Leonardo da Vinci, Artist, Thinker, and Man of Science, by Eugene Muntz,
2 vols., New York, 1892, is perhaps the most complete treatment of all
phases of Leonardo's work as a scientist as well as an artist. The older
French work, Essai sur les ouvrages physico-mathématiques de Léonard
de Vinci, by J. B. Venturi, Paris, 1797, is excellent. In German, H.
Grothe's Leonardo da Vinci als Ingénieur und Philosophy Berlin, 1874, is
good.



III.--MODERN COSMICAL AND TELLURIC SCIENCES

Agassiz, L. See vol. iii., p. 147.

Etudes sur les glaciers, Neuchâtel, 1840. Arago, François J. D. See vol.
Hi., p. 67.

Ouvres (complete), if vols., Paris, 1854-1862. Arago's Meteorological
Essays, trans, into English, London, 1855. This has an introduction by
Humboldt.

Boscovich, Roger Joseph. See vol. iii., p. 293.

Theoria philosophio naturalis redacta ad unicam legem virium in natura
existentium, Vienna, 1758. Bradley, James. See vol. iii., p. 13.

Concerning an Apparent Motion Observed in Sotne of the Fixed Stars,
London, 1748, Phil. Trans., vol. xlv., pp. 8,9.

Cuvier,*Baron de. See vol. iv., p. 103.

Recherches sur les ossements fossiles de quadrupèdes, 4 vols., Paris,
1812. (The introduction to this work was translated and published as a
volume bearing title of Theory of the Earth, New York, 1818.)

Delambre, Jean Baptiste Joseph. See vol. iii., p. 16.

Histoire d'astronomie, Paris, 1817-1821. This work contains not only
the history of the discoveries in astronomy, but is also a complete
text-book of astronomy as understood at this period.

Falconer, Hugh. See vol. iii., p. 99.

In Paloontological Memoirs, vol. ii., pp. 596-598. 252

Herschbl, William. See vol. iii., p. 20 ff.

On the Proper Motion of the Solar System, Phil. Trans., vol. 73, for
1783. (This paper was read in March, 1783.) The Constitution of the
Heavens, Phil. Trans, for 1785, vol. 75, p. 213. Howard, Luke. See vol.
iii., p. 182.

Philosophical Magazine, 1803. Humboldt, Alexander von. See vol. iii., p.
192.

Des lignes isothermes et de la distribution de la chaleur sur le globe,
published in vol. iii., of Mémoires de physique et de chimie de la
Société d'Arcueil, Paris, 1819. Hutton, James. See vol. iii., p. 178.

Theory of Rain, in Transactions of the Royal Society of Edinburgh, 1788,
vol. i., pp. 53-56. See vol. iii., p. 121. From Transactions of the
Royal Society of Edinburgh, 1788, vol. i., pp. 214-304. A paper on the
"Theory of the Earth," read before the society in 1781.

Kant, Immanuel (i724-1804). See vol. iii., p. 27.

Allgemeine Naturgeschichte und Théorie des Himmels, 1755. Cosmogony, ed.
and trans, by W. Hartie, D.D., Glasgow, 1900.

Laplace, M. le Marquis de. See vol. iii., p. 32.

Exposition du système du monde, Paris, 1796, is available in Ouvres
completes, in 12 vols., Paris, 1825-1833^01. vi., p. 498. Lyell,
Charles. See vol. iii., p. 88.

Principles of Geology, 4 vols., London, 1834.

Marsh, O. C. See vol. Hi., p. 107.

Fossil Horses in America (reprinted from American Naturalist, vol.
viii., May, 1874), pp. 288, 289.

Playpair, John. See vol. iii., pp. 131, 165.

Illustrations of the Huttonian Theory, 1802.

Scrope, G. Poulett. See vol. iii., p. 132.

Consideration of Volcanoes, London, 1823, pp. 228-234.

Wells, W. C. See vol. iii., p. 185. Essay on Dew, London, 1818.



IV.--MODERN PHYSICAL AND CHEMICAL SCIENCES

Black, Joseph. See vol. iv., p. 12.

