Home
  By Author [ A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z |  Other Symbols ]
  By Title [ A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z |  Other Symbols ]
  By Language
all Classics books content using ISYS

Download this book: [ ASCII ]

Look for this book on Amazon


We have new books nearly every day.
If you would like a news letter once a week or once a month
fill out this form and we will give you a summary of the books for that week or month by email.

Title: Philipp Reis: Inventor of the Telephone - A Biographical Sketch
Author: Thompson, Silvanus P. (Silvanus Phillips)
Language: English
As this book started as an ASCII text book there are no pictures available.
Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

*** Start of this Doctrine Publishing Corporation Digital Book "Philipp Reis: Inventor of the Telephone - A Biographical Sketch" ***

This book is indexed by ISYS Web Indexing system to allow the reader find any word or number within the document.



[Illustration: MEDALLION AND AUTOGRAPH FROM MONUMENT TO PHILIPP REIS AT
FRIEDRICHSDORF.]



                             PHILIPP REIS:

                              INVENTOR OF

                            THE TELEPHONE.

                        A BIOGRAPHICAL SKETCH,

            WITH DOCUMENTARY TESTIMONY, TRANSLATIONS OF THE
                      CONTEMPORARY PUBLICATIONS.

                                  BY

                  SILVANUS P. THOMPSON, B.A., D.Sc.,
   PROFESSOR OF EXPERIMENTAL PHYSICS IN UNIVERSITY COLLEGE, BRISTOL.

                            [Illustration]

                                LONDON:
                  E. & F. N. SPON, 16, CHARING CROSS.
                     NEW YORK: 35, MURRAY STREET.
                                 1883.



PREFACE.


The title of this little work sufficiently indicates its nature and
scope. The labour of preparing it has not been slight, and has involved
the expenditure of much time in prosecuting inquiries both in this
country and in Germany amongst the surviving contemporaries of Philipp
Reis. To set forth the history of this long-neglected inventor and of
his instrument, and to establish upon its own merits, without special
pleading, and without partiality, the nature of that much-misunderstood
and much-abused invention, has been the aim of the writer. The thought
that he might thus be of service in rendering justice to the memory
of the departed worthy has inspired him to his task. He has nothing
to gain by making Reis’s invention appear either better or worse than
it really was. He has therefore preferred to let the contemporary
documents and the testimony of eye-witnesses speak for themselves, and
has added that which seemed to him desirable in the way of argument in
the form of four appendices.

The author’s acknowledgments are due in an especial manner to Mr.
Albert Stetson, A.M., of Cohasset, Massachusetts, who has given
him much valuable assistance in the collection of information both
in Germany and in this country, and who has also assisted in the
translation of some of the contemporary documents to be found in the
work. To the friends, acquaintances, and pupils of Philipp Reis, and
especially to the surviving members of the family at Friedrichsdorf,
who have most kindly furnished many details of information, the author
would express his most cordial thanks. The testimony now adduced as
to the aim of Philipp Reis’s invention, and the measure of success
which he himself attained, is such, in the author’s opinion, and in
the opinion, he trusts, of all right-thinking persons, to place beyond
cavil the rightfulness of the claim which Reis himself put forward
of being the inventor of the Telephone. Full and sufficient as that
testimony is, much more remains as yet unpublished. The author has, for
example, been permitted to examine a mass of evidence collected by the
Dolbear Telephone Company, which entirely corroborates that which is
here presented. It is, however, for certain reasons beyond the author’s
control, deemed well at the present moment to withhold this testimony
for a little while from publication. The appearance of this volume at
the present time needs no apology from the author. He is conscious that
all he can do will add little or nothing to the lustre with which the
name of Philipp Reis will be handed down to posterity. When the Jubilee
of Philipp Reis comes to be celebrated in 1884 (January 7th), the world
will find out its indebtedness to the great man whose thoughts survive
him.



PHILIPP REIS.



CHAPTER I.

BIOGRAPHY OF THE INVENTOR.

[Compiled chiefly from papers left by the deceased, and from the
biographical notice of the late Professor Schenk.]


Philipp Reis, or, as his full name appears from his autobiographical
sketch to have been, Johann Philipp Reis, was born on the 7th of
January, 1834, at Gelnhausen, in the principality of Cassel. His
father, who belonged to the Evangelical Church, was a master baker,
but also pursued farming to some extent, as the circumstances of small
provincial towns generally require. As his mother had died young, his
paternal grandmother undertook the bringing up of the boy. “While my
father,” writes Herr Reis, “strove constantly to cultivate my mental
powers by instruction concerning the things which surrounded me (by
discussing that which was actually observed), my grandmother turned
her activity to training my disposition and to the development of
the religious sentiments to which she was eminently fitted by the
experiences of a long life, by being well-read, and especially by her
gift of narration.”

On attaining his sixth year the boy was sent to the common school of
his native town. His teachers soon recognised that he possessed no
ordinary endowments, and sought to induce his father to entrust him
later to a higher institution of learning. His father agreed to this;
and the plan was to have been carried out after the boy had passed the
middle-class of the common school. How the father contemplated the
carrying out of the plan is not known; he died ere the son had yet
completed his tenth year.

As a considerable number of children from Frankfort-on-the-Main
and its neighbourhood, attended that time Garnier’s Institute at
Friedrichsdorf, near Homburg, the idea occurred to his guardian and his
grandmother to entrust the boy to this school. He entered there when in
his eleventh year. “The foreign languages, English and French, taught
in the Institute, attracted me specially. The library of the Institute,
rich and well chosen for its size, gave my mind excellent nourishment.”
At the end of his fourteenth year he had passed through the school,
organised as it then was, and he now went to Hassel’s Institute at
Frankfort-on-the-Main. His delight in the study of language induced him
to learn Latin and Italian. And here, also, the taste for the study of
natural sciences and mathematics appears to have been awakened in him.
The lively zeal with which he applied himself to both these disciplines
induced his teachers to advise his guardian that he should allow
the boy to attend the Polytechnic School at Carlsruhe, on finishing
his course at the Institute. “All the endeavours of my well-wishing
teachers shattered themselves, however, against the will of one of
my guardians, who was also my uncle. He wished that I should follow
mercantile pursuits.... I wrote him at that time that I should, indeed,
be obedient and learn the pursuit prescribed for me, but that I should
in any case continue my studies later.”

On the 1st of March, 1850, Philipp Reis entered the colour
establishment of Mr. J. F. Beyerbach, of Frankfort, as an apprentice.
By diligence and punctuality he soon won the esteem of his principal.
All his leisure time he bestowed upon his further education. He took
private lessons in mathematics and physics, and attended the lectures
of Professor R. Böttger, on Mechanics, at the Trade School. And so the
end of his apprenticeship arrived. At the conclusion of it he entered
the Institute of Dr. Poppe, in Frankfort. “Several of my comrades in
this establishment, young people of sixteen to twenty years old, found
it, as I did, a defect that no natural history, history, or geography,
was taught. We determined, therefore, to instruct one another in these
subjects. I undertook geography, and formed from this first occasion of
acting as teacher the conviction that this was my vocation. Dr. Poppe
confirmed me in this view and aided me by word and deed.”

In the year 1851, whilst resident in Frankfort, Reis had become a
member of the Physical Society of that city. This Society, which still
flourishes, then held, and still continues to hold, its meetings in the
Senckenburg Museum. Lectures in Chemistry and Physics are delivered
by resident professors in regular courses every week throughout the
winter, under the auspices of this Society; and every Saturday evening
is devoted to the exposition of recent discoveries or inventions in
the world of physical science, astronomy, etc. The most active members
of this Society during the time of Reis’s connection with it were
the late Professor Böttger, Professor Abbe (now of Jena), and Dr.
Oppel, all of whom contributed many valuable original memoirs to the
_Jahresberichte_, or Annual Reports, published by the Society. Amongst
its corresponding and honorary members it counted the names of all
the best scientific men of Germany, and also the names of Professor
Faraday, Professor Sturgeon, and Sir Charles Wheatstone. Doubtless the
discussion of scientific questions at this Society greatly influenced
young Reis. He remained for three years a member, but dropped his
connexion for a time on leaving Frankfort. He subsequently rejoined
the Society in the session of 1860-61, remaining a member until 1867,
when he finally resigned.

In the winter of 1854-5 we find him most zealously busied with
preparations for carrying out his decision to become a teacher. In
1855, he went through his year of military service at Cassel. Returning
to Frankfort, he worked away with his customary and marvellous energy,
attended lectures on mathematics and the sciences, worked in the
laboratory, and studied books on Pedagogy. “Thus prepared, I set my
mind on going to Heidelberg in order to put the finishing touch to my
education as teacher. I wanted to settle down in Frankfort in this
capacity, and undertake instruction in mathematics and science in
the various schools. Then in the spring of 1858, I visited my former
master, Hofrath Garnier, in whom I had ever found a fatherly friend.
When I disclosed to him my intentions and prospects, he offered me a
post in his Institute. Partly gratitude and attachment, and partly the
ardent desire to make myself right quickly useful, induced me to accept
the proffered post.”

In the autumn of the year 1858 he returned to Friedrichsdorf, and in
September 1859 he married and founded his peaceful home.

Until Easter, 1859, he had but few lessons to give; that he utilised
every moment of his spare time most conscientiously in earnest activity
and sound progress is nothing more than was to be expected from what
has been said above.

It was during this time that Reis undertook the first experimental
researches of an original nature. Working almost alone, and without
any scientific guide, he was led into lines of thought not previously
trodden. He had conceived an idea that electrical forces could be
propagated across space without any material conductor in the same way
as light is propagated. He made many experiments on the subject, the
precise nature of which can never now be known, but in which a large
concave mirror was employed in conjunction with an electroscope and a
source of electrification. The results which he obtained he embodied
in a paper, of which no trace now remains, bearing as its title ‘On
the Radiation of Electricity.’ This paper he sent in 1859 to Professor
Poggendorff for insertion in Poggendorff’s well-known ‘Annalen der
Physik.’ Greatly to his disappointment the memoir was not accepted by
Professor Poggendorff. Its rejection was a great blow to the sensitive
and highly strung temperament of the young teacher; and as will be seen
was not without its consequences.

The other piece of original work undertaken at this time was the
research which resulted in his great invention--the Telephone. From the
brief biographical notes written by the lamented inventor in 1868 we
extract the following:--

“Incited thereto by my lessons in Physics in the year 1860, I
attacked a work begun much earlier concerning the organs of hearing,
and soon had the joy to see my pains rewarded with success, since
I succeeded in inventing an apparatus, by which it is possible to
make clear and evident the functions of the organs of hearing, but
with which also one can reproduce tones of all kinds at any desired
distance by means of the galvanic current. I named the instrument
‘Telephon.’ The recognition of me on so many sides, which has taken
place in consequence of this invention, especially at the Naturalists’
Association (Versammlung Deutscher Naturforscher) at Giessen, has
continually helped to quicken my ardour for study, that I may show
myself worthy of the luck that has befallen me.”

His earliest telephones were made by his own hands, in a little
workshop behind his house, whence he laid on wires into an upper
room. He also carried a wire from the physical cabinet of Garnier’s
Institute across the playground into one of the class-rooms for
experimental telephonic communication; and a firmly established
tradition of the school is still preserved, that the boys were afraid
of making a noise in that class-room for fear Herr Reis should hear
them in his place amongst his favourite instruments.

In 1862 Reis sent once again to Professor Poggendorff a memoir, this
time on the Telephone. This, in spite of the advocacy of Professor
Böttger and of Professor Müller of Freiburg, both of whom wrote, was
declined by Professor Poggendorff, who treated the transmission of
speech by electricity as a myth. Reis, who was convinced that the
rejection was because he was “only a poor schoolmaster,” was more
deeply pained than ever.

Of the various public exhibitions of the Telephone given by Reis in
the years 1861 to 1864, much will be found in the latter part of this
book in which the contemporary notices are reprinted. The first public
lecture was in 1861, before the Physical Society of Frankfort (see
p. 50), the last the above-mentioned occasion at Giessen (see p. 93)
in 1864. By this time Reis’s invention was becoming widely known. In
addition to his own lectures on the subject, the Telephone had been
the subject of lectures in various parts of Germany. It was lectured
upon by Professor Buff in Giessen twice, by Professor Böttger both in
Frankfort and in Stettin; by Professor H. Pick, by Professor Osann of
Würtzburg, by Professor Paul Reis of Mainz, and by others. In 1863
Reis’s Telephone was shown by Dr. Otto Volger, Founder and President of
the Free German Institute (Freies Deutsches Hochstift), to the Emperor
of Austria and to King Max of Bavaria, then on a visit to Frankfort.

Telephones were being sent to various parts of the world. They were to
be found in the Physical Laboratories of Munich, Erlangen, Wiesbaden,
Vienna, and Cologne. They were sent to distant parts of the world,
to London,[1] to Dublin, to Tiflis in the Caucasus. In Manchester,
before the Literary and Philosophical Society, Reis’s Telephone was
shown in 1865 by Professor Clifton, who, however, from not having
Reis’s own original memoirs on the subject before him, utterly
mistook--if the Journal of Proceedings be not in error--the nature of
the instrument, and not knowing the theory of vibration of the tympanum
so beautifully demonstrated by Reis, imagined the instrument to be a
mere harmonic telegraph for transmitting code signals in fixed musical
tones! Telephones, too, were becoming an article of commerce and,
good and bad,[2] were being bought for the purpose of placing them
in collections of scientific apparatus. The invention was, however,
too soon for the world. To Reis’s great disappointment, the Physical
Society of Frankfort took no further notice of the invention, the
lustre of which shone upon them. He resigned his membership in the
Society in October 1867. The Free German Institute of Frankfort, to
which Reis had next betaken himself, though electing him to the dignity
of honorary membership, left the invention aside as a philosophic
toy. The Naturalists’ Assembly, including all the leading scientific
men of Germany, had indeed welcomed him at Giessen; but too late. The
sensitive temperament had met with too many rebuffs, and the fatal
disease with which he was already stricken told upon his energies. In
particular the rejection of his earlier researches had preyed upon his
disposition. It is narrated by eye-witnesses still living, how, after
his successful lecture on the Telephone at Giessen, Reis was asked
by Professor Poggendorff, who was present, to write an account of his
instrument for insertion in the ‘Annalen,’ to which request Reis’s
reply was: “_Ich danke Ihnen recht sehr, Herr Professor; es ist zu
spät. Jetzt will_ =ich= _nicht ihn schicken. Mein Apparat wird
ohne Beschreibung in den Annalen bekannt werden._“

Hæmorrhage of the lungs and a loss of voice, which eventually became
almost total, intervened to incapacitate him for work, and especially
from working with the telephone. In 1873 he disposed of all his
instruments and tools to Garnier’s Institute. To Herr Garnier he made
the remark that he had showed the world the way to a great invention,
which must now be left to others to develop. At last the end came. The
annual Report of Garnier’s Institute for the academic year 1873-1874
contains the following brief notice of the decease and labours of
Philipp Reis:--

“At first active in divers subjects of instruction, he soon
concentrated his whole faculties upon instruction in Natural Science,
the subject in which his entire thought and work lay. Witnesses of this
are not only all they who learned to know him in Frankfort, in the
period when he was preparing for his vocation as teacher, but also his
colleagues at the Institute, his numerous pupils, and the members of
the Naturalists’ Association (Naturforscher Versammlung) at Giessen,
who, recognising his keen insight, his perseverance and his rich gifts,
encouraged him to further investigations in his newly propounded
theories. To the Association at Giessen he brought his Telephone. To
the Association at Wiesbaden, in September 1872, he intended to exhibit
a new ingeniously constructed gravity-machine, but his state of health
made it impossible. This had become such during several years, that he
was enabled to discharge the duties of his post only by self-control
of a special, and, as is generally admitted, unusual nature; and the
practice of his vocation became more difficult when his voice also
failed. In the summer of 1873 he was obliged, during several weeks, to
lay aside his teaching. As by this rest and that of the autumn vacation
an improvement in his condition occurred, he acquired new hopes of
recovery, and resumed his teaching in October with his customary
energy. But it was only the last flickering up of the expiring lamp of
life. Pulmonary consumption, from which he had long suffered, laid him
in December upon the sickbed, from which after long and deep pains, at
five o’clock in the afternoon, on the 14th of January, 1874, he was
released by death.”

The closing words of his autobiographical notes, or “_curriculum
vitæ_,” as he himself styled them, were the following:--

“As I look back upon my life I can indeed say with the Holy Scriptures
that it has been ‘labour and sorrow.’ But I have also to thank the Lord
that He has given me His blessing in my calling and in my family, and
has bestowed more good upon me than I have known how to ask of Him. The
Lord has helped hitherto; He will help yet further.”

In 1877, when the Magneto-Telephones of Graham Bell began to make their
way into Europe, the friends of Philipp Reis were not slow to reclaim
for their deceased comrade the honours due to him. In December 1877, as
the columns of the _Neue Frankfurter Presse_ show, a lecture was given
upon the history of the Telephone, at the Free German Institute, in
Frankfort, by Dr. Volger, its President, the same who in 1863 had shown
the Telephone to the Emperor of Austria. On that occasion the Telephone
of Reis’s own construction, presented by him to the Institute after his
exhibition of it in 1862, was shown.

Early in 1878 a subscription was raised by members of the Physical
Society of Frankfort for the purpose of erecting a monument to the
memory of their former colleague. This monument, bearing a portrait
medallion, executed by the sculptor, Carl Rumpf, was duly inaugurated
on Sunday, December 8, 1878, when an appropriate address was pronounced
by the late Dr. Fleck, of Frankfort. The ‘Jahresbericht,’ of the
Physical Society for 1877-78 (p. 44), contains the following brief
record:--

    “The Society has erected to the memory of its former member,
    the inventor of the Telephone, Philipp Reis (deceased in 1874),
    teacher, of Friedrichsdorf (see ‘Jahresbericht,’ 1860-61, pp.
    57-64; and 1861-62, p. 13), in the cemetery of that place,
    a monument which was inaugurated on the 8th of December,
    1878. This monument, an obelisk of red sandstone, bears in
    addition to the dedication, a well-executed medallion portrait
    of Philipp Reis, modelled by the sculptor, A. C. Rumpf, and
    executed galvanoplastically by G. v. Kress.”

The inscription on Reis’s monument in the Friedrichsdorf Cemetery is:--

[Illustration:

                               HIER RUHT
                             PHILIPP REIS
                          GEB. 7. JANUAR 1834
                         GEST. 14. JANUAR 1874

                        SEINEM VERDIENSTVOLLEN
                               MITGLIEDE
                           DEM ERFINDER DES
                               TELEPHONS
                       DER PHYSIKALISCHE VEREIN
                                  ZU
                            FRANKFURT-A-M.

                               ERRICHTET
                                 1878
]


PRINCIPAL DATES IN REIS’S LIFE.

  1834  January 7      Philipp Reis born.

  1850  March 1        Apprenticed to Beyerbach.

  1855                 Year of Military Service at Cassel.

  1858                 Settled in Friedrichsdorf.

  1859  September 14   Married.

  1860                 Invented the Telephone.

  1861  October 26     Read Paper “On Telephony by the
                         Galvanic Current” before the Physical
                         Society of Frankfort-on-the-Main.

   "    November       Read Paper to the Physical Society
                         of Frankfort-on-the-Main, entitled
                         “Explanation of a new Theory
                         concerning the Perception of Chords
                         and of Timbre as a Continuation
                         and Supplement of the Report on
                         the Telephone.”

  1861  December       Wrote out his Paper “On Telephony,”
                         as printed in the ‘Jahresbericht.’

  1862  May 8          Notice in ‘Didaskalia’ of Reis’s
                         invention.

   "    May 11         Lectured and showed the Telephone
                         to the Free German Institute
                         (Freies Deutsches Hochstift) in
                         Frankfort-on-the-Main.

   "                   Article on the Telephone, communicated
                         by Inspector Von Legat to the
                         Austro-German Telegraph Society,
                         and subsequently printed in its
                         ‘Zeitschrift’ (Journal).

  1863  July 4         Showed his improved Telephone to
                         the Physical Society of Frankfort-on-the-Main.

   "    September 6    Reis’s Telephone shown to the Emperor
                         of Austria and the King of
                         Bavaria, then visiting Frankfort.

   "    Sept. 17-24    Meeting of the “Deutscher Naturforscher”
                         at Stettin; Reis’s Telephone
                         shown there by Professor
                         Böttger.

  1864  February 13    Meeting of the “Oberhessische Gesellschaft
                         für Natur- und Heilkunde”
                         at Giessen; Lecture by
                         Professor Buff, and exhibition by
                         Reis of his Telephone.

   "    September 21   Meeting of the “Deutscher Naturforscher”
                         at Giessen. Reis gave
                         an explanation of the Telephone
                         and the history of its invention,
                         and exhibited it in action before
                         the most distinguished scientific
                         men of Germany.

  1872  September      Meeting of the “Deutscher Naturforscher”
                         at Wiesbaden; Reis
                         announced to show his “Fallmaschine,”
                         but prevented by ill-health.

  1874  January 14     Philipp Reis died.

[Illustration: Fig. 1.
Monument to Philipp Reis in the Cemetery at Friedrichsdorf.]

FOOTNOTES:

[1] An autograph letter of Philipp Reis to Mr. W. Ladd, the well-known
instrument maker of Beak Street, London, describing his telephone, is
still preserved, and is now in possession of the Society of Telegraph
Engineers and Electricians of London. It is reproduced at p. 81.

[2] As to the difference in quality of the instruments, see the
testimony of the maker, Albert of Frankfort, on p. 44. Prof. Pisko (see
p. 101) seems to have had a peculiarly imperfect instrument.



CHAPTER II.

THE INVENTOR’S APPARATUS.


In describing the various forms successively given by the inventor
to his apparatus, as he progressed, from the earliest to the latest,
it will be convenient to divide them into two groups, viz. the
Transmitters and the Receivers.


_A.--Reis’s Transmitters._

So far as can be learned, Reis constructed transmitters in some ten or
twelve different forms. The complete series in this course of evolution
does not now exist, but the principal forms still remain and will be
described in their historical order. Theoretically, the last was no
more perfect than the first, and they all embody the same fundamental
idea: they only differ in the mechanical means of carrying out to
a greater or less degree of perfection the one common principle of
imitating the mechanism of the human ear, and applying that mechanism
to affect or control a current of electricity by varying the degree of
contact at a loose joint in the circuit.


_First Form._--THE MODEL EAR.

Naturally enough the inventor of the Telephone began with crude and
primitive[3] apparatus. The earliest form of telephone-transmitter now
extant, was a rough model of the human ear carved in oak wood, and of
the natural size, as shown in Figs. 2, 3, 4, & 5.

[Illustration: Fig. 2.]

[Illustration: Fig. 3.]

[Illustration: Fig. 4.]

[Illustration: Fig. 5.]

The end of the aperture _a_ was closed by a thin membrane _b_, in
imitation of the human tympanum. Against the centre of the tympanum
rested the lower end of a little curved lever _c d_, of platinum wire,
which represented the “hammer” bone of the human ear. This curved lever
was attached to the membrane by a minute drop of sealing-wax, so that
it followed every motion of the same. It was pivoted near its centre
by being soldered to a short cross-wire which served as an axis; this
axis passing on either side through a hole in a bent strip of tin-plate
screwed to the back of the wooden ear. The upper end of the curved
lever rested in loose contact against the upper end _g_ of a vertical
spring, about one inch long, also of tin-plate, bearing at its summit a
slender and resilient strip of platinum foil. An adjusting-screw, _h_,
served to regulate the degree of contact between the vertical spring
and the curved lever. The conducting-wires by which the current of
electricity entered and left the apparatus were connected to the screws
by which the two strips of tin-plate were fixed to the ear. In order
to make sure that the current from the upper support of tin should
reach the curved lever, another strip of platinum foil was soldered
on the side of the former, and rested lightly against the end of the
wire-axis, as shown in magnified detail in Fig. 6. If now any words or
sounds of any kind were uttered in front of the ear the membrane was
thereby set into vibrations, as in the human ear. The little curved
lever took up these motions precisely as the “hammer”-bone of the
human ear does; and, like the “hammer”-bone, transferred them to that
with which it was in contact. The result was that the contact of the
upper end of the lever was caused to vary. With every rarefaction of
the air the membrane moved forward and the upper end of the little
lever moved backward and pressed more firmly than before against the
spring, making better contact and allowing a stronger current to flow.
At every condensation of the air the membrane moved backwards and the
upper end of the lever moved forward so as to press less strongly than
before against the spring, thereby making a less complete contact than
before, and by thus partially interrupting the passage of the current,
caused the current to flow less freely. The sound waves which entered
the ear would in this fashion throw the electric current, which flowed
through the point of variable contact, into undulations in strength.
It will be seen that this principle of causing the voice to control
the strength of the electric current by causing it to operate upon
a loose or imperfect contact, runs throughout the whole of Reis’s
telephonic transmitters. In later times such pieces of mechanism
for varying the strength of an electric current have been termed
current-regulators.[4] It would not be inappropriate to describe the
mechanism which Reis thus invented as a combination of a tympanum
with an electric current-regulator, the essential principle of the
electric current-regulator being the employment of a loose or imperfect
contact between two parts of the conducting system, so arranged that
the vibrations of the tympanum would alter the degree of contact and
thereby interrupt in a corresponding degree the passage of the current.

[Illustration: Fig. 6.]

Mr. Horkheimer, a former pupil of Reis, informs me that a much larger
model of the ear was also constructed by Reis. No trace of this is,
however, known.


_Second Form._--TIN TUBE.

The second form, a tube constructed by Reis himself, of tin, is
still to be seen in the Physical cabinet of Garnier’s Institute, at
Friedrichsdorf, and is shown in Fig. 7. It consists of an auditory tube
_a_, with an embouchure representing the pinna or flap of the ear. This
second apparatus shows also a great similarity with the arrangement of
the ear, having the pinna or ear-flap, the auditory passage, and the
drum-skin (_a_, _b_, _c_). Upon the bladder _c_ there still remains
some sealing-wax, by means of which a little strip of platinum, for
the all-essential loose-contact that controlled the current, had
formerly been cemented to the apparatus.

[Illustration: Fig. 7.]


_Third Form._--THE COLLAR-BOX.

[Illustration: Fig. 8.]

The third form, also preserved in the collection in Garnier’s
Institute, is given in Fig. 8, which, with the preceding, is taken by
permission from the pamphlet of the late Professor Schenk, consists
of a round tin box, the upper part of which fits upon the lower
precisely like the lid of a collar-box. Over this lid _b_, which is 15
centimetres in diameter, was formerly stretched the vibrating membrane,
there being also an inner flange of metal. Into a circular aperture
below opened an auditory tube _a_, with an embouchure representing
the pinna. The precise arrangements of the contact-parts of this
apparatus are not known. Mr. Horkheimer, who aided Reis in his earlier
experiments, has no knowledge of this form, which he thinks was made
later than June 1862. This is not improbable, as the design with
horizontal membrane more nearly approaches that of the tenth form, the
“Square-box” pattern.


_Fourth Form._--THE BORED-BLOCK.

The instrument described by Reis in his paper “On Telephony,” in
the Annual Report of the Physical Society of Frankfort-on-the-Main,
for 1860-61 (see p. 50), comes next in order. The inventor’s own
description of this telephone (Fig. 9) is as follows:--

[Illustration: Fig. 9.]

“In a cube of wood, _r s t u v w x_, there is a conical hole _a_,
closed at one side by the membrane _b_ (made of the lesser intestine
of the pig), upon the middle of which a little strip of platinum is
cemented as a conductor [or electrode]. This is united with the binding
screw _p_. From the binding screw _n_ there passes likewise a thin
strip of metal over the middle of the membrane, and terminates here
in a little platinum wire, which stands at right-angles to the length
and breadth of the strip. From the binding-screw _p_ a conducting
wire leads through the battery to a distant station.” The identical
apparatus used by Reis was afterwards given by him to Professor
Böttger, who later gave it to Hofrath Dr. Th. Stein, of Frankfort, from
whose hands it has recently passed into the possession of the author
of this work. It possesses one feature not shown in the original cut,
viz. an adjusting screw, _h_, which, so far as the writer can learn,
was put there by Reis himself. There appears no reason to doubt this,
since there was an adjusting screw in Reis’s very earliest form of
transmitter, the wooden ear. A section of the actual instrument is
given in Fig. 10.

[Illustration: Fig. 10.]


_Fifth Form._--THE HOLLOW CUBE.

Another form, a mere variety of the preceding, is described as follows
by Professor Böttger in his “Polytechnisches Notizblatt” (see p. 61):--

“A little light box, a sort of hollow cube of wood, has a large opening
at its front side and a small one at the back of the opposite side. The
latter is closed with a very fine membrane (of pig’s smaller intestine)
which is strained stiff. A narrow springy strip of platinum foil, fixed
at its outer part to the wood, touches the membrane at its middle;
a second platinum strip is fastened by one of its ends to the wood
at another spot, and bears at its other end a fine horizontal spike,
which touches the other little platinum strip where it lies upon the
membrane.”


_Sixth Form._--THE WOODEN CONE.

[Illustration: Fig. 11.]

Another transmitter, also a mere variety of the Fourth Form, has been
described to me by Herr Peter, of Friedrichsdorf, who assisted Reis
in his earlier experiments. Fig. 11 is prepared from a rough sketch
furnished me by the kindness of Karl Reis. Herr Peter describes the
apparatus as having been turned out of a block of wood by Reis upon
his own lathe. The conical hole was identical with that of Fig. 9, but
the surrounding portions of the wood were cut away, leaving a conical
mouth-piece.


_Seventh Form._--“HOCHSTIFT” FORM.

[Illustration: Fig. 12.]

The engraving presented below (Fig. 12) has been engraved with the
utmost fidelity by Mr. J. D. Cooper, from a photograph lent to the
author by Ernest Horkheimer, Esq., of Manchester, a former pupil of
Reis. The original photograph was taken in 1862, having been sent by
Reis in June of that year to Mr. Horkheimer, who had left for England.
The photograph was taken by Reis himself with his own camera, the
exposure being managed by a slight movement of the foot, actuating a
pneumatic contrivance of Reis’s own invention, which was originally
designed to turn over the pages of a music book at the piano. Reis is
here represented as holding in his hand the telephone with which he
had a few days preceding (May 11, 1862) achieved such success at his
lecture before the Freies Deutsches Hochstift (Free German Institute)
in Frankfort (see p. 66). This instrument was constructed by Reis,
young Horkheimer assisting him in the construction. Mr. Horkheimer has
very obligingly indicated from memory the form of the instrument--but
dimly seen in the photograph--in a sketch from which Fig. 13 has been
prepared. Mr. Horkheimer adds that the cone was a wooden one; and that
the square patch behind at the back was, he thinks, a box to contain an
electro-magnet.

[Illustration: Fig. 13.]


_Eighth Form._--LEVER FORM.

[Illustration: Fig. 14.]

The Transmitter described with so much minuteness by Inspector von
Legat in his Report on Reis’s Telephone in 1862 (see p. 70), differs
from the earliest and latest forms, so much so that some have doubted
whether this form was really invented by Reis. It is not described
anywhere else than in Legat’s Report (in the “Zeitschrift” of the
Austro-German Telegraph Union, reprinted also in Dingler’s Journal),
except in Kuhn’s Handbook, where, however, the description is taken
from Legat. Nevertheless a comparison of this instrument (Fig. 14) with
the original model of the ear, from which Reis started, will show that
it embodies no new point. There is, first, a conical tube to receive
the sound, closed at its end with a tympanum of membrane. There is next
a curved lever, _c d_, the lower end of which rests against the centre
of the membrane. Thirdly, there is a vertical spring, _g_, which makes
contact lightly against the upper end of the curved lever. Lastly,
there is an adjusting screw. It may be further pointed out that in
each case the current enters (or leaves, as the case may be) the lever
at its middle point. This form of transmitter is so closely allied
indeed to the primitive “ear” as to be alike in every feature save
the external form of the sound-gathering funnel. The only reasonable
doubt is not whether it be, as Legat asserts, Reis’s transmitter, but
whether it ought not in chronological order to rank second. Legat’s
paper was not published, however, till 1862, whilst the fourth form was
described by Reis in 1861. No trace of any instrument corresponding in
form to Fig. 14, save modern reproductions from Legat’s drawing, has
been found. The instrument held by Reis in his hand in the photograph
(Fig. 12) is so strikingly like the form described by Legat, that it
furnishes an additional reason for accepting Legat’s statement that
this transmitter really is Reis’s invention.

[Illustration: Fig. 15.]

[Illustration: Fig. 16.]


_Ninth Form._--TRANSITIONAL FORM.

Our knowledge of this form is derived solely from information and
sketches supplied by Mr. E. Horkheimer, who assisted Reis in its
construction. Figs. 15 and 16 are engraved after Mr. Horkheimer’s
sketches. The conical mouthpiece was of wood: the contact pieces of
platinum. The point _c_ was attached to a springy slip of brass, _g_,
fixed across the wooden box; and the adjusting-screw, _h_, served to
regulate the degree of initial pressure at the point of contact which
controlled the current.


_Tenth Form._--THE SQUARE BOX.

[Illustration: Fig. 17.]

[Illustration: Fig. 18.]

The last form of Reis’s Transmitter is that which has become best
known, being the only one (except Fig. 9) which found its way into the
market. It is here named, for the sake of distinction, as the “Square
Box” pattern. It consisted of a square wooden box, having a hinged lid.
Fig. 17 is reproduced from Reis’s “Prospectus” (see page 85), whilst
Fig. 18 is taken from Prof. Schenk’s biographical pamphlet.

In this instrument the idea of the human ear is still carried out. The
tin funnel, with its flaring embouchure, still represents the auditory
tube and pinna. The tympanum, no longer at the very end of the tube, is
strained across a circular aperture in the lid. Upon it rests the strip
of platinum foil which serves as an electrode, and resting in loose
contact with this lies the little angular piece of metal which Reis
called the “Hämmerchen.” Above all lay a circular glass disk (a cover
to keep out the dust), which was removed when the instrument was used.
So sensitive did this form prove itself that it was found unnecessary
to speak right into the mouthpiece, and the speaker in practice talked
or sang with his mouth at some little distance vertically above the
instrument; a method which had the advantage of not so soon relaxing
the membrane by the moisture of the breath. The figures show also the
auxiliary apparatus attached at the side, consisting of a key for
interrupting the circuit (added at first to enable the experimenters to
single out the “galvanic tones” from the reproduced tones, and later
applied, as Reis explains in his “Prospectus,” on page 87), and an
electro-magnet to serve as a “call,” by which the listener at the other
end could signal back to the transmitter.

This form of instrument, which has been so frequently described in
the Text-books of Physics, was constructed for sale first by Albert
of Frankfort, later by Ladd of London, König of Paris, and Hauck of
Vienna. Further details concerning it will be found in this book, in
Reis’s “Prospectus,” and in other contemporary documents.

Although this form is the one most commonly referred to as “the Reis
Telephone,” it is evident from a consideration of the entire group of
forms that Reis’s invention was in no way limited to one individual
pattern of instrument. For in all these forms there was embodied one
all-embracing principle;--that of controlling the electric current by
the voice working upon a point of imperfect contact, by the agency of
a tympanum, thereby opening or closing the circuit to a greater or less
degree, and so regulating the flow of the current.


_B.--Reis’s Receivers._


_First Form._--THE VIOLIN RECEIVER.

[Illustration: Fig. 19.]

The first form of apparatus used by Reis for receiving the currents
from the transmitter, and for reproducing audibly that which had been
spoken or sung, consisted of a steel knitting-needle, round which was
wound a spiral coil of silk-covered copper-wire. This wire, as Reis
explains in his lecture “On Telephony,” was magnetised in varying
degrees by the successive currents, and when thus rapidly magnetised
and demagnetised, emitted tones depending upon the frequency, strength,
etc., of the currents which flowed round it. It was soon found that
the sounds it emitted required to be strengthened by the addition
of a sounding-box, or resonant-case. This was in the first instance
attained by placing the needle upon the sounding-board of a violin.
At the first trial it was stuck loosely into one of the _f_-shaped
holes of the violin (see Fig. 19): subsequently the needle was fixed
by its lower end to the bridge of the violin. These details were
furnished by Herr Peter, of Friedrichsdorf, music-teacher in Garnier’s
Institute, to whom the violin belonged, and who gave Reis, expressly
for this purpose, a violin of less value than that used by himself in
his profession. Reis, who was not himself a musician, and indeed had
so little of a musical ear as hardly to know one piece of music from
another, kept this violin for the purpose of a sounding-box. It has now
passed into the possession of Garnier’s Institute. It was in this form
that the instrument was shown by Reis in October 1861 to the Physical
Society of Frankfort.


_Second Form._--THE CIGAR-BOX RECEIVER.

[Illustration: Fig. 20.]

Later a shallow rectangular wooden box was substituted for the violin,
and the spiral was laid horizontally upon it (Fig. 20). The date when
this modification was made was either at the end of 1861 or the early
spring of 1862. A cigar-box was the actual sounding-box, and the needle
was supported within the coil, but not touching it, with its ends
resting upon two wooden bridges.


_Third Form._--THE ELECTRO-MAGNET RECEIVER.

Though the precise history of this form of telephonic receiver is
defective, there can be little doubt that it was conceived by Reis
amongst his earliest researches. When there were in common use so
many electric and telegraphic instruments in which an electro-magnet
is employed to move an armature to and fro, it is not surprising that
Reis should have thought of availing himself of this method for
reproducing the vibrations of speech. Speaking of the two parts of his
invention, the Transmitter and the Receiver, Reis himself says:[5]
“The apparatus named the ‘Telephone,’ constructed by me, affords the
possibility of evoking sound-vibrations in every manner that may be
desired. _Electro-magnetism_ affords the possibility of calling into
life at any given distance vibrations similar to the vibrations that
have been produced, and in this way to give out again in one place
the tones that have been produced in another place.” A remark, almost
identical with this, is also made by Inspector von Legat (see p. 74)
in his Report on Reis’s Telephone. It may be here remarked that the
form of this receiver is known only from the figure and description
given in that Report, and from the extract therefrom printed in Kuhn’s
‘Handbook’ (see p. 109). Reis seems to have very soon abandoned this
form, and to have returned to the needle, surrounded by a coil, in
preference to the electro-magnet. The electro-magnet form is, however,
of great importance, because its principle is a complete and perfect
anticipation of that of the later receivers of Yeates, of Gray, and of
Bell, who each, like Reis, employed as receiver an electro-magnet the
function of which was to draw an elastically mounted armature backwards
and forwards, and so to throw it into vibrations corresponding to
those imparted to the transmitting apparatus. Fig. 21 shows the
disposition of the electro-magnet, and of its vibratory armature upon
a sounding-board. This apparatus was a good deal larger than most of
Reis’s instruments. The sounding-board was nearly a foot long: the
coils of the electro-magnet were six inches long, and over an inch
thick. The armature, a rod of iron of elliptical section, was affixed
cross-wise at the end of a “light and broad” vertical lever, about
seven inches long, which seems to have been made of wood, as in Legat’s
Report it is also denominated as a “plank” (Balken).

[Illustration: Fig. 21.]


_Fourth Form._--THE KNITTING-NEEDLE RECEIVER.

[Illustration: Fig. 22.]

[Illustration: Fig. 23.]

The final form adopted by Reis for his Reproducing-apparatus is that
commonly known as the Knitting-needle Receiver. It differs only from
the first form in that the needle and its surrounding spiral no longer
stand upright on a violin, but lie horizontally upon a rectangular
sounding-box of thin pine wood. The coil of silk-covered copper wire
is wound upon a light wooden bobbin, instead of being twisted round
the needle itself. Two wooden bridges stand upon the sounding-box, and
through these pass the protruding ends of the needle, whilst an upper
box or lid, hinged to the lower at the back, is added above. Figs.
22 and 23 show this form, the former being reproduced from Reis’s
own Prospectus (see p. 85), the latter being from Müller-Pouillet’s
‘Text-book of Physics’ (see p. 95). Herr Albert, mechanician, of
Frankfort, who made and sold the Reis telephones, says that the upper
box was added at his suggestion. Originally it was so constructed (see
Fig. 22), that when closed it pressed upon the steel needle. In the
instruments of later date, the notches which fitted over the needle
were cut so deeply (see Fig. 23), that the lid did not press upon
the wire. Reis’s own instructions are (see p. 86) that the sound is
intensified by firmly pressing the lid against the needle, as was done
occasionally by the listeners who pressed their ears against the lid in
order to hear more distinctly. The little key seen at the end of the
sounding-box, in Fig. 22, was used for interrupting the current and so
to telegraph back signals to the transmitter.

FOOTNOTES:

[3] Dr. Messel, F.C.S., a former pupil of Reis, and an eye-witness of
his early experiments, makes, in a letter to Professor W. F. Barrett,
the following very interesting statement: “The original telephone was
of a most primitive nature. The transmitting instrument was a bung of
a beer-barrel hollowed out, and a cone formed in this way was closed
with the skin of a German sausage, which did service as a membrane. To
this was fixed with a drop of sealing-wax a little strip of platinum
corresponding to the hammer of the ear, and which closed or opened the
electric circuit, precisely as in the instruments of a later date. The
receiving instrument was a knitting needle surrounded with a coil of
wire and placed on a violin to serve as a sounding board. It astonished
every one quite as much as the more perfect instruments of Bell now
do. The instrument I have described has now passed into the hands of
the Telegraph Department of the German Government.” [The instrument
now in the museum of the Reichs Post-Amt in Berlin is not this, but is
the first of the “Improved” Telephones described later by Reis in his
“Prospectus” (see p. 85), and is stamped “Philipp Reis,” “1863,” “No.
1.”] S.P.T.

[4] Or sometimes “tension-regulators,” though the latter term is
acknowledged by most competent electricians to be indescriptive and
open to objection.

[5] See _Die Geschichte und Entwickelung des Elektrischen
Fernsprechwesens_ (issued officially from the Imperial German
Post-office, 1880), p. 7.



CHAPTER III.

THE CLAIM OF THE INVENTOR.


In the present century, when so many facilities exist for the
diffusion of knowledge, and when every new discovery and invention is
eagerly welcomed and immediately noised abroad to every country of
the globe, it is hard to believe that the inventor of an instrument
of the highest scientific value, destined to play an important part
in social and commercial life, should have been suffered to live and
die in unrecognised obscurity. Still harder is it to believe that his
invention passed into almost complete oblivion, unacknowledged by most
of the leading scientific men of his day and generation. But hardest
of all is it to believe that when at last attempts were made to give
to him, whose name and fame had thus been permitted to languish, the
credit of the splendid researches in which he wore his life away, those
attempts could be met on the one hand by an almost complete apathy, and
on the other by a chorus of denial, not only that any such invention
was made, but that the inventor had ever intended to invent anything
of the kind. Yet nothing less than this has happened. Philipp Reis,
the inventor of the Telephone, the first to scheme, and carry out
into execution, an instrument for conveying to a distance by means
of electric currents the tones of human speech and human song, is no
longer amongst the living. He cannot reclaim for himself the honours
that have been showered upon the heads of others, who, however worthy
of those honours they were--none will deny that--were only not the
first to deserve them. In his quiet grave, in the obscurity of the
German village where his daily work was done, he sleeps undisturbed
by the strife of tongues. To him it matters nothing now, whether his
genius be recognised and his invention applauded, or whether ignorance,
and calumny, and envy, alike decry both. Nevertheless, the memory of
him and of his work will live, and will descend to posterity as of
one whom his own generation knew not, whose peculiar greatness passed
unheeded save by a chosen few. Nor will posterity be the less ready
to accord _honour_ to him who in his own day could not even obtain
justice. Yet something more than a mere historic justice for the poor
schoolmaster of Friedrichsdorf does the world owe; justice to the great
invention that is now imperishably associated with his name: justice to
the struggling family whom, instead of enriching, it impoverished; and,
not least, the justice of patience, whilst the story of his life and
work, and the words he himself has written thereupon, are unfolded.

The point at issue, and for which justice has been invoked, and of
which ample proof is given in these pages, is not whether Philipp Reis
invented _a_ telephone--that is not denied--but whether Philipp Reis
invented _the_ Telephone. The irony of fate, not to say the curious
ignorance which is often called by a less polite name, has decreed by
the mouth of popular scientific writers, of eminent engineers, and of
accomplished barristers, that Reis’s invention was not an instrument
for transmitting human speech at all--was not intended even for
this--that it was a purely musical instrument in its inception, and
that it has always so remained. These clever persons begin to persuade
themselves of this view, and forthwith invent a question-begging
epithet, and dub the instrument as a mere “_tone-telephone_”! If some
unprejudiced person ventures to speak of Reis’s instrument as having,
as a matter of history, transmitted speech, all the contemptuous reply
that he gets from the eminent somebody, who poses as an authority for
the moment, is: _Oh, but, you know, it was only a tone-telephone,
a musical toy, and when some one was singing to it you fancied you
caught the words of the song which, during singing, were occasionally
projected along with the music. I’ve always regarded the accounts of
its transmission of speech as a good joke; all it could possibly do was
occasionally to utter an articulate noise in combination with a musical
tone. Besides, you know, Mr. Reis was a musical man, who only intended
it to sing, and if it spoke it only spoke by accident; but such an
accident never did or could occur, because the construction of it shows
that it not only did not but could not transmit speech. If Mr. Reis
had really penetrated the fundamental principle of the articulating
telephone, he would have arranged his instruments very differently; and
then, you know, if he really had transmitted speech the discovery would
have attracted so much attention at the time. Moreover, if he had meant
it to talk, he would have called it the articulating telephone, and not
a telephone for transmitting tones, you know; no one before Graham Bell
ever dreamed of using a tympanum to catch articulate sounds, or had he
done so he would have been laughed at._

To all such clap-trap as this--and there has been enough _ad nauseam_
of such--the one reply is silence, and a mute appeal to the original
writings of Reis and his contemporaries, and to the tangible witness of
inexorable scientific facts. All the most important of these will be
found in their appropriate places. They amply establish the following
points:--

I.--Reis’s Telephone _was expressly intended to transmit speech_.

II.--Reis’s Telephone, _in the hands of Reis and his contemporaries,
did transmit speech_.

III.--Reis’s Telephone _will transmit speech_.

Before proceeding to discuss these three points we will pause for a
moment, first to clear away a lurking verbal fallacy, then to point out
the partial historic acknowledgment already conceded to Reis’s claims.

Reis did not call his instrument an “_articulating telephone_.”
Neither did he call it a “_tone telephone_.” He called it simply
“_The Telephone_” (Das Telephon),[6] as will be seen in his own first
memoir (p. 57). He did speak of his instrument again and again as an
instrument “_for reproducing tones_.” But it must be remembered that
the German word _Ton_ (plural _Töne_) used by Reis is more nearly
equivalent to our English word “sound,” and includes articulate as well
as musical tones, unless the context expressly indicates otherwise. So
that when Reis talked of the _Reproduction of Tones_ he was using words
which did not limit his meaning to musical tones, as indeed his memoirs
show in other ways. He started from a consideration of the mechanical
structure of the human ear, and endeavoured to construct an instrument
on those lines because the ear can take up _all_ kinds of tones. Reis
was not so foolish as to imagine that the construction of the human
ear was solely designed for musical, to the exclusion of articulate
tones. We are not aware that the epithet, Tone-Telephone, was ever
applied to Reis’s instruments until it became advisable(!) to seek a
means of disparaging an old invention in order to exalt a new one. And
it is a curious point that the true musical “tone-telephones,” _i.e._
instruments designed expressly to transmit specific musical tones for
the purpose of multiple telegraphy, were invented (by Varley, Gray, La
Cour, Graham Bell, and Edison) long after Reis’s Telephone, between
the years 1870 and 1876. All these were dependent practically upon the
tuning-fork system of vibration, whereas Reis’s system was based on the
tympanum of the ear. To classify Reis’s invention with these would be
absurd.

Having shown the fallacy bound up in the term “tone-telephone,” we will
dismiss the point with the remark that henceforth it will be a waste of
time to argue with any person who applies that question-begging epithet
to Reis’s invention.

Partial historic acknowledgments of Reis’s claims as inventor of The
Telephone have been made from time to time by those best qualified to
speak.

Mr. Edison, the inventor of the famous lamp-black button transmitter,
which he christened later as “The Carbon Telephone,” has himself
stated in his account of his inventions,[7] that he was started upon
this line of investigation by having put into his hand, by the late
Hon. Mr. W. Orton, a manuscript translation of Legat’s Report on
Reis’s Telephone, given in the Journal of the Austro-German Telegraph
Union (see Translation, p. 70). So that he was, therefore, aware at
least of this: that in Reis’s instruments “single words uttered, as
in reading, speaking, and the like, were perceptible indistinctly,
nevertheless, here also the inflexions of the voice, the modulations of
interrogation, exclamation, wonder, command, etc., attained distinct
expression.” So far as Mr. Edison is concerned, therefore, Reis is his
starting-point by his own direct avowal.

Professor Graham Bell has not failed to acknowledge his indebtedness to
Reis, whose entry “into the field of telephonic research” he explicitly
draws attention to by name, in his “Researches in Electric Telephony,”
read before the American Academy of Sciences and Arts, in May 1876, and
repeated almost verbatim before the Society of Telegraph Engineers,
in November 1877. In the latter, as printed at the time, Professor
Bell gave references to the researches of Reis, to the original paper
in Dingler’s ‘Polytechnic Journal’ (see Translation, p. 61); to the
particular pages of Kuhn’s volume in Karsten’s ‘Encyclopædia’ (see
p. 106), in which diagrams and descriptions of two forms of Reis’s
Telephone are given; and where mention is also made of the success
with which exclamatory and other articulate intonations of the voice
were transmitted by one of these instruments; and to Legat’s Report,
mentioned above (and given in full on p. 70). Professor Bell has,
moreover, in judicial examination before one of the United States
Courts expressly and candidly stated,[8] that whilst the receivers of
his own early tone-telephones were constructed so as to respond to one
musical note only, the receiver of Reis’s instrument, shown in Legat’s
Report (as copied in Prescott’s ‘Speaking Telephone,’ p. 10), and given
on p. 109 of this work, was adapted to receive tones of any pitch, and
not of one tone only. It is further important to note that in Professor
Bell’s British Patent he does not lay claim to be the inventor, but
only the improver of an invention: the exact title of his patent is,
“_Improvements_ in Electric Telephony (Transmitting or causing sounds
for Telegraphing Messages) and Telephonic Apparatus.”

So far as Professor Bell is concerned, therefore, he is guiltless of
stigmatising the Reis instrument as a mere “tone-telephone.”

Professor Dolbear, the inventor of the “Static Receiver” form of
Telephone, is still more explicit in avowing Reis’s claim. In the
report of his paper on “the Telephone,” read, March 1882, before the
Society of Telegraph Engineers and of Electricians[9] we find: “The
speaker could testify that the instrument would talk, and would talk
well. The identical instruments employed by Reis would do that, so
that Reis’s transmitters would transmit. Secondly, his receiver would
receive; and Reis did transmit and receive articulate speech with such
instruments.”

As far as Professor Dolbear is concerned, therefore, he admits in
unequivocal terms the whole claim of Reis to be the inventor of _The
Telephone_.

Count du Moncel, author of a work on the Telephone, which has run
through several editions, though he has classified Reis’s instrument
as a mere “tone-telephone,” has recently admitted[10] that he was,
until the year 1882, ignorant of some of Reis’s instruments and of his
original papers. He has, moreover, added these words: “Nevertheless, it
would not be just not to acknowledge that the Reis Telephone _formed
the starting-point of all the others_;” also these significant lines:
“It is probable that in this matter, as in the greater number of
modern inventions, the _original inventor_ obtained only insignificant
results, and that it was the man who first succeeded in arranging his
apparatus so as to obtain really striking results that received the
honour of the discovery and rendered it popular.”

So far as the Count du Moncel is concerned, therefore, the claims of
Philipp Reis to be the inventor of the telephone are admitted, though
hesitatingly, to be historically just.

We now return to the proof of the three points previously enunciated.


I.--Reis’s Telephone was expressly intended to transmit speech.

Reis’s first instrument was (see p. 16) nothing else than a model of
the mechanism of the human ear. Why did he choose this fundamental
type which runs through all his instruments from first to last? The
reason is given in his own first memoir (p. 51), “_How could a single
instrument reproduce at once the total actions of all the organs
operated in human speech? This was ever the cardinal question._” Reis
constructed his instrument therefore with intent to reproduce human
speech. For this reason he borrowed from the ear the suggestion of a
_tympanum_. Of the operation of the tympanum he had the most exact
and perfect conception. He says (p. 54), “_Every tone, and every
combination of tones_”--and this includes articulate tones, of course,
and is just as true of them as of any other kind--“_evokes in our ear,
if it enters it, vibrations of the drum-skin, the motions of which may
be represented by a curve_.” And further: “_As soon, therefore, as
it shall become possible, at any place and in any prescribed manner,
to set up vibrations whose curves are like those of any given tone,
or combination of tones, we shall then receive the same impression
as that tone or combination of tones would have produced upon us._”
Again, it is clear that his study of acoustics led him to employ
the tympanum, because of its special value in responding to all the
complex vibrations of human speech. It is no less significant that
when a decade later Varley, Gray, and Bell, set themselves to invent
tone-telephones for the purpose of multiple telegraphy, they abandoned
tympanums as being _unsuitable_ for tone-telephones, and in lieu
thereof employed vibrating tongues like those of tuning-forks. Reis’s
use of the tympanum had a very definite meaning then; it meant nothing
less than this: I intend my instrument to transmit any sound that a
human ear can hear. That it was explicitly within his intention to
transmit speech is confirmed by another passage of his first memoir
(p. 58), wherein he remarks with a shade of disappointment that though
“the consonants are for the most part tolerably distinctly reproduced,
the vowels are not yet to an equal degree.” To his own pupils and
co-workers he communicated his ideas. One of the former, Mr. E.
Horkheimer, now of Manchester, expressly says (see p. 117) that Reis’s
intention was to transmit speech, and that the transmission of music
was an afterthought adopted for the convenience of public exhibition,
just as was the case with the public exhibitions of Bell’s Telephone
fifteen years later.

Nor did this imperfection cause Reis to hide his intentions from
the world. He modestly claimed such success as he had obtained, and
left the rest. In 1863 he drew up a Prospectus (given in extenso on
p. 85), which was printed to accompany the instruments which were
sold; and of which copies are still extant. In this document he says:
“Besides the human voice, according to my experience, there can also
be reproduced the tones of good organ pipes, from F to c''', and those
of a piano.” In this same Prospectus (p. 87) occur the instructions
for the use of the signal call by which the listener communicates his
wishes to the speaker. Those instructions run: “One beat = _sing_; two
beats = _speak_.” Can any sane person doubt that Reis intended his
instrument to transmit speech, when such directions stand printed in
his own Prospectus? Legat’s Report (1862) speaks of Reis’s instrument
as intended (see p. 77) to speak, and further describes the use of an
elliptic cavity to which the listener can apply his ear. Kuhn (1866)
(see p. 106) says that the square-box transmitter (Figs. 17, 18)
did not send speech well, and complains that he could only get from
it an indistinguishable noise. Doubtless he spoke too loudly, Pisko
(1865) speaks of the Reis instrument as intended for speaking (p.
105). Further, in the letter which Reis wrote in 1863 to Mr. W. Ladd,
of London, he expressly emphasises by underscoring the word that his
Telephone can transmit “_any_ sound” that is sufficiently loud, and
he refers to the speaker and listener at the two ends of the line as
“the correspondents.” The only reply henceforth possible to any person
who shall assert that Reis’s Telephone was not expressly intended to
transmit articulate speech is the good honest retort: _impudentissime
mentiris_.


II.--Reis’s Telephone, in the hands of Reis and his contemporaries, did
transmit speech.

Of the performance of his instruments Reis speaks modestly and
carefully, nothing extenuating of his failures, nothing exaggerating
of his successes. I shall not attempt to be wiser than he; nor seek
to make out his instrument to have been either more perfect or more
reliable than he himself knew it to be. The membrane tympanum of
his transmitter was liable to become relaxed by the moisture of the
breath rendering the instrument--as Graham Bell found fifteen years
later with his membrane magneto-transmitters--uncertain in its action.
Moreover, in some earlier forms of Reis’s transmitter, notably those
with a vertical tympanum, the adjustment of the contact-points that
controlled the current was a matter of delicacy requiring experience
and practice, so that casual experimenters failed to obtain the results
which Reis himself obtained;[11] they obtaining only a noisy snarl
where he obtained intelligible speech. Lastly, the very delicacy of the
essential parts, the conducting strips of metal which lay lightly in
contact against one another, militated against a uniformity of success
when tried with different voices, some of which were too low to produce
any effect, others so loud as to rattle the delicate contact-pieces in
a manner fatal to the attainment of the desired result.

In spite of all these drawbacks, which were not inherent in the
principle of the instrument, there is plenty of evidence that _Reis’s
Telephone did transmit speech_. Reis himself records this fact:

(1.) In 1861, in his memoir ‘On Telephony’ (see p. 58), “_The
consonants are for the most part tolerably distinctly reproduced, but
the vowels not yet in an equal degree._”

(2.) In his ‘Prospectus’ (p. 86) Reis says that the tones of
organ-pipes and of the piano can be reproduced as well as the tones of
the human voice, “_according to my experience_.”

(3.) The fact is attested by Inspector Wilhelm von Legat, in his
Report in the ‘Zeitschrift’ (p. 77), 1862. After alluding to the
indistinctness of the vowels, he says: “_Single words, uttered as
in reading, speaking, and the like, were perceptible indistinctly,
nevertheless, here also the inflexions of the voice, the modulations of
interrogation, exclamation, wonder, command, etc., attained distinct
expression._”

(4.) Professor Quincke, of Heidelberg, testifies (see p. 113) that he
heard and understood words spoken through a Reis Telephone in 1864.

(5.) Professor Böttger, editor of the ‘Polytechnisches Notizblatt,’ in
1863 says (see p. 90): “The experimenters could even communicate words
to one another, though certainly indeed, only such as had often been
heard by them.”

(6.) Dr. Rudolph Messel, an old pupil of Reis, and an eye-witness of
his early experiments, has written[12]: “There is not a shadow of a
doubt about Reis having actually achieved imperfect articulation. _I
personally recollect this very distinctly_, and could find you plenty
more people who witnessed the same.”

(7.) Herr Peter, a former colleague of Philipp Reis, whose testimony
will be found on page 126, narrates how he doubted the powers of the
instrument until he had verified them for himself by speaking into it
words which could not possibly be premeditated.

(8.) Mr. E. Horkheimer, who aided Reis in his earlier work, though he
left Germany when the development of the instrument was yet very far
from complete, has even given (see p. 117) a list of the words and
expressions which he has heard transmitted by the earlier forms of the
instrument.

(9.) Herr Philipp Schmidt, brother-in-law of Philipp Reis, and
now acting-paymaster in the Imperial German Navy at Wilhelmshavn,
says: “he succeeded finally in reproducing at a distance, words and
whole sentences.” “There never was any understanding between my
brother-in-law and myself as to particular words and sentences: on the
contrary, these were quite spontaneous.”

(10.) Mr. S. M. Yeates, of Dublin, who in 1865 constructed a modified
Reis Telephone (see p. 128), has thus described the performance of the
instrument: “Before disposing of the apparatus, I showed it at the
November meeting (1865) of the Dublin Philosophical Society, when both
singing _and the distinct articulation of several words were heard
through it, and the difference between the speakers’ voices clearly
recognised_.”[13]

It is difficult to conceive how testimony on this point could be
stronger. From so many different sources it is alike agreed that--with
the instrument presumably in good adjustment--_Reis’s Telephone_, in
the hands of Reis and his contemporaries, _did transmit articulate
speech_.


III.--Reis’s Telephone will transmit speech.

Reis’s Telephone consists of two parts: a “transmitter,” into which
the speaker speaks; and a “receiver,” at which the hearer listens.
Their various forms have been described in detail in the preceding
chapter. All that we are concerned with at this place is, whether these
instruments will at the present day do what is asserted. The writer
has tested every form of Reis’s transmitter, save only some of the
tentative historic forms shown in Figs. 2-8, 13, 15, & 16, _ante_,
and has found them perfectly competent to transmit speech, provided
proper precautions were taken: namely, that the contacts were clean
and in adjustment, that the tympanum was tightly stretched, and that
the speaker did not speak too loudly:[14] in other words, that the
instruments were properly used. Any one who wants _not to succeed_ in
transmitting speech with Reis’s transmitter has only to neglect these
reasonable precautions. It is not, therefore, difficult to fail. The
writer has also tested both the better-known forms of Reis’s receiver
(Figs. 21, 22, & 23), and finds that both are perfectly competent to
receive speech electrically and reproduce it audibly, both vowels
and consonants being perfectly distinct and articulate, though never
as loud as in more modern forms of telephone-receiver. From a steel
wire, magnetised, as prescribed by Reis, by surrounding it with a coil
of wire through which the current passes, the writer has obtained
articulation exceeding in perfection of definition, both of vowels and
of consonants, the articulation of any other telephone-receiver he
has ever listened to. Perhaps it may be objected that it is difficult
to listen to a steel wire. Reis met this difficulty in his own way
by mounting his steel wire upon a small sounding-box to strengthen
the sounds, and added a flat upper case against which the ear of the
listener can be pressed, and which can be removed, or opened as a
lid, when a whole audience is to hear simultaneously the tones of
the instrument when working in a loud and disagreeable manner, as a
transmitter of the coarser vibrations of a loudly sung melody. The
lid is not wanted for this latter purpose--is an encumbrance; which,
nevertheless, by its presence proves the more delicate functions of
the instrument. Reis’s instructions in his ‘Prospectus,’ p. 86, are
that pressing this lid down firmly upon the steel core increases the
loudness of the sounds. Any one who wants _not to succeed_ in receiving
speech with Reis’s receiver has, as before, only to neglect reasonable
precautions. He has only to use an imperfect or bad transmitter, or use
it carelessly, or put the receiver to a sufficient distance from his
ear, to attain this result. There are people who have failed to make
Reis’s receiver receive.

This is not the place to discuss a doctrinaire objection sometimes
raised, that it is theoretically impossible for Reis’s instruments to
work. For the moment we are concerned with the practical question: Do
they work? No one practically experienced in telephones, even if he
should deny that Reis had any such intention, will dispute that they
can now be made to transmit speech. Professor Dolbear, himself no mean
authority on telephones, testifies, as quoted above (p. 41), “that _the
instruments would talk, and would talk well_.” He would, indeed, be a
bold man who would come forward to deny what can be shown any day as an
experimental fact: that _Reis’s Telephone will transmit speech_.

We have now shown that Philipp Reis was the undisputed inventor of an
instrument which he called the Telephone, which instrument can now be
used to transmit speech; which was then used to transmit speech; and
which was invented on purpose to transmit speech. So far the result of
the examination into the facts of the case is conclusive enough. A more
complete case could hardly be desired. No honest person could hesitate
for want of proof, either greater in amount or more direct to the point.

Nevertheless, I propose in another section to go a little further and
to prove a technical point of highest interest; namely, that there is
not in the Telephone Exchanges of England to-day, any single telephone
to be found in which the fundamental principles of Reis’s Telephone
are not the essential and indispensable features. These considerations
being, however, of a strictly technical nature, will be best considered
in an Appendix. As, however, we are able to show that those instruments
which are now in daily use for transmitting speech, embody the two
fundamental principles upon which Reis based the instrument which he
called “_Das Telephon_,” it would be dishonest to the memory of the
deceased inventor to claim anything less than that he was the “first
and true inventor” of the Telephone.

FOOTNOTES:

[6] The name “Telephone” had already been applied by Sir C. Wheatstone
(1831) to an acoustic arrangement for transmitting sounds through
wooden rods to a distant place in a purely mechanical manner. It
is needless to observe that speech as well as music can be thus
transmitted; and though Wheatstone gave telephonic concerts, this
does not prove (nor do telephonic concerts given through Reis’s
instrument prove) that speech could not be transmitted also. The name
“Fernsprecher,” _now_ used in Germany for the Telephone, was only
suggested in 1877 by Dr. Stephan, Postmaster of the German Empire, in
obedience to the absurd fashion which has raged since 1871 in Germany
of rejecting words of classic derivation.

[7] See proceedings in U. S. Court (Dowd suit), Edison’s second answer,
and Prescott’s ‘The Speaking Telephone,’ p. 218.

[8] Published volume of Proceedings in the United States Patent Office,
before the Commissioner of Patents. Evidence for A. G. Bell, p. 6.

[9] Proc. Soc. Telegr. Engin. and Electr. vol. xi. p. 134, 1882.

[10] ‘Electrical Review,’ July 22, 1882, p. 49.

[11] Mr. E. Albert, of the firm of J. W. Albert and Sohn, of Frankfurt,
to whom Reis entrusted the manufacture of Telephones for public sale,
thus writes: “The most important part was the membrane, because the
delicacy of the apparatus depended principally upon that part. As it
was not possible to make every membrane equally good, so it came about
that instruments of different degrees of superiority came into use, and
various decisions were arrived at as to the ability of the instrument
to perform the functions for which it was designed. Those who happened
to have a poor instrument were able to hear but little; while those
who possessed a good instrument were astonished at its performances.
A good instrument reproduced the words sung into it in such a manner
that not only the pitch but also the words of the song were perfectly
understood, even when the listener was unacquainted with the song and
the words.”

M. St. Edmé, of Paris, who contributed to ‘Cosmos,’ vol. xxiv. p. 349,
1864, an article on Reis’s Telephone, of which he had seen an example
in König’s _atelier_, said that when the scale was sung it needed a
trained ear to distinguish the notes amidst the noises of the receiver.
He must have got hold of an uncommonly bad transmitter with a flabby
tympanum to have failed so completely.

[12] Letter of Dr. Messel to Professor W. F. Barrett quoted, in
Professor Barrett’s memoir, ‘On the Electric Telephone,’ read Nov. 19,
1877, to the Dublin Royal Society. Vide Proc. Roy. Soc. Dubl. 1877.

[13] See Barrett’s ‘Telephones Old and New’ (1878), p. 12.

[14] See Reis’s own remark at bottom of p. 57.



CHAPTER IV.

CONTEMPORARY DOCUMENTS.


The following documents, drawn from the scientific literature of the
time, are placed in chronological order, beginning with the first
memoir published by Philipp Reis himself, in the _Jahresbericht_ of the
Physical Society of Frankfort, for the year 1860-61. Every care has
been taken that the translations here given shall be faithful in every
detail to the originals. All notes and comments by the translator are
distinguished by being enclosed in square brackets.


[=1.=] ON TELEPHONY BY THE GALVANIC CURRENT.

_By_ PHILIPP REIS.

    [Translated from the Annual Report (Jahresbericht) of the
    Physical Society of Frankfurt-am-Main, for 1860-1861.]

The surprising results in the domain of Telegraphy, have often
already suggested the question whether it may not also be possible to
communicate the very tones of speech direct to a distance. Researches
aiming in this direction have not, however, up to the present time,
been able to show any tolerably satisfactory result, because the
vibrations of the media through which sound is conducted, soon fall off
so greatly in their intensity that they are no longer perceptible to
our senses.

A _reproduction_ of the tones at some distance by means of the
galvanic current, has perhaps been contemplated; but at all events the
practical solution of this problem has been most doubted by exactly
the very persons who by their knowledge and resources should have
been enabled to grasp the problem. To one who is only superficially
acquainted with the doctrines of Physics, the problem, if indeed he
becomes acquainted with it, appears to offer far fewer points of
difficulty because he does not foresee most of them. Thus did I, some
nine years ago (with a great _penchant_ for what was new, but with only
too imperfect knowledge in Physics), have the boldness to wish to solve
the problem mentioned; but I was soon obliged to relinquish it, because
the very first inquiry convinced me firmly of the impossibility of the
solution.

Later, after further studies and much experience, I perceived that my
first investigation had been very crude and by no means conclusive: but
I did not resume the question seriously then, because I did not feel
myself sufficiently developed to overcome the obstacles of the path to
be trodden.

Youthful impressions are, however, strong and not easily effaced. I
could not, in spite of every protest of my reason, banish from my
thoughts that first inquiry and its occasion; and so it happened that,
half without intending it, in many a leisure hour the youthful project
was taken up again, the difficulties and the means of vanquishing them
were weighed,--and yet not the first step towards an experiment taken.

How could a single instrument reproduce, at once, the total actions of
all the organs operated in human speech? This was ever the cardinal
question. At last I came by accident to put the question in another
way: How does _our ear_ take cognizance of the total vibrations of
all the simultaneously operant organs of speech? Or, to put it more
generally: How do we perceive the vibrations of several bodies emitting
sounds simultaneously?

In order to answer this question, we will next see what must happen in
order that we may perceive a single tone.

Apart from our ear, every tone is nothing more than the condensation
and rarefaction of a body repeated several times in a second (at least
seven to eight times[15]). If this occurs in the same medium (the air)
as that with which we are surrounded, then the membrane of our ear will
be compressed toward the drum-cavity by every condensation, so that in
the succeeding rarefaction it moves back in the opposite direction.
These vibrations occasion a lifting-up and a falling-down of the
“hammer” [_malleus_ bone] upon the “anvil” [_incus_ bone] with the same
velocity, or, according to others, occasion an approach and a recession
of the atoms of the auditory ossicles, and give rise, therefore, to
exactly the same number of concussions in the fluid of the _cochlæa_,
in which the auditory nerve and its terminals are spread out. The
greater the condensation of the sound-conducting medium at any given
moment, the greater will be the amplitude of vibration of the membrane
and of the “hammer,” and the more powerful, therefore, the blow on
the “anvil” and the concussion of the nerves through the intermediary
action of the fluid.

The function of the organs of hearing, therefore, is to impart
faithfully to the auditory nerve, every condensation and rarefaction
occurring in the surrounding medium. The function of the auditory nerve
is to bring to our consciousness the vibrations of matter resulting at
the given time, both according to their number and their magnitude.
Here, first, certain combinations acquire a distinct name: here, first
the vibrations become musical _tones_ or _discords_ (Misstöne).

That which is perceived by the auditory nerve, is, therefore, merely
the action of a _force_ affecting our consciousness, and as such may be
represented graphically, according to its duration and magnitude, by a
curve.

[Illustration: Fig. 24.]

Let the line _a, b_, indicate any given length of time, and the
curve above the line a condensation (+), the curve below the line a
rarefaction (-), then every ordinate erected at the end of an abscissa
will give [according to the height of it], at a moment indicated by the
position of the foot of the ordinate, the strength of the condensation
that is causing the drum-skin to vibrate.

Our ear can perceive absolutely nothing more than is capable of
being represented by similar curves, and this method is completely
sufficient to bring before our clear consciousness every tone and every
combination of tones.

If several tones are produced at the same time, then the medium that
conducts sound is placed under the influence of several simultaneous
forces; and the two following laws hold good:--

If all the forces operate in the same sense, the resultant motion is
proportional in magnitude to the sum of the forces.

If the forces operate in opposite senses, the resultant motion is
proportional in magnitude to the difference of the opposing forces.