De acido e cibis orlo, et de magnesia, reprinted at Edinburgh, 1854. In
this he sketched his discovery of carbonic acid. Later this paper
was incorporated in his Experiments on Magnesia, Quicklime, and Other
Alkaltne Substances.

Bunsen, William. See vol. iv., p. 69.

Cavendish, Henry. See vol. iv., p. 15.

"Experiments on Air," in Phil. Trans., 1784, p. 119. This paper contains
Cavendish's discovery of the composition of water and of nitric acid.

Daguerre, Louis J. M. See vol. iv., p. 70.

Historique et description des procédés du daguerréotype et du diorama,
Paris, 1839. (This was translated into English.)

Dalton, John. See vol. iv., p. 40.

"On the Absorption of Gases by Water," read before the Literary
and Philosophical Society of Manchester, October 21, 1803. This
was published in 1805, and contains the atomic weight of twenty-one
substances, some of which were probably added, or corrected, between the
date of the first reading and the publication.

Davy, Sir Humphry. See vol. iv., pp. 48, 209.

"Some Chemical Agencies of Electricity," in Phil. Trans, for 1806, vol.
viii. Researches, Chemical and Philosophical, chiefly concerning Nitrous
Oxide or De-phlogisticated Nitrous Air and its Respiration, London,
1800.

Dewar, James. See vol. v., p. 39.

"Solid Hydrogen," in Proc. Roy. Inst, for 1900. "The Nadir of
Temperature and Allied Problems " (Bakerian Lecture), Proc. Roy. Soc,
1901.

Dufay, Cisternay. See vol. ii., p. 267.

Histoire de l'Académie Royale des Sciences, between 1733 and 1737,
contains Dufay's principal papers.

Eulbr, Leonard (1707-1783). See vol. iii., p. 17.

Lettres a une Princesse d'Allemagne sur quelques sujets de physique et
de philosophie, St. Petersburg, 1768.

Faraday, Michael. See vol. iii., p. 241.

On the Induction of Electric Currents, in Phil. Trans. of Royal Society
for 1832, pp. 126-128. Explication of Arago's Magnetic Phenomena, by
Michael Faraday, F.R.S., Phil. Trans, of Royal Society for 1832, pp.
146-149. Franklin, Benjamin. See vol. ii., p. 286.

New Experiments and Observations on Electricity, London, 1760.

Galvani, Luigi (1737-1798). See vol. iii., p. 229.

De viribus electricitatis in motu musculari commentatio, Bologna, 1791.
This discovery of Galvani was first brought to notice by Volta's famous
paper to the Royal Society, entitled "An Account of some Discoveries
made by Mr. Galvani, of Bologna," published in the Phil. Trans, for
1793, pp. 10-44.

Gay-Lussac, Joseph Louis. See vol. iv., p. 41.

Mémoire sur la combinaison des substances gazeuses, Mem. Soc. d'Arcueil,
1809.

Halley, Edmund. See vol. iii., p. 7.

An Account of Several Extraordinary Meteors or Lights in the Sky, in
Phil. Trans., vol. xxix., pp. 159-162, London, 1714. Helmholtz, H. L. F.
See vol. iii., p. 280.

Handbuch der physiologische Optik, Leipzig, 1867.

Joule, J. P. See vol. iii., p. 269.

On the Calorific Effects of Magneto-Electricity and the Mechanical Value
of Heat, in Report of the British Association for the Advancement of
Science, 1843, vol. xii" p. 33-

Kirwan, R. See vol. iv., p. 3 ff.

An Essay on Phlogiston and the Constitution of Acids, London, 1789.
This is interesting, written as it was just before Lavoisier's Elements
treated the same subject from the stand-point of the anti-phlogistic
chemists.

Kleist, Dean von. See vol. ii., p. 280.

In the Danzick Memoirs, vol. i. contains the description given by Von
Kleist of his discovery of the Leyden jar. A translation is given also
in Priestley's History of Electricity.

Lavoisier, Antoine Laurent. See vol. iv., p. 33.

Traité élémentaire de chimie, Paris, 1774, trans, as Elements of
Chemistry, by Robert Kerr, London and Edinburgh, 1790. Lister, Joseph
Jackson. See vol. iv., p. 113.