Let us exhibit the condensation-curves for three tones--each singly
(Table I.)[16]: then, by adding together the ordinates corresponding
to equal abscissæ, we can determine new ordinates and develop a new
curve which we may call the combination-curve [or resultant curve].
Now this gives us just exactly what our ear perceives from the three
simultaneous tones. It ought to cause us as little wonder that a
musician can recognize the three tones, as that (as is the fact) a
person conversant with the science of colour, can recognize in green,
blue and yellow tints. The combination-curves of table I. present,
however, very little difficulty, since in them all the proportions of
the component curves recur successively. In chords consisting of more
than three tones (Table II.), the proportions of the components are no
longer so easy to recognize in the drawing. But it is also difficult to
an accomplished musician, in such chords to recognize the individual
notes.

Table III. shows us a discord. Why discords affect us so unpleasantly I
leave provisionally to the contemplation of the gentle reader, as I may
perhaps return to this point in another memoir.

It follows from the preceding that:--

(1.) Every tone and every combination of tones evokes in our ear, if
it enters it, vibrations of the drum-skin, the motions of which may be
represented by a curve.[17]

(2.) The motions of these vibrations evoke in us the perception
(sensation) of the tone: and every change in the motion must change the
sensation.

As soon, therefore, as it shall be possible at any place and in any
prescribed manner, to set up vibrations whose curves are like those
of any given tone or combination of tones, we shall receive the same
impression as that tone or combination of tones would have produced
upon us.[18]

Taking my stand on the preceding principles, I have succeeded in
constructing an apparatus by means of which I am in a position to
reproduce the tones of divers instruments, yes, and even to a certain
degree the human voice. It is very simple, and can be clearly explained
in the sequel, by aid of the figure:

[Illustration: Fig. 25.]

In a cube of wood, _r s t u v w x_, there is a conical hole, _a_,
closed at one side by the membrane _b_ (made of the lesser intestine
of the pig), upon the middle of which a little strip of platinum is
cemented as a conductor of the current [or electrode]. This is united
with the binding-screw, _p_. From the binding-screw _n_ there passes
likewise a thin strip of metal over the middle of the membrane, and
terminates here in a little platinum wire which stands at right angles
to the length and breadth of the strip.

From the binding-screw, _p_, a conducting-wire leads through the
battery to a distant station, ends there in a spiral of copper-wire,
overspun with silk, which in turn passes into a return-wire that leads
to the binding-screw, _n_.

The spiral at the distant station is about six inches long, consists
of six layers of thin wire, and receives into its middle as a core
a knitting-needle, which projects about two inches at each side. By
the projecting ends of the wire the spiral rests upon two bridges of
a sounding-box. (This whole piece may naturally be replaced by any
apparatus by means of which one produces the well-known “galvanic
tones.”)

If now tones, or combinations of tones, are produced in the
neighbourhood of the cube, so that waves of sufficient strength
enter the opening _a_, they will set the membrane _b_ in vibration.
At the first condensation the hammer-shaped little wire _d_ will
be pushed back. At the succeeding rarefaction it cannot follow the
return-vibration of the membrane, and the current going through the
little strip [of platinum] remains interrupted so long as until the
membrane, driven by a new condensation, presses the little strip
(coming from _p_) against _d_ once more. In this way each sound-wave
effects an opening and a closing of the current.

But at every closing of the circuit the atoms of the iron needle
lying in the distant spiral are pushed asunder from one another.
(Müller-Pouillet, ‘Lehrbuch der Physik,’ see p. 304 of vol. ii. 5th
ed.). At the interruption of the current the atoms again attempt
to regain their position of equilibrium. If this happens then in
consequence of the action and reaction of elasticity and traction,
they make a certain number of vibrations, and yield the longitudinal
tone[19] of the needle. It happens thus when the interruptions and
restorations of the current are effected relatively slowly. But if
these actions follow one another more rapidly than the oscillations due
to the elasticity of the iron core, then the atoms cannot travel their
entire paths. The paths travelled over become shorter the more rapidly
the interruptions occur, and in proportion to their frequency. The iron
needle emits no longer its longitudinal tone, but a tone whose pitch
corresponds to the number of interruptions (in a given time). But this
is saying nothing less than that _the needle reproduces the tone which
was imparted to the interrupting apparatus_.

Moreover, the strength of this tone is proportional to the original
tone, for the stronger this is, the greater will be the movement of the
drum-skin, the greater therefore the movement of the little hammer, the
greater finally the length of time during which the circuit remains
open, and consequently the greater, up to a certain limit, the movement
of the atoms in the reproducing wire [the knitting needle], which we
perceive as a stronger vibration, just as we should have perceived the
original wave.

Since the length of the conducting wire may be extended for this
purpose, just as far as in direct telegraphy, I give to my instrument
the name “_Telephon_.”

As to the performance attained by the Telephone, let it be remarked,
that, with its aid, I was in a position to make audible to the members
of a numerous assembly (the Physical Society of Frankfort-on-the-Main)
melodies which were sung (not very loudly) into the apparatus in
another house (about three hundred feet distant) with closed doors.

Other researches show that the sounding-rod [i.e. the knitting needle]
is able to reproduce complete triad chords (“Dreiklänge”) of a piano on
which the telephone [i.e. the transmitter] stands; and that, finally,
it reproduces equally well the tones of other instruments--harmonica,
clarionet, horn, organ-pipes, &c., always provided that the tones
belong to a certain range between _F_ and _f''_[20].

It is, of course, understood that in all researches it was sufficiently
ascertained that the direct _conduction_ of the sound did not come
into play. This point may be controlled very simply by arranging at
times a good shunt-circuit directly across the spiral [i.e. to cut the
receiving instrument out of circuit by providing another path for the
currents of electricity], whereby naturally the operation of the latter
momentarily ceases.

Until now it has not been possible to reproduce the tones of human
speech with a distinctness to satisfy everybody. The consonants are for
the most part tolerably distinctly reproduced, but the vowels not yet
in an equal degree. Why this is so I will endeavour to explain.

According to the researches of Willis, Helmholtz, and others, vowel
sounds can be artificially produced by causing the vibrations of one
body to reinforce those of another periodically, somewhat after the
following scheme:--

[Illustration: Fig. 26.]

An elastic spring is set in vibration by the thrust of the tooth of a
cog-wheel: the first swing is the greatest, and each of the others is
less than the preceding one (see Fig. 26).

After several vibrations of this sort (without the spring coming to
rest) let another thrust be given by the tooth; the next swing will
again be a maximum one, and so on.

The height or depth of the sound produced in this fashion depends
upon the number of vibrations made in a given time; but the quality
of the note depends upon the number of variations of amplitude
(Anschwellungen) occurring in the same time.

Two vowels of equal pitch may be distinguished from each other somewhat
after the manner represented by the curves (1) (2): while the same tone
devoid of any vowel quality, is represented by curve (3).

[Illustration: Fig. 27.]

Our organs of speech create the vowels probably in the same manner by a
combined action of the upper and lower vocal chords, or of the latter
and of the cavity of the mouth.

Now my apparatus gives the number of the vibrations, but with far less
strength than the original ones; though also, as I have cause to think,
always proportional to one another up to a certain degree. But because
the vibrations are throughout smaller, the difference between large
and small vibrations is much more difficult to recognize than in the
original waves, and the vowel is therefore more or less indefinite.

Whether my views with respect to the curves representing combinations
of tones are correct, may perhaps be determined by aid of the new
phonautograph described by Duhamel. (See Vierordt’s ‘Physiology,’ p.
254.)

There may probably remain much more yet to be done for the utilisation
of the telephone in practice (zur praktischen Verwerthung des
Telephons). For physics, however, it has already sufficient interest in
that it has _opened out_ a new field of labour.

                                             Philipp Reis.

  Friedrichsdorf, near Frankfort-on-the-Main,
              in December 1861.

[Though the foregoing memoir, as printed in the ‘Jahresbericht,’ of the
Physical Society of Frankfort-on-the-Main, is dated “December 1861,” it
was delivered verbally on October 26th preceding, as the ‘Proceedings’
of the Society show. From the ‘Jahresbericht’ for the succeeding year
we learn that three weeks after the delivery of this communication
Reis made a second communication to the Society on a kindred matter.
The entry is as follows (‘Proceedings’ of the Society, p. 13): “On the
16th November, by the same: Explanation of a new Theory concerning the
Perception of Chords and of Timbre (‘Klangfarben’), as a Continuation
and Supplement of the Memoir on the Telephone.” So far as can now
be learned, the substance of this communication was embodied in the
latter part of the paper “On Telephony,” when written out in December
for publication. On the 8th of January, 1862, the formal thanks of the
Society were voted to Reis for the manuscript which he had contributed
to the ‘Jahresbericht.’

It is of interest, moreover, to note that the matter did not
immediately drop. Professor Böttger, who as one of the regular
lecturers of the Physical Society, held fortnightly discourses on
matters of scientific novelty, took occasion on the 7th of December
to recur to the subject then attracting so much attention. The title
of his discourse (see ‘Proceedings’ of the Society, p. 11) was
“Application of an Experiment relating to the Transmission of Musical
Tones to any desired distance by means of the Galvanic Current.”
It is not quite certain whether Reis was present on this occasion.
Early in the spring of 1863, appeared in Böttger’s ‘Polytechnisches
Notizblatt’ (No. 6 of that year) an article which contains in condensed
form Böttger’s discourse. This article was copied into Dingler’s
‘Polytechnisches Journal’ for May 1863. vol. clxviii. p. 185, and also
into the ‘Polytechnisches Centralblatt’ for July 1863, vol. xxix. p.
858. An extract of Reis’s own paper, condensed from the ‘Jahresbericht’
by Dr. Roeber (now President of the Physical Society of Berlin),
appeared in the ‘Berliner Berichte’ (_i. e._ the ‘Fortschritte der
Physik’) for 1861, vol. xvii. pp. 171-173. It is interesting to note
that Reis’s paper was then deemed worthy to stand in the pages of the
‘Fortschritte’ by the side of the classic researches of Thomson on
Regelation, and of Maxwell on Magnetic Lines of Force. The following is
a translation of Böttger’s notice mentioned above.]


[=2.=] ON THE TRANSMISSION OF TONES TO A DISTANCE AS FAR AS DESIRED, BY
THE HELP OF ELECTRICITY (TELEPHONY).

    [Translated from the original notice by Professor Böttger,
    which appeared in Böttger’s ‘Polytechnischen Notizblatt,’
    1863, No. 6, p. 81, in Dingler’s ‘Polytechnisches Journal,’
    1863, vol. clxviii. p. 185, and in the ‘Polytechnisches
    Centralblatt,’ 1863, t. xxix. p. 858.]

Two decades ago we had not yet gone beyond the first attempts to give
signals at a great distance by the aid of electricity. Since then
telegraphy has attained such a completeness, and the telegraph wire has
reached such a universal extension, that there seems little left for
even the boldest wish to desire.

Now there crops up a first serious research to reproduce tones at any
desired distance by the aid of electricity. This first experiment which
has been crowned with some success, has been made by the teacher of
Natural Science at Friedrichsdorf, not far from Frankfort-on-the-Main,
Herr Ph. Reis, and has been repeated in the Auditorium of the Physical
Society in Frankfort, before numerous assembled members on the 26th
of October, 1861. He caused melodies to be sung not very loudly
into one part of his apparatus, which was placed in a building (the
Bürger-Hospital), about 300 feet distant, with closed windows and
doors. These same melodies were _audible_ to the members in the
meeting-hall by means of the second part of the apparatus. These
wonderful results were attained with the following simple pieces of
apparatus. A little light box, a sort of hollow cube of wood, has a
large opening at its front side, and a small one at the back on the
opposite side. The latter is closed with a very fine membrane (of pig’s
smaller-intestine) which is strained stiff. A narrow springy strip
of platinum foil, fixed at its outer part to the wood, touches the
membrane at its middle; a second platinum strip is fastened by one of
its ends to the wood at another spot, and bears at its other end a fine
horizontal spike, which touches the other little platinum strip where
it lies upon the membrane.

As is known, tones arise from rarefactions and condensations of the air
following quickly after one another. If these motions of the air, known
as waves, strike upon the thin membrane, they press it against the
little plate of platinum with which it is in contact, and immediately
let it vibrate back again into the hollow cube (or so-called artificial
ear): they act so that the membrane now takes a form hollowed toward
the cube, now bulged toward the outside. The little plate of platinum
touching it thereby acquires a vibrating motion, so that it now is
pressed against the spike of the second [platinum plate], now leaves
the same.

If now one little plate of platinum be united by a wire with one pole
of a voltaic battery, and the electricity be led, by a wire fastened to
the other pole of the battery, to any desired distance; there carried
through a spiral, about six inches long, made of a six-fold winding of
very thin covered copper wire; thence led back to the second platinum
strip on the wooden cube through a second insulated wire; then at every
vibration of the membrane an interruption in the current of electricity
takes place because the platinum point no longer touches the other
little strip of platinum. Through the hollow of the wire-spiral there
is stuck a thin iron wire (a strong knitting-needle), which is ten
inches long, and which rests upon two bridges of a sounding-board by
its ends which project on both sides about two inches out of the spiral.

It is known[21] that if an electric current be led through a spiral
which surrounds an iron rod in the manner described, at every
interruption of the same a tone is audible arising from the vibration
of the rod. If the closings and interruptions of the circuit follow
one another relatively slowly, then there is produced by the changes
of position of the molecules of the rod, evoked by the electricity, a
tone,--the so-called longitudinal tone of the rod,--which is dependent
upon the length and stoutness of the rod. But if the closings and
interruptions of the electric current in the spiral follow one another
more rapidly than the vibrations of the smallest particles of the
iron rod,[22] which vibrations are determined by its elasticity, then
these particles cannot complete their paths, receive new impacts,
their vibrations become smaller, but quicker, and follow one another
as frequently as the interruptions. The iron rod then no longer gives
its longitudinal tone, but a tone, which is higher according as the
interruptions are more frequent in the given time, or lower, as they
are less frequent. It is known that the height and depth of tones
depends only on the number of air-waves which follow one another in a
second. We have seen above that by this is determined the number of
interruptions of the electric current of our apparatus by means of the
membrane and the platinum strip. The iron wire must therefore give out
the tone in the same height or depth as that which struck the membrane.
Now since a very far leading of the electricity makes it suffer
scarcely any weakening in proper apparatus, it is intelligible that one
can make the tone which acts on the membrane at one place audible, by
means of the iron rod, at any desired distance.

That the tone is made audible at a distance by the electric
agitations, and not by direct conduction of the sound-waves through the
wires is proved in the most evident way of all, because one instantly
hears no more the tone through the spiral when a good short circuit is
made, as, for example, by laying upon the two wires which conduct the
electricity a strip of sheet metal right in front of the spiral.

The reproduced tones are, of course, somewhat weaker than the original
ones, but the number of vibrations is similar. If thus the reproduction
[of tones] in exactly similar height and depth is easily attained, it
is however difficult for our ear, amidst the always smaller vibrations,
to which the diminished strength of the tone is due, to evaluate
exactly the magnitude of the vibrations. But the character of the tone
depends upon the number of variations of amplitude (Anschwellungen),
that is to say, depends upon whether, for example, in the tones which
have similar pitch and therefore a similar number of waves per second,
the fourth, sixth, eighth, tenth, or sixteenth wave is stronger than
the others. For physicists have shown that an elastic spring is set
in vibration by the thrust of the teeth of a cog-wheel; the first
vibration is the greatest, all those that follow being less. If there
comes, before the spring comes to rest, a fresh thrust from a cog,
then the next vibration is again equal to the greatest first vibration
without the spring making any more vibrations on that account; and by
this means vowel-tones may be artificially produced.

One may also be yet far removed from being able to carry on a
conversation with a friend dwelling a hundred miles distant, and
recognise his voice, as if he sat near us; but it can no longer be
maintained that this is impossible. Indeed the probability that this
will be attained[23] is already become as great as the probability of
the reproduction of natural colours in photography has become through
the notable researches of Niepce.

       *       *       *       *       *

[The second public exhibition which Reis made of the telephone was,
like the first, in Frankfort-on-the-Main, but this time before a
Society known as the _Freies Deutsches Hochstift_, or Free German
Institute, a kind of Athenæum Club for the city of Frankfort, now for
many years established in the well-known house where the poet Goethe
was born, in the Grosse Hirschgraben. In 1862, however, the Free
German Institute held its meetings in another building known as the
Saalbau. And on May the 11th of that year Philipp Reis lectured upon
and exhibited the Telephone. A journal which appeared then, and still
appears, in Frankfort, with the title of ‘Didaskalia,’ devoted to light
literary and artistic news, popular science, and general intelligence
of an informing character, ordinarily inserted notices of the chief
meetings of the Hochstift. On this occasion a preliminary paragraph was
inserted in the following terms:--]


[=3.=] TELEPHONY, _i.e._ SOUND-TRANSMISSION.

[TRANSLATION FROM ‘DIDASKALIA,’ MAY 8TH, 1862.]

The excellent physicist, Mr. Phil. Reis, of Friedrichsdorf, calls
by this name his surprising invention for using the telegraph line
to transmit really audible tones. Our readers will perhaps remember
having heard some time since of this invention, the first trials with
which Mr. Reis performed here in the Physical Society. Since then the
invention has been constantly developed, and will, no doubt, become of
great importance.

[The lecture which followed this announcement was duly given on the
11th of May. In the Saalbau there is a suite of four rooms. The
Lecture to the assembled members of the Hochstift was delivered in the
Auditorium, at one end of the suite: the wires were passed through the
two intervening rooms to the fourth chamber, where the transmitter was
placed, the doors being closed. The battery and wires were borrowed
from the Physical Society for this occasion, permission for their use
having been granted on May 2nd, as appears in a formal entry in the
minute-book. The following notice of Reis’s discourse, believed to
have been written by Dr. Volger, Founder and first President of the
Hochstift, appeared in ‘Didaskalia’ for May 14th.]


[=4.=] TRANSLATION FROM ‘DIDASKALIA,’ 12TH MAY, 1862.

Yesterday’s meeting of the Free German Institute was a very numerously
attended one from the fact that the subject in the order of business,
“Telephony by Transmission of the Galvanic Current,” as explained by
the inventor himself, Mr. Phil. Reis, excites so great an interest that
it rightly deserves the most general attention.

In a lecture exceedingly interesting, universally understood, clear,
and concise, Mr. Reis gave a historical outline of the origin
and development of his idea of the practical possibility of the
transmission of tones in a galvanic way.

His first attempts were mostly unsuccessful in solving the cardinal
question propounded by him. “How is it possible that a single
instrument can reproduce at once the total action of all the organs
operated in human speech?” Until finally it occurred to him to seek
the solution of the problem in the question, “How does our ear take
cognisance of the total vibrations of all the organs of speech acting
at once?” or “How do we perceive the vibrations of several bodies
sounding at once?”

In order to answer this question the lecturer went more closely into
the anatomy of the ear and into the formation of tones in general.
After this was determined, he took up again his experiments in
reference to the transmission of tones by means of galvanism.

Afterwards Mr. Reis constructed considerably enlarged the parts of the
ear necessary for hearing, by which it was finally possible for him to
transmit the tones brought to the mechanically-imitated ear.

The experiments by him some months ago in the Physical Society, were,
to the astonishment of all, exceedingly plain and clear, whereas the
experiment following the lecture of yesterday was less successful. This
was due partly to the poor conductivity of the wires, partly to the
locality.

Although much is still left to be done for the practical utilisation
(Verwerthung) of the telephone, yet a new and interesting field of
labour is hereby opened to physics.

[No more complete report than the foregoing is to be found, and it is
believed that the discourse, which like all those given by Reis was
delivered extempore, was never committed to writing. Its resemblance to
the discourse of the preceding autumn before the Physical Society is
great; and indeed it may be said that all Reis’s discourses upon the
telephone were practically identical in their contents. A few months
after this lecture, Reis presented a pair of instruments, transmitter
and receiver, to the Hochstift. These instruments were not the same as
those used by Reis at his lecture, but were of the “improved” type,
whilst those used by Reis at his lecture to the Hochstift, were, so far
as respects the transmitter at least, more like the form described by
W. von Legat, and figured in Plate II., Fig. A;[24] and according to
Mr. Horkheimer, who helped Reis on this occasion, the transmitter was
provided with a conical mouthpiece of wood. The transmitter presented
later by Reis is of the “square-box” form (Fig. 17), and is stamped,
“1863, Philipp Reis, 2,” and the receiver is of the “knitting-needle”
form (Fig. 23). These instruments are carefully preserved by the
Hochstift in the “Goethehaus,” amongst their archives “in everlasting
remembrance” of the inventor. A few months later, in 1863, the Emperor
of Austria and the late king Max of Bavaria were residing at Frankfurt
and visited the “Goethehaus;” and on this occasion Reis’s instruments
were shown to these distinguished visitors by the Founder and President
of the Hochstift, Dr. Volger.

In honour of his brilliant invention Reis was, shortly after his
lecture, elected an honorary member of the Freies Deutsches Hochstift.]

       *       *       *       *       *

[The next document in order is a Report by Wilhelm von Legat,
communicated to the Austro-German Telegraph Union (Verein) in 1862, and
printed in the ‘Journal’ of that Society. It was reprinted verbatim
in Dingler’s ‘Polytechnisches Journal,’ for 1863, vol. clxix. p. 29.
This Report is of great importance. It is quoted by Graham Bell, in
his earliest account of _his_ telephone. It was this Report, moreover,
which in 1875 or 1876, in a translated manuscript form, was put into
Mr. Edison’s hands by the then President of the Western Union Telegraph
Company, and which formed the starting-point of Edison’s subsequent
work.]


[=5.=] ON THE REPRODUCTION OF TONES IN THE ELECTRO-GALVANIC WAY.

By V. LEGAT, Inspector of the Royal Prussian Telegraphs in Cassel.

    [Translated from the Journal of the Austro-German Telegraph
    Society (edited by Dr. Brix), vol. ix. p. 125, 1862.
    (Zeitschrift des deutschösterreichischen Telegraphen-Vereins,
    1862.)]

It might not be uninteresting to make known to wider circles
the following ideas concerning the reproduction of tones in an
electro-galvanic way, which have recently been put forward by Herr
Philipp Reiss [_sic_] of Friedrichsdorf, before the Physical Society,
and before the meetings of the Free German Institute (Freies Deutsches
Hochstift) in Frankfort-on-the-Main; also to state what has hitherto
been attained in the realisation of this project, in order that
building upon the collected experiences and the efficacy of the
galvanic current, what has already been made serviceable to the human
intellect for the advancement of its correspondence, may in this
respect also be turned to profit.

In what is here announced we are concerned not with the action of
the galvanic current in moving telegraphic apparatus of whatever
construction for producing _visible_ signals, but with its application
for the production of _audible_ signals--of _tones_!

The air-waves, which by their action within our ears awaken in us
the sensation of sound, by first of all setting the drum-skin into
a vibrating motion, are thence, as is known, conveyed to the inner
part of the ear and to the auditory nerves lying there by a lever
apparatus of the most marvellous fineness,--the auditory ossicles
(including “Hammer,” “Anvil,” and “Stirrup”). The experiment for the
reproduction of tones is based upon the following: viz. to employ an
artificial imitation of this lever-apparatus and to set it in motion by
the vibrations of a membrane like the drum-skin in the ear, and thus
to open and close a galvanic circuit which is united by a metallic
conductor with a distant station.

Before the description of the necessary apparatus is followed out,
it might be necessary, however, to go back to the point how our ear
perceives the vibrations of a given tone, and the total vibrations of
all the tones simultaneously acting upon it; because by this means will
be determined the various requisite conditions which must be fulfilled
by the transmitting and receiving apparatus for the solution of the
problem that has been set.

Let us consider first the processes which take place in order that a
single tone should be perceived by the human ear; so shall we find that
each tone is the result of a condensation and rarefaction several times
repeated in a certain period of time. If this process is going on in
the same medium (the air) in which our ear is situated, the membrane
will at every condensation be forced toward the hollow of the drum, and
at every rarefaction will move itself in the opposite direction.

These vibrations necessitate a similar motion of the auditory ossicles,
and thereby a transference to the auditory nerves is effected.

The greater the condensation of a sound-conducting medium at any given
moment, the greater also will be the amplitude of vibration of the
membrane and of the auditory ossicles and of their action; and in the
converse case the action will be proportionally less. It is, therefore,
the function of the organs of hearing to communicate with fidelity to
the auditory nerves every condensation and rarefaction occurring in
the surrounding medium; whilst it remains to be the function of the
auditory nerves to bring to our consciousness the number as well as
the magnitude of the vibrations ensuing in a given time.

Here in our consciousness a definite name is given to a certain
composition, and here the vibrations brought to the consciousness
become “tones.”

That which is perceived by our auditory nerves is consequently the
effect upon our consciousness of a force which, according to its
duration and magnitude, may for the sake of better comprehension, be
exhibited graphically.

[Illustration]

Let, for example, the length of the line _a b_ be any definite duration
of time, and let the curves above this line denote the condensations
(+), and the curves below this line the rarefactions (-); then every
ordinate erected at the extremity of an abscissa gives us the strength
of the condensation in consequence of which the drum-skin vibrates, at
the moment indicated by the position of the foot of the ordinate.

Anything more than that which is exhibited in this way or by similar
curves our ear cannot in the least perceive, and this is sufficient to
bring to our consciousness each single tone and each given combination
of tones. For, if several tones are produced at the same time,
the sound-conducting medium is put under the influence of several
simultaneously acting forces which are subject to the laws of mechanics.

If all the forces operate in the same sense, then the magnitude of the
motion is proportional to the sum of the forces. If the forces act in
opposite directions, the magnitude of the motion is proportional to the
difference between the opposing forces.

Consequently it is possible out of the condensation-curves of several
simultaneously-occurring tones to compound, by the foregoing
principles, a condensation-curve which exactly expresses that which our
ear experiences on the reception of these simultaneously-acting tones.
The objection ordinarily made to this, that a musician, or even any
one, is able to hear separately the single tones of which this combined
curve is built and constructed, cannot be admitted as a proof to the
contrary; for one expert in the science of colour will, for example,
in the same way discern in green a mixture of yellow and blue in their
various shades: and the one phenomenon equally with the other may be
referred back to this; that, to the person concerned, the factors which
make up the product of that which reaches his consciousness are well
known.

According to that which has been already explained, it is easy to
construct the condensation-curves of various tones, chords, &c., and
for the sake of clearness some examples follow:--

Fig. 1, Plate I.,[25] shows a combination curve of three tones, in
which all the proportions of the components recur successively.

Fig. 2 shows such a curve of more than three tones, in which the
proportions in the drawing can no longer so evidently be given; yet
the practised musician would here recognise them, even although in
practice it might be difficult for him to single out, in such chords,
the separate tones.

This method of exhibiting the action of tones upon the human ear offers
the advantage of a very clear perception of the process; and that which
is exhibited (Fig. 3) shows also why a discord must affect our ear
unpleasantly.

This apparent digression from the aim set forth was necessary in
order to indicate that as soon as it is possible for us to create
anywhere, and in any manner whatever, vibrations whose curves and
magnitudes are similar to the vibrations of any given tone, or of any
given combination of tones, we shall have the same impression as this
original tone or this original combination of tones would have produced
upon us.

The apparatus hereafter described offers the possibility of creating
these vibrations in every fashion that may be desired, and the
employment of electro-galvanism gives us the possibility of calling
into life, at any given distance, vibrations similar to the vibrations
that have been produced, and in this way to reproduce at any place the
tones that have been originated at another place.

In Fig. 4, Plate II.,[26] herewith presented, A is the transmitter
(Tonabgeber), and B the receiver (Tonempfänger), which two instruments
are set up at different stations. I make, however, the preliminary
remark that the manner of joining the instruments for interchangeable
use backward and forward is here omitted for the sake of clearness,
and the more so because the whole is not here propounded as a final
fact, but in order to bring that which has been hitherto accomplished
to the knowledge of a wider circle. The possibility of the working of
the apparatus to a greater distance than that which at present limits
in practice the direct working of the galvanic current may also be
left out of consideration, since these points may be easily rendered
possible by mechanical precautions, and do not affect the essential
part of the phenomena now described.

Let us next turn to the transmitter, Fig. A. It is put into
communication on one side with the metallic conductor leading to the
neighbouring station, and by means of this with the receiver, Fig.
B; on the other side it is connected, by means of the electro-motive
power, C, with the earth or a metallic return-conductor.

The transmitter, Fig. A, consists of a conical tube, _a b_, of about
15 centimetres length, 10 centimetres in the front, and 4 centimetres
in the back aperture.

(In the practical investigations it has been established that the
choice of material for this tube is without influence on the use of the
apparatus, and moreover a greater length of the same for the certainty
[of action] of the apparatus is without effect. A greater width of the
cylinder spoils the usefulness of the apparatus; and it is recommended
that the interior surface be as smooth as possible.)

The narrow hinder aperture of the cylinder is closed by a membrane,
_o_, of collodion, and on the middle of the circular surface formed
by this membrane rests one end, _c_, of the lever, _c d_, the fulcrum
(point of support), _c_, of which, supported on a bearing, remains
joined to the metallic conductor.

The choice of the length of the two arms of the lever, _c e_ and _e d_,
is determined by the laws of force of levers. It is recommended that
the arm, _c e_, be constructed longer than the arm _e d_, in order to
bring the smallest movement at _c_ into action at _d_ with the greatest
possible force; but, on the other hand, it is desirable to make the
lever itself as light as possible, in order that it may follow the
motions of the membrane. An uncertain following of the lever, _c d_,
produces impure tones at the receiving station. In the condition of
rest the contact, _d g_, is closed, and a delicate spring, _n_, holds
the lever firmly in this position of rest.

The second part of this apparatus, the pillar, _f_, consists of a
metallic support, which is united with one pole of the battery, C,
while the second pole of the battery is carried to the metallic
conductor of the other station.

Upon the support, _f_, there is a spring, _g_, with a contact, which
corresponds to the contact at _d_ of the lever _c d_, and whose
position is regulated by a screw, _h_.

In order not to weaken the action of the apparatus by the
communication of the air-waves which are produced in using the
apparatus, against the back of the membrane, it is recommended, in
using the apparatus, to place over the tube, _a b_, at right angles to
its longitudinal axis, a screen of about 50 centimetres diameter, which
fixes tight upon the outer surface of the tube.

The receiver, Fig. B, consists of an electro-magnet, _m m_, which
reposes upon a sounding-box, _u w_, and whose wire coils are
respectively connected with the metallic conductor and with the earth
or metallic return-conductor.

Opposite the electro-magnet, _m m_, stands an armature, which is
connected with a lever, _i_, which is long as possible, but light and
broad.

The lever, _i_, is fastened, pendulum-wise, to the support, _k_, and
its movements are regulated by the screw, _l_, and the spring, _p_.

In order to improve the action of the apparatus, this receiver can be
placed in one focus of an elliptically arched cavity of corresponding
size, in which case, then, the ear of him who is listening to the
reproduced tones may be placed at the second focus of this cavity.

The action of the two apparatuses here described, is the following:--

In a condition of rest the galvanic circuit is closed.

In the apparatus, Fig. A, by speaking (singing, or leading into it the
tones of an instrument) into the tube _a b_, in consequence of the
condensation and rarefaction of the air present in this tube, there
will be evoked a motion of the membrane closing the tube at its narrow
end, corresponding to this condensation or rarefaction. The lever,
_c d_, follows the motion of the membrane, and opens and closes the
galvanic circuit at _d g_, so that by each condensation of the air in
the tube an opening, and at each rarefaction a closing of the galvanic
circuit ensues.

In consequence of this process, the electro-magnet of Fig. B (the
receiver) will be demagnetised and magnetised correspondingly with the
condensations and rarefactions of the mass of air in the tube A, _a b_
[the mouth-piece of the transmitter], and the armature belonging to the
magnet will be set into vibrations similar to those of the membrane
in the transmitting apparatus. The plank, _i_, connected with the
armature, conveys these similar vibrations to the air surrounding the
apparatus, Fig. B, which finally transmits to the ear of the listener
the tones thus produced.

We are not, therefore, dealing here with a propagation of sound through
the electric current, but only with a transference to another place of
the tones that have been produced, by a like cause being brought into
play at this second place, and a like effect produced.

Here, however, it must not be overlooked that the preceding apparatus
reproduces, indeed, the original vibrations in equal number, but that
equal strength in the reproduced vibrations has not yet been attained,
and the production of these is reserved for a completion of the
apparatus.

One consequence of this temporary incompleteness of the apparatus,
is that the slighter differences of the original vibrations are more
difficult to discern: that is to say, the vowel appears more or less
indistinct, the more so since each tone is dependent, not only on the
number of vibrations of the medium, but also on the condensation or
rarefaction of the same.

By this it is also explained, that, in the practical investigations
heretofore carried on, chords, melodies, etc., were transmitted
with marvellous fidelity; while single words uttered as in reading,
speaking, and the like, were perceptible more indistinctly.
Nevertheless, here also the inflexions of the voice, the modulations
of interrogation, exclamation, wonder, command, &c., attained distinct
expression.

There remains no doubt, that before expecting a practical utilisation
with serviceable results (praktische Verwerthung mit Nutzen), that
which has been here spoken of will require still considerable
improvement, and in particular mechanical science must complete
the apparatus to be used; yet I am convinced by repeated practical
experiments that the prosecution of the subject here explained is of
the highest theoretical interest, and that our intelligent century will
not miss the practical utilisation (Verwerthung) of it.

       *       *       *       *       *

[This article was also reprinted verbatim in Dingler’s Polytechnisches
Journal, vol. clxix. p. 29, 1863.]

       *       *       *       *       *

[A peculiar interest is attached to the foregoing article, partly on
account of the unique nature of the instruments therein described,
partly because of the mystery attaching to the author of the article.
Wilhelm von Legat was Inspector of the Royal Prussian Telegraphs
at Cassel. How or when he became acquainted with Philipp Reis is
not known--possibly whilst the latter was performing his year of
military service at Cassel in 1855. None of Reis’s intimate friends
or colleagues now surviving can give any information as to the nature
of von Legat’s relations with Reis, as not even his name is known to
them, save from this Report. Yet he was for one year only (1862), the
year in which this Report was made, a member of the Physical Society
of Frankfort-on-the-Main. It is possible that he may have been present
at Reis’s discourse in the preceding October. It is probable that he
was present at Reis’s subsequent discourse in May, 1862, to the Freies
Deutsches Hochstift. Dr. Brix, then editor of the ‘Journal of the
Telegraph Union,’ informs me that Inspector von Legat based his article
upon information derived direct from Reis, whom he knew, and that the
article was submitted to Reis before being committed to the ‘Journal.’
The particular form of transmitter described in von Legat’s Report
(see also p. 25, _ante_) has also some important points in common with
that believed to have been used by Reis at the Hochstift. Neither of
the specific forms described by Inspector von Legat are now known to
be extant. Inquiries made in Frankfort and in Cassel have failed to
find any trace of them. Neither at the local Naturalists’ Society, nor
anywhere else in Cassel, did von Legat describe the invention. He met
with a tragic end during the Bavarian War in 1866, in the battle near
Aschaffenburg, having, according to some, been shot, or, according to
others, fallen from his horse.]

       *       *       *       *       *

[The next extract is from an article entitled ‘Telephonie,’ which
appeared in a journal of science published at Leipzig, under the title
‘Aus der Natur.’ This article is essentially a paraphrase of Reis’s
memoir read to the Physical Society in the preceding December (see
p. 50), and contains the same illustrations, including a cut of the
transmitter identical with Fig. 9, p. 20.]


[=6.=] AUS DER NATUR. (Vol. xxi. 1862. July-October. pp. 470-474.)

“Until now, however, it was not possible to reproduce human speech with
a distinctness sufficient for every person. The consonants are mostly
tolerably distinctly reproduced, but the vowels not in an equal degree.”

       *       *       *       *       *

[About this time there arose a Correspondence in the ‘Deutsche
Industrie Zeitung’ (‘German Journal of Industry’) concerning the
telephone. In No. xvi. p. 184 (1863), a correspondent who signs himself
“K” asks whether the account of the telephone is true? In No. xviii.
p. 208, there is given a brief answer; and No. xxii. contains, on p.
239, an extract from Legat’s Report, on Reis’s Telephone (see p. 70 of
this work), together with an editorial remark to the effect that he had
received a letter from Herr J. F. Quilling, of Frankfort-on-the-Main,
who gives the information that in the transmission of singing in the
telephone, the singer could be recognized by his voice.]


[=7.=] [EXTRACT FROM THE ANNUAL REPORT OF THE PHYSICAL SOCIETY OF
FRANKFORT-ON-THE-MAIN (1863).]

...; “and on the 4th of July, 1863, by Mr. Philipp Reis, teacher, of
Friedrichsdorf, _On the Transmission of Tones to any desired Distance,
by the help of Electricity, with the production of an Improved
Telephone, and Exhibition of Experiments therewith_.”

[This was Reis’s second occasion of bringing his Telephone before the
Physical Society. The instrument had now-assumed the “square-box”
pattern described at p. 27 of this work.]


[=8.=] LETTER OF PHILIPP REIS.

[In July 1863, Mr. W. Ladd, the well-known instrument-maker of London,
bought one of Reis’s Telephones of Messrs. J. W. Albert and Son of
Frankfort. Philipp Reis wrote to Mr. Ladd the following letter of
instructions, having heard that Mr. Ladd proposed to exhibit the
instrument at the approaching meeting of the British Association. The
autograph letter, written in English, is still preserved, and has been
presented by Mr. Ladd to the Society of Telegraph Engineers and of
Electricians of London.]

                                 “Institut Garnier,
                                          “Friedrichsdorf.
    “Dear Sir!

    “I am very sorry not to have been in Francfort when you were
    there at Mr. Albert’s, by whom I have been informed that
    you have purchased one of my newly-invented instruments
    (Telephons). Though I will do all in my power to give you the
    most ample explanations on the subject, I am sure that personal
    communication would have been preferable; specially as I was
    told, that you will show the apparatus at your next sientifical
    meeting and thus introduce the apparatus in your country.

    “Tunes[27] and sounds of any kind are only brought to our
    conception by the condensations and rarefactions of air or
    any other medium in which we may find ourselves. By every
    condensation the tympanum of our ear is pressed inwards, by
    every rarefaction it is pressed outward and thus the tympanum
    performs oscillations like a pendulum. The smaller or greater
    number of the oscillations made in a second gives us by help of
    the small bones in our ear and the auditory nerve the idea of a
    higher or lower tune.

    “It was no hard labour, either to imagine that any other
    membrane besides that of our ear, could be brought to make
    similar oscillations, if spanned in a proper manner and if
    taken in good proportions, or to make use of these oscillations
    for the interruption of a galvanic current.

    “However these were the principles wich (_sic_) guided me
    in my invention. They were sufficient to induce me to try
    the reproduction of tunes [_i.e._, tones--see footnote.--S.
    P. T.] at any distance. It would be long to relate all the
    fruitless attempts, I made, until I found out the proportions
    of the instrument and the necessary tension of the membrane.
    The apparatus you have bought, is now, what may be found most
    simple, and works without failling when arranged carefully in
    the following manner.

    “The apparatus consists of two separated parts; one for the
    singing station A, and the other for the hearing station B.[28]

    [Illustration: Fig 28.]

    “The apparatus A, a square box of wood, the cover of which
    shows the membrane (_c_) on the outside, under glass. In the
    middle of the latter is fixed a small platina plate to which
    a flattened copper wire is soldered on purpose to conduct the
    galvanic current. Within the cercle you will further remark
    two screws. One of them is terminated by a little pit in which
    you put a little drop of quiksilver; the other is pointed. The
    angle, which you find lying on the membrane, is to be placed
    according to the letters, with the little whole [hole] (_a_)
    on the point (_a_) the little platina foot (_b_) into the
    quicksilver screw, the other platina foot will then come on the
    platina plate in the middle of the membrane.

    “The galvanic current coming from the battery (which I compose
    generally of three or four good elements) is introduced at
    the conducting screw near (_b_) wherefrom it proceeds to the
    quicksilver, the movable angle, the platina plate and the
    complementary telegraph to[29] the conducting screw (_s_). From
    here it goes through the conducter to the other station B and
    from there returns to the battery.

    “The apparatus B, a sonorous box on the cover of which is
    placed the wire-spiral with the steel axis, wich will be
    magnetic when the current goes through the spiral. A second
    little box is fixed on the first one, and laid down on the
    steel axis to increase the intensity of the reproduced
    sounds. On the small side of the lower box you will find the
    correspondent part of the complementary telegraph.

    “If a person sing at the station A, in the tube (_x_) the
    vibrations of air will pass into the box and move the
    membrane above; thereby the platina foot (_c_) of the movable
    angle will be lifted up and will thus open the stream at
    every condensation of air in the box. The stream will be
    re-established at every rarefaction. For this manner the
    steel axis at station B will be magnetic once for every full
    vibration; and as magnetism never enters nor leaves a metal
    without disturbing the equilibrium of the atoms, the steel-axis
    at station B must repeat the vibrations at station A and thus
    reproduce the sounds which caused them.

    “_Any_[30] sound will be reproduced, if strong enough to set
    the membrane in motion.

    “The little telegraph, which you will find on the side of the
    apparatus is very usefull and agreable for to give signals
    between both of the correspondents. At every opening of the
    stream and next following shutting the station A will hear a
    little clap produced by the attraction of the steel spring.
    Another little clap will be heard at station (B) in the
    wire-spiral. By multiplying the claps and producing them in
    different measures you will be able as well as I am to get
    understood by your correspondent.

    “I am to end, Sir, and I hope, that what I said will be
    sufficient to have a first try; afterward you will get on quite
    alone.

    “I am, Sir,
       “Your most obediant Servant,
                  “Ph. Reis.

      “Friedrichsdorf, 13/7, 63.”


[=9.=] REIS’S PROSPECTUS.

[The following “Prospectus” of instructions was drawn up by Reis to
accompany the Telephones which were sold by Herr Wilh. Albert of
Frankfort. The author of this book is in possession of original copies,
of which a number are extant. The “Prospectus” was also reprinted
in its entirety at page 241 of Professor Pisko’s book ‘Die neueren
Apparate der Akustik,’ published at Vienna in 1865.]


TELEPHON.

Each apparatus consists, as is seen from the above illustration, of
two parts: the Telephone proper, A, and the Reproduction apparatus
[Receiver], C. These two parts are placed at such a distance from each
other, that singing, or the tones of a musical instrument, can be heard
from one station to the other in no way except through the apparatus
itself.

Both parts are connected with each other, and with the battery, B,
like ordinary telegraphs. The battery must be capable of effecting the
attraction of the armature of the electromagnet placed at the side of
station A (3-4 six-inch Bunsen’s elements suffice for several hundred
feet distance).

The galvanic current goes then from B to the screw, _d_, thence through
the copper strip to the little platinum plate at the middle of the
membrane, then through the foot, _c_, of the angular piece to the
screw, _b_, _in whose little concavity a drop of quicksilver is put_.
From here the current then goes through the little telegraph apparatus,
_e-f_, then to the key of station C, and through the spiral past _i_
back to B.

[Illustration: Fig. 29.]

If now sufficiently strong tones are produced before the
sound-aperture, S, the membrane and the angle-shaped little hammer
lying upon it are set in motion by the vibrations; the circuit will
be once opened and again closed for each full vibration, and thereby
there will be produced in the iron wire of the spiral at station C
the same number of vibrations which there are perceived as a tone
or combination of tones (chord). By imposing the little upper case
(Oberkästchen) firmly upon the axis of the spiral the tones at C are
greatly strengthened.

Besides the human voice (according to my experience) there also can
be reproduced the tones of good organ-pipes from F--c' and those of a
piano. For the latter purpose A is placed upon the sounding-board of
the piano. (Of thirteen triads (Dreiklänge) a skilled experimentor
could with all exactness recognise ten).

As regards the telegraph apparatus placed at the side, it is clearly
unnecessary for the reproduction of tones, but it forms a very
agreeable addition for convenient experimenting. By means of the same,
it is possible to make oneself understood right well and certainly by
the other party. This takes place somewhat in the following manner:
After the apparatus has been completely arranged, one convinces oneself
of the completeness of the connexion and the strength of the battery
by opening and closing the circuit, whereby at A the stroke of the
armature is heard, and at C a very distinct ticking.

By rapid alternate opening and closing at A it is asked at C whether
one is ready for experimenting, whereupon C answers in the same manner.

Simple signals can by agreement be given from both stations by opening
and closing the circuit one, two, three, or four times; for example:--

                1 beat  = Sing.
                2 beats = Speak, &c.

I telegraph the words thus--that I number the letters of the alphabet
and then transmit their numbers--

                1 beat  = _a_.
                2 beats = _b_.
                3   "   = _c_.
                4   "   = _d_.
                5   "   = _e_, &c.

_z_ would accordingly be designated by twenty-five beats.

This number of beats would, however, appear wasteful of time, and would
be uncertain in counting, wherefore I employ for every five beats a
dactyl-beat (Dactylusschlag), and there results

[Illustration:--~ ~] for _e_.

[Illustration:--~ ~] and one beat for _f_, &c.

_z_, = [Illustration:--~ ~,--~ ~,--~ ~,--~ ~,--~ ~] which is more
quickly and easily executed and easier to understand.

It is still better if the letters are represented by numbers which are
in inverse proportion to the frequency of their occurrence.

                         Phil. Reis,
      Teacher at L. F. Garnier’s Institute for boys.
  Friedrichsdorf, near Homburg-by-the-Height,
      August 1863.

[The foregoing “Prospectus” was accompanied by a further document
printed as a postscript by Reis, at the top of which the figure of the
instrument was repeated, and which ran as follows:--]

    “P. P.,

    “Since two years ago I succeeded in effecting the possibility
    of the reproduction of tones by the galvanic current, and in
    setting up a convenient apparatus therefor, the circumstance
    has found such a recognition from the most celebrated men of
    science, and so many calls to action have come to me, that I
    have since striven to improve my originally very incomplete
    apparatus, so that the experiments might thereby become
    accessible to others.

    “I am now in the position to offer an apparatus which fulfils
    my expectations, and with which each physicist may succeed in
    repeating the interesting experiments concerning reproduction
    of tones at distant stations.

    “I believe I shall fulfil the wish of many if I undertake to
    bring these improved instruments into the possession of the
    [physical] cabinets. Since the preparation of the same requires
    a complete acquaintance with the leading principles and a
    tolerable experience in this matter, I have decided myself to
    prepare the most important parts of the same, and to leave the
    fashioning of the accessory parts, as also of the external
    adornments, to the mechanician.

    “The distribution of the same I have made over to Herr J.
    Wilh. Albert, mechanician, in Frankfort-on-the-Main, and have
    placed him in the position to deliver these instruments in
    two qualities, differing only in external adornment, at the
    prices of 21 florins and 14 florins (12 thalers and 8 thalers
    current), inclusive of packing. Moreover, the instruments can
    also be obtained direct from me at the same prices, upon a cash
    remittance of the amount.

    “Each apparatus will be tested by me before sending off, and
    will then be furnished with _my name, an order-number, and with
    the year_ of manufacture.

    “Friedrichsdorf, near Homburg-by-the-Height,
             “in August 1863.
                               “Phil. Reis,

        “Teacher at L. F. Garnier’s Institute for Boys.”

[In September of the same year the telephone was shown by Prof.
R Böttger at the meeting of the German Naturalists’ Association
(Naturforscher), which met on that occasion at Stettin. Little or
nothing is known of what took place at this exhibition, but Professor
von Feilitzsch, of the neighbouring University of Greifswald, has
informed the author of this work that the Telephone there shown was of
the form figured in Reis’s Prospectus (p. 86), and that Reis claimed at
that time to be able to transmit words by his instruments. In the same
autumn the following notice appeared in Böttger’s ‘Notizblatt,’ and was
copied thence into Dingler’s ‘Journal,’ and other scientific papers.]


[=10.=] ON THE IMPROVED TELEPHONE.

    [Translated from the original notice which appeared in
    Böttger’s ‘Polytechnisches Notizblatt,’ 1863, No. 15, p. 225,
    and in Dingler’s ‘Polytechnisches Journal,’ 1863, vol. clxix.
    p. 399.]

At the meeting of the Physical Society of Frankfort-on-the-Main,
on the 4th of July, a member of this Society, Herr Ph. Reis, of
Friedrichsdorf, near Homburg-vor-der-Höhe, exhibited some of his
improved Telephones (means for the reproduction of tones at any desired
distance by the galvanic current). It is now two years since Herr Reis
first gave publicity to his apparatus,[31] and though even already at
that time the performances of the same in their simple artless form
were capable of exciting astonishment, yet they had then the great
defect that experimenting with them was only possible to the inventor
himself. The instruments exhibited in the above-named meeting scarcely
reminded one of the earlier ones. Herr Reis has also striven to give
them a form pleasing to the eye, so that they may now occupy a worthy
place in every Physical Cabinet. These new apparatus may now also be
handled by every one with facility, and work with great certainty.
Melodies gently sung at a distance of about 300 feet were repeated by
the instrument which was set up, much more distinctly than previously.
The scale was reproduced especially sharply. The experimenters could
even communicate words to one another, though certainly indeed only
such as had often been heard by them. In order moreover that others who
are less accustomed [to experimenting] may be able to understand one
another through the apparatus, the inventor has placed on the side of
the same a little arrangement,[32] which according to his explanation
is completely sufficient, the speed of communication of which is
indeed not so great as that of modern Telegraphs, but which works
quite certainly, and requires no special skill on the part of the one
experimenting with it.

We would bring to the notice of gentlemen who are professional
physicists that the inventor of these interesting pieces of apparatus
now has them prepared for sale under his oversight (the important parts
he makes himself), and the same can be procured from him direct, or
through the mechanician, Mr. Wilhelm Albert, of Frankfort-on-the-Main,
at 14 and at 21 florins, in two qualities, differing only in external
adornment.

[A review, written by Dr. Röber of Berlin, of this and other articles
relating to the Telephone appeared subsequently in the ‘Fortschritte
der Physik,’ 1863, p. 96.]

[Another consequence of the publicity thus given to the Telephone was
the appearance of an article on that instrument, under the title of
“Der Musiktelegraph,” in a popular illustrated weekly family paper,
‘Die Gartenlaube,’ published at Leipzig. This article, from the pen, it
is believed, of Dr. Oppel of Frankfort, is made up chiefly of slightly
altered extracts from the previously quoted documents. The form of
the instrument described is identical with that described in Reis’s
‘Prospectus,’ and the figure given in the ‘Gartenlaube,’ No. 51, p.
809, is a reprint, apparently from the same wood-block of the figure
which heads Reis’s Prospectus, and which is reproduced on p. 86 of this
work. The only passage of further interest is a brief sentence relating
to the exhibition of the Telephone at the German Naturalists’ Assembly
at Stettin in 1863, and is as follows:--]


[=11.=] “Now in order also to give to a still wider circle, especially
to technologists (Fachmännern), the opportunity of witnessing with
their own eyesight the efficiency of this apparatus,--lately, in fact
essentially improved,--Professor Böttger of Frankfort-on-the-Main
exhibited several experiments therewith at the meeting of the German
Naturalists (Naturforscher) and Physicians recently held at Stettin, in
the Section for Physics; which [experiments] would certainly have been
crowned with still greater success if the place of meeting had been in
a less noisy neighbourhood, and had been filled with a somewhat less
numerous audience.”

[The next extract is a brief record from the Report of a scientific
society meeting in Giessen, which during the Austro-Prussian war of
1866 had become disorganised, and which in 1867 published a condensed
account of its proceedings for the preceding years. Amongst those
proceedings was a lecture by the late Professor Buff, at which Reis’s
Telephone was shown, and at which Reis himself is believed to have been
present.]


[=12.=] [EXTRACT FROM THE ‘TWELFTH REPORT OF THE UPPER-HESSIAN
ASSOCIATION FOR NATURAL AND MEDICAL SCIENCE,’ (‘Oberhessische
Gesellschaft für Natur und Heilkunde,’) Giessen, February 1867.]

P. 155. Report on the doings and condition of the Association from the
1st of July, 1863, to the 1st of July, 1865, by Herr Gymnasiallehrer
Dr. W. Diehl.

... On the 13th of February [1864], ‘On the Tones of the Magnet, with
Application to the Telephone, with experiments,’ by Professor Buff.


    EXHIBITION OF THE TELEPHONE TO THE NATURALISTS’ ASSOCIATION OF
    GERMANY. (DEUTSCHE NATURFORSCHER VERSAMMLUNG.)

[By far the most important of all the public exhibitions given by
Reis of his Telephone, was that which took place on the 21st of
September, 1864, at Giessen, on the occasion of the meeting of the
German Naturalists’ Association (Versammlung Deutsche Naturforscher).
Here were assembled all the leading scientific men of Germany,
including the following distinguished names, many of whom are still
living:--Prof. Buff (Giessen), Prof. Poggendorff (Berlin), Prof. Bohn
(Frankfurt-a.-M., now of Aschaffenburg), Prof. Jolly (Munich), Dr.
Geissler (Bonn), Prof. Weber (Göttingen), Prof. Plücker (Bonn), Prof.
Quincke (Heidelberg), Prof. Dellmann (Kreutznach), Prof. Böttger
(Frankfurt-a.-M. and Mainz), Prof. Kekule (Bonn), Prof. Gerlach
(Erlangen), Dr. J. Frick (Carlsruhe), Dr. F. Kohlrausch (Würtzburg),
Prof. Reusch (Tübingen), Prof. J. Müller (Freiburg), Prof. Helmholtz
(Heidelberg), Prof. Melde (Marburg), Prof. Kopp (Marburg), Prof. A.
W. Hoffmann (London, now of Berlin), Mons. Hofmann (Paris, optician),
Hofrath Dr. Stein (Frankfurt-a.-M.), Dr. W. Steeg (Homburg), Mons.
Hartnack (Paris, and of Pottsdam), Prof. G. Wiedemann (Basel, now of
Leipzig), E. Albert (Frankfurt-a.-M., mechanician), Dr. Thudichum
(London), W. Schultze (York, apothecary), Dr. J. Barnard Davis
(Shelton), E. J. Chapman (London, chemist), Dr. L. Beck (London,
chemist), Prof. Chas. J. Himes (U.S.A., chemist), E. W. Blake (New
Haven, U.S.A., student), C. G. Wheeler (United States Consul in
Nürnberg), and many others. Dr. C. Bohn (now of Aschaffenburg) was
Secretary of the Association, and also Secretary of the Section of
Physics. The meetings of this Section were held in the Laboratory of
Professor Buff. Reis came over from Friedrichsdorf accompanied by
his young brother-in-law, Philipp Schmidt. A preliminary trial on the
morning of that day was not very successful, but at the afternoon
sitting, when communications were made to the Section by Prof. Buff,
by Reis himself, and by Prof. Poggendorff, the instrument was shown
in action with great success. Reis expounded the story how he came to
think of combining with the electric current interruptor a tympanum
in imitation of that of the human ear, narrating his researches in
an unassuming manner that won his audience completely to him; and
the performance of the instrument was received with great applause.
Various professors essayed to experiment with the instrument, with
varying degrees of success according to whether their voices suited the
instrument or not. Amongst these were Prof. Böttger and Prof. Quincke
of Heidelberg, whose account of the occasion is to be found on p.
112. Dr. Bohn, the Secretary of the Section, wrote for the ‘Journal’
(Tagesblatt), issued daily, the following notice.]


[=13.=] EXTRACT FROM THE REPORT OF THE GERMAN NATURALISTS’ SOCIETY,
HELD AT GIESSEN (1864).

“Afternoon sitting on 21st September, 1864.

“Prof. Buff speaks about the tones of iron and steel rods when
magnetised, and exhibits the corresponding experiments.

“Dr. Reis demonstrates his Telephone, gives thereupon an explanation
and the history of this instrument.

“Prof. Poggendorff produces tones in a metal cylinder, the slit up
edges of which touch one another firmly, and which is placed loosely
round an induction-bobbin through which there goes an interrupted
current.”

[This occasion was the crowning point of Philipp Reis’s career, and
might have proved of even greater importance but for two causes: the
inventor’s precarious health, and the indifference with which the
commercial world of Germany viewed this great invention. Where the
keen insight of Reis contemplated the vast possibilities opened out
by the invention of a new mode of inter-communication, others saw only
an ingenious philosophical toy, or at best a pleasing illustration
of certain known principles of acoustic and electric science. And in
spite of the momentary enthusiasm which the exhibition of the Telephone
had evoked, the interest in it dwindled away. A few of the public
journals of that date, noticed the invention in eulogistic terms and
spoke of the prospect it afforded of communication between distant
friends and of simultaneous concerts being given in different towns,
all transmitted telephonically from one orchestra. But the invention
came too early. The public mind was not yet prepared to take it up,
and the enthusiasm died away. Still in a few of the more important
books on Physics, Acoustics, and Electricity, the matter continued to
receive attention. In the well-known Müller-Pouillet’s ‘Textbook of
Physics’ (Lehrbuch der Physik) edited by Professor J. Müller; in the
‘Technical Physics’ of Hessler, of Vienna, edited by Professor Pisko;
in Pisko’s ‘Recent Apparatus of Acoustics,’ and particularly in Kuhn’s
admirable ‘Handbook of Applied Electricity,’ the Telephone was accepted
as a definite conquest of science, and was described and figured. From
the works named we transcribe the extracts which follow, and which
sufficiently explain themselves.]


[=14.=] EXTRACT FROM MÜLLER-POUILLET’S ‘TEXTBOOK OF PHYSICS AND
METEOROLOGY’ (LEHRBUCH DER PHYSIK UND METEOROLOGIE).

[Published at Brunswick, Sixth ed., 1863, vol. ii. page 352, fig. 325;
and Seventh ed., 1868, vol. ii. pages 386-388, figs. 348-350. The
following translation is from the latter edition.]

“This tone ... has Reis used for the construction of his Telephone.

“Figure 348[33] exhibits Reis’s interrupting apparatus. In the lid of
a hollow cube of wood A, a circular opening is made, which is closed
by an elastic membrane (pig’s lesser intestine) strained over it. Upon
the centre of this membrane is glued a little plate of platinum, which
stands in conductive communication with the clamping-screw _a_ by means
of a quite thin little strip of metal _f_ (distinctly visible in Fig.
349) [Fig. 31].

“Upon the middle of the little platinum plate, rests a short little
platinum pencil, which is fastened at _g_ to the under-side of the
strip of tin-plate _h g i_, one end of which, _h_, rests upon the
little metal pillar _l_, while a little platinum spike fastened upon
its under-side at _i_, dips into the hollow of the little metal pillar
_k_, containing some quicksilver. The clamping-screw _b_, is put into
conductive communication with the little metal pillar _k_.

“From one pole of the battery there goes a conducting-wire to the
clamping-screw _a_ of the interrupting apparatus Fig. 348 [Fig. 30],
from the other pole of the same there goes a wire to the clamping-screw
_d_ of the reproducing apparatus, Fig. 350 [Fig. 32], which is to be
presently described. The clamping-screw _c_, of this apparatus, is
connected by a wire with _b_, Fig. 348 [Fig. 30]. The clamping-screws
_c_ and _d_ are connected with the ends of the wire of the small
magnetising spiral M, Fig. 350 [Fig. 32]; with the connexion described
above, the current of the current-generator (battery) goes, therefore,
through the spiral M.

“As soon now as the sound-waves of an adequately powerful tone enter
through the mouth-piece S into the hollow cube A, the elastic membrane
which closes this at the top is set into vibrations. Each wave of
condensation on entering lifts the little platinum plate together
with the little spike which sits upon it; but if the membrane swings
downwards, the tin-piece _h g i_, with the little spike at _i_, cannot
follow it quick enough; there therefore occurs here, at each vibration
of the membrane, an interruption of the current which lets itself be
recognised by a little spark appearing at the place of interruption.

[Illustration: Fig. 30.]

[Illustration: Fig. 31.]

[Illustration: Fig. 32.]

“Now in the spiral M is stuck a knitting-needle, which, as the figure
shows, is fastened into a sounding-board. A lid provided with second
sounding-board may be clapped over the spiral, and the tone be thereby
greatly strengthened.

“If now, tones are produced before the mouth-piece S, whilst one sings
into the same or whilst one blows organ-pipes, one at once hears at the
reproducing apparatus a peculiar creaking noise which is independent of
the pitch of the tones produced at the interrupting apparatus, _but,
beside this, those tones are themselves reproduced by the steel wire
distinctly perceptibly_, and indeed Reis found that this is the case
for all tones between F and _f''_.

“In Reis’s experiments the interrupting apparatus was 300 feet distant
from the spiral, and was indeed set up in another house with closed
doors. But since the length of the conducting wire can be extended
just as far as in direct telegraphy, Reis gave to his apparatus
the name _Telephone_ (Jahresbericht des physikalischen Vereins zu
Frankfurt-a.-M. für 1860/61).”


[=15=.] EXTRACT FROM PISKO’S ‘DIE NEUEREN APPARATE DER AKUSTIK.’

[This book, ‘The more recent Apparatus of Acoustics,’ by Dr. Francis
Joseph Pisko, Professor of Physics in the Gewerbeschule in Vienna,
was published at Vienna in 1865. At that time the novelties in
acoustics were König’s apparatus for the graphic study of sounds,
König’s manometric flames, Schaffgotsch’s singing flames, Helmholtz’s
‘Researches on the Quality of Sounds,’ Duhamel’s Vibrograph, Scott and
König’s Phonautograph, and Reis’s Telephone. The account given of the
latter is more detailed in some respects than any other published at
the time.]

Page 94.--PRINCIPLE OF THE “TELEPHON” OF REIS.

51. (_a._) Allied to the Membrane Phonautograph is the “Telephon” of
Reis[34] (Fig. 33). Upon the little membrane, _m m_, in the middle,
is fastened with adhesive wax the round end _s_ of a light strip of
platinum, _n s_, so that the platinum strip can join in with all the
vibrations of the membrane. Very near to the central end, _s_, of the
little platinum strip, _n s_, a platinum spike stands, in such a way
that it is brought into contact, by the vibrations of the membrane,
with the platinum strip that vibrates with the latter. Suppose now that
the outer end, _n_, of the platinum strip and the platinum spike are
connected with the poles of a galvanic battery, then, by the vibration
of the membrane the galvanic current will, according to the phase of
the vibration, be alternately established and interrupted. Inserted
in this circuit, an electro-magnetic bell, or an electro-magnetic
telegraph, will give signals to great distances that somebody is
speaking;[35] though, obviously, it cannot inform _what_ is being
spoken.

[Illustration: Fig. 33.]

(_b._) As is known, an iron wire around which flow rapidly-interrupted
powerful galvanic currents, is thereby thrown into tones which,
according to circumstances, may be longitudinal or transverse or
both together. Such an iron wire, lying in a multiplying wire-coil,
_G_, Reis inserted at the second [receiving] station, _C_. The wire
emitted sounds when the membrane was set into vibrations by singing or
speaking (at _S_, Fig. 33) into the hollow cubical piece _A_. In the
investigations made by me with the telephone, the rod (of iron) never
altered the pitch of its tone with the most different kinds of tones
and clangs, and always gave only the rhythm of the words sung or spoken
into the piece _A_ (the transmitter) at _S_. Usually the air of the
song that was sung could be recognised by its rhythm.[36] The special
researches on these points follow in paragraph 53. However, it is so
far clear that there is still plenty of time yet before we have the
_simultaneous concerts_, and the transmission of singing to different
towns, as the daily newspapers have sanguinely expected. The apparatus
of Reis is certainly a “Telephone” but not a “Phonic Telegraph.”
The single means of transmission for song and speech--and that only
for moderate distances--remains the old familiar speaking-tube.
Nevertheless, the experiment of Reis must ever be reckoned amongst the
most beautiful and interesting of school-experiments. And since the
means for this are so simple, the apparatus of Reis will certainly
find a speedy entrance into educational establishments that are only
moderately endowed. It is easily proved that the tones of the wire in
the telephone do not arise from acoustic conduction, for by cutting out
the coil from the circuit the tones immediately cease.

    1. The Telephone of Reis originally consisted of a cube of wood
    with a conical boring. The smaller opening was strained over
    with a membrane. A knitting-needle which served for a sounding
    wire projected about 2 inches on each side of the multiplying
    coil, and lay upon the two bridges of a sounding-box. The
    surrounding helix consisted of six layers of thin wire. Fig.
    33 shows the Telephone as it is constructed at the present
    time by the mechanician, Albert, in Frankfort, and by the
    mechanician, Hauck, in Vienna, according to the directions of
    the inventor.

       *       *       *       *       *

                  [52.] Details about the Telephone.

(_a._) The same (Fig. 33) consists in its essentials:

    1. Of a transmitter, _A_;

    2. Of a receiver, _C_;

    3. Of a galvanic battery, _B_, and lastly,

    4. Of the conducting wires that connect them.

(_b._) The transmitter, _A_, is essentially a parallelepipedal body
of wood. The upper part, _u x_, of it is cut out of one piece [of
wood] with square cross-section, the side, _x x_, of which measures 9
centimetres, and its height, _u x_, 2·8 centimetres.

This part is moveable upon a hinge on the lower little box, A A. If
the cover, _x u_, is laid back, one sees that a small circle of 3·9
centimetres diameter has been cut out in the same. Into this hole
passes a brass collar with a flange 8 millimetres broad, which is
furnished at one side with a groove like a pulley. Over the collar
there is stretched the membrane, _m m_, by means of a silk thread lying
in the shoulder of the same. This circular membrane is surrounded by
a wider circular aperture, _b b_, = 8·5 centimetres. A shovel-shaped
little strip of platinum, _n s_, lies (over it) leading to the brass
binding-screw, _d_, with the circular part, _s_, falling upon the
centre of the membrane.

By means of some sealing-wax this circular part is fastened to the
membrane, and thereby compelled to take part in the vibrations of the
same. The further transmission of the galvanic current from the centre
takes place by means of a platinum or steel point resting in a cup of
mercury, which is extended in a screw, which transmits the current
farther. The point _a_ serves as a support for the angular hook, _a
s b_, which in general is supported like a tripod, in order that the
point of contact, _s_, may remain as constant as possible. The hook, _a
s b_, is simply struck with a hole at _a_ upon a projecting point, and
lies upon a broader under part. From _b_ the galvanic circuit proceeds
by means of an overspun wire to the brass key _e_ (A, Fig. 33), and
from there farther in the direction represented by the arrow.

The lower part A A of the transmitter is put together of thin wood and
forms a parallelepiped, whose height = 6·8 cm., and whose width = 7·7
cm. An inclined mouthpiece of tin with funnel-shaped opening serves
to receive the tones. The longer side of this mouthpiece measures 6·7
cm., the shorter 4·7 cm.; the longer diameter of the widening measures
7·15 cm., the shorter diameter 7·5 cm., and finally the diameter of the
narrow tube 3·9 cm.

    It is clear that, if necessary, the platinum strip can be
    replaced by a strip of thin sheet-brass, the platinum or steel
    points by iron. Only in this case the points of contact must be
    oftener cleaned to a metallic polish.

(_c._) The receiver (Zeichengeber) C is in general a double resonant
box, whose upper part, “the cover,” is moveable upon two hinges, and
can be laid back. The length of this cover is 16·4 cm., its width 9·5
cm., and its height 3·2 cm. The length of the lower box measures 22·9
cm., its width 9·6 cm., and its height 2·5 cm. The under part of the
resonant box bears two wooden bridges, which stand about 7·4 cm. from
each other, and which serves as supports for the 21·5 cm. long, and 0·9
cm. thick iron needle destined for reproducing the tones. The length of
spiral wound over the needle, and designed for making an electro-magnet
of the same, is 15 cm. The wooden covers of both parts, scraped as
thin as possible, and the greatest breadth of the circular holes shown
in the figure, measures 13 mm.

(_d._) For a battery one can successfully use a small Smee’s consisting
of four elements, or two larger Bunsen’s cells.

The conductor must be at least sufficiently long that one cannot
perceive the tones that are produced. For correspondence between the
two stations the inventor has employed the electro-magnetic telegraph
arrangement, _e v g h_, seen in the mechanism, and easily understood.
An agreement in reference to corresponding signs can be easily
arranged, and the simplest way is to accept the signals arranged by the
inventor. (See ‘Prospectus.’)

The receiver C gives, when the key _e_ is pressed, the corresponding
telegraphic signals by means of tones in the rod E E, while at the
transmitter, A, the electro-magnet _v_ gives the signals by means of
the springy armature _z_.

                 [53.] Experiments with the Telephone.

(_a._) As soon as one brings the mouth to the funnel S and sings, the
membrane of the transmitter, A, vibrates in a corresponding manner, and
the iron rod, E E, at the second station begins to give forth a tone.
Every time a spark is seen at the first station _s_, the rod at the
other station certainly gives forth a tone. The same is true when one
hears the peculiarly snarling tone which arises from the stroke of the
vibrating platinum strip against the spike of angular hook resting upon
it.

The appearance of these sparks or of the peculiar snarling at the
transmitter A gives the sign to the observers at the station A that
the rod in C is giving a tone. Tones and melodies which were sung into
the sound aperture, and especially sounds in which the teeth and bones
of the head also vibrated (so-called humming tones), always evoked
a tone in the rod or needle E E, and indeed, as already mentioned (§
51), without change in the pitch, but only with the reproduction of the
rhythm of the respective song or words.

The pitch of the tone excited at C in the rod E E was in the apparatus
at my disposal _h_; its strength not very great and its clang snarly,
similar to that of a lightly sounding reed-whistle, somewhat like that
of a child’s wooden trumpet. The cuticle lying about the heart of the
smaller and even the larger mammals (from calves, &c.) makes the best
membranes. Goldbeater’s-skins reproduce only the deeper tones. The
cover of the sounding-box appeared in my apparatus superfluous, and
indeed the tone was somewhat stronger without the cover.

    1. In experiments with the telephone, one must look closely
    as to whether the ends of the platinum strip is still
    fastened to the membrane, and one must, if necessary, press
    upon the membrane. If the strip will no longer stick, heat
    a knife-blade, touch a small piece of sealing wax with it,
    and carry thus the melted sealing-wax to the under side of
    the round end of the platinum-strip, _n s_. Then press it
    immediately on the membrane, _m m_.

    Ph. Reis showed his apparatus in very primitive form for
    the first time in October, 1861, to the Physical Society at
    Frankfort-on-the-Main; on July 4th, 1863, before the same
    society, he showed the form represented in Fig. 33. This time
    he experimented upon a distance of 300 feet. Professor Boettger
    brought the apparatus before the Naturforscher-Versammlung at
    Stettin (1863) in the section for Physics.


[=16.=] HESSLER’S ‘TEXT-BOOK OF TECHNICAL PHYSICS,’ vol. i. p. 648.

[Next in chronological order comes a notice of the Telephone in
Hessler’s ‘Lehrbuch der technischen Physik,’ edited by Prof. Pisko,
and published at Vienna in 1866. The brief account given in this work
adds nothing to the accounts previously given, and is evidently written
by some person ignorant of Reis’s own work, for beside omitting all
mention of the transmission of speech by the instrument, or of its
being constructed upon the model of the human ear, the writer appears
not even to know how to spell Reis’s name,[37] and speaks of him as
“Reuss.”]