On Some Properties in Achromatic Object Glasses Applicable to the
Improvement of the Microscope, in Phil. Trans, for 1830.

Maxwell, James Clerk-. See vol. iii., p. 45.

" On the Motions and Collisions of Perfectly Elastic Spheres " in
Philosophical Magazine for January and July, i860. The Scientific Papers
of J. Clerk-Maxwell, edited by W. D. Nevin (2 vols.), vol. i., pp.
372-374, Cambridge, 1896. This is a reprint of Maxwell's prize paper of
1859. Mayer, Dr. Julius Robert. See vol. iii., p. 259.

The Forces of Inorganic Nature, 1842. This is Mayer's statement of the
conservation of energy. Mendelèepp, Dmitri Ivanovitch. See vol. iv., p.
68.

Principles of Chemistry, 2 vols., London, 1868-1870. (There have been
several subsequent editions.)

Oersted, Hans Christian. See vol. iii., p. 236.

Experiments with the Effects of the Electric Current on the Magnetic
Needle, published at Berlin, 1816.

Priestley, Joseph. See vol. iv., pp. 20, 36.

Experiments and Observations on Different Kinds of Air, 3 vols.,
Birmingham, 1790. History of Electricity, 256 vol. ii., p. 280, London,
1775. The Doctrine of Phlogiston Established, 1800.

Ramsay and Ravlbigh. See vol. v., p. 86.

"On an Anomaly Encountered in Determining the Density of Nitrogen Gas,"
in Proc. Roy. Soc, April, 1894. A statement of the properties of argon
was made by the discoverers to the Royal Society, given in Phil. Trans.,
clxxxvi., p. 187, January, 1895.

ScHBBLB, Karl William. See vol. iv., p. 23.

Om Brunsten, eller Magnesia, och dess Egenakaper, Stockholm,1774. This
contains his discovery of chlorine. His book, Chemische Abhandlung von
der Luft und dent Feuer, was published in 1777.

Thompson, Benjamin (Count Rumford). See vol. iii., p. 208. Essays
Political, Economical, and Philosophical (2 vols.), vol. ii., pp.
470-493, London, T. Cadell, Jr., and W. Davies, 1797. Thomson, William
(Lord Kelvin). See vol. iii., p. 276.

On a Universal Tendency in Nature to the Dissipation of Mechanical
Energy, in Transactions of the Royal Society of Edinburgh, 1852.

Wollaston, William Hyde. See vol. iv., p. 41.

Phil. Trans, for 1814, vol. civ., p. i, contains a synoptic scale of
chemical equivalents. This paper was confirmatory of Dalton's theory.

Young, Thomas. See vol. iii., p. 218.

On the Colors of Thin Plates» I.e. in Phil. Trans, for 1802, pp. 35-37.



V.--MODERN BIOLOGICAL SCIENCES

Avenbruggbr, Lbopold. See vol. iv., p. 200.

Inventum novum ex percussione thoracis humant interni pectoris morbos
detegendi, Vienna, 1761. vot. V.-17 257

Bell, Sir Charles See vol. iv., p. 249.

An Exposition of the Natural System of Nerves of the Human Body, being
a Republication of the Papers delivered to the Royal Society on the
Subject of the Nerves in 1811, etc.

Bernard, Claude. See vol. iv., p. 137.

BOERHAAVB, HERMANN. See Vol. IV., p. 182.

Institutions medicos, Leyden, 1708; and De chemie expurgante suos
errores, Lugduni Batavorum, 1718. Brown, Robert. See vol. iv., p. 115.

On the Organs and Mode of Fecundation of Orchideo and Asclepiadeo, in
Miscellaneous Botanical Works, London, 1866.

Chambers, Robert. See vol. iv., p. 161.

Vestiges of the Natural History of Creation, London, 1844 (published
anonymously). His Sequel to Vestiges was published a year later.
Charcot, Jean Martin. See vol. iv., p. 269.

Leçons sur Us maladies du système nerveux, Paris, beginning in 1873.
Cuvier, George, Baron de. See vol. iv., p. 159.

Histoire naturelle des animaux sans vertèbres, Paris, 1815. Système des
connaissances positives de Vhomme, Paris, 1820.

Darwin, Erasmus. See vol. iv., pp. 94, 147.