[=17.=] KUHN’S ‘HANDBOOK OF APPLIED ELECTRICITY,’

(‘Handbuch der Angewandten Elektricitätslehre,’ von Carl Kuhn), being
vol. xx. of Karsten’s ‘Universal Encyclopædia of Physics’ (Karsten’s
‘Allgemeine Encyclopädie der Physik’).

[Karsten’s ‘Encyclopædia of Physics,’ which has been for many years
a standard work of reference, both in Germany and in this country,
consists of a number of volumes, each of which is a complete treatise,
written by the very highest authorities in Germany. Thus Helmholtz
contributed the volume on Physiological Optics, Lamont that on
Terrestrial Magnetism, whilst the names of Dr. Brix, Professor von
Feilitzsch, and others, are included amongst the authors. Carl Kuhn,
who wrote vol. xx., was Professor in the Royal Lyceum of Munich, and
member of the Munich Academy. Kuhn’s volume on ‘Applied Electricity,’
published in 1866, is to be found on the shelves of almost every
library of any pretensions in Great Britain. The account given therein
of Reis’s Telephone is interesting, because it describes two forms,
both of transmitter and of receiver. In fact the descriptions and
figures are taken almost directly from von Legat’s Report (p. 70), and
from Reis’s Prospectus (p. 87). The extract translated below includes
all the matter that is of importance.]

P. 1017. The researches established by Reis on the 26th of October,
1861, in Frankfurt[38] have already shown that if the current
interruptions follow one another almost continuously and very rapidly,
in a spiral arranged with a thin iron core, the iron wire can be set
into longitudinal vibrations, whereby therefore the same is constrained
to reproduce tones of different pitch.

       *       *       *       *       *

[Here follows a reference to Petrina’s Electric Harmonica.]

       *       *       *       *       *

From the communications made known by Legat, it follows that “the ideas
concerning the reproduction of tones by means of electro-galvanism
which were put forward some time since by Philipp Reis of
Friedrichsdorf, before the Physical Society, and the meeting of the
Free German Institute in Frankfort-on-the-Main,” relate to similar
arrangements. “What has hitherto been attained in the realisation of
this project,” Legat announces in his report, and we extract therefrom
only that part which gives an explanation of the disposition of the
telegraphic apparatus, with which it is said to be possible to produce
the vibrations and the excitement of tones in any desired manner,
and by which the employment of electro-galvanism is said to make it
possible “to call into life at any given distance vibrations similar to
the vibrations that have been produced, and in this way to reproduce at
any place the tones that have been originated at another place.”

This apparatus consists of the tone-indicator (transmetteur) and
the tone-receiver (récepteur). The tone-indicator (Fig. 34, p. 109)
consists of a conical tube, _a b_, having a length of about 15 cm., a
front aperture of about 10 cm., and a back aperture of about 4 cm.,
the choice of the material and the greater length of which is said to
be indifferent, while a greater width is said to be injurious; the
surface of the inner wall should be as smooth as possible. The narrow
back aperture of the tube is closed by a membrane, _o_, of collodion,
and upon the centre of the circular surface formed by this membrane
rests the one end, _c_, of the lever, _c d_, the supporting-point
of which, _e_, being held by a support, remains in connection with
the metallic circuit. This lever, the arm, _c e_, of which must be
considerably longer than _c d_, should be as light as possible, so
that it can easily follow the movements of the membrane, because an
uncertain following of the lever, _c d_, will produce impure tones at
the receiving station. During the state of rest the contact, _d g_, is
closed, and a weak spring, _n_, keeps the lever in this state of rest.
Upon the metallic support, _f_, which is in connection with one pole
of the battery, there is a spring, _g_, with a contact corresponding
to the contact of the lever, _c d_, at _d_, the position of which
is regulated by means of the screw, _h_. In order that the effect
of the apparatus may not be weakened by the produced waves of air
communicating themselves towards the back part, a disc “of about 50
(?) cm. diameter, which rests fixedly upon the exterior wall of the
tube,” is to be placed above the tube, _a b_, at right angles with its
longitudinal axis.

[Illustration: Fig. 34.]

The tone-receiver consists of an electro-magnet, _m m_, which rests
upon a resounding-board, _u w_, and the surrounding coils of which
are connected with the metallic circuit and the earth. Opposite to
the electro-magnet there stands an armature, which is connected with
a lever, _i_, as long as possible but light and broad, and which
lever together with the armature, is fastened like a pendulum to
the support _k_; its movements are regulated by the screw _l_ and
the spring _q_. “In order to increase the effect of the apparatus,
this tone-receiver may be placed in the one focus of an elliptically
hollowed cavity of sufficient size, while the ear of the person who
listens to the reproduced sounds ought to be placed at the second focus
of the cavity.” The action of the two apparatus, the general manner
of connection of which may be seen from the illustrations--at the one
station being the tone-indicator, at the other the tone-receiver--is
the following:--By speaking into, singing, or conducting the tones
of an instrument into the tube, _a b_, there is produced in the
tone-indicator (Fig. 34) in consequence of the condensation and
rarefaction of the enclosed column of air, a motion of the membrane,
_c_, corresponding to these changes. The lever, _c d_, follows the
movements of the membrane, and opens or closes the circuit according
as there occurs a condensation or rarefaction of the enclosed air. In
consequence of these actions, the electro-magnet, _m m_ (Fig. 13),
is correspondingly demagnetised or magnetised, and the armature (and
the armature-lever) belonging to it is set into vibrations similar to
those of the membrane of the transmitting apparatus. By means of the
lever, _i_, connected with the armature, the similar vibrations are
transmitted to the surrounding air, and these sounds thus produced
finally reach the ear of the listener (the sounding-board increasing
the effect). As regards the effectiveness of this apparatus, the author
remarks that while the similar number of the produced vibrations is
reproduced by the receiver, their original strength has not yet been
obtained by it. For this reason also small differences of vibration
are difficult to hear, and during the practical experiments hitherto
made, chords, melodies, &c., could be, it is true, transmitted with
astonishing (?) fidelity, while single words in reading, speaking, &c.,
were less distinctly perceived.

       *       *       *       *       *

    [The rest of the article deals with the “square-box”
    transmitter described in Reis’s Prospectus, and adds nothing to
    the information already published.]

[This is the last of the contemporary documents bearing upon the
performance of Reis’s instruments. From the prominent notice obtained
at the time by the inventor, it is clear that his invention was even
then accorded an honourable place amongst the acknowledged conquests
of science. A critical examination of this body of evidence proves not
only the substantial nature of Reis’s claim, but that the claim was
openly recognised and allowed by the best authorities of the time. The
thing was not done in a corner.]

FOOTNOTES:

[15] [This was the number formerly accepted on the authority of
Despretz as the minimum number of vibrations that could evoke the
sensation of a tone in the human ear. The limit now more usually
recognized is that of Helmholtz, who assigns from thirty to forty
double vibrations per second as the minimum.]--S. P. T.

[16] [The three plates or tables with which Reis accompanied his
Memoir, containing a variety of undulatory curves corresponding
to various combinations of tones, both of musical concords and of
dissonant sounds, are not reprinted in this book in their entirety.
Table I. contained three sets, the first of which is reproduced by
photo-lithography in reduced facsimile in Fig. 47, p. 173. It was also
reproduced by W. von Legat in his Report from which Plate I. at end of
this book is copied, Fig. 1 of that plate being the same as Fig. 1 of
Reis’s Table I. Fig. 2 of Plate 1, was in like manner copied by Legat
from the first figure of Reis’s Table II., and Fig. 3 of Plate I.,
which represents the curves of a non-harmonious combination is the same
as Reis’s Table III., the only difference being that in Reis’s Table
III. the irregular undulations of the resultant curve were emphasised
by being labelled ‘Dissonanz.’]--S. P. T.

[17] [This is true for speech-tones as well as for musical tones. Each
kind of tone may be represented by its own characteristic curve.]--S.
P. T.

[18] [This is the fundamental principle, not only of the telephone, but
of the phonograph; and it is wonderful with what clearness Reis had
grasped his principle in 1861.]--S. P. T.

[19] [That is, at any single demagnetisation of the needle, it vibrates
and emits the same tone as if it had been struck or mechanically caused
to vibrate longitudinally.]--S. P. T.

[20] [This range was simply due to the degree of tension of
the tympanum; another tympanum differently stretched, or of
different proportions, would have a different range according to
circumstances.]--S. P. T.

[21] [The so-called “galvanic tone” heard on opening or closing the
circuit _was_ well-known, and Wertheim had shown that this tone
was, for any given rod of iron, identical with its “longitudinal
tone,” _i.e._ the tone produced by striking it on the end so as to
produce longitudinal vibrations. But it was one of the most important
discoveries in Reis’s researches that such a rod could take up _any_
tone in obedience to the vibrations forced upon it by periodic
interruptions in the magnetising current in the spiral of any degree of
rapidity within very wide limits. The translator has had occasion to
examine this point, and has found iron, steel, and cobalt wires varying
from 4 to 10 inches in length, including some used by Reis himself as
receivers, to be capable of taking up vibrations from as slow as 40
per second to the very shrillest whistle audible to human ears, or
exceeding 36,000 per second. It is sometimes also mistakenly supposed
that such a wire can respond only to the vibrations of tones that are
musical, not to those that are articulate, including both consonants
and vowels. This, however, is an entire mistake. For, using such a
wire as a receiver (surrounded by its proper coil and mounted with an
appropriate sounding board, or, better still, tympanum), in conjunction
with a well-adjusted transmitter, the articulation transmitted
surpasses that obtainable with any of the ordinary magnetic receivers
in distinctness, though not in loudness. This discovery of Reis’s is of
the greatest importance, especially as some who ought to know better
have very unjustly denied the capability of this part of the apparatus
to act as a telephone receiver for articulate sounds.]--S. P. T.

[22] [This limit is a mistake of Professor Böttger’s. The longitudinal
tone of an unstrained iron or steel wire 10 inches long would be a
note about four octaves above the middle _c_ of the piano; whereas, in
fact, any note of the whole piano-gamut down to the lowest note, can be
reproduced by such a wire, as stated in preceding footnote.]--S. P. T.

[23] [Professor Böttger had not to wait long for the fulfilment to a
very large degree of this anticipation; for within six months Dingler’s
Journal, in which this article appeared, contained Legat’s report
on Reis’s instruments, in which not only were various modifications
in their construction made known, but also the transmission of
voice-tones, not yet perfectly but with recognisable modulations and
intonations, was recorded. Reis had, indeed, succeeded nearly as well
as this with his first instrument, as his memoir of 1861 shows. See p.
58.]

[24] [Compare ‘_Die Geschichte und Entwickelung des Fernsprechwesens_,’
a pamphlet issued officially in 1880 from the Imperial German
Post-Office in Berlin, p. 6.]

[25] [Plate VIII. of the original in Vol. IX. of the Zeitschrift.]

[26] [Plate IX. of the original Memoir.]

[27] [This word, as the context and ending of the paragraph shows,
should have been spelled _tones_. The letter, written in English by
Reis himself, is wonderfully free from inaccuracies of composition;
the slip here noted being a most pardonable one since the plural of
the German “_ton_” is “_tönen_,” the very pronunciation of which would
account for the confusion in the mind of one unaccustomed to write
in English. So far as is known, this is the only piece of English
composition ever attempted by Reis.--S. P. T.]

[28] [Reis here sketched a figure identical in all its parts with that
which a fortnight later was issued in his ‘Prospectus.’ His sketch is
reproduced in facsimile in Fig. 28.]

[29] [This was the little auxiliary signalling apparatus at the side of
the box, placed there for the same reasons as the auxiliary call-bell
attached to modern telephones.]

[30] [This word is underscored in Reis’s original letter.]

[31] [Compare Böttger Polyt. Notizbl. 1863, p. 81, the notice
translated at p. 61 preceding.]--S. P. T.

[32] [This rather obscure passage refers to the call-key or
communicator fixed to the side of the instruments, and which as the
inventor explains in his Prospectus (see p. 87), to be intended, like
the call-bell or communicator of modern telephones, as a means of
sending signals to the speaker, and which, as the Prospectus says,
can also be used--as any call-bell can--for telegraphing words by a
pre-arranged code of signals.]--S. P. T.

[33] [Fig. 30 of this book.]

[34] [References.] _Telephon von Reis_ im Jahresbericht des
physikalischen Vereins zu Frankfurt-a.-M. für 1860-1861, pag. 57 bis
64. _Müller-Pouillet_, Physik, 1863, 6. Auflage, II pag. 352, Fig. 325.
_Berl. Ber._ für 1861, xvii. pag. 171 bis 173. Der Musiktelegraph in
der “Gartenlaube” 1863, Nr. 51, pag. 807 bis 909. Aus der Natur 1862,
xxi. pag. 470 bis 484; _König’s_ Catalog, 1865, pag. 5.

[35] [This part of the apparatus is in fact a “call,” serving precisely
the same function as the call-bell attached to ordinary telephones, by
which the subscriber can be “called up” to listen to the instrument. It
is not without importance to observe that this function was perfectly
well-known at the time; for it was gravely argued during a former
telephone law-suit in England that the presence of this “signal-call”
at the side of the Reis Transmitter was a proof that it was intended
to transmit singing only _and not speech_, or “else there would not
have been that little Morse-instrument at the side by which to talk”!
This suggestion is, however, self-evidently absurd, because if this
had been the case the little electromagnetic Morse telegraph would
have been fixed, not on the side of the transmitter but on that of the
receiver. Reis himself explains the use of the “call” (see p. 87) in
his “Prospectus.”]--S. P. T.

[36] [Professor Pisko seems to have got hold of an unusually
unfortunate specimen of the instrument if he could make it neither
speak nor sing. His transmitter must have been in exceedingly bad
condition to fail so completely.]

[37] This error has been copied by Count du Moncel, along with
the other defects of the article, into the fifth volume of his
‘Applications of Electricity,’ published in 1878. It is rather amusing
now to read, at p. 106, of Du Moncel’s treatise that “Heisler” (_sic_)
“pretends” that the telephone of “Reuss,” which “appears” to have been
invented “anterior to the year 1866,” was capable of transmitting vocal
melodies! Count du Moncel, though he has since posed as an authority on
the telephone, did not in 1878 shine in that capacity, for on the very
same page of the Count’s book may be found the following astounding
sentiment:--“_If it is true_, as Sir W. Thomson has assured us, _that
at the Philadelphia Exhibition of 1876 there was a telegraphic system
transmitting words_, we may recognize,” &c. Count du Moncel has since
found out that it _is_ true that there was a Telephone in Philadelphia
in 1876: perhaps he will next discover that “Reuss” did, “anterior to
the year 1866,” actually “appear” to transmit not only what “Heisler”
“pretends” he did, but that he also transmitted spoken words.--S. P. T.

[38] Ueber Fortpflanzung der Töne auf wilkührlich weite Entfernungen,
mit Hülfe der Elektricität (Telephonie). Polyt. Journ. clxviii. 185;
aus Böttger’s Notizbl. 1863, Nr. 6. [See translation on page 61.]



CHAPTER V.

TESTIMONY OF CONTEMPORARY WITNESSES.

  1. Professor G. Quincke.
  2. Professor C. Bohn.
  3. Herr Léon Garnier.
  4. Ernest Horkheimer, Esq.
  5. Dr. R. Messel, F.C.S.
  6. Herr Heinrich Holt.
  7. Herr Heinrich F. Peter.
  8. Mr. Stephen M. Yeates.
  9. Dr. William Frazer.


                         Professor G. Quincke,

_Professor of Physics in the University of Heidelberg_.

    [Professor Quincke, whose name is so well known in connection
    with his researches in molecular physics and in many problems
    of the highest interest to those acquainted with electrical
    science, was one of those present at the Naturforscher
    Versammlung held at Giessen in 1864, where Reis’s Telephone
    was publicly exhibited by its inventor, see page 93, _ante_.
    His testimony, coming from so high authority, is therefore of
    exceptional value.]

“Dear Sir,

“I was present at the Assembly of the German Naturalists’ Association
(Naturforscher Versammlung) held in the year 1864 in Giessen, when
Mr. Philipp Reis, at that time teacher in the Garnier Institute at
Friedrichsdorf, near Frankfort-on-the-Main, showed and explained to the
assembly the Telephone which he had invented.

“I witnessed the performance of the instruments, and, with the
assistance of the late Professor Böttger, heard them for myself.

“The apparatus used consisted of two parts--a transmitter and a
receiver. The transmitter was a box, one side of which was furnished
with a tube into which the speaking was to be done. At the top or the
side of the box there was a circular opening, covered by a tympanum of
membrane, upon which was fastened a piece of platinum. This piece of
platinum was in communication with one pole of the galvanic battery.
Over the membrane, resting upon the platinum, and in contact with
it, was a piece of metal furnished with a platinum point, also in
connection with one pole of the battery.

“The receiver consisted of a common knitting needle of steel,
surrounded by a magnetising coil of insulated wire, which also formed a
part of the circuit, the whole resting on a resonant box.

“I listened at the latter part of the apparatus, and heard distinctly
both singing and talking. I distinctly remember having heard the words
of the German poem, ‘Ach! du lieber Augustin, Alles ist hin!’” &c.

“The members of the Association were astonished and delighted, and
heartily congratulated Mr. Reis upon the success of his researches in
Telephony.

  (Signed)      “Dr. G. Quincke, Professor.

  “Heidelberg, 10th March, 1883.”

       *       *       *       *       *

                          Professor C. Bohn.

    [Professor C. Bohn, of Aschaffenburg, was formerly Secretary
    to the German “Naturforscher” Association, was also Secretary
    to the Physical Section of this Society (vide p. 93). In that
    capacity he had every opportunity of knowing what was going on
    in science; hence the following (translated) letter, addressed
    to the author of this book, is of peculiar value.]

“Most esteemed Sir,

“I willingly answer, as well as I am able to do so, the questions put
by you. In order to explain that my recollections may not have all
the sharpness that might be wished, I make the following prefatory
statement. I have, about 1863, held numerous conferences with Mr.
Reis and with my deceased colleague, Professor H. Buff, of Giessen,
and on these occasions have argued the question how it is that the
transmission of thoughts to a distance by the sensation of the ear has
a distinctly less value than transmission by that which is written....

“And now to your questions. I was not at Stettin in 1863. At the
experiments at Giessen in the Naturforscher Assembly on 21st
September, 1864, I was present; the short notice about them in
the journal (‘Tagesblatt’) is from my pen. I was Secretary of the
Assembly and of the Physical Section. I remember, however, almost
absolutely nothing about _these_ experiments. But I remember well that
_previously_--therefore probably as early as 1863--having jointly made
the experiments with Reis’s telephone in Buff’s house in Giessen....
I have _myself_, as speaker and as hearer, at least twice, in the
presence of Reis, made the experiments.

“It was known to me (in 1863-64) that Reis intended to transmit words,
and certainly spoken words as well as those sung. My interest in the
matter was, however, a purely scientific one, not directed to the
application as a means of profit.

“With great attention the sense of the words was understood. I have
understood such myself, without knowing previously what would be
the nature of the communication through the telephone. Words sung,
especially well accentuated and peculiarly intoned, were somewhat
better (or rather less incompletely) understood than those spoken in
the ordinary manner. There was indeed a boy (son of Privy-Councillor
Ihering, now of Göttingen, then of Giessen), who was known as specially
accomplished as a speaker. He had a rather harsh North-German dialect,
and after the first experiments hit on the right way to speak best,
essential for understanding. I myself _did not_ understand Professor
Buff through the telephone. Whether the speaker could be recognized
by his voice I doubt. We knew beforehand each time who speaks. Yet I
remember that a girl could be distinguished from that boy by the voice.

“The ear was at times laid upon the box of the apparatus, also upon the
table which supported the telephone. Then it was attempted to hear at a
distance, with the ear in the air; in this respect, when singing, with
good result. At times the lid was taken off, or the same was connected
more or less tightly or loosely with the lower part. The result of
these changes I can no longer give with distinctness....

“Should you desire further information, I am ready to give you it
according to my best knowledge.

  “Hochachtungsvoll ergebenster,
  “Dr. C. Bohn.

  “Aschaffenburg,
  “_10th September, 1882_.”

       *       *       *       *       *

                             Léon Garnier.

    [Herr Léon Garnier, Proprietor and Principal of the Garnier
    Institute at Friedrichsdorf, is the son of the late Burgomaster
    Garnier, who founded the establishment, and who, as previously
    narrated, encouraged Philipp Reis in his work and offered him
    the post of teacher of Natural Science. Herr Léon Garnier owns
    the small collection of instruments which Reis left behind, and
    which are preserved in the Physical Cabinet attached to the
    Institute, where also may be seen the gravitation machine--an
    ingenious combination of the principles of Atwood’s and Morin’s
    machines--and the automatic weather-recorder invented by Reis,
    both, however, very greatly out of repair. Herr Garnier has
    furnished to a friend the following particulars about Reis and
    his invention.]

“I knew Philipp Reis, now deceased, during his life-time.... About the
year 1859, he was employed by my father, then proprietor and director
of the Friedrichsdorf Garnier Institute, as teacher of mathematics and
natural sciences. He employed his hours of leisure in experimenting
for himself in a house occupied by himself, and in which he had
established a physical laboratory with a view mainly of realizing
an idea which he had conceived sometime before of transmitting the
human voice over divers metallic conductors by means of a galvanic
current.... I remember especially, that, standing at the end of
the wire or conductor, Mr. Reis speaking through his instrument, I
distinctly heard the words: ‘Guten Morgen, Herr Fischer’ (Good morning,
Mr. Fischer); ‘Ich komme gleich’ (I am coming directly); ‘Passe auf!’
(Pay attention!); ‘Wie viel Uhr ist es?’ (What o’clock is it?); ‘Wie
heisst du?’ (What’s your name?) We often spoke for an hour at a time.
The distance was about 150 feet.

  “Léon Garnier.”

       *       *       *       *       *

                  Ernest Horkheimer, Esq.
                               “Manchester, _Dec. 2, 1882_.

  “Professor S. P. Thompson,
    “Dear Sir,

“In reply to your favour of 31st instant, I shall be very happy to
give you all the information I can with respect to the telephonic
experiments of my late friend and teacher Mr. Philipp Reis. I would
express my gratification at finding that you are trying to put my old
teacher’s claims on their just basis. I have always felt that in this
race for telephonic fame, his claims have been very coolly put aside
or ignored. That he did invent the Telephone there is not the remotest
doubt. I was, I think, a great favourite of his; and at the time his
assumption was that I was destined for a scientific career, either
as a physicist or a chemist; and I believe that he said more to me
about the telephone than to any one; and I assisted him in most of his
experiments prior to the spring of 1862.

“Philipp Reis intended to transmit speech by his telephone--this
was his chief aim; the transmitting of musical tones being only an
after-thought, worked out for the convenience of public exhibition
(which took place at the Physical Society at Frankfort-on-the-Main). I
myself spent considerable time with him in transmitting words through
the instruments. We never (in my time) got the length of transmitting
complete sentences successfully, but certain words, such as ‘_Wer da?_’
‘_gewiss_,’ ‘_warm_,’ ‘_kalt_,’ were undoubtedly transmitted without
previous arrangement. I believe Reis made similar experiments with his
brother-in-law.

[Illustration: Fig. 35.]

[Illustration: Fig. 36.]

“I recollect the instrument in the shape of the human ear very well:
it was Reis’s earliest form of transmitter. The transmitter underwent
a great many changes, even during my time. The form you sketch (Fig.
9, p. 20) was almost the oldest one, and was soon superseded by the
funnel-shape (Fig. 35). The back was always closed by a tympanum
of bladder, and many a hundred bladders were stretched, torn, and
discarded during his experiments. I recollect him stating to me that
he thought a very thin metal tympanum would eventually become the
proper thing, and one was actually tried, coated over on one side with
shellac, and on the other likewise, except at the point of contact
(Fig. 36). I believe it was made of very thin brass, but at the time
the experiments were not satisfactory. Talc was also tried, but without
success, the platinum contacts being in all cases preserved.

“I remember very well indeed the receiver with a steel wire, surrounded
by silk-covered copper wire. The first one was placed on an empty
cigar-box, arranged thus:--

[Illustration: Fig. 37.]

“The wire was a knitting-needle and the copper wire was spooled on a
paper case.

[Illustration]

“The spiral was supported by a little block of wood, so as to allow the
knitting-needle not to touch it anywhere. Later on a smaller cigar-box
was invented as a cover--thus; (Fig. 38)--having two holes cut into it
like the _f_-holes in a violin.

[Illustration: Fig. 38.]

“The practice was to place the ear close to the receiver, more
particularly so when the transmission of words was attempted.

“The spiral was, during the early experiments, placed on a violin--in
fact, a violin which I now possess was sometimes used, as it was of a
peculiar shape, which Reis thought would help the power of tone.

“I have already enumerated some of the words which were transmitted,
but there were many more; on one occasion a song, known in this country
as ‘The Young Recruit’ (Wer will unter die Soldaten) was transmitted,
the air and _many_ of the words being clearly intelligible.

“I do not recollect seeing the receiver shewn in the woodcut (Fig.
21), but Reis often said that he would make such a one, although the
sketch he made for me then differed in some details from your woodcut.
Reis intended to keep me fully informed of all he could achieve,
but, immediately after leaving his tuition, I fell ill, and was laid
up for a very long time. Shortly afterwards I left for England, and
then he died, and I never saw him again. The electromagnet form was
certainly strongly in his mind at the time we parted, and he drew many
alternative suggestions on paper, which have probably been destroyed;
but the electromagnets in all of them were placed upright, sometimes
attached to the top of a hollow box, and sometimes to the bottom of a
box arranged thus (Figs. 39, 40); but, to my recollection, they never
got beyond the stage of drawings, whatever he may have done after he
and I parted company.

[Illustration: Fig. 39.]

[Illustration: Fig. 40.]

“In conclusion, I beg to send you herewith a photograph of Philipp
Reis (see Fig. 12, p. 23), holding in his hand the instrument I helped
him to make, and which photograph he took of himself, exposing the
camera by a pneumatic arrangement of his own, and which formed part
of a little machine which he concocted for turning over the leaves of
music-books.

“The instrument used by Reis at the Physical Society may have been
the square block form: I believe that this cone-form was not quite
completed then. At the Saalbau (Hochstift), however, I am _sure_ the
instrument shown in my photograph was employed; not with a tin cone,
but a wooden one. I send you herewith a sketch of what I remember that
instrument to have been. I am not absolutely certain whether in the
instrument there was not an electromagnet introduced, but I think not.
My recollection leads me to suppose that the electromagnet arrangement
was added subsequently. Thinking it over again, I should, however,
think that the instrument in the photo must have been one in which a
bent lever was placed behind the tympanum, and that the rectangular
patch seen above was a wooden casing to shelter the parts. There may
be some confusion in my mind as to the position of this box, but I
somehow think the rectangular patch is only part of a larger box which
is not apparent in the photograph. I have no idea where the original
instrument is now, but I should hardly think it could be in existence.
Reis used to take some instruments to pieces to utilise parts in
subsequent experiments, and I recollect how keen he used to be about
the bits of platinum, which he always described as ‘ein sehr kostbares
Metall.’ What always was a great puzzle was the attaching of the
platinum plate to the membrane, which he did generally by sealing-wax,
saying at the same time: ‘Es ist nicht recht so, aber ich weiss nicht
wie es anders gemacht werden kann!’

  “Believe me, my dear Sir, yours truly,
                               “Ernest Horkheimer.”

       *       *       *       *       *

                          Dr. Rudolph Messel.

    [The following letter from Dr. Rudolph Messel, F.C.S.,
    addressed to the author of this book, in reply to enquiries
    concerning Reis and his inventions, speaks for itself. Dr.
    Messel’s letter differs from almost all the others here
    reprinted in having been specially written for the purpose of
    being inserted in this volume.--S. P. T.]

                       “36, Mark Lane, London, _30th April, 1883_.
  “Dear Professor Thompson,

“At last I find a moment to comply with your request. My knowledge
of Philipp Reis dates from 1860, when I was a pupil at Professor
Garnier’s School at Friedrichsdorf, of which school Reis was one of
the undermasters. Reis, naturally communicative, was very fond of
talking to us boys about his scientific researches. And it was on the
occasion of one of our daily walks together that he told me how, when
an apprentice at Beyerbach’s (colour-manufacturer), in Frankfurt-a.-M.,
he was one day amusing himself in watching the behaviour of a small
magnetic compass. This compass he found, on being placed near to
the base of various iron columns in the warehouse, was attracted.
Disturbed by the entrance of one of the principals, who imagined
that Reis ought to employ his time more profitably, he withdrew to a
stage where he could pursue his experiments unobserved. Much to his
surprise, he now found that the pole attracted by the base was repulsed
at the top of the columns, which observation led him to examine
other pieces of iron on the premises. He next built up a column with
all the weights in the warehouse, and having verified his previous
observations, he communicated what he believed to be his first and
great discovery either to Professor Böttger or to Dr. Oppel. Great was
his disappointment to learn at this interview that he had unwittingly
stumbled across a well-known physical fact: but his disappointment
stimulated in him the desire to learn more of the marvellous laws and
mysteries of nature. That Reis evoked a similar desire in those with
whom he came in contact need not cause surprise, and thus it came
about that Horkheimer, Küster, Schmidt, and myself, soon enjoyed the
privilege of private instructions in physics, and of being permitted
to witness his telephonic experiments amongst others. I was, however,
very young, and am sorry that much that I then saw and heard has been
forgotten, Reis insisted that his transmitter (which he called the
‘ear’) should be capable of performing the functions of that organ, and
he never tired of drawing diagrams of the numerous curves of sounds to
explain how necessary it was that the transmitter should follow these
curves before perfect speaking could be attained, and which kind of
curves the instrument so far could reproduce. Numerous experiments
were made with transmitters, exaggerating or diminishing the various
component parts of the ear. Wooden and metallic apparatus, rough and
smooth, were constructed in order to find out what was essential, and
what was not.

[Illustration: Fig. 41.]

“One form of transmitter was at that time constructed which I miss
amongst the various woodcuts you were good enough to send me, and one
which Reis based great hopes upon. The instrument was very rough,
however, consisting of a wooden bung of a beer-barrel (which I had
hollowed out for an earlier telephone--it was not turned inside
like others), and this was closed with a membrane. The favourite
‘Hämmerchen’ was replaced by a straight wire, fixed in the usual way
with sealing-wax, and the apparatus stood within a sort of tripod,
membrane downwards, the pin just touching the surface of a drop of
mercury contained in a small cup forming one of the terminals of the
circuit. The apparatus started off with splendid results, but may
probably have been abandoned on account of its great uncertainty,
thus sharing the fate of other of his earlier instruments. In my
belief it is to these mechanical imperfections, due principally to
the want of sufficient means at his command, that we must look to
find the reason why Reis’s telephone did not come to an earlier fame.
Thus Reis informed me that he intended to exhibit it once at some
scientific meeting at Cassel, but notwithstanding a perfect rehearsal
it was impossible to show the working to the audience; the failure
was attributed by Reis to atmospheric influence (stretching of the
diaphragm), and he felt much grieved at having lost his chance. To
make matters worse, the early transmitters had no adjusting screws,
and the contact was only regulated by a piece of bent wire, and the
‘hammer’ was fixed to the membrane. Philipp Schmidt should recollect
what I state, as many experiments were made when only he, Reis, and
myself were present, he being at one and I at the other end of the
apparatus. The wire was stretched from Reis’s house, in the main road,
through the yard to a hayloft, near the garden or field. We transmitted
musical sounds (organ, &c.), singing popular songs (‘Wer will unter die
Soldaten,’ ‘Ich hatt’ einen Kameraden,’ &c.) and speaking, or, more
correctly, reading. We had a book, and were to find out what part of
the page the reader was just transmitting. We frequently used a sort
of ‘Exercier Reglement,’ a soldiers’ instruction book, or something of
that sort. I have a distinct recollection of electromagnetic receivers
being used, but not of their construction, except that the use of
one of them was accompanied by a rattling and disturbing noise. The
knitting-needle put in the _f_ of a violin was, however, the more
favoured receiver, but at this time, in Reis’s mind, all seemed to
hinge on the electromagnet, as it had before, and, I dare say, did
again afterwards on the transmitter. I left Friedrichsdorf in ’62, and
rarely saw Reis after that, except a few times at Mechanicus Albert’s
(who made some of his apparatus), and at Professor Böttger’s, to whom
he introduced me. Reis attended Professor Böttger’s lectures at the
Physikalischer Verein, when in Frankfort, prior to his settling down
at Friedrichsdorf; but I do not know that any particularly intimate
relation existed between them. Dr. Poppe, director of the Gewerbeschule
(Trade School), now deceased, on whose advice he chiefly relied,
was then one of his more intimate friends, Professor Oppel being
occasionally consulted about more intricate mathematical problems. Of
the ‘meteorological recorder’ invented by Reis I recollect but its
existence, but nothing at all of a ‘fall-machine’ of his construction.
The velocipede I only recollect, because he lent it to me for a
masquerade. At his suggestion we altered it into a large musical-box,
putting Herr Peter inside, who played on the clarinet when I turned
a handle. Dr. Kellner states that its chief merit consisted in being
able to go downhill, and that poor Reis came back (uphill) puffing
away, dragging his velocipede behind him. Kellner no doubt could give
valuable information on Reis’s theory of electricity, his conviction
that there was only one kind of electricity, his acoustic researches,
and those on radiation of electricity, his galvanoplastic experiments,
&c., &c.

“In personal appearance Reis was not very refined, but he had a
striking countenance and a very powerful look. Though occasionally
very irritable, especially with dunces, he was always warm-hearted,
and showed great kindness to those who cared to understand him. Reis’s
views of the telephone may, of course, have changed after I knew
him, and looking at his later instruments, one of which I possess, I
cannot help thinking they did; at any rate, I do not see how, in these
instruments, the current got interrupted at all, and the instruments
must have acted like microphones, whether known or unknown to him. When
listening to the instrument he frequently said to me, “You understand
it is a ‘molekular Bewegung’ (molecular motion).

“I am sorry that, owing to the lapse of time, I am unable to throw
more light on Reis’s original labours in a field of physical science
which promised so much for the future; but insufficient as are my
recollections, they may not be without public interest, and at any rate
I am glad of this opportunity of offering my humble tribute of regard
and affection to the memory of my old teacher and friend.

  “Yours truly,
         “Rudolph Messel.”

       *       *       *       *       *

                            Heinrich Hold.

    [Herr Hold, formerly a colleague of Philipp Reis in the Garnier
    Institute at Friedrichsdorf, but now proprietor of a leather
    factory in the same place, was teacher of mathematics. He was
    in his younger days a fellow-student of Professor Tyndall
    at Halle, and was well acquainted with physical science in
    general. His intimate connection with Reis, and close knowledge
    of Reis’s work, enable him to confirm the testimony of others
    in many important points.]

  To Professor S. P. Thompson in Bristol.

  “Esteemed Sir,

“I have much pleasure in furnishing you with the following particulars
concerning my late colleague Philipp Reis, the inventor of the
Telephone. He was himself educated at the Garnier’s Institute in
Friedrichsdorf where I was also teacher of mathematics. I knew him very
well during his life-time. Among his numerous original researches,
his invention of the telephone was the principal one. His idea was
to reproduce the tones both of musical instruments and of the human
voice by means of electricity, using a covered wire wound in a spiral
round an iron core, the same being placed upon a resonant box. In
this he succeeded, inasmuch as with an apparatus, which he showed
to the Physikalischer Verein in Frankfurt-a.-M., in the year 1861,
he reproduced music, singing, single words and short sentences; all
of which were distinctly audible over a short distance from his
dwelling-house through the yard to the barn. Every voice was not
equally well adapted for speaking into the apparatus, neither could
every ear understand the telephone language equally well. Words spoken
slowly, and singing, both in a middle tone, were the most easy to
reproduce. I helped Mr. Reis to make many of his experiments, and have
spoken and sung into the telephone, the same being generally heard and
understood. I have also heard and understood short sentences when I was
standing at the end station. A brother-in-law of Mr. Reis, who is now
paymaster in the Imperial Navy at Wilhelmshavn, generally conducted the
speaking and singing in the telephone.

  “Heinrich Hold.”

       *       *       *       *       *

                       Heinrich Friedrich Peter.

    [Herr Peter is still Music-teacher in the Garnier Institute,
    and has a vivid recollection of his former colleague Philipp
    Reis, and of the experiments with the telephone.]

  “Dear Sir,

“The following particulars concerning Reis’s Telephone I have several
times narrated. I was teacher of music in Garnier’s Institute at the
time when Mr. Reis invented the telephone, in the year 1861. I was much
interested in his experiments, and visited him daily, giving him help
and making suggestions. His first idea was to imitate the construction
of the human ear. He constructed a funnel-shaped instrument, the back
of which was covered with a skin of isinglass, upon which was fastened
a piece of platinum, against which rested a platinum point. As receiver
of the electric current he used a common knitting-needle, surrounded
by a coil of insulated green wire, which was at first merely laid on a
table. At first the tones were very much interfered with by a buzzing
noise. At my suggestion he placed the spiral upon my violin as a
resonant-box; whereupon the tones were perfectly understood, though
still accompanied by the buzzing noise. He continued experimenting,
trying various kinds of membranes, and made continual improvements
in the apparatus. I was present and assisted at the experiments at
Frankfort-on-the-Main, on the 26th of October, 1861; and after the
meeting broke-up, I saw the members of the Society as they came and
congratulated Mr. Reis on the success of his experiments. I played
upon the English horn, and Philipp Schmidt sang. The singing was
heard much better than the playing. At an experiment which we made
at Friedrichsdorf, in the presence of Hofrath Dr. Müller, Apothecary
Müller, and Professor Dr. Schenk, formerly Director of Garnier’s
Institute, an incident occurred which will interest you. Singing was
at first tried; and afterwards his brother-in-law, Philipp Schmidt,
read long sentences from Spiess’s ‘Turnbuch’ (Book of Gymnastics),
which sentences Philipp Reis, who was listening, understood perfectly,
and repeated to us. I said to him, ‘Philipp, you know that whole
book by heart;’ and I was unwilling to believe that his experiment
could be so successful unless he would repeat for me the sentences
which I would give him. So I then went up into the room where stood
the telephone, and purposely uttered some nonsensical sentences, for
instance: ‘Die Sonne ist von Kupfer’ (The sun is made of copper),
which Reis understood as, ‘Die Sonne ist von Zucker’ (The sun is made
of sugar); ‘Das Pferd frisst keinen Gurkensalat’ (The horse eats no
cucumber-salad); which Reis understood as ‘Das Pferd frisst....’ (The
horse eats ...). This was the last of these experiments which we tried.
Those who were present were very greatly astonished, and were convinced
that Reis’s invention had opened out a great future.

  “H. F. Peter, Musiklehrer.”

       *       *       *       *       *

                     Stephen Mitchell Yeates, Esq.

[Illustration: Fig. 42.]

    [Mr. Yeates is a well-known instrument-maker in the city of
    Dublin, and in 1865, purchased from Mr. W. Ladd, of London,
    a Reis’s Telephone of the form shown in Reis’s Prospectus
    (Fig. 29). Mr. Yeates, after a few experiments, rejected the
    knitting-kneedle receiver, and replaced it by the instrument
    shown in Fig. 42, which consisted of an electromagnet mounted
    above a sound-box, having a vibrating armature furnished
    with an adjusting screw to regulate its distance from the
    poles of the electromagnet. This instrument worked, even when
    the armature was in absolute contact with both poles of the
    electromagnet, and as the magnet did not during the experiments
    lose its hold on the armature, it was clear that the effects
    were due to alterations in the intensity of the magnetism of
    the magnet. The apparatus was shewn at the November meeting
    of the Dublin Philosophical Society, when singing and words
    were transmitted. With a careful adjustment it was possible
    to distinguish all the quality of the note sung into the
    transmitter and to distinguish the difference between any
    two voices. The instruments were then sold to the late Rev.
    Mr. Kernan, who was then Professor of Physics in Clongowes
    Wood College. The following recent letter from Mr. Yeates
    corroborates the above facts.]

                                       “2, Grafton Street, Dublin,
                                          “_March 1st_, 1883.

  “Dear Sir,

“There are several residing at present in Dublin who were present at my
telephonic experiments in 1865; three of them, namely, Dr. W. Frazer,
Mr. A. M. Vereker, and Mr. E. C. Tuke, took an active part in the
experiments, and remember all the circumstances connected with them.
The voice of each was instantly recognised in the receiver; in fact,
this point attracted special attention at the time.

“I had no knowledge at that time that Reis had used an electromagnetic
receiver, nor did I know that Reis was the inventor of the instrument
which I got from Mr. Ladd.

“The original instrument made by me is, I believe, still in the Museum
at Clongowes Wood College. The President kindly lent it to me some
time ago, and I returned it to him again after showing it to Professor
Barrett. I have a cut of this receiver, which I will send to you if it
will be of any use to you.

  “Yours truly,
    “S. M. Yeates.”

       *       *       *       *       *

                     William Frazer, Esq., M. D.,

                                     “20, Harcourt Street, Dublin,
                                            “_March 13_, 1883.

  “Dear Sir,

“I have a distinct recollection of the Telephone. We had a small
private club meeting once each month for scientific purposes. On
referring to my note-books, I find that there was a meeting on Thursday
evening, October 5th, 1865. It was held in Nassau Street, at the
residence Mr. Horatio Yeates, now in Australia, and brother of Mr.
Stephen Yeates. The Telephone was upstairs, in the third story of the
house, and the voice heard in the hall. Mr. Vereker, of the Bank of
Ireland, Mr. John Rigby, of rifle celebrity, the two Mr. Yeates, and, I
think, Mr. Tuke, were present with myself. There were some others, whom
I cannot now recollect, but our club was small.

“Rigby sang ‘Patrick’s Day’ and ‘God save the Queen,’ and various
questions were asked and answered. The separate words were most
distinct, the singing less so; but there was no difficulty in
recognising the individual who spoke by his voice.

“Being much interested in the subject, I got Mr. Yeates to allow the
apparatus to be shewn at a Conversazione (Presbyterian Young Men’s)
at the Rotunda on October 12, at 8 P.M. His assistant, Mr. Tuke, took
charge of it that night. It was placed in a side room off the main
round room of the buildings.

“I exhibited at the October 5th meeting of our club a specimen termed
‘Locust gum,’ probably derived from some _Robinia_, but really can tell
you nothing more about it. There is merely a brief note of it in my
private memoranda.

      “Yours, dear Sir,

          Believe me very truly,

              “William Frazer,

     “Fellow and Examiner, Royal College of Surgeons,
     “Ireland, Member of Council, Royal Irish
     “Academy, &c.”

  “Silvanus P. Thompson, Esq., University College, Bristol.”



APPENDIX I.

COMPARISON OF REIS’S TRANSMITTERS WITH RECENT INSTRUMENTS.


Any one who compares together the many different forms of Reis’s
Transmitters cannot fail to notice that amidst the great variety of
form, two essential points are preserved throughout, the presence
of which is fundamental. These two essentials are, firstly, the
tympanum to collect the voice-waves, and, secondly, an electric
mechanism, consisting of two or more parts in loose or imperfect
contact with each other, and so arranged in combination with the
tympanum that the motions of the latter should alter the degree of
contact, and consequently interrupt, to a greater or less degree,
the current of electricity flowing between the contact-pieces. It
was of course familiar to all electricians, long before Reis, that a
bad, or imperfect, or loose contact in a circuit offered a resistance
and interrupted the flow of an electric current. In all ordinary
telegraphic and electric apparatus great care was taken to avoid loose
and imperfect contacts by using clamping-screws and solid connectors.
But Reis, having made up his mind (see p. 77) that the action due to
the magnetising current must vary in a manner corresponding with, and
therefore proportional to, the vibrations of the voice, utilised this
property of imperfect contacts which alter their resistance according
to the degree of contact, by arranging his mechanism so as to apply
the voice to vary the degree of contact. This was the essence of his
transmitters. In other words, he applied the voice to control or
moderate the strength of the current generated by a battery. His
“interruptors” may therefore with propriety be called “electric current
contact regulators;” and put into technical language, the essence of
this part of his invention lay in the combination with a tympanum of
electric current regulators working upon the principle of variable
contact.

In another appendix is discussed the precise nature of that which
occurs at a point of variable or imperfect contact, and which results
in a corresponding change of electrical resistance when the degree of
contact is varied. Suffice it to say here that it is impossible to vary
the degree of contact between two bodies which are lightly pressing one
against the other, and through which an electric current is flowing,
without altering the resistance offered to the current by this joint in
the circuit. If the two surfaces are pressed together, so that there is
a good contact, the current flows more freely, finding less resistance.
If, on the other hand, by altering the pressure or the amount of
surface exposed, we change the degree of contact and cause fewer atoms
of one piece to touch those of the other piece, the current meets with
greater obstruction and cannot flow with such strength as before: it is
partially “interrupted,” to use the expressive term employed by Reis.

Now this operation of varying the degree of pressure in order to vary
the resistance of the interrupter or contact regulator, was distinctly
contemplated by Reis. We find his definite instructions, for example
(see p. 75), for arranging the relative lengths of the two parts of
the curved lever in one of his transmitters, so that the movement of
one contact-piece may act on the other contact-piece with the greatest
possible _force_; in other words, he shortened his lever at the working
end, sacrificing its range of motion in order to get a greater range of
pressure at the contact-point.

It has often been said, but incorrectly, that Reis intended his
“interruptors” or contact regulators to make and break the electric
circuit abruptly in the manner of a telegraphic key worked by hand.
No doubt in the mouth of a professional telegraph operator the words
“interrupting” the circuit, and “opening” and “closing” the circuit,
do now-a-days receive this narrow technical meaning. But Reis was not
a professional telegraph operator: he did not (see p. 87) even know
the signals of the Morse code, and it is self-evident that he did not
use the terms in any such restricted or unnatural sense as abrupt
“make-and-break,” because he proposed at the outset to interrupt the
current in a manner represented by the gradual rise and fall of a
_curve_, stating emphatically in his very first memoir on telephony (p.
55), that to reproduce any tone or combination of tones all that was
necessary was “to set up vibrations whose curves are like those” of the
given tone or combination of tones. Moreover, in the construction of
almost all his transmitters, even in the very first--the model of the
human ear--he purposely introduced certain parts which could have no
other effect than to prevent the occurrence of complete breaks in the
continuity of the current. In fact, instead of using rigid supports
for his interruptor, he mounted one or both of the contact-parts
with springs, so that one should follow the movement of the other
with a gentle pressure never amounting to absolute break, except
perhaps in the accidental case of a too loud shout. By employing these
following-springs, he introduced, in fact the element of _elasticity_
into his interruptor; and clearly he introduced it for the very purpose
of avoiding abrupt breaking of the contact. In the first form Fig. 5,
p. 16 (the “ear”), there was one spring; in the fourth form, Figs.
9 and 10, p. 21 (the “bored block”), there were two springs, one of
steel, curved, and one, a straight but springy strip, of copper; in
the eighth form (the “lever” form), Fig. 14, p. 25, there were two
springs; in the ninth form, Fig. 15, p. 26, there was a springy strip
of brass. In the final form, Figs. 17 and 18, p. 27 (the “square-box”
pattern), there was, it is true, a springy strip of copper, but the
light adjustment of contact was in this form obtained, not by a spring,
but by the inertia of the upper contact-piece which by its own weight
pressed gently upon the lower contact-piece. In every one of these
forms, except the last, there was moreover an adjusting-screw to
determine the exact degree of initial pressure between the contact
surfaces. Doubtless the difficulty of adjusting this screw to give the
exact degree of contact, enhanced as that difficulty was in consequence
of the liability of the membraneous tympanum to become flaccid by the
moisture of the breath, induced Reis to think that the later form of
the apparatus in which this adjustment was no longer retained would be
more easy to use, or, as he says in his Prospectus, more accessible
to others. Yet undoubtedly the absence of the spring at the contacts
led some persons to fancy that the instrument was intended to be
shouted or sung to so loudly that every vibration should make the
upper contact-piece jump up from the lower, and as Professor Müller
even suggests (p. 98), produce a spark! But such a manner of using the
instrument would entirely defeat Reis’s most fundamental principle,
that the interruptions should be such as to correspond to the
_undulating curve_ which represents the pressure due to vibration of
the sound-wave; the possibility of representing the degree of pressure
by a curve being one of the two principles set forth in his paper “on
Telephony” (p. 55), in which he remarks, that “Taking my stand on the
preceding principles, I have succeeded in constructing an apparatus by
means of which I am in a position to reproduce ... even to a certain
degree the human voice.” Reis was perfectly well aware, as his curves
show, that a complicated sound-wave does not consist invariably of
_one_ condensation followed by _one_ rarefaction, but that there are
all sorts of degrees of condensation which may follow one another, and
all capable of being represented by a curve. If all sounds consisted of
one rarefaction following immediately after each one condensation there
might be some propriety in proposing that after each “make” of contact
there should be a “break” in the sense of an abrupt or complete breach
in the continuity of the current. But, obviously, the fact that one
condensation may follow another without a rarefaction between (which
Reis’s curves show that he knew) must be amply sufficient to prove
that on Reis’s own principle _his interruptor was meant to produce
variations in the degree of contact in exact correspondence with the
variations in the degree of pressure_, whatever these might be. Had he
not meant this, he could not have talked about “taking his stand” on
the principle of representing varying pressures by an undulatory curve.
Now, from what has been adduced, the following points are clear:--

_Firstly_, that the contact-regulator which Reis combined with the
tympanum was meant to interrupt the current, more or less, according to
the varying movements imparted to it by the voice.

_Secondly_, that Reis intended such interruptions or variations of
contact to be proportional to, or to “correspond” with, the variations
indicated by the undulatory curve of varying pressures.

_Thirdly_, that for the purpose of preventing the occurrence of abrupt
breaks in the continuity of the circuit, he used springs and adjusting
screws, and in one form availed himself of the inertia of the moving
parts to attain a similar end.

It is also clear from his own prospectus, that he was aware that for
the simpler and ruder purpose of transmitting musical airs, in which
the number of the vibrations is the only consideration and where each
single condensation is actually followed by a rarefaction, actual
abrupt breaks in the continuity of the circuit are admissible. Reis
chose this simple case as the one capable of being readily grasped by
a general audience, though it was obviously only a partial explanation
of the action of the apparatus in the simplest case that could be
presented.

       *       *       *       *       *

Turning now to some of the more modern transmitters, we will
inquire how far Reis’s fundamental principles are involved in their
construction. We will first take Berliner’s transmitter, of which Fig.
43 is a drawing, reproduced from the sketch in the specification of his
British Patent. This transmitter consists of a tympanum of thin metal
to collect the sound-waves, and behind it is attached an interrupter
or current regulator, identical in almost every respect with that of
Reis. One of the contact-pieces, marked _E_, circular in form, is fixed
to the centre of the tympanum, and vibrates with it, precisely as in
Reis’s latest, and in some also of his earlier instruments. Against
this there rests in light contact a second contact-piece, in the form
of a small blunt spike, _F_, screwed into a short arm, loosely jointed
to the part _N_, where the circuit is connected. As in Reis’s latest
transmitter (Fig. 17, p. 27), so here, the contact-pieces are kept in
contact by gravity. When any person talks to the tympanum it vibrates,
and, as a result, the degree of contact between the two surfaces is
varied, resulting in a greater or less interruption of the current, the
inertia of the upper contact-piece, serving to prevent complete abrupt
“break” of the circuit, except under unusually strong vibrations. In
fact, if the speaker talks too loudly when speaking into Berliner’s
transmitter, he will cause abrupt breaks to occur instead of partial
interruptions; and a rattling noise comes in to confuse the speech
at the receiving end of the line. But this is precisely what occurs
in a Reis’s transmitter if one talks too loudly to it. It is obvious
that if Berliner’s transmitter is a “make-and-break” instrument, so
is Reis’s, because the principle of action is identical: and it is
also obvious that if Berliner’s instrument is capable of varying the
resistance at the contact-points by interrupting the current in a
manner corresponding to the pressures of the air in the sound-waves, so
also is Reis’s instrument.

[Illustration: Fig. 43.]

It is a fact that in Berliner’s instrument it is usual to make the
contact-pieces, or one of them, of hard artificial coke-carbon, as
this substance will neither fuse nor rust. But Berliner’s transmitter
will transmit speech perfectly if the contact parts be of brass,
silver, platinum, carbon, or almost any other good conductor. In most
of Reis’s instruments the contact-pieces were usually of platinum; but
they work quite as well if artificial coke-carbon is substituted. In
fact, Reis’s principle of variable and elastic contact is applicable
to contact-pieces of _any material that is a good enough conductor of
electricity_ and hard enough for the purpose. The main improvement in
Berliner’s transmitter is the substitution of the metal tympanum for
the membraneous one, which was liable to become flabby with moisture.

[Illustration: Fig. 44.]

We pass on to Blake’s transmitter, which is the one more generally
used in Great Britain than any other. The drawing, Fig. 44, of this
instrument is taken from the specifications of Blake’s British Patent,
and shews all that concerns the contact-parts. It does not show the
accessories, the induction-coil, or the form of adjusting screw and
frame peculiar to this instrument. Inspection of the figure shows that
this transmitter consists of a mouthpiece in the form of a conical
hole bored through a stout plank of wood, and closed at the back by a
metal tympanum of exactly the same size as that of Reis, behind which
the interruptor is placed, precisely as in some of Reis’s instruments.
In this interruptor both the contact-parts are supported on springs,
resembling, even in the curve given to them, the springs Reis used.
The first of the contact-pieces is a small metal spike. Concerning it
Mr. Blake remarks (page 4 of Specification):--“It is desirable that
it should be formed of, or plated with, some metal, like platinum or
nickel, which is not easily corroded. It may be attached directly to
the diaphragm, but I prefer to support it independently, as shewn, upon
a light spring.” ... “This method of supporting the electrode _ensures
its contact_ with the other electrode _under some circumstances
when otherwise they would be liable to be separated and the circuit
broken_.” In fact this spring serves functions precisely identical with
those of the springs used by Reis. The second of the contact-pieces
may be described as a mass of metal at the end of a spring. Of it
the patentee remarks:--“This weight may be of metal which may serve
directly as the electrode, but I have obtained better results by
applying to it, at the point of contact with the other electrode, a
piece of gas-coke or a hard-pressed block of carbon.” As a matter
of fact, a mass of silver or of nickel or of platinum will transmit
talking perfectly, but these metals, though better conductors, are more
liable to corrode and fuse, and may require therefore more frequent
renewal, than gas-coke. Since, then, it is immaterial to the action
of a Blake transmitter what substance is used for the contact-pieces,
it is clear that the principle of employing an interruptor mounted on
springs is the real feature of the instrument. Reis also mounted his
interrupters with springs, and for the very same purpose. The function
of the weight on the second spring of the Blake transmitter is to
resist the movement of the tympanum, and to “modify by its inertia
the variations of pressure” between the two contact-pieces. In other
words, it acts partly as Berliner’s transmitter, by inertia. So did
one of Reis’s instruments, as we have seen. In the Blake instrument
there is the happy idea of applying both the spring-principle and
the inertia-principle at once. Yet, in spite of this, if the speaker
shouts too loudly into a Blake transmitter, he will cause abrupt breaks
between the contact-pieces instead of producing partial interruptions
in the contact, and in that case speech will, as heard at the other
end of the line, be spoiled by a rattling noise. It is possible, also,
with Reis’s instruments to spoil the articulation by shouting too
loudly, and causing actual abrupt breaks in the continuity. If Blake’s
interruptor can be worked as a make-and-break in this sense, so can
Reis’s: for there is not one of the features which is essential to
Blake’s instrument that cannot be found in Reis’s also.

By way of further carrying out the comparison between Reis’s methods
of combining his tympanum with his contact-regulator, and the methods
adopted by later inventors, we give, in Fig. 45, ten comparative
sketches, the first five of which illustrate Reis’s methods. In these
sketches the only liberty taken is that of representing no more of
the instruments than the actual parts wanted in the comparison. No.
1 represents the working-parts of Reis’s first model ear, with its
curved lever, platinum-tipped spring, and adjusting screw. No. 2
shows the springs, screw, and contact-pieces of Reis’s bored-block
transmitter (“fourth form:” compare Figs 9 and 10, p. 21). No. 3 shows
the curved lever, the springs, and the adjusting screw of Reis’s eighth
transmitter (“lever” form). No. 4 gives the working parts of Reis’s
ninth transmitter, described in detail on p. 27. No. 5, in which the
tympanum is placed in a vertical position, merely for convenience of
comparison with the other figures, shows the working parts of Reis’s
final form of instrument, in which gravity and the inertia of the upper
contact-piece enabled him to dispense with the adjustment of spring
and screw. No. 6 shows in profile Berliner’s transmitter, which may
be instructively compared with No. 5. No. 7 shows the working part
of Blake’s transmitter, which should be compared with Nos. 2 and 4:
even the curve of the springs imitates that adopted by Reis. Nos.
8, 9, and 10 are forms of transmitter devised by Edison. No. 8 is
copied from Fig. 10 of the specification of Edison’s British Patent.
It will be seen that here there is an interruptor placed on each side
of the tympanum, and that each interruptor consists of a short spike
mounted on a spring and furnished with an adjusting-screw. “Platina
foil disks,” says the inventor, are to be secured to each side of the
diaphragm, and against these disks, as in Reis’s instruments, press
the contact-points of the interruptors. The patentee also states (p.
7 of his Specification), that for these contact-points “any substance
not liable to rapid decomposition” may be used. This term includes
all the substances used by Reis, and a great many others. It will
therefore be seen that this whole device is nothing more than a Reis
transmitter with the contact parts duplicated. Yet this instrument
was intended by Edison to transmit speech, and will, like Reis’s
instrument, transmit speech if properly used. No. 9 of the set of
sketches is taken from Fig. 25 of Edison’s British Specification,
but omits the induction-coil and other accessories, retaining the
parts wanted for comparison. The patentee thus describes the parts
figured. “The tension-regulator [meaning thereby the interruptor or
contact-regulator] is made of platina-foil upon the surface of two soft
rubber tubes; one on the diaphragm, the other on the adjusting-screw.”
It is interesting to note here how the ingenuity of the later inventor
led him to vary the construction adopted by the original inventor in
substituting an elastic cushion of soft rubber for the springs of the
older instruments. But the principle of combining a tympanum with a
contact-regulator, which was Reis’s fundamental notion, is here also
the leading idea; and the further idea of obviating abrupt breaks
in the current by applying elastic supports is also carried out.
Edison even copies Reis in having an adjusting-screw, and he applies
the very same substance--platinum foil--which Reis used in his very
first and his very last transmitter. Edison’s transmitter transmits
speech very fairly, even without any of such later accessories as
induction-coils; and why should it not? It is constructed on the very
lines, nay, with details almost identical with those prescribed by Reis
in describing his invention. It embodies those fundamental ideas which
Reis set before him when he said, “Taking my stand upon the preceding
principles, I have succeeded.”

[Illustration: Fig. 45.]

The last of the ten sketches of Fig. 45 is taken from Edison’s first
American Patent specification [No. 203,014, filed July 20, 1877],
and shows a duplicated interrupter with springs and adjusting-screws
combined with a tympanum. Further comment on this arrangement
is needless, save to remark that in this patent for “_speaking_
telegraphs,” Edison himself describes the contact-apparatus which Reis
termed an “interrupter,” as a “circuit-closer,” or in another place
as “circuit-breaking connections,” and, in his British Patent quoted
above, as a “tension-regulator.” It is evident that if Reis could
transmit speech by an interrupter which closed and opened the circuit
(always in proportion to the vibrations) there is no reason why Edison
seventeen years afterwards should not accomplish the same result by a
similar means. But it has lately been fashionable to deny that any such
device as an interrupter mounted on springs can transmit speech at all!

We have now compared with Reis’s transmitters several of the more
modern inventions. It would be possible to carry comparison further
were that course needed. We have not thought it worth while to rake
up Edison’s now discarded lamp-black button transmitter; and we have
not yet spoken of Crossley’s transmitter nor of Theiler’s transmitter,
nor of their parent the Hughes’ microphone, nor of dozens of other
forms. In some of these there is no specific “tympanum,” but only
a sounding-board of pine-wood, and in most of them the points of
loose-contact, where interruption more or less complete may occur, are
multiplied. But they all come back in the end to Reis’s fundamental
idea, namely that of setting the voice to vary the degree of contact
in a mechanism which he called an interruptor, and which others have
called a current-regulator (or, less correctly, a tension-regulator)
which, because the degree of contact between its parts was varied,
caused those parts to offer more or less resistance to the flow of the
current, and thereby threw it into vibrations corresponding to those of
the sound-wave impressed upon the tympanum. There is not a practical
transmitter used in any of the telephone exchanges of Great Britain
to-day that does not embody this principle.

Reis did, indeed, penetrate to the very heart the principles necessary
to be observed in a successful telephone. He was master of the
situation. For, as in every practical transmitter in use to-day, so in
his transmitter, there was _a loose contact in the circuit so arranged
that the voice could act upon it, and thereby regulate the strength of
the current_. If you eliminate this part of the apparatus,--screw up
the loose-contacts of your transmitters, so that your voices cannot
affect them,--what will your telephones be worth? No: the essential
principle of the transmitter--“Das Telephon” emphatically as its
inventor styled it--is _variable contact_; and that all-essential
principle was invented and applied for the purpose of transmitting
speech by Philipp Reis in 1861.

If this does not suffice as a claim for the invention of the Telephone
transmitter, it may well be wondered what will. We can dispense with
all other features save this one. We can even dispense with the
tympanum or diaphragm which Reis introduced, and can operate on the
contact-parts without the intervention of this part of the combination.
We can use the very metals which Reis used, and dispense with
lamp-black and all the fallacious rubbish that has been subsequently
devised about semi-conductors, whatever that term may mean. We can
even dispense with springs and adjusting screws. _But with the
principle of variable contact we can not dispense._ That which alone is
indispensable Philipp Reis discovered.



APPENDIX II.

ON THE VARIATION OF ELECTRIC RESISTANCE AT A POINT OF IMPERFECT CONTACT
IN A CIRCUIT.


Ever since electricians had experimented with voltaic currents, and
especially since the introduction of the electric telegraph, it had
been a familiar fact that a loose or imperfect contact in the circuit
caused a resistance to the flow of the current and interrupted it
more or less completely. To obviate the occurrence of loose or
imperfect contacts, binding-screws were invented; and many were the
precautions taken to make tight contacts at joints in the line, the
resistance of which it was desirable to maintain at a minimum. Young
telegraphists were particularly instructed to press their keys well
down in signalling, because a light contact would offer some resistance
which, on an increase of pressure, would disappear. In fact, it was
generally well known that the resistance of two pieces of metal or
other conducting material in contact with one another might be made
to vary by varying the goodness or badness of the contact with the
application of more or less force. This fact was known to apply to
good conductors, such as copper and other metals, and it was known
to apply also to non-metallic conductors, such as plumbago. Plumbago
points were used by Varley for the contacts of relays; it having been
found that points of platinum were liable to become fused together
with the passage of the current, and by so sticking rendered the
instrument useless. Since plumbago was known to be infusible, it was
hoped that a plumbago contact would prove more reliable. In practice,
however, the plumbago relay did not turn out so well. True it did not
fuse, or stick, or rust; but it was even more liable than platinum to
form imperfect contacts, the resistance of the light contact being so
high that a sufficient current did not pass. It is not known whether
other non-metallic substances were tried; probably not, because of
non-metallic substances plumbago is one of the few that are good
conductors.

According to Edison (British Patent, No. 792, 1882), compressed
graphite is a substance of _great conductivity_. According to Faraday
(‘Exp. Res.’ vol. i. p. 24), retort-carbon is an _excellent conductor_.
Both graphite and retort-carbon agree with the metals in the property
that the electric resistance offered at a point of contact between
them varies when the pressure at the contact is varied. It is indeed
remarkable through what wide ranges of resistance the contact between
two good conductors may vary. The resistance of contact between two
pieces of copper may be made to vary in a perfectly continuous manner
by changes of pressure through a range, according to Sir W. Thomson,
from a small fraction of one _ohm_, up to a resistance of many
thousand _ohms_. The same is true of silver, brass, and many other
good conductors, including graphite and retort-coke, though with the
latter materials the range of resistances is not so great. With partial
conductors, such as oxide of manganese, sulphide of copper, sulphide
of molybdenum, &c., and with bad conductors, such as lamp-black and
selenium, whose conductivity is millions of times less than that of
graphite, copper, and other good conductors, it is impossible to get
equally wide variations of resistance, as the amount of pressure at a
point which will bring the bad conductors into intimacy of contact,
will not turn them into good conductors. Platinum being in the category
of good conductors, is amongst those substances which yield a very
wide range of electrical resistances at the contact-points which are
submitted to varying pressures.

With the very highest conductors, such as silver and copper, the
electrical range of contact-resistance is higher than with those of
lesser conductivity, such as lead, platinum, graphite, and retort-coke.

But though the range of variation in electrical resistance at contacts
is highest for the best conductors, there comes in another element,
namely, the range of distance through which the contact-pieces, or
either of them, must be moved in order to pass through the range of
variations of resistance. This is quite a different matter, for here
the best conductors have the smallest range, and some that are not
so good a greater range. In any case the available range of motion
is very small--to be measured in minute fractions,--millionth-parts,
perhaps,--of an inch. So far as experiments go, however, silver has the
smallest range of all, then gold, then copper. Platinum and nickel have
a considerably wider range, plumbago and retort-coke a still wider one.

It is an extremely difficult matter to decide what is the precise
nature of that which goes on at a point of contact between two
conductors when the pressure at the point is altered. The principal
suggestions hitherto advanced have been that the change of resistance
observed is due:--

    (_a_) To the mere changes in the amount of surface in contact.

    (_b_) To a change in the resistance of the substance of the
    conductor itself.

    (_c_) To the formation of a minute voltaic “arc,” or electric
    discharge.

    (_d_) To the change in the thickness of the intervening film of
    air.

    (_e_) To the change in resistance of the parts in contact
    consequent on the evolution of heat by the current.

It is admitted that this last suggestion, though it might account for
a difference between different substances, in so far as they differ
from one another in the effect of heat upon their specific resistance,
implies as a preliminary fact that the amount of surface in contact
shall be varied by the pressure. No convincing proof has yet been given
that the alleged layer of air or other gases has any real part to play
in the phenomena under discussion. Nor can the hypothesis, that minute
voltaic arcs are formed at the contact be regarded as either proven or
probable.

The only two theories that have really been investigated are (_a_) and
(_b_) of the above series. Of these two (_b_) is certainly false, and
(_a_) is probably, at least to a very large extent, true.

It is often said by persons imperfectly acquainted with the scientific
facts of the case, that carbon is used in telephone-transmitters,
because the resistance of that substance varies with the pressure
brought to bear upon it, whilst with metals no such effect is observed.
This statement, taken broadly, is simply false. Mr. Edison has,
indeed, laid claim to the “discovery” (_vide_ Prescott’s ‘Speaking
Telephone,’ p. 223), that “semi-conductors,” including powdered carbon
and plumbago, vary their resistance with pressure. All that Mr. Edison
did discover was that certain substances, whose properties of being
conductors of electricity had been known for years, conducted better
when the contact between them was screwed up tightly than when loose.
The experiments made to test this alleged “property” of carbon are
absolutely conclusive. The author of this book has shown[39] that when
a rod of dense artificial coke-carbon, such as is used in many forms of
telephone transmitters, such as Crossley’s for example, is subjected
to pressure varying from less than one dyne per square centimetre up
to twenty-three million times that amount, the resistance of the rod
did not decrease by so much as one per cent. of the whole. In this
case any doubt that might have been introduced by variable contact was
eliminated at the outset by taking the precaution of electro-plating
the contacts.

In 1879, Professors Naccari and Pagliani, of the University of Turin,
published an elaborate series of researches[40] on the conductivity of
graphite and of several varieties of coke-carbon, and found, even with
great changes of pressure, that the changes of electric resistance were
practically too small to be capable of being measured, and that the
only changes in resistance appreciable were due to changes of contact.

In January 1882, Mr. Herbert Tomlinson communicated to the Royal
Society[41] the results of experiments on a number of electric
conductors. The change of conductivity by the application of stress
was found to be excessively small. For carbon it was less than
one-thousandth part of one per cent. for an increase of fifteen lbs.
on the square inch in the pressure. For iron it was slightly greater,
and for lead nearly twice as great, but with all other metals less. If
this alleged property were the one on which the action of telephone
transmitters depended, then lead ought to be twice as good a substance
as graphite; whereas it is not nearly so good.

Professor W. F. Barrett, in 1879,[42] made some experiments on the
buttons of compressed lamp-black used in Edison’s transmitter, and
found that when an intimate contact was satisfactorily secured at the
beginning, “pressure makes no change in the resistance.”

In the face of all this precise evidence, it is impossible to maintain
the theory that the electric resistance of plumbago or of any other
such conductor varies under pressure. The only person who has seriously
spoken in favour of the theory is Professor T. C. Mendenhall, but in
his experiments he took no precautions against variability of contacts,
so that his conclusions are invalid.

More recently still, Mr. O. Heaviside and Mr. Shelford Bidwell have
experimented on the variations of resistance at points of contact.[43]
Mr. Heaviside’s experiments were confined to contacts between pieces of
carbon, and though extremely interesting as showing that the resistance
of such contacts are not the same, even under constant pressure, when
currents of different strength are flowing, do not throw much light on
the general question, because they leave out the parallel case of the
metals. Mr. Bidwell’s very careful researches were chiefly confined to
carbon and bismuth. The choice is unfortunate, because bismuth the
most fusible and worst conductor amongst metals (save only quicksilver)
is the one metal _least_ suited for use in a telephone transmitter. Mr.
Bidwell’s conclusions, so far as they are comparative between carbon
and “the metals,” are therefore necessarily incomplete.

Professor D. E. Hughes, whose beautiful invention, the Microphone,
attracted so much attention in 1878, has lately thrown the weight
of his opinion in favour of the view that with carbon contacts
the effect is due chiefly to an electric discharge or arc between
the loosely-contiguous parts. But Professor Hughes’s innumerable
experiments entirely upset the false doctrine that a “semi-conductor”
is necessarily required for the contact-parts. Speaking recently,[44]
he has said: “I tried everything, and everything that was a conductor
of electricity spoke.” In 1878, in a paper “On the Physical Action of
the Microphone,” Professor Hughes stated:[45] “the best results as
regards the human voice were obtained from two surfaces of solid gold.”
Hughes also found carbon impregnated with quicksilver in its pores to
increase its conducting power to work better than non-metallised carbon
of inferior conductivity. Quite lately Mr. J. Munro has constructed
successful transmitters of metal gauze, having many points of
loose-contact between them.