The Botanic Garden, London, 1799. The Temple of Nature, or The Origin
of Society, edition published in London, 1807. Darwin, Charles. See vol.
iii., p. 95, and vol. iv., p. 173. The Origin of Species, London, 1859.

Pechner, Gustav. See vol. iv., p. 263. Elemente du Psychophysik, i860.
Flourens, Marie Jean Pierre. See vol. iv., p. 270.

Experiences sur le système nerveux, Paris, 1825. Cours sur la
génération, Vovologie, et Vembryologie, Paris, 1836, etc.

Gall, Franz Joseph. See vol. iv., p. 248.

Recherches sur le système nerveux en général, et sur celui du cerveau en
particulier, Paris, 1809. (This paper was laid before the Institute of
France in March, 1808.) Goethe, Johann Wolfgang. See vol. iv., p. 140.

Die Metamorphose der Pflanzen, 1790. Gray, Stephen. See vol. ii.t p.
262.

Most of his original papers appeared in the PhU. Trans, between 1720 and
1737.

Haeckel, Ernst Heinrich. See vol. v., p. 144.

Naturlich Schopfungsgeschichte, 1866, rewritten in a more popular
style two years later as Natural History of Creation. Some of his more
important monographs are: Radiolaria (1862), Siphonophora (1869),
Monera (1870), Calcarious Sponges (1872), Arabian Corals (1876), another
Radiolaria, enumerating several thousand new species, accompanied by one
hundred and forty plates (1887), and Die Weltrâthsel, trans, in 1900
as The Riddle of the Universe. Hahnemann, Wilhelm von. See vol. iv., p.
189.

Organon der rationellen Heilkunde, Dresden, 1810. Hall, Marshall, M.D.,
F.R.S.L. See vol. iv., p. 251.

On the Reflex Functions of the Medulla Oblongata and the Medulla
Spinalis, in Phil. Trans, of Royal Society, vol. xxxiii., 1833. Hunter,
John. See vol. iv., p. 92.

On the Digestion of the Stomach after Death, first edition, pp. 183-188.

Jenner, Edward. See vol. iv., p. 190.

An Inquiry into the Causes and Effects of the Variolo Vaccino, London,
1799.

Laénnec, René Théophile Hyacinthe. See vol. iv., p. 201.

Traité d'auscultation médiate, Paris, 1819. Lamarck, Jean Baptiste de.
See vol. iv., p. 152.

Philosophie zoologique, 8 vols., Paris, 1801. His famous statement of
the supposed origin of species occurs on p. 235 of vol. i., as follows:
"Everything which nature has caused individuals to acquire or lose by
the influence of the circumstance to which their race is long exposed,
and consequently by the influence of the predominant employment of such
organ, or its constant disuse, she preserves by generation to the new
individuals proceeding from them, provided that the changes are
common to the two sexes, or to those which have produced these new
individuals."

Libbig, Justin. See vol. iv., p. 131.

Animal Chemistry, London, 1843.

Libbig and Wôhler. See vol. iv., p. 56.

The important work of Liebig and Wôhler appeared until 183a mostly in
Poggendorff's Armalen, but after 1832 most of Liebig's work appeared in
his own Annalen. About the earliest as well as one of his most important
separate works is Anleitung zur Analyse organischen, Korper, 1837.

Lotze, Hermann. See vol. iv., p. 263.

Medizinische Psychologie, oder Physiologie der Seele, Leipzig, 1852.

Mohl, Hugo von. See vol. iv., p. 125.

Uber der Saftbewegung im Innern d. Zelle, Bot. Zei-tung, 1846. Morgagni,
Giovanni Battista. See vol. iv., p. 76.

De sedibus et causis ntorborum, 2 vols., Venice, 1761.

Oken, Lorenz. See vol. iv., p. 160.

Philosophie der Natur, Zurich, 1802.

Pasteur, Louis. See vol. iv., pp. 217, 233.

Studies on Fermentation, London, 1879. His famous paper on attenuation
and inoculation was published in the Compte Rendu of the Academy of
Science, Paris, 1881 (vol. xcii.).

Saint-Hilaire, Etienne Geoffroy. See vol. iv., p. 160.

Philosophie anatomique, vol. i., Paris, 1818. Schwann, Theodor. See vol.
iv., p. 119.

Mikroskopische Untersuchungen uber die Ubereinstim-mung in der Structur
und dem Wachsthum der Thiere und Pflanzen, Berlin, 1839. Trans, by
Sydenham Soc., 1847. Spencer, Herbert. See vol. iv., p. 268.

Principles of Psychology, London, 1855. 260

Treviranus, Gottfried Reinhold. See vol. iv.t p. 159. Biologie, oder
Philosophie der lebenden Natur, 1802.

Weber, E. H. See vol. iv., p. 263.

The statement of "Weber's Law*' was first made in articles by Weber
contributed to Wagner's Handwârter-buch der Physiologie, but is
again stated and elaborated in Fechner's Psychophysik. (See Fechner.)
Weismann, August. See vol. iv., p. 179.

Studies in the Theories of Descent. Trans, by Professor R. Meldola,
London, 1882. The introduction to this work was written by Darwin.
Wohler, Friedrich. ' (See Liebig and Wôhler.) Wundt, Wilhelm Max. See
vol. iv., p. 268.

Grundzuge der physiologischen Psychologie, 1874. Many articles by Wundt
have appeared in the Philosophische Studien, published at Leipzig.



V.--ASTRONOMY

Astronomische G es disc haft.

A quarterly journal of astronomy published in Leipzig.

Berry, Arthur.

A Short History of Astronomy, New York, 1899. Bertrand, J. L. F.

Les fondateurs de Vastronomie modern: Copernic, Tycho Brake, Kepler,
Galileo, et Newton, Paris, 1865. This gives an interesting account of
the lives and works of these philosophers.

Flammarion, C.

Vie de Copernic, et histoire de la découverte du système du monde,
Paris, 1872. Forster, W.

Johann Kepler und die Harmonie der Sphcren, Berlin, 1862.

Jensen, P.

Die Kosmologie der Babylonier, Strasburg, 1890. 261

Lockyer, Joseph Norman.

The Dawn of Astronomy; a Study of the Temple Worship and Mythology of
the Ancient Egyptians, London, 1894. Loom is.

History of Astronomy, New York, 1855.

Rothmann.

History of Astronomy (in the Library of Useful Knowledge), London, 1834.

Société Astronomique de France. Monthly bulletin, Paris.

Thompson, R. Campbell.

Reports of the Magicians and Astrologers of Nineveh and Babylon, p. 19,
London, 1900.

Wolf, R.

Geschichte der Astronomie, Munich, 1877.



VI.--PHYSICS (ELECTRICITY)

Annalen der Physik, Leipzig. Edited by Dr. Paul Drude. (Note--Heavy,
scientific, up-to-date. Is apparently under the patronage of all the big
physicists, such as Roentgen, etc.)

A tit della Associazione Elethotecnica Italiana (at Rome). A large
bi-monthly magazine, strictly technical, devoted largely to theoretical
problems of electricity and allied subjects.

Bulletin International de VElectricitê et Journal de VElectricitê
{réunis). A semi-monthly four-page paper dealing with the technical
application of electricity in its various fields.

Die Dissozuerung und Umwandlung chemischer Atome, by Dr. Johannes Stark,
1903. Price 150 m. "A comprehensive view of the application of the
electron theory to certain phenomena."--Nature, May, 1904.

Die Kathodenstrahlen, by G. C. Schmidt, Brunswick, 1904.

"A concise and complete account of the properties of the cathode
rays."--Nature, June, 1904.

Electrical Engineer.

Electrical Magazine.

Electricity. A weekly journal, published by the Electricity Newspaper
Co., New York. Devoted largely to questions of the practical application
of electricity, but dealing also with the theoretical side.

Elements of Electro-magnetic Theory, by S. J. Barnett, Le-land Stanford,
Junior, University. Macmillan & Co., 1904.

($3.)

Handbuch der Physik, by Dr. A. Winkelmann, Leipzig, 1904. "An
indispensable storehouse of expert knowledge."--Nature, July, 1904.

Hardin.

Rise and Development of the Liquefaction of Gases, New York, 1899.