It seems, therefore, much the most probable in the present state
of investigations, that the electric resistance of a contact for
telephonic purposes is determined solely by the number of molecules
in contact at the surface, and by the specific conductivity of those
molecules. The element of fusibility comes in to spoil the constancy
of the surfaces in action; and hence the inadmissibility of general
conclusions with respect to all metals drawn from the behaviour of
the most fusible of them. At a mere point in contact physically with
another point, there may be hundreds or even millions of molecules
in contact with one another, all acting as so many paths for the flow
of the electric current. An extremely small motion of approach or
recession may suffice to alter very greatly the number of molecules in
contact, and the higher the specific conductivity of the substance,
and the denser its molecules, the shorter need be the actual range of
motion to bring about a given variation in the resistance offered. Just
as in a system of electric lamps in parallel arc, the resistance of
the system of lamps increases when the number of lamps through which
the current is flowing is diminished, and diminishes when the number
of lamps connecting the parallel mains is increased; so it is with the
molecules at the two surfaces of contact. Diminishing the number of
molecules in contact increases the resistance, and _vice versâ_. Each
molecule as it makes contact with a molecule of the opposite surface
diminishes, by so much relatively to the number of molecules previously
in contact, the resistance between the surfaces. Each molecule as it
breaks from contact with its opposite neighbour adds to the resistance
between the contact-surfaces. It may therefore be that the variations
of resistance which are observed at contacts between all conductors,
from the best to the worst, are all made up, though they _appear_ to
pass through gradual and continuous changes, of innumerable minute
makes-and-breaks of molecular contact. The very minuteness of each
molecular make-or-break, and the immense number that actually must
occur at every physical “point” of contact, explain why the effect
seems to us continuous. We owe, moreover, to Mr. Edison[46] the
experimental proof that actual abrupt makes-and-breaks of contact _can_
produce an undulating current when they recur very rapidly. Whether the
heating action of the current itself may not also operate in changing
the conductivity of the molecules which happen at the moment to be in
contact is another matter. It may be so; but if this should hereafter
be demonstrated, it will but confirm the contact-theory of these
actions as a whole.

Assuming, then, broadly, that the observed resistance at a point of
contact is due to the number of molecules in contact and to their
individual resistances, it is evident that the property of varying
resistance at contact ought to be most evident, _ceteris paribus_,
in those substances which are the best conductors of electricity.
Unfortunately, the _cetera_ are not _paria_, for the question of
fusibility comes in to spoil the comparison; and carbon, which has less
fusibility than the metals, is commonly credited with giving a better
result than any. This common opinion is, however, based on comparisons
made without taking into consideration the question of range of motion
between the parts in contact, and without taking into consideration the
point that whilst some forms of carbon are excellent conductors, others
do not conduct at all. In a telephonic transmitter so arranged that
the actual range of motion shall be very small, the metals are just as
good as carbon--some of them better. I have heard from a transmitter
with contacts of pure bright silver better articulation than with
any carbon transmitter. And this is exactly what theory would lead
one to expect. As to the suggestion that plumbago makes a successful
transmitter, because it is a “semi-conductor”--whatever that term may
mean[47]--it is one of those suggestions which are peculiarly fitted
to catch the unscientific mind as affording an easy explanation for an
obscure fact; unfortunately, like a good many other similarly catching
suggestions, _it is not true_. The very best conductor--_silver_--will
serve to transmit articulate speech: and so will the one of the very
worst conductors--_lamp-black_! So much for this fallacious doctrine of
semi-conductors!

Reis used for his contact-points substances which, by reason of
their non-liability to fuse or oxidize, were customary in electrical
apparatus, and chiefly platinum. In his earliest transmitter (model
ear), and in his last, platinum was used. In his lever-form of
transmitter, so minutely described by von Legat, the material is not
specified. The lever-shaped contact-piece was to be a conductor, and
as light as possible, and since all metallic parts are particularly
described as metallic, whilst this is not so described, the obvious
inference is that this was non-metallic. The number of light,
non-metallic conductors is so few that the description practically
limits choice to some form of hard carbon. No other materials are
named by Reis, but Pisko says (p. 103) that brass, steel, or iron
might be used for contacts. Any one of these materials is quite
competent, when made up into properly-adjusted contact-points, to vary
the resistance of a circuit by opening and closing it in proportion
to the vibrations imparted to the contact-points. That is what
Reis’s transmitter was intended to do, and did. That is what all the
modern transmitters--Blake’s, Berliner’s, Crossley’s, Gower-Bell’s,
Theiler’s, Johnson’s, Hunning’s do, even including Edison’s now
obsolete lamp-black button transmitter. Mr. Shelford Bidwell has very
well summarized the action of the current-regulator in the following
words: “The varying pressure produces alterations in the resistance at
the points of contact in exact correspondence with the phases of the
sound-waves, and the strength of a current passing through the system
is thus regulated in such a manner as to fit it for reproducing the
original sound in a telephone.”

Reis constructed an apparatus consisting of a tympanum in combination
with a current-contact-regulator, or “interruptor,” which worked
on this principle of variable contact, and he called it “The
Telephone” (see pp. 57, 85). The very same apparatus we now-a-days
call a “Telephone-transmitter,” or simply a “transmitter.” It is
curious to note that Reis seems to have regarded his receiver or
“reproducing-apparatus” as no new thing. He says explicitly (p. 56)
that his receiver might be replaced by “any apparatus that produces
the well-known galvanic tones.” “_The_ Telephone” was with Reis
emphatically the _transmitter_. Bell in 1876 invented an instrument
which would act either as transmitter or receiver, and which, though
never now used as transmitter, is still called “a Telephone.” Edison’s
“sound-telegraph,” or “telegraphic apparatus operated by sound,” was
patented in 1877. In his specification _he never called his transmitter
a “telephone_;” that name he reserved exclusively for his receiver.
He found it, however, convenient a year later to rechristen his
transmitter as the “_carbon telephone_,” though throughout the whole
of his specification _neither “carbon” nor “telephone” are mentioned_
in connection with the transmitter! Within that year Hughes had
brought out another instrument--“The Microphone”--which, like Reis’s
instrument, embodied the principle of variable contact. Hughes’s
instrument, usually constructed with contacts made of loose bits of
coke-carbon, was simply a Reis’s Telephone minus the circular tympanum;
and the really important new fact it revealed, was that very minute
vibrations, such as those produced by the movements of an insect,
when transmitted immediately through the wooden supports, sufficed to
vary the resistance of a telephonic circuit, though far too slight in
themselves to affect it if they had to be first communicated to the air
and then collected by a tympanum. Put a specific tympanum to a Hughes’s
microphone, and you get a Reis’s telephone. Take away the tympanum from
a Reis’s telephone, and you get a Hughes’s microphone. Hughes is not
limited to one material, nor is Reis. But the fundamental principle of
the electrical part of each is identical. The Blake transmitter (Fig.
44), and the Berliner transmitter, and also Lüdtge’s microphone,[48]
which was even earlier than that of Hughes, are all embodiments of the
same fundamental principle of variable contact which Reis embodied in
his “Telephone.”

The numerous experiments which Reis made, and the many forms of
instruments which he devised, prove his conviction of the importance of
his invention to have been very deeply rooted. He had indeed penetrated
to the very soul of the matter. He did not confine himself to one
kind of tympanum, he tried many, now of bladder, now of collodion,
now of isinglass, and now of thin metal. He varied the forms of his
instruments in many ways, introducing the element of elasticity by
springs and adjusting-screws. Though he chiefly employed one metal for
his contact-pieces, he did not limit himself to that one, but left
us to infer that the principle of variable contact was applicable to
any good conductor, metallic or non-metallic. He knew better, indeed,
than to limit himself in any such fashion; better, indeed, than some
of the eminent persons who are now so willing to ignore his claims.
Modern practice has taught us to improve the tympanum part of Reis’s
invention, and to obviate the inconveniences to which a membrane is
liable: in that part we have gone beyond Reis. But in the question of
contact-points for opening and closing the circuit in correspondence
with the vibrations, we are only beginning to find how much Reis was
a-head of us. We have been thrown off the track--blinded perhaps--by
the false trail of the “semi-conductor” fallacy, or by the arbitrary
and unnatural twist that has been given by telegraphists to Reis’s
expression, “opening and closing the circuit,” forgetting that he
practically told us that this operation was to be proportional to, “in
correspondence with,” the undulations of the tympanum. When we succeed
in freeing ourselves from the dominance of these later ideas, we shall
see how much we still have to learn from Philipp Reis, and how fully
and completely he had grasped the problem of the Telephone.

FOOTNOTES:

[39] ‘Philosophical Magazine,’ April 1882.

[40] ‘Atti del R. Istituto Veneto di Scienze,’ vol. vi. ser. 5.

[41] Proc. Roy. Soc. No. 218, 1882.

[42] See Proc. Roy. Dubl. Soc. Feb. 17, 1879.

[43] Vide ‘The Electrician,’ Feb. 10, 1883.

[44] Journal Soc. Telegr. Engin. and Electricians, vol. xii. p. 137.

[45] Proc. Physical Soc. vol. ii. p. 259, 1878.

[46] ‘Journal Soc. Telegraphic Engineers,’ vol. iv. p. 117, 1874.

[47] The term “semi-conductor” is very rarely used by electricians, who
prefer the term “partial conductor” as being more correct. Moreover,
electricians, from Faraday downwards, are practically agreed in calling
plumbago a good conductor, and worthy of being classified by reason of
its high conductivity along with the metals. The substances known as
“semi-conductors” are those given in Ferguson’s ‘Electricity,’ p. 49
(edition of 1873), namely, alcohol, ether, dry-wood, marble, paper,
straw, and ice. Mascart and other eminent authorities agree in this
classification. It would tax even Mr. Edison’s unrivalled ingenuity to
make of these materials a transmitter that should alter its resistance
by pressure!

[48] Lüdtge’s German Patent, dated Jan. 12, 1878, describes a “Universal
Telephone” in which a tympanum was applied to convey vibrations to an
interruptor made of hard coke-carbon.



APPENDIX III.

COMPARISON OF REIS’S RECEIVERS WITH RECENT INSTRUMENTS.


The receivers invented by Reis for the purpose of reconverting into
audible mechanical vibrations the varying electric currents transmitted
from the speaking end of the line were of two classes, viz.:

(1.) Those in which the magnetic expansion and contraction of a rod
of steel or iron, under the influence of the varying current, set up
mechanical vibrations and communicated them to a sound-board.

(2.) Those in which the current by passing round the coils of an
electro-magnet caused the latter to vary the force with which it
attracted its armature, and threw the latter into corresponding
mechanical vibrations.

The first of these principles is embodied in the “knitting-needle”
receiver described above and depicted in figures 22 & 23 on page 33.
This receiver differs wholly from the later instruments of Bell, and
others, and depended for its action upon the phenomenon of magnetic
expansion discovered by Page and investigated by Joule. It was well
known before Reis’s time that when a needle or bar of iron was
magnetised it grew longer, and when demagnetised it grew shorter.
Page detected the fact by the “tick” emitted by the bar during the
act of magnetisation or demagnetisation. Joule measured the amount
of expansion and contraction. To these discoveries Reis added two
new facts; _first_, that if the degree of magnetisation be varied
with rapid fluctuations corresponding to those of the sound waves
impressed on the transmitter, the expansion and contraction of the
rod followed these fluctuations faithfully, and therefore emitted at
the receiving end sounds similar to those uttered at the transmitter.
_Secondly_, by employing a needle of _steel_ instead of the bar of
iron used by Page, Reis obtained an instrument which once used could
never become completely demagnetised on the cessation of the current;
it was thenceforth a _permanent magnet_, and all that the fluctuating
currents could do was to vary its degree of magnetisation. Reis
carefully explained in his memoir “On Telephony,” how the frequency of
such fluctuations in the magnetising current could act in reproducing
the pitch, and further, how the amplitude of the fluctuations set
up vibrations of corresponding amplitude in the rod: he added with
significance, that the quality of the reproduced note depended upon
a number of variations of amplitude occurring in a given time. His
theory of these actions was that the atoms (or perhaps our modern
word _molecules_ would more correctly represent what Reis spoke of as
atoms) of the rod or needle were pushed asunder from one another in
the act of magnetisation, and that on the cessation of the magnetising
influence of the current, these same atoms strove to return to their
previous position of equilibrium, and thus the oscillations of the
atoms led to the vibration of the needle as a whole. Whether all Reis’s
speculations as to the behaviour of the atoms under varying degrees of
magnetising force are justified in the present aspect of science or
not, is, however, not of any great importance; the important point is,
that, whether his theory be right or wrong, the instrument he devised
will perform the function he assigned to it: it will reproduce speech,
not loudly, but in reality far more articulately than many of the
telephonic receivers in use under the names of Bell, Gower-Bell, &c.

One very curious point in connection with this “knitting-needle”
receiver of Reis, is its extremely bad acoustical arrangements. It
was laid horizontally upon a small sounding-box covered by a lid. If
the _end_ of the needle had been made to press on the resonant-board
(as indeed appears to have been done at first with the violin, p. 29)
the vibrations would have been much more directly reinforced. But
when merely supported by two wooden bridges the direct communication
was largely lost. The pressure of the lid downwards upon the spiral,
as recommended by Reis, is no doubt an important matter acoustically.
It is strange that a man who had grappled in so masterly a way with
the acoustical problem of the transmitter, and had solved it by
constructing that transmitter on the lines of the human ear, should not
have followed out to the same extent those very same principles in the
construction of his receiver. An extended surface he did employ, in
the shape of a sounding-board; but it was not applied in the very best
manner in this instrument.

The second principle applied by Reis in the construction of his
telephone-receivers, was that of the electro-magnet. He arranged an
electro-magnet so that the fluctuating currents passing round the coils
set up corresponding variations in the degree of force with which it
attracted its armature of iron, and so forced the latter to execute
corresponding mechanical vibrations. This principle is common both to
the receiver of Reis, and to the later receivers of Yeates, Bell, and
Edison. Reis’s armature was an iron bar of oval section; Yeates’s an
iron strip screwed to a sound-board, Bell’s was an iron plate, and
Edison’s an iron plate also.

For the better comparison of Reis’s electro-magnetic receiver with
those of more modern date, we here present in Fig. 46 a comparative
view of a number of different forms of receiver in which Reis’s
principle of causing an electro-magnet to set up vibrations in an
armature is applied. In this set of figures, _A_ and _B_ are the
suggested forms mentioned in the letter of Mr. Horkheimer, p. 119,
and show an electro-magnet, opposite the poles of which is placed an
armature (a bar) which must be of iron or other metal capable of having
magnetism induced in it, and which, by reason of its attachment to an
elastic spring, is capable of being made to oscillate to and fro when
attracted with a varying force. Reis clearly recognised the necessity
of further providing a sufficient resounding surface by means of
which the surrounding air could be set in motion: for in the case of
these two suggestions the electro-magnet and its elastically-mounted
armature were placed within a cigar box. _C_ is a plan of the receiving
instrument previously described and figured in Plate II. and in figures
21 and 34 on pages 32 and 109. In this instrument the electro-magnet
was horizontal, the armature, a bar of iron of oval section (which in
the original drawing in plate II. appears to have been in reality a
hollow bar or tube) attached to a thin lever described as a plank,
pivoted like a pendulum to an upright support, but prevented by a
set-screw and a controlling spring from vibrating in the manner
of a pendulum. Such an arrangement, in fact, vibrates in perfect
correspondence with any vibrations that may be forced upon it by the
electro-magnet. The broad flat surface of the lever--he specially
directed that it should be broad and light--transfers the vibrations
to the air, and is aided by the surface of the sounding-board on which
the apparatus stands. This apparatus has, therefore, all the elements
of a successful receiver, except only that its shape renders it
inconvenient for portability. But by reason, firstly of its armature
of iron, secondly of the elastic mounting of that armature, thirdly of
the extended surface presented, it is admirably adapted to serve as an
instrument for reproducing speech.

[Illustration: Fig. 46.]

Fig. 46 _D_ represents the excellent electro-magnetic receiver devised
in 1865 by Yeates (compare Fig. 42, p. 128) to work with the Reis
transmitter, and is in many respects identical with the preceding form.
The armature, a strip of iron, was attached at one end by a very stiff
steel spring to a pine-wood sounding-board over a hollow box, from the
base of which rose the metal pillar which supported the electro-magnet.
This receiver also contains all the elements of a successful receiver,
the armature being of a material capable of inductive action, and
elastically supported; whilst the sound-box provided adequate surface
to communicate the vibrations to the air.

We now come to the more modern instruments of Gray, Bell, and
Edison. So far the receivers of Reis and of Yeates were intended for
reproducing any sound; but now for the first time, ten years after the
date of these early telephonic receivers, we meet with instruments
devised with the express purpose of receiving only certain selected
tones.

For the purposes of multiple acoustic telegraphy, that is to say for
the purpose of signalling the “dots” and “dashes” of the Morse code
in a number of different fixed musical notes, each of which is to
be signalled out and repeated by a receiver adapted to vibrate in
that note alone, it is clear that the instruments of Reis, adapted
as they were to transmit and receive _any_ sound that a human ear
can hear, would not answer. Accordingly those experimenters, who
from about the year 1873 to the year 1870, applied themselves to
multiple telegraphy--foremost amongst them being Mr. Elisha Gray and
Prof. Graham Bell--dropped the use of the tympanum in the transmitter
and devised new transmitters and new receivers, in most of which
the ruling idea was that of employing a vibrating tongue or reed,
tuned up to one particular note. Now it is obvious that a receiver
which, like those of Reis, is adapted to receive _any_ tone, can
also receive a musical note. But for the operation of “selective”
reception, a receiver must be employed, not only tuned to one note,
but tuned to the very note emitted by the particular transmitter
with which it is to be in correspondence. Elisha Gray found this out
very early in his researches. In the winter of 1873-4[49] he was
transmitting musical tones by a sort of tuning-fork interruptor, and
received them on an instrument shown in Fig. 46 E, which represents
a form of electro-magnet mounted for the purpose. It was “a common
electro-magnet, having a bar of iron rigidly fixed at one pole,
which extends across the other pole, but does not touch it by about
one sixty-fourth part of an inch. In the middle of this armature a
short post is fastened, and the whole is mounted on a box made of
thin pine, with openings for acoustic effects.” It was, in fact,
very similar to Yeates’s receiver just described, and Gray found it
capable of receiving not only simple musical tones but composite tones,
and even harmonies and discords. In fact, like Reis’s and Yeates’s
receivers, it could receive anything that the transmitter sent to
it, even including speech. Now this did not suit Gray, who wished to
have selective receivers, one to take up note A, another note C, &c.
Accordingly in 1870 we find Gray taking out a fresh patent[50] for
selective receivers, which he also called harmonic analysers, each
of which consisted of “a tuned bar or reed suitably attached to an
electro-magnet, and the whole mounted upon a resonant box.” Fig. 46 _F_
is reproduced from Gray’s British patent. “A vibrating tongue reed,
or bar” of steel “is united with one pole of the magnet. The free end
of the reed passes close to, but does not touch the other pole of the
magnet.” Gray further says that the reed is made with parallel sides
and tuned by cutting it away at one point, as this mode prevents false
nodal vibrations from occurring.

Selective receivers for multiple telegraphy were also invented by
Graham Bell. The form shown in Fig. 46 _I_ is transcribed from Fig. 15
of Bell’s Specification to his British Patent, No. 4765, of the year
1876 (dated 9th December), which the inventor thus describes: “It is
preferable to employ for this purpose an electro-magnet _E_, Fig. 15,
having a coil upon only one of its legs. A steel spring armature _A_ is
firmly clamped by one extremity to the uncovered leg _h_ of the magnet,
and its free end is allowed to project above the pole of the covered
leg.” In fact the arrangement was almost identical with, but not quite
as good mechanically as that patented seven months previously by Gray.
The inventor further said that a number of these instruments might be
placed on one circuit, and that if one of them were set in vibration,
only those would respond which were in unison with its note; and
further that “the duration of the sound may be used to indicate the dot
or dash of the Morse alphabet, and thus a telegraphic despatch may be
indicated by alternately interrupting and renewing the sound.”

Anything more totally different from Reis’s telephone than these
selective harmonic telegraphs with their tuned tongues can hardly be
imagined. Reis was not aiming at selective harmonic telegraphy; he
wanted his one instrument to transmit every sound that a human ear
could hear. He did not dream of using a tuned bar or reed; his typical
structure was the tympanum of the ear. In fact, as we have seen above,
the tuned reed or tongue was introduced into telegraphy for the
purpose of transmitting single selected notes to the exclusion of all
others.

Strange though it may seem, a tongue receiver like those of Graham
Bell and of Gray just described can be used for receiving speech!
It is true, as Gray remarks, that a thick bar of steel, cut away as
described, is best adapted for its own tone only. But Bell’s thin
steel tongue, though it has its own fundamental note (and so has every
tympanum, for that matter) when left free to vibrate in its own time,
will reproduce _any_ other note or sound that may be _forced_ upon it
by the varying attraction of the electro-magnet. There is, indeed, the
whole difference between “free” and “forced” vibrations. One of the
strangest delusions that has somehow grown up in recent telephonic
discussions is the almost incredible proposition that a tongue cannot
talk because it is a tongue. It would be equally veracious to affirm
that an ear (_i.e._ a tympanum) cannot hear because it is an ear.

But leaving harmonic telegraphy and its “tuned bars,” both Gray and
Bell applied themselves to the old problem of transmitting human
speech. What was their very first step? They threw away their “tuned
bars” and “steel springs,” and returned _to the tympanum_! Elisha Gray
devised the receiver shown in Fig. 46, _G_, taken from his caveat of
date February 14, 1876.[51] In that document Gray says: “My present
belief is that the most effective method of providing an apparatus
capable of responding to the various tones of the human voice, is
a _tympanum_, drum, or diaphragm,” stretched across one end of a
chamber. He adds that in the receiver there is (see Fig. 46, _G_) an
electro-magnet, acting upon a diaphragm to which is attached a piece of
soft iron, and which diaphragm is stretched across a vocalising chamber.

Graham Bell’s receiver (the American specification of which was
filed the same day as Gray’s caveat) is shown (in the form patented
in Great Britain, Dec. 9, 1876) in Fig. 46 _H_, which is taken from
Fig. 19 of Bell’s British patent. “The armature,” says the inventor,
“is fastened loosely by one extremity to the uncovered leg, _h_, of
the electro-magnet _E_, and its other extremity is attached to the
centre of a stretched membrane.” The armature, in fact, was capable of
vibrating like a pendulum on its pivot, but was elastically restrained
by its attachment to the tympanum; the armature would therefore vibrate
in perfect correspondence with any vibrations forced upon it by the
electro-magnet. This instrument as also that of Gray, was admirably
adapted to receive speech, for it embodied the three essential points
which Reis had already discovered: viz., firstly, that the armature
must be of iron, or capable of being acted upon by magnetic induction;
secondly, that it must be elastically mounted; thirdly, that it
should present an extended surface. Bell’s form of receiver had the
advantage over Reis’s (compare p. 158), that its extended surface was
a true tympanum of membrane, and not a mere broad thin plank. Being a
tympanum, it therefore realised Reis’s fundamental notion of imitating
the human ear more fully than even Reis’s own receiver did.

Figures 46, _J_, _K_, and _L_ represent the more recent types of
receiver of Bell and Edison. Fig. 46 _J_ is reproduced from Fig. 20
of Bell’s British Patent, and shows the substitution of a thin steel
plate, attached to a frame, in front of the electro-magnet, for the
membrane and iron armature. This form of instrument also embodies
Reis’s three principles--but with this improvement, the armature
capable of inductive action, the elastic mounting, and the extended
surface, are here all united in one organ, the thin flexible tympanum
of steel. Apart from this unification of parts there is absolutely
nothing in this form of Bell’s receiver, that Reis did not invent
fourteen years before. Bell’s great and most signal improvement was not
this beautiful mechanical modification of the Reis receiver, but lay in
the entirely new suggestion to use such a receiver _as a transmitter_
to work by magneto-electric induction. Two of Reis’s receivers (Fig.
21) if coupled up with a battery will talk together as transmitter
and receiver: but Reis did not know and never suggested this. Two of
Yeates’s receivers (Fig. 42) if coupled up with a battery will talk
together as transmitter and receiver; but Yeates did not know and
never suggested this. Bell did discover this, and thereby invented a
transmitter which, though now abandoned as a transmitter, for want of
loudness, was more reliable than the anterior transmitters of Reis
had been. He made another discovery, presently to be alluded to--that
of putting a permanent magnet into the transmitter, to enable him to
dispense with the battery; but beyond this and the other mechanical
simplifications previously mentioned, all that he discovered may be
summed up by saying that he found out that a receiver constructed on
Reis’s principles could work as a transmitter also. That was Bell’s
really great and important discovery which took all the world by storm
at the Centennial Exhibition of 1876.

Bell subsequently added to his claims the substitution of a permanent
magnet with an iron pole-piece, in place of the simple electro-magnet,
thus enabling him to transmit his fluctuating currents without the
trouble of using a battery, and the Bell transmitter, thus modified,
is used to this day as a receiver, Reis had in his “knitting-needle”
telephone, employed a permanent magnet of steel to serve as a receiver,
he had not, however, applied it as Bell did to attract a plate of thin
steel.

Fig. 46, _K_, exhibits a form of electro-magnetic receiver described
in Edison’s British Specification, No. 2909, 1877, Fig. 24. This
instrument, though patented seven months after Bell’s instrument,
differs from it in no point of importance. Its armature was a thin
plate of iron, elastic, and having an extended surface; being, in fact,
a tympanum.

No one can examine the set of receiving instruments collected in Fig.
46 without being struck with the extraordinary similarity of design
which pervades the entire series. In every one of the set there is an
electro-magnet, the function of which is to set an armature[52] into
vibration by attracting it with a variable force. In every one the
armature is of a material capable of magnetic induction; that is to
say, iron, steel, or equivalent material. In every one of them the
armature is either elastically mounted, or is in itself elastic. In
every one of them (save only the two quite recent forms, _F_ and _I_,
which were intended not to speak, but to emit only one fixed musical
note) there is an extended surface (either a sound-board or a tympanum)
to communicate the vibrations to the air. Lastly, every one of these
forms, when connected with the line through which the telephonic
currents are being transmitted, is perfectly capable of reproducing
articulate speech. But the inventor who had the genius to discover all
these essential points, and to combine them in an instrument, and to
use it to reproduce articulate speech, is surely the true inventor of
the system. The inventor of the system embodying these essential points
was Philipp Reis.

FOOTNOTES:

[49] See Prescott’s ‘Speaking Telephone,’ p. 158.

[50] ‘British Patent,’ No. 1874, of the year 1876 (dated 4th May).

[51] Prescott, ‘Speaking Telephone,’ p. 203.

[52] Yet Bell’s claim (British Patent Specification) runs: “I claim
the production of any given sound or sounds from the _armature_ of the
receiving instrument.”



APPENDIX IV.

ON THE DOCTRINE OF UNDULATORY CURRENTS.

    “_In this Specification the three words ‘oscillation,’
    ‘vibration’ and ‘undulation,’ are used synonymously._”--Graham
    Bell, U.S. Patent, No. 174,465, filed Feb. 14, 1876.


In the preceding appendices it has been demonstrated that all that
is essential in both transmitter and receiver of a Telephonic system
was to be found existing in 1863 in the Telephone of Reis. There
yet remains to be met the _doctrinaire_ objection that as Reis
never explicitly mentions an undulatory current as distinguished
from an intermittent one, he never intended to use such a current.
This objection is advanced only by those persons who have committed
themselves to the idea that speech cannot be transmitted by a
transmitter which opens and closes the circuit.

It is certain that Reis did not in any of his writings explicitly
name an undulatory current: but it is equally certain that, whether
he mentioned it or not, he both used one and intended to use one. He
did not concern himself as to the precise manner in which the current
fluctuated provided only he attained the end in view--namely, that
the vibrations of the armature of the receiver should be similar to
those of the transmitter. This he did lay down with great clearness
and emphasis as his guiding principle; and he cared not about the
intermediate question as to how the current did the work. He told the
world that the electromagnet at the receiving end must be magnetised
and demagnetised correspondingly with the vibrations imparted by the
air to the tympanum of his transmitter, in order that the armature
might be set into vibrations similar to those of the speaker’s
voice. If the tympanum of the transmitter vibrated or oscillated or
undulated--the terms are synonymous--so must the armature of the
receiver. Graham Bell has told us precisely the same thing: “The
current traversing the coils of the electromagnet _E_ occasions an
increase and diminution in its intensity” [that is to say, magnetises
and demagnetises it], “and the armature _A_^1 is thrown into vibration”
... “and thus imparts to the air at _n_^1 a facsimile copy of the
motion of the air that acted upon the membrane _n_.” Bell agrees then
absolutely in every detail with what Reis said on this point. That
sound-waves should be transmitted by a Telephone requires indeed a
process of several stages. (1.) The sound-waves must strike upon the
tympanum of the transmitter and make it undulate, or, oscillate, or
vibrate--whichever term you please--in a corresponding manner. (2.)
The undulating tympanum must act upon the circuit, and either itself
induce undulating or vibrating currents (Bell’s plan, by magnetic
induction), or else throw a current already flowing there, into
undulations, or vibrations, or oscillations (Reis’s plan, by varying
contact-resistance), but in either case these undulations of the
current must correspond to the original undulations of the air-waves.
(3.) The undulating, or vibrating, or oscillating current must run
round the coils of the electromagnet and cause its magnetic force
to undulate, or oscillate, or vibrate by demagnetising it and then
magnetising it, but this also must be in a manner corresponding to the
original undulations. (4.) Further, the armature of the receiver must
be set into undulations, or vibrations, or oscillations corresponding
to those of the force of the electromagnet, and therefore to the
undulations of the current that is magnetising and demagnetising it,
and therefore identically corresponding with the original undulations
of the sound-waves. (5.) The armature must communicate its vibrations
to the air and to the ear of the listener. Of these successive stages
Reis explicitly told the world that his instrument was to do the
first one and the last three, and he several times emphasized the
statement, that the final undulations of the last stage were to be
similar to the original undulations of the first stage. The air at the
listening end, the armature of the receiver, and the magnetism of the
magnet, were all to be set by the fluctuations of the current into
undulations corresponding with those of the tympanum at the speaker’s
end, and of the waves of his voice. It is perfectly clear therefore,
that he regarded as self-evident the intermediate stage, and he did not
dwell upon the necessity of the point, that his transmitting-current
must also vibrate, because this was obviously so, and was only an
intermediate matter of secondary moment. He chose rather to point out
the necessity of unification between the first and last stages, leaving
it to common sense to see that the “interruption” or the “opening and
closing” of the circuit must be effected in a manner corresponding to
the undulations of the impressed sound-wave. Had the “interruptions”
not been of the nature of corresponding variations of contact, the
current could not have been set into corresponding vibrations, and the
armature of the electromagnet could not have reproduced the vibrations
of the transmitter. Clearly Reis’s whole conception of telephony
included as a minor and intermediate step the fact that the current
was, by the action of the transmitter, caused to vary in strength in
correspondence with the undulations of the tympanum--that, in fact,
it was made to undulate by the action of the tympanum and of the
interruptor which opened and closed the circuit in obedience to the
undulations of the tympanum and in proportion to them.

A difficulty has been raised by telegraph operators that opening
and closing the circuit means opening and closing the circuit in
abrupt alternations of make-and-break. Reis never said so. Reis
never used the phrase in this restricted and technical sense. He was
not a professional telegraphist, and, as pointed out in Appendix
I., he so arranged his contacts with the following springs and
other contrivances, that the “opening and closing” of the circuit
should not and could not be abrupt. A Reis transmitter is no more
a “make-and-break” instrument than the Blake transmitter is. Both
will give undulatory currents by opening and closing the circuit
to a greater or less degree, if spoken gently to. Both will give
abrupt makes-and-breaks of the circuit if shouted to, in spite of the
following-springs, which are used to prevent abrupt interruptions.
The term “opening and closing” which Reis applied to his transmitter,
is used by him in exactly the same way as the phrase is used by
engineers in describing the action of the governing throttle-valve of
a steam-engine. The function of the governor, we are told in treatises
on engineering, is to open and close the throttle-valve in a manner
corresponding to the fall or rise of the governor-balls. No one in
his senses imagines that the opening and closing action here referred
to means an absolutely abrupt intermittence in the supply of steam.
If the governor-balls rise a little by increase of speed, there is
a corresponding closing, proportionate in amount to the amount of
rise. If any person were to impress an oscillatory motion of rise
and fall upon the governor, the supply of steam would be thrown into
corresponding undulations. The matter stands precisely so with Reis’s
“interruptor” or “regulator;” it opens and closes the circuit in a
manner corresponding with the undulations communicated to it. If it did
not, it would violate the principle of correspondence so emphatically
laid down by Reis.

It is, however, true that Reis’s instruments, in spite of springs and
adjusting screws, and other devices to prevent abrupt make-and-break
occurring, were prone, by reason of the very lightness of the parts,
to break contact, if too loudly spoken to. They share this fault with
the more perfect transmitters of Blake and Berliner which are used
to-day so generally. The undulatory currents of these transmitters
are, like those of Reis’s transmitters, liable to an occasional
abrupt interruption, which, though it may not seriously affect the
intelligibility of the words, does, to some extent, mar the perfection
of the articulation. Still, in practice, to judge by the instruments
used in the telephone exchanges of Great Britain, the Blake transmitter
with its liability to make-and-brake abruptly is a more satisfactory
instrument than the Bell transmitter, which is not used at all. Now
the Bell transmitter working on the principle of which Bell is the
first and undisputed inventor, is one in which the degree of contact
in the circuit is never changed: for it works by the principle of
“induction,” whereby currents are set up in a circuit that is never
opened or closed, either partially or wholly. Nevertheless the Blake
transmitter, which opens and closes the circuit in proportion to the
undulations of the tympanum, is the more satisfactory instrument
for producing the undulating currents required to procure the
all-essential correspondence between the undulations of the tympanum
of the transmitter and those of the armature of the receiver. To sum
the matter up, it appears that an instrument which opens and closes
the circuit on Reis’s principle of transmitting is in practice a
more satisfactory transmitter of undulatory currents than Bell’s
transmitter which cannot open or close the circuit in the least. Reis,
with his instruments, transmitted speech--as Herr Hold tells us (p.
126)--when the words spoken were not too loud. That is a proof that
he did really use, whether he knew it or not, undulatory currents of
electricity: and an undulatory current is none the less an undulatory
current, even if occasionally abruptly interrupted. A speech is none
the less a speech, even if the orator sneeze once or twice while
speaking. Nay, we may go further, and say that an undulatory current
is an undulatory current, even though the finer ripples of the waves
are lost in transmission. This is what seems to have been the case
with Reis’s instruments as they were in 1861 and 1862. The consonants
were satisfactorily transmitted, and so were all musical tones within
the range of the instrument. But the finer ripples of the vowels were
lost somehow in transmission. Reis, whose innate honour and modesty
led him always rather to understate than overstate the facts, most
frankly acknowledged this, nay even invited attention to the fact,
and discussed the imperfection from a high scientific standpoint. He
proposed to rely for the correctness of his views upon the actual
recorded curves of sound-waves, as taken down automatically by the then
newly-invented phonautograph of Scott (see p. 60). It is perfectly
marvellous how precise his views were upon the correspondence between
the graphic curve or wave-form of a sound and the actual sound itself;
a precision amply justified by the experience and the discoveries of
the last ten years.