La théorie de Maxwell et les oscillations hertziennes, la Télégraphie
sans flt by H. Poincaré, Paris, 1904 (price 2 fr.). Interesting studies
of light, etc. An interesting brochure.--Revue Scientifique, July, 1904.

Le radium et la radioactivité, by Paul Besson, Paris, 1904 (price 2
fr. 75). A good exposition of the known properties of radium, marred,
however, by an attempt to put in accord science and religion--à propos
du radium! --Revue Scientifique, July, 1904.

Lehrbuch der Physik, by Von O. D. Chwolson, St. Petersburg, 1904. 2
vols. out. First vol. covers general physics and mechanics. Second vol.
sound and radiant energy. "Excellent and quite comprehensive."--Science,
review.

Park, Benjamin.

The Intellectual Rise in Electricity, New York, 1895. This is a popular
account of the progress in the field of electricity from Gilbert to
Franklin.

Radium and all About It, by S. Bottone, London, 1904. Published by
Whittaker & Co. Price is. "An accurate account of the most important
phenomena."--Nature, June, 1904.

The Physical Review. A monthly journal of experimental and theoretical
physics. Published for Cornell University by the Macmillan Company. 263

Theory of Heat, by Thomas Preston, F.R.S. Second edition just out.
Macmillan & Co., 185.



VII.-CHEMISTRY

American Chemical Journal. Edited by Ira Remsen, president of Johns
Hopkins University. Published monthly at Baltimore, Maryland. Price $5
per annum. A strictly technical journal.

Bacon, Roger.

Mirror of Alchemy, and Admirable Power of Art and Nature, London, 1597.

Berthblot, P. E. M.

Introduction a l'étude de la chimie des anciens et du moyen age, Paris,
1889.

Les origines de l'alchimie, Paris, 1885.

Bulletin de la Société Chimique de Paris. A monthly technical journal,
treating all phases of the science of chemistry.

Food Inspection and Analysis, by Albert E. Leach, S. B. (John Wiley &
Sons, N. Y., $7.50). Note. --This book is designed for the use of public
analysts, health officers, food economists, etc.

Hoefer, J. C. F.

Histoire de la chimie, Paris, 1866-1869. This gives biographical
sketches of many of the great chemists as well as the history of the
development of chemistry.

Jahresbericht uber die Fortschritte der Chemie. A journal of the
progress in chemistry, published irregularly in Brunswick.

Kopp, H.

Geschichte der Chemie (4 vols.), Brunswick, 1843-1847. This is an
exhaustive history of the development of chemistry.

Lehrbuch der Stereochemie, by A. Werner, Jena, 1904, price 10 m. "Should
be in the hands of every organic chemist."--Nature for August, 1904.

Lemoine, Y. F.

La vitalism et l'aminisme de Stahl, Paris, 1864. This discusses fully
Stahl's famous theories of matter and life. Meyer, E. von.

A History of Chemistry from the Earliest Times to the Present Day,
London, 1898. This treats fully the subject of the phlogiston theory and
its influence in the development of chemistry. Muir, M. P.

Story of Alchemy and the Beginnings of Chemistry, London and New York,
1899. A popular account of the development of the phlogiston theory
from alchemy, giving explanations of the curious beliefs and methods of
working of the alchemists. Rodwell, G. F.

The Birth of Chemistry, London, 1874. Thompson, C. J. S.

The Mystery and Romance of Alchemy and Pharmacy, in the Scientific
Press, London, 1897. This is very interesting and readable. Thompson, T.

The History of Chemistry, London, 1830, 1831. Waite, Arthur Edward.

Lives of Alchemisttcal Philosophers, London, 1888. A biographical
account of the most noted alchemists. This is very complete. Waite has
also collected a list of the principal works of the alchemists, this
list filling about thirty pages of fine print.



VIII.--GEOLOGY. BIOLOGY, PALEONTOLOGY

American Geologist.

American Museum of Natural History Bulletins, New York.

A merican Naturalist.

Annales de l'Institut Pasteur (18 fr. per annum). A monthly bulletin of
the Pasteur Institute, containing mostly technical articles, but also
articles of interest to persons interested in problems of immunization
and immune sera.

Annales des sciences naturelles: zoologie et paléontologie, Paris.

Annals and Magazine of Natural History, including zoology, botany, and
geology. Monthly. London. A technical magazine. Of little interest to
the general reader.

Archiv fur Naturgeschichte. A journal of natural history published
bi-monthly at Berlin.

Archiv fur Rassen-und--Gesellschaft--Biologie einschliefslich
Rassen--und Gesell.-Hygiene.

Archives de biologie (quarterly), Liège.

Archives des sciences biologiques. St. Petersburg. Five numbers a year.

Archives Italiennes de biologie. Turin. Bi-monthly.

Biological Bulletin of the Marine Biological Laboratory, Wood's Holl,
Massachusetts. Published monthly by the laboratory. Managing editor,
Prank R. Lillie. Scientific and technical--very good.

Biologie générale des bactéries, by E. Bodin, professor of bacteriology,
University of Rennes, Paris, 1904. Price 2 It. 50. Studies of bacteria
in general treated in a semi-popular manner. Some new ideas prepared to
explain bacterial action in normal life--very good.--Revue Scientifique,
review, August, 1904.

Biometrika. A journal for the statistical study of biological problems
(quarterly), 305. per annum. Edited, in consultation with Francis
Galton, by W. F. R. Weldon, Karl Pearson, and C. B. Davenport. A bulky
journal, beautifully illustrated with plates and line cuts. Largely
technical, but containing many articles of interest to general readers
on laws of inheritance, hereditary influences, etc.

Bulletin of the Geological Society of America. Published irregularly at
Rochester.

Gcologische und Paloontologische Abhandlungen, Jena.

Johns Hopkins University, Memoirs from the Biological ^ Laboratory.

L'Échange Revue Linnienne, fondée par le Docteur Jacquet. Directeur,
M. Pic. A monthly journal of natural history, devoted largely to
entomology--small and technical. Of interest to entomologists only.

Les lois naturelles, par Félix le Danteg, charge du cours d'embryologie
générale à la Sorbonne, Paris, 1904. Price 6 fr. A study in biology.
"The name corresponds exactly with the contents of this admirable
work."--Revue Scientifique, review, September, 1904.

Marine Biological Association of the United Kingdom, Plymouth.

Société Dauphinoise d'Ethnologie et d'Anthropologie. Quarterly bulletin.
Grenoble.

Société Zoologique de France. Monthly bulletin.

Text-book of Geology, by Sir Archibald Geikie, a vols. Fourth edition.
$10. Macmillan & Co., 1904.

Text-book of Paleontology (Macmillan, 1904, $3), by Carl A. von Zittel,
University of Michigan.

The Geological Magazine, or Monthly Journal of Geology, edited by Henry
Woodward, LL.D., F.R.S., etc. London, 15. éd. per copy. A high-class
technical magazine.

The American Journal of Psychology, edited by G. Stanley Hall, E. C.
Sanford, and E. B. Titchnener. Published at Worcester, Massachusetts,
monthly. A technical journal devoted to psychological researches.

The Naturalist, London. A monthly journal for the north of England.
Edited by J. Sheppard, P.G.S., and T. W. Woodhead, F.L.S. Annual
subscription, 65. 6d. A local journal, but containing general articles
of interest. Semi-popular.

The Quarterly Journal of Microscopical Science, edited by E. Ray
Lankester, M.A., LL.D., F.R.S.



IX.--MEDICINE

American Journal of Insanity.

American Journal of the Medical Sciences, Philadelphia.

Annales medico-psychologiques, Paris.

Arbeiten aus dem leaiserlichen Gesundheitsamte. A journal of hygiene
published irregularly at Berlin.

Archiv fur Anatomie und Physiologic. A semi-monthly journal of the
progress in anatomy and physiology, published at Leipzig.

Archiv fur die gesammte Physiologie, Bonn.

British Medical Journal, London.

Immune Sera, by Professor A. Wassermann, M.D., trans, by Charles
Bolduan, M.D., New York and London, 1904. "We confidently commend this
little book to all persons desirous of acquainting themselves with the
essential facts on the subject of immune sera."--Nature, July, 1904.

Lancet, London.

Leclerc, Lucien.