This matter of representing sounds--or rather the varying density of
the air in the sound-wave--by a graphic curve, was a vital one to
Reis. Had he had a less clear view of the nature of sound-waves than
that afforded by a graphic _curve_, I doubt whether he would ever
have grasped the problem of the telephone--that the final vibrations,
or undulations, or oscillations of the armature in the receiver must
_correspond with_--must be the very counterpart of--those of the
tympanum of the transmitter. The clearness with which Reis saw this is
only surpassed by the clearness with which he expressed himself upon
it. For him a sound was simply a complicated series of variations in
the density of the air, and capable, in all its complexity, of being
represented by the rise and fall of an undulatory _curve_. “Every
tone, and every combination of tones, evokes in our ear vibrations
... the motions of which may be represented by a _curve_” (p. 54).
“That which is perceived by the auditory nerve ... _may be represented
graphically according to its duration and magnitude by a curve_”
... (p. 53). “Our ear can perceive absolutely nothing more than is
capable of being represented by _similar curves_” (p. 53). The curves
with which he accompanied his original memoir--and now reproduced in
facsimile, from Legat’s plates, at the end of this volume--are evidence
of the thoroughness of his grasp on the undulatory principle. And
he explicitly states this principle amongst “the various requisite
conditions which must be fulfilled by the transmitting _and receiving_
apparatus for the solution of the problem that has been set” (Legat’s
Report, p. 71). He declared that so soon as it should become possible
“at any place, and _in any prescribed manner_” (that is to say, whether
by electric undulations or by mechanical undulations, as in the string
of the toy telephone, or by any other means), “to set up vibrations
whose _curves_ are like those of any given tone or combination of
tones,” we should then receive the same impression as that tone or
combination of tones would have produced upon us.

So much for Reis’s principle of correspondence of undulations between
the transmitter and the receiver; we have seen how clear and precise,
yet how comprehensive it was, and how the general proposition
necessarily included within itself, as an intermediate step, the
particular minor proposition that the undulations of the current must
also be in correspondence with the voice.

Keeping these points in mind, it is very remarkable that when Graham
Bell, fourteen years later, followed Reis “into the field of telephonic
research,” he selected the very same method of expressing the relations
between sounds and the undulations which corresponded with them.
To show how remarkably in agreement the views of Reis and Bell are
upon this question of representing by a curve the undulations which
correspond to the voice, we select the following paragraphs and place
them in parallel columns.

    _Reis._

    That which is perceived by
    the auditory nerve ... may
    be =represented graphically=,
    according to its duration and
    magnitude by a =curve=.--(Memoir
    ‘On Telephony’ in the
    Jahresbericht of the Physical
    Society of Frankfurt-a.-M.
    1860-61, p. 59.) [p. 53.]

    =The height or depth of
    the sound produced= ...
    depends upon =the number of
    vibrations made in a given
    time=.--(_Ib._ p. 63.) [p. 59.]

        _Bell._

        Electrical undulations, induced
        by a body capable of
        inductive action, can be =represented
        graphically=, without
        error by the same sinusoidal
        =curve= which expresses the vibration
        of the inducing body
        itself, and the effect of its vibration
        upon the air; for, as
        stated above, the rate of oscillation
        in the electrical current
        corresponds to the =rate of vibration=
        of the inducing body--that
        is, to =the pitch of the
        sound produced=.--(Specification
        of U. S. Patent No.
        174,465, dated March 7, 1876.)

    _Reis._

    The greater the condensation
    of the sound-conducting
    medium at any given moment,
    the greater will be the =amplitude=
    of vibration of the membrane.--(_Ib._
    p. 58.) [p. 52.]

        _Bell._

        The intensity of the current
        varies with the =amplitude= of
        the vibration--that is, with
        the loudness of the sound;--(_Ib._)

    _Reis._

    ... each tone is dependent
    not only on the number of
    vibrations of the medium, but
    also on the =condensation or
    rarefaction= of the same.--(Legat’s
    Report, Zeitschrift des
    D.-Oesterr. Telegr. Vereins,
    1863, p. 125.) [p. 77.]

        _Bell._

        and the polarity of the current
        corresponds to the direction of
        the vibrating body,--that is,
        to the =condensations and
        rarefactions= of air produced
        by the vibration.--(_Ib._)

    _Reis._

    Let us exhibit the condensation
    curves for three tones--each
    singly (Plate I): then,
    by adding together the ordinates
    corresponding to equal
    abscissæ, we can determine
    new ordinates and develop a
    new curve which we may call
    the =combination-curve=. Now
    this gives us just exactly what
    our ear perceives from the
    =three simultaneous tones=.--(Memoir
    ‘On Telephony,’
    p. 59.) [p. 54.]

        _Bell._

        The combined effect of A
        and B, when induced simultaneously
        on the same circuit,
        is expressed by the curve
        A + B, Fig. 4, which is the
        algebraical sum of the sinusoidal
        curves A and B. This
        curve A + B also indicates the
        actual motion of the air when
        =two musical notes= considered
        are sounded =simultaneously=....
        (_Ib._) The
        electrical movement, like the
        aerial motion, can be represented
        by a sinusoidal curve, or
        by the =resultant of several=
        sinusoidal =curves=.--(_Ib._)

The very remarkable agreement of the preceding passages receives
a most striking confirmation by comparing the curves respectively
drawn by Reis and by Bell. These are facsimiled below, Reis’s
“combination”-curve (Fig. 47) from Plate I. of his Memoir (also Plate
I. of this volume), and Bell’s “resultant”-curve (Fig. 48) from Fig. 4
of his United States Patent Specification No. 174,465.

The most casual observer cannot fail to notice here that the three
lines of undulatory curves of Bell’s specification are practically
identical with the three lower lines of undulatory curves of Reis’s
memoir. They are, moreover, in each case introduced for the sake of
showing how a complex curve corresponds to a compound undulation.

_Reis._.

[Illustration: Fig. 47.]

_Bell._.

[Illustration: Fig. 48.]

Far be it from me even to hint that either curve was plagiarised from
the other. Bell tells us that his curve is to represent electrical
oscillations, which, he adds, have the same curve as that both of
the vibrating body and of the air. Reis tells us that his curve is
to represent the oscillations of a tympanum, or of the air, or of
the magnetisation of the magnet, or of the armature at the receiving
end. How the magnetization of the electro-magnet was made to vary
“correspondingly with the condensations and rarefactions of the air,”
as represented by such a curve, Reis did not explicitly say, but left
to the common sense of his readers to infer. Though the inference was
obvious, Bell, who possibly had not then read Reis’s researches,
seized upon this intermediate stage of the process employed by Reis,
and probably quite unconscious that Reis had already employed it,
announced it as a discovery of his own; and then, losing sight of the
point that all that was wanted was to secure correspondence between
the initial and final stage, he magnified to an absurd and unwarranted
importance this intermediate correspondence of the vibrations of the
current with those of the tympanum, which correspondence any one
reading Reis’s papers would know at once Reis had implicitly assumed
and actually employed when he transmitted articulate speech.

If we pass from the method of graphically representing undulations by
curves, and proceed to compare the language in which Reis described the
action of his machine in reproducing the undulations imparted to the
transmitter, with that in which Graham Bell described the action of his
machine some fourteen years later, we shall find[53] an agreement even
more precise.

    _Reis._

    The =electromagnet= ...
    will be demagnetised and magnetised
    correspondingly with
    the condensations and rarefactions
    of the mass of air, ... and
    =the armature ... will be
    set into vibrations= similar to
    those of the =membrane= in
    the transmitting apparatus.--(Legat’s
    Report, Zeitschrift,
    p. 128, 1862.) [p. 77.]

        _Bell._

        The current traversing the
        coils of the =electromagnet E=,
        occasions an increase and diminution
        in its intensity, and =the
        armature A^1 is thrown into
        vibrations= ... and thus imparts
        to the air at _n^1_ a =facsimile=
        copy of the motion of
        the air that acted upon the
        =membrane= _n_.--(Specification
        of British Patent, No. 4765,
        Dec. 9th, 1876, p. 17.)

    _Reis._

    The transmitter, Fig. A,
    consists of a =conical tube= ...
    closed by a =membrane= ... by
    speaking ... into the tube ...
    there will be evoked a motion
    of the =membrane= ... (_op. cit._)

        _Bell._

        A =cone A= is used to converge
        sound vibrations upon
        the =membrane=.

        When a sound is uttered in
        the cone the =membrane= _a_ is
        set in vibration....

    _Reis._

    The apparatus ... offers
    the possibility of =creating
    these vibrations= in every
    fashion that may be desired,
    and the employment of electro-galvanism
    gives us the possibility
    of calling into life, at
    any given distance, =vibrations
    similar to the vibrations=
    that have been produced, and
    in this way to reproduce at any
    place the tones that have been
    originated at another place.--(Legat’s
    Report, _op. cit._)

        _Bell._

        ... and thus electrical =undulations
        are created= upon the
        circuit E _b_ _e_ _f_ _g_.... The
        undulatory current passing
        through the electromagnet _f_
        influences its armature _h_ to
        copy the motion of the armature
        _c_.... These =undulations
        are similar in form
        to the air undulations
        caused by the sound=.

    _Reis._
    As soon therefore as it shall
    be possible ... to set up
    vibrations whose =curves are
    like= those of any given tone or
    combination of tones, we shall
    receive the same impression
    as that tone or combination of
    tones would have produced
    upon us.--(Memoir ‘On Telephony,’
    p. 60.) [p. 55.]

        _Bell._

        --that is, they are represented
        graphically by =similar
        curves=....

        A similar sound to that
        uttered into A is then heard to
        proceed from I.--(Specification
        of U. S. Patent, No. 174,465.)

  _Reis._

  =Any sound will be reproduced=,
  if strong enough to set
  the membrane in motion.--(Letter
  to Mr. Ladd, 1863.)
  [p. 84.]

        _Bell._

        There are many other uses
        to which these instruments
        may be put, such as ... the
        telegraphic transmission of
        noises or =sounds of any
        kind=.--(_Ib._)

        I would have it understood
        that what I claim is:--...
        Tenth. In a system of
        electric telegraph or telephony
        consisting of transmitting and
        receiving instruments united
        upon an electric circuit, I claim
        the production in the armature
        of each receiving instrument
        of any given motion by subjecting
        said armature to an attraction
        varying in intensity, however
        such variation may be
        produced in the magnet, and
        hence =I claim the production
        of any given sound or
        sounds from the armature
        of the receiving instrument=
        by subjecting said armature
        to an attraction varying
        in intensity in such manner
        =as to throw the armature
        into that form of vibration
        that characterizes the
        given sound= or sounds.--(Specification
        of British Patent,
        No. 4765, Dec. 9, 1876.)

    _Reis._
    =the armature= belonging to
    the magnet =will be set into
    vibrations similar to those
    of the membrane in the
    transmitting apparatus=.--(Legat’s
    Report, 1862.) [p. 77.]

One cannot help thinking that some claims to great inventions are just
a little “too previous.”

If it should still be said that Reis’s method of transmitting speech,
whether it did its work by undulatory currents or no, was avowedly
_imperfect_, and that therefore such a claim as that quoted above is
justified by the subsequent invention of an instrument the articulation
of which was more reliable, let us compare what each inventor has said
about the imperfections[54] of his own instrument.

    _Reis._

    That which has here been
    spoken of will still require
    considerable improvement,
    and in particular mechanical
    science must complete the
    apparatus to be used.--(Legat’s
    Report, 1862.) [p. 78.]

        _Bell._

        It is a mistake, however, to
        suppose that the articulation
        was by any means perfect....
        Still the articulation was there,
        and I recognized the fact that
        the indistinctness was entirely
        due to the imperfection of the
        instrument.--(‘Researches in
        Telephony,’ Journal of Soc. of
        Telegr. Engineers, Dec. 1877.)

If it should be said that Bell is here speaking only of an early
and experimental form, and not of his real invention, it should be
remembered that Bell here refers to the apparatus with cone and
membrane, identical with that exhibited at Glasgow in September,
1876, by Sir William Thomson (who had received it from Bell) and by
him described as the very “hardihood of invention,” and “by far the
greatest of all the marvels of the electric telegraph.” It certainly
worked upon the principle of undulatory currents,[55] whether it
articulated or not. Bell had himself, speaking in May 1876, before the
American Academy of Arts and Sciences upon his researches, even more
explicitly admitted the imperfections of his own instrument.

        The effects were not sufficiently
        distinct to admit of
        sustain ed conversation through
        the wire. Indeed, as a general
        rule, =the articulation was
        unintelligible=, excepting
        when familiar sentences were
        employed.--(Proceedings of
        American Academy of Arts
        and Sciences, vol. xii. p. 7.)

Yet this most imperfect machine, of which the articulation was, as a
general rule, unintelligible, had, two months previously, had a patent
granted to it as a new invention, the claim being for “the method of,
and apparatus for, transmitting vocal or other sounds telegraphically,
as herein described, by causing electrical undulations similar in
form to the vibrations of the air accompanying the said vocal or other
sounds, substantially as set forth.”

If then mere mechanical imperfections do not make an invention any
the less a true invention capable of legal recognition, it would be
dishonest to the last degree to deny to Philipp Reis the honour of his
invention, of which he honestly and openly stated both the successes
and the imperfections. He told the world what he aimed at, and in what
measure success had crowned his aims. His claim to be the inventor of
the Telephone he considered to be justified by that measure of success.
If he was so far in advance of his time that the world was unprepared
to receive or use the splendid discovery which he gave freely to it,
that was not his fault; nor does neglect or apathy make him in one
single degree the less entitled to the credit of his inventions. _Tulit
alter honores_ has not unfrequently been truly said concerning the men
of genius who have had the misfortune to live in advance of the age.

But posterity does not let the names of such truly great ones perish in
the dust. The inventor of the Telephone will be remembered and honoured
in the coming if not in the present age.

SCHEDULE OF AUTHORITIES

  Key to Title of Work:

  A. ‘Jahresbericht des Physikalischen Vereins zu Frankfurt-am-Main’
  B. ‘Fortschritte der Physik’ (Krönig and Beetz)
  C. Dingler’s ‘Polytechnisches Journal’
  D. ‘Polytechnisches Central-Blatt’(Schnedermann and Böttcher)
  E. Böttger’s ‘Polytechnisches Notizblatt’
  F. ‘Didaskalia’
  G. ‘Zeitschrift des Deutsch-Oesterreichischen Telegraphen Vereins’
     (Dr. Brix)
  H. Kuhn’s ‘Handbuch der angewandten Elektricitätslehre’
  I. Pisko’s ‘Die Neueren Apparate der Akustik’
  J. (Pisko’s) ‘Hessler’s Lehrbuch der Technischen Physik’
  K. Müller Pouillet’s ‘Lehrbuch der Physik’

  +----------+------------+--------+---------------------+-------------+
  |  Title   | Place of   | Date.  |   Volume and        |   British   |
  | of Work. |  Issue.    |        |      Page.          |   Museum.   |
  +----------+------------+--------+---------------------+-------------+
  |   A.     | Frankfurt  |{1860-1 | p. 57              }| Ac. 4428    |
  |          | -a.-M.     |{1863   | p. 129             }|             |
  |          |            |        |                     |             |
  |   B.     | Berlin     |{1861   | xvii. p. 171-173   }| Ac. 3775    |
  |          |            |{1863   | ----? p. 96        }|             |
  |          |            |        |                     |             |
  |   C.     | Stuttgart  | 1863   |{clxviii. p. 185-187}| Pp. 1780    |
  |          |            |        |{clxix. p. 23       }|             |
  |          |            |        |{clxix. p. 399      }|             |
  |          |            |        |                     |             |
  |   D.     | Cassel     | 1863   | xxix. p. 858        | Pp. 1615 b. |
  |          |            |        |                     |             |
  |   E.     | Mainz      | 1863   |{No. 6              }| Pp. 1787    |
  |          |            |        |{No. 15             }|             |
  |          |            |        |                     |             |
  |   F.     | Frankfurt  | 1862   | May 8, May 14       |     ..      |
  |          | -a.-M.     |        |                     |             |
  |          |            |        |                     |             |
  |   G.     | Berlin     | 1862   | ix. p. 125          |     ..      |
  |          |            |        |                     |             |
  |          |            |        |                     |             |
  |   H.     | Leipzig    | 1866   | p. 1017-1021        | 2244 i      |
  |          |            |        |                     |             |
  |   I.     | Vienna     | 1865   |{p. 94-103          }| 8705 cc.    |
  |          |            |        |{p. 241-243         }|             |
  |          |            |        |                     |             |
  |   J.     | Vienna     | 1866   | Vol. I. p. 648      |     ..      |
  |          |            |        |                     |             |
  |   K.     | Brunswick  | 1868   | Vol. II. p. 386-388 |     ..      |
  |          |            |        |                     |             |
  +----------+------------+--------+---------------------+-------------+


AND REFERENCES.


  Key to references:
  1. Royal Society.
  2. Ronald’s Library.
  3. Institution Civil Engineers.
  4. Royal Institution.
  5. Great Seal Patent Office.
  6. School of Mines.
  7. University College, London.
  8. Bodleian Library, Oxford.
  9. King’s College.
  10. Oxford University Museum Library.

  +---------+-----+---+---+-------+------+---+-----+---------+---+---+
  |  Title  | 1.  | 2.| 3.|   4.  |  5.  | 6.|  7. |    8.   | 9.|10.|
  | of Work.|     |   |   |       |      |   |     |         |   |   |
  +---------+-----+---+---+-------+------+---+-----+---------+---+---+
  |   A.    |1846 | ..| ..|  ..   |  ..  | ..| ..  |   ..    | ..| ..|
  |         |-1860|   |   |       |      |   |     |         |   |   |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   B.    |  x  | ..| x |   x   |6546, | x |  x  |   ..    | x | x |
  |         |     |   |   |       |118 E |   |     |         |   |   |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   C.    |  x  | ..| x |   x   |1296, | x | ..  |   ..    | ..| ..|
  |         |     |   |   |       | 94 A |   |     |         |   |   |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   D.    | ..  | ..| ..|  ..   |1132, | ..| ..  |   ..    | ..| ..|
  |         |     |   |   |       | 94 I |   |     |         |   |   |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   E.    | ..  | ..| ..|  ..   |  ..  | ..| ..  |   ..    | ..| ..|
  |         |     |   |   |       |      |   |     |         |   |   |
  |   F.    | ..  | ..| ..|  ..   |  ..  | ..| ..  |   ..    | ..| ..|
  |         |     |   |   |       |      |   |     |         |   |   |
  |   G.    | ..  | ..| x |  ..   |9511, | ..| ..  |   ..    | ..| ..|
  |         |     |   |   |       | 24 E |   |     |         |   |   |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   H.    | ..  | x | ..|   x   |13146,| ..| ..  |198 e 133| ..| ..|
  |         |     |   |   |       |163 C |   |     |         |   |   |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   I.    |  x  | ..| ..|  ..   |  ..  | ..| ..  |   ..    | ..| x |
  |         |     |   |   |       |      |   |     |         |   |   |
  |   J.    | ..  | x | ..|  ..   |  ..  | ..| ..  |   ..    | ..| ..|
  |         |     |   |   |       |      |   |     |         |   |   |
  |   I.    | ..  | ..| ..|A newer|  ..  | x |(Ed. |   ..    | ..| x |
  |         |     |   |   |edition|      |   |1876)|         |   |   |
  |         |     |   |   |(1872) |      |   |     |         |   |   |
   +---------+-----+---+---+-------+------+---+-----+---------+---+---+


FOOTNOTES:

[53] In making these comparisons in parallel columns, I wish to
repudiate in the most emphatic way any sinister inference that might be
drawn as to Graham Bell’s use of descriptions and curves identical in
so many points with those of Reis. For, in the first place, I believe
Professor Bell to be incapable of such contemptible appropriations,
and the candour with which he has himself invited comparison by
giving various references to Reis’s papers, itself precludes such
inference. In the second place, I do not think that at the date of
these quotations Bell understood German sufficiently well to comprehend
Reis’s very precise statement of the problem of the Telephone. I simply
exhibit these parallel extracts to show the thoroughness with which
Reis had grappled with the problem with which, fourteen years later,
Bell also grappled; and to prove in the most irrefragable manner, from
the necessary identity in the terms selected for expressing the facts
of the solution of the problem, that the problem to which each found a
solution was identical. The circumstance that does, however, puzzle me,
and which does not appear in these parallel extracts, is that, whilst
in his original memoir, Reis speaks in detail of the auditory ossicles
and their movements as having suggested his transmitter, and casually
mentions the phonautograph of Scott in support of his views, Bell, in
his original lecture before the American Academy, speaks in detail of
Scott’s phonautograph as having suggested his transmitter, and casually
refers to the auditory ossicles and their movements.

[54] Reis’s failures were chiefly with the vowels, Bell’s more
particularly with the consonants. Reis’s contacts were liable to break,
and the following-springs of his contact-regulators too little pliable.
Bell’s transmitter could not open and close the circuit proportionally
with the motions of the tympanum, and owing to the sluggishness due to
self-induction in the coils of his telephone, the induced undulations
of the current failed to come up in suddenness to those of the
tympanum. In consequence _whip_ sounded like _whim_, and _kiss_ like
_kith_, even in the perfected Bell Telephones made two years after
Bell’s first “improvements” in telephony were patented.

[55] The following very remarkable passage occurs in the evidence given
by Professor Graham Bell concerning Reis’s Telephones. (See published
volume of ‘Proceedings in the United States Patent Office before the
Commissioner of Patents.’ _Evidence for A. G. Bell_, p. 14.)

_Question 37._ “If a Reis Telephone, made in accordance with the
descriptions published before the earliest dates of your invention,
would in use transmit and receive articulate speech as perfectly as
the instruments did which were used by you on June 25, 1876, at the
Centennial, would it be proof to you that such Reis’s Telephones
operated by the use of undulatory movements of electricity in
substantially the same way as your instruments did upon the occasion
referred to?”

_Answer by Bell._ “The supposition contained in the question cannot be
supposed. Were the question put that if I were to hear an instrument
give forth articulate speech transmitted electrically as perfectly as
my instruments did on the occasion referred to in the question, I would
hold this as proof that the instrument had been operated by undulatory
movements of electricity, I would unhesitatingly answer, Yes.”

Surely no better authority is needed to support the proposition that
if Reis made his Telephone speak, as he said he did, he employed
undulatory currents.



ADDITIONAL PREFERENCES CONCERNING REIS’S TELEPHONE.


    Schenk’s _Philipp Reis, der Erfinder des Telephons_, 1878.

    Sack’s _Die Entwickelung der elektrischen Telephonie_, 1878.

    Ferguson’s _Electricity_ (Ed. 1867), p. 257.

    Wiedemann’s _Galvanismus_ (1874), Vol. ii. p. 598.

    _Gartenlaube, die_; for 1863, No. 51, p. 807-809.

    _Aus der Natur_; for 1862, xxi. p. 470-474.

    _Cosmos_, Vol. xxiv. p. 349 (1864).

    _Proc. Lit. Phil. Soc. Manchester_ (1865), Nov. 10, 1864.

    _Rep. Brit. Assoc_. (1863), p. 19.

    _Die Geschichte und Entwickelung des elektrischen
    Fernsprechwesens_, 1880. (Officially issued from the Imperial
    German Post-Office, Berlin.)


    LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD
    STREET AND CHARING CROSS.


  Plate 1.

[Illustration: REPRODUCTION OF TONES IN THE ELECTRO-GALVANIC WAY.]

    THO^s. KELL & SON. LITH 40, KING S^t. COVENT GARDEN #/


REPRODUCTION OF TONES IN THE ELECTRO-GALVANIC WAY.

[Illustration]

    THO^s. KELL & SON. LITH 40, KING S^t. COVENT GARDEN #/



BOOKS RELATING

TO

=APPLIED SCIENCE=

PUBLISHED BY

=E. & F. N. SPON,=

LONDON: 16, CHARING CROSS.

NEW YORK: 44, MURRAY STREET.


    _A Pocket-Book for Chemists, Chemical Manufacturers,
    Metallurgists, Dyers, Distillers, Brewers, Sugar Refiners,
    Photographers, Students, etc., etc._ By Thomas Bayley, Assoc.
    R.C. Sc. Ireland, Analytical and Consulting Chemist and
    Assayer. Second edition, with additions, 437 pp., royal 32mo,
    roan, gilt edges, 5_s_.

                         SYNOPSIS OF CONTENTS:

          Atomic Weights and Factors--Useful Data--Chemical
      Calculations--Rules for Indirect Analysis--Weights
      and Measures--Thermometers and Barometers--Chemical
      Physics--Boiling Points, etc.--Solubility of
      Substances--Methods of Obtaining Specific
      Gravity--Conversion of Hydrometers--Strength of Solutions
      by Specific Gravity--Analysis--Gas Analysis--Water
      Analysis--Qualitative Analysis and Reactions--Volumetric
      Analysis--Manipulation--Mineralogy--Assaying--Alcohol--Beer--Sugar
      --Miscellaneous Technological matter relating to Potash,
      Soda, Sulphuric Acid, Chlorine, Tar Products, Petroleum,
      Milk, Tallow, Photography, Prices, Wages, Appendix, etc.,
      etc.

    _The Mechanician_: A Treatise on the Construction and
    Manipulation of Tools, for the use and instruction of Young
    Engineers and Scientific Amateurs, comprising the Arts of
    Blacksmithing and Forging; the Construction and Manufacture
    of Hand Tools, and the various Methods of Using and Grinding
    them; the Construction of Machine Tools, and how to work
    them; Machine Fitting and Erection; description of Hand and
    Machine Processes; Turning and Screw Cutting; principles of
    Constructing and details of Making and Erecting Steam Engines,
    and the various details of setting out work, etc., etc. By
    Cameron Knight, Engineer. _Containing_ 1147 _illustrations_,
    and 397 pages of letter-press. Third edition, 4to, cloth, 18_s_.


    _On Designing Belt Gearing_. By E. J. Cowling Welch, Mem. Inst.
    Mech. Engineers, Author of ‘Designing Valve Gearing.’ Fcap.
    8vo, sewed, 6_d_.


    _A Handbook of Formulæ, Tables, and Memoranda, for
    Architectural Surveyors and others engaged in Building_. By J.
    T. Hurst, C.E. Thirteenth edition, royal 32mo, roan, 5_s_.

      “It is no disparagement to the many excellent publications
      we refer to, to say that in our opinion this little
      pocket-book of Hurst’s is the very best of them all,
      without any exception. It would be useless to attempt a
      recapitulation of the contents, for it appears to contain
      almost _everything_ that anyone connected with building
      could require, and, best of all, made up in a compact form
      for carrying in the pocket, measuring only 5 in. by 3 in.,
      and about ¾ in. thick, in a limp cover. We congratulate
      the author on the success of his laborious and practically
      compiled little book, which has received unqualified and
      deserved praise from every professional person to whom we
      have shown it.”--_The Dublin Builder_.


    _The Cabinet Maker_; being a Collection of the most approved
    designs in the Mediæval, Louis-Seize, and Old English styles,
    for the use of Cabinet Makers, Carvers, &c. By R. Charles. 96
    _plates_, folio, half-bound, 10_s_. 6_d_.


    _Quantity Surveying_. By J. Leaning. With 42 illustrations,
    crown 8vo, cloth, 9_s_.

                               Contents:

      A complete Explanation of the London Practice.
      General Instructions.
      Order of Taking Off.
      Modes of Measurement of the various Trades.
      Use and Waste.
      Ventilation and Warming.
      Credits, with various Examples of Treatment.
      Abbreviations.
      Squaring the Dimensions.
      Abstracting, with Examples in illustration of each Trade.
      Billing.
      Examples of Preambles to each Trade.
      Form for a Bill of Quantities.
      Do. Bill of Credits.
      Do. Bill for Alternative Estimate.
      Restorations and Repairs, and Form of Bill.
      Variations before Acceptance of Tender.
      Errors in a Builder’s Estimate.
      Schedule of Prices.
      Form of Schedule of Prices.
      Analysis of Schedule of Prices.
      Adjustment of Accounts.
      Form of a Bill of Variations.
      Remarks on Specifications.
      Prices and Valuation of Work, with Examples and Remarks
        upon each Trade.
      The Law as it affects Quantity Surveyors, with Law Reports.
      Taking Off after the Old Method.
      Northern Practice.
      The General Statement of the Methods recommended by the
       Manchester Society of Architects for taking Quantities.
      Examples of Collections.
      Examples of “Taking Off” in each Trade.
      Remarks on the Past and Present Methods of Estimating.


    _A Practical Treatise on Heat, as applied to the Useful Arts_;
    for the Use of Engineers, Architects, &c. By Thomas Box. _With
    14 plates._ Third edition, crown 8vo, cloth, 12_s_. 6_d_.


    _A Descriptive Treatise on Mathematical Drawing Instruments_:
    their construction, uses, qualities, selection, preservation,
    and suggestions for improvements, with hints upon Drawing and
    Colouring. By W. F. Stanley, M. R. I. Fifth edition, _with
    numerous illustrations_, crown 8vo, cloth, 5_s_.


    _Spons’ Architects’ and Builders’ Pocket-Book of Prices and
    Memoranda_. Edited by W. Young, Architect. Royal 32mo, roan,
    4_s_. 6_d_.; or cloth, red edges, 3_s_. 6_d_. _Published
    annually._ Tenth edition. _Now ready_.


    _Long-Span Railway Bridges_, comprising Investigations of the
    Comparative Theoretical and Practical Advantages of the various
    adopted or proposed Type Systems of Construction, with numerous
    Formulæ and Tables giving the weight of Iron or Steel required
    in Bridges from 300 feet to the limiting Spans; to which are
    added similar Investigations and Tables relating to Short-span
    Railway Bridges. Second and revised edition. By B. Baker,
    Assoc. Inst. C.E. _Plates_, crown 8vo, cloth, 5_s_.


    _Elementary Theory and Calculation of Iron Bridges and Roofs_.
    By August Ritter, Ph.D., Professor at the Polytechnic School at
    Aix-la-Chapelle. Translated from the third German edition, by
    H. R. Sankey, Capt. R.E. With 500 _illustrations_, 8vo, cloth,
    15_s_.


    _The Builder’s Clerk_: a Guide to the Management of a Builder’s
    Business. By Thomas Bales. Fcap. 8vo, cloth, 1_s_. 6_d_.


    _The Elementary Principles of Carpentry_. By Thomas Tredgold.
    Revised from the original edition, and partly re-written, by
    John Thomas Hurst. Contained in 517 pages of letter-press, and
    _illustrated_ with 48 _plates_ and 150 _wood engravings_. Third
    edition, crown 8vo, cloth, 18_s_.

      Section I. On the Equality and Distribution of
      Forces--Section II. Resistance of Timber--Section
      III. Construction of Floors--Section IV. Construction
      of Roofs--Section V. Construction of Domes and
      Cupolas--Section VI. Construction of Partitions--Section
      VII. Scaffolds, Staging, and Gantries--Section VIII.
      Construction of Centres for Bridges--Section IX.
      Coffer-dams, Shoring, and Strutting--Section X. Wooden
      Bridges and Viaducts--Section XI. Joints, Straps, and other
      Fastenings--Section XII. Timber.


    _Our Factories, Workshops, and Warehouses_: their Sanitary and
    Fire-Resisting Arrangements. By B. H. Thwaite, Assoc. Mem.
    Inst. C.E. _With_ 183 _wood engravings_, crown 8vo, cloth, 9_s_.


    _Gold_: Its Occurrence and Extraction, embracing the
    Geographical and Geological Distribution and the Mineralogical
    Characters of Gold-bearing rocks; the peculiar features and
    modes of working Shallow Placers, Rivers, and Deep Leads;
    Hydraulicing; the Reduction and Separation of Auriferous
    Quartz; the treatment of complex Auriferous ores containing
    other metals; a Bibliography of the subject and a Glossary of
    Technical and Foreign Terms. By Alfred G. Lock, F.R.G.S. _With
    numerous illustrations and maps_, 1250 pp., super-royal 8vo,
    cloth, 2_l_. 12_s_. 6_d_.


    _Progressive Lessons in Applied Science_. By Edward Sang,
    F.R.S.E. Crown 8vo, cloth, each Part, 3_s_.

      Part 1. Geometry on Paper--Part 2. Solidity, Weight, and
      Pressure--Part 3. Trigonometry, Vision, and Surveying
      Instruments.


    _A Practical Treatise on Coal Mining._ By George G. André,
    F.G.S., Assoc. Inst. C.E., Member of the Society of Engineers.
    _With_ 82 _lithographic plates_. 2 vols., royal 4to, cloth,
    3_l_. 12_s_.


    _Sugar Growing and Refining_: a Comprehensive Treatise on
    the Culture of Sugar-yielding Plants, and the Manufacture,
    Refining, and Analysis of Cane, Beet, Maple, Milk, Palm,
    Sorghum, and Starch Sugars, with copious statistics of their
    production and commerce, and a chapter on the distillation of
    Rum. By Charles G. Warnford Lock, F.L.S., &c., and G. W. Wigner
    and R. H. Harland, FF.C.S., FF.I.C. _With_ 205 _illustrations_,
    8vo, cloth, 30_s_.


    _Spons’ Information for Colonial Engineers._ Edited by J. T.
    Hurst. Demy 8vo, sewed.

      No. 1. Ceylon. By Abraham Deane, C.E. 2_s_. 6_d_.

                               CONTENTS:

      Introductory Remarks--Natural Productions--Architecture
      and Engineering--Topography, Trade, and Natural
      History--Principal Stations--Weights and Measures, etc.,
      etc.

      No. 2. Southern Africa, including the Cape Colony, Natal, and
      the Dutch Republics. By Henry Hall, F.R.G.S., F.R.C.I. With
      Map. 3_s_. 6_d_.

                               CONTENTS:

      General Description of South Africa--Physical Geography
      with reference to Engineering Operations--Notes on Labour
      and Material in Cape Colony--Geological Notes on Rock
      Formation in South Africa--Engineering Instruments for
      Use in South Africa--Principal Public Works in Cape
      Colony: Railways, Mountain Roads and Passes, Harbour
      Works, Bridges, Gas Works, Irrigation and Water Supply,
      Lighthouses, Drainage and Sanitary Engineering, Public
      Buildings, Mines--Table of Woods in South Africa--Animals
      used for Draught Purposes--Statistical Notes--Table of
      Distances--Rates of Carriage, etc.

      No. 3. India. By F. C. Danvers, Assoc. Inst. C.E. With Map.
      4_s_. 6_d_.

                               CONTENTS:

      Physical Geography of India--Building
      Materials--Roads--Railways--Bridges--Irrigation--River
      Works--Harbours--Lighthouse Buildings--Native
      Labour--The Principal Trees of India--Money--Weights and
      Measures--Glossary of Indian Terms, etc.


    _A Practical Treatise on Casting and Founding_, including
    descriptions of the modern machinery employed in the art. By N.
    E. Spretson, Engineer. Third edition, with 82 _plates_ drawn to
    scale, 412 pp., demy 8vo, cloth, 18_s_.

    _The Clerk of Works_: a Vade-Mecum for all engaged in the
    Superintendence of Building Operations. By G. G. HOSKINS,
    F.R.I.B.A. Third edition, fcap. 8vo, cloth, 1_s._ 6_d._

    _Tropical Agriculture_; or, the Culture, Preparation, Commerce,
    and Consumption of the Principal Products of the Vegetable
    Kingdom, as furnishing Food, Clothing, Medicine, etc., and
    in their relation to the Arts and Manufactures; forming a
    practical treatise and Handbook of Reference for the Colonist,
    Manufacturer, Merchant, and Consumer, on the Cultivation,
    Preparation for Shipment, and Commercial Value, etc., of the
    various Substances obtained from Trees and Plants entering into
    the Husbandry of Tropical and Sub-Tropical Regions. By P. L.
    SIMMONDS. Second edition, revised and improved, 515 pages, 8vo,
    cloth, 1_l._ 1_s._

    _Steel: its History, Manufacture, and Uses._ By J. S. JEANS,
    Secretary of the Iron and Steel Institute. 860 pages and _24
    plates_, 8vo, cloth, 36_s._

    _American Foundry Practice_: Treating of Loam, Dry Sand, and
    Green Sand Moulding, and containing a Practical Treatise