Histoire de la médecine arabe, 2 vols., Paris, 1876. This work is very
complete and well written.

Medical Record, New York.

Medical Times, New York.

Pagel, Julius.

Einfuhrung in die Geschichte der Medicin, Berlin, 1898. This is not as
exhaustive as Baas's book, but is written in a much more readable style.

Park, Roswell.

Epitome of thf History of Medicine, Philadelphia, 1899.

Paul of AEgina.

The Works of, published by the Sydenham Society, London, 1841, are well
worth reading, as giving a clear understanding of the status of medicine
in the seventh century.

Sprengal, K. P. J.

Histoire de la médecine depuis son origine jusqu'au dix-neuvième siècle,
8 vols., Paris, 1815-1820. This is a French translation of the German
work, and is more available than the original volumes. It is, perhaps,
the most exhaustive history of medicine ever attempted.

The Journal of Hygiene, edited by George H. F. Nuttall, M.D., Ph.D.
A quarterly journal of hygiene (2 is. per annum), containing many
interesting articles on subjects connected with hygiene and of interest
to general readers.

The Journal of Physiology, edited by Sir Michael Foster, K.C.B., M.D.,
F.R.S., and J. N. Langley, Sc.D., F.R.S. Issued quarterly. Price Ss. C.
J. Clay & Sons, London.



X.--ANTHROPOLOGY AND ARCHAEOLOGY

American Anthropologist. F. W. Hodge, editor, Washington, D. C.
Published quarterly for the American Anthropological Association ($4.50
per annum). Technical (or semi-technical). "A medium of communication
between students of all branches of anthropology." Much space devoted
to Indian language, etc.--;a very good journal. American Journal of
Archoology. American Journal of Sociology.

Archivo per V antropologia e V etnologia, Florence. Three numbers a
year. A journal devoted to anthropology and ethnology. Avebury, Lord
(Sir John Lubbock).

The Origin of Civilization and the Primitive Condition of Man. Mental
and social condition of modern savages. New York, 1870. Brinton, Daniel
Garrison, M.D.

The Basis of Social Relation, a Study in Ethnic Psycliol-ogy, edited by
L. Farrand, New York, 1902. Clodd, Edward.

Myths and Dreams, London. 1885. Story of Primitive Man, 3d edition,
London, 1897. The Childhood, of tlte World. A simple account of man in
early times. London, 1893. Dawkins, W. Boyd.

Early Man in Britain, London, 1880. Cave Hunting. Researches on the
evidence of caves respecting the early inhabitants of Europe. London,
1874. Dellenbaugh, Frederick S.

The North Americans of Yesterday, New York, 1901. Deniker, Joseph.

Races of Man. An outline of anthropology and ethnology. London, 1900.
Grierson, P. J. H. Hamilton.

The Silent Trade. A contribution to the early history of human
intercourse. London, 1903. Haeckel, Dr. Ernst Heinrich.

Anthropogenic; oder Entwickelungsgeschichtc des Men-schen, 4th edition,
2 vols., Leipzig, 1891. 269

Müller, Friedrich.

Ethnographie; auf Grund des von K. von Scherzer gesammetten Materials.
Vienna, 1868.

Murtillbt, Gabriel de.

Le préhistorique antiquité de Vhomme. Paris, 1883.

Powell, John Wesley.

"Relation of Primitive Peoples to Environment." In Smithsonian
Institution Report. Washington, 1896. Reports of American Ethnology, in
the annual reports of the U. S. Bureau of Ethnology since 1877.

Quatrepages (A. de Q. de Brun).

Histoire générale des races humaines. Paris, 1889.

Ratzel, Friedrich.

The History of Mankind, 3 vols., trans, by A. J. Bubler, London,
1896-1898.

Revue de l'Ecole d'Anthropologie de Paris. Monthly. Published by the
professors. Treats all phases and branches of anthropology.

Science de l'homme et méthode anthropologique, by Alphonse Cels, Paris
and Brussels, 1904. 7 francs. "As a highly abstract and suggestive
exposition of the nature and scope of anthropology, this book deserves
a place in the library of the anthropologist."--Nature, September 24,
1904.

Société Académique d'Archéologie, Paris.





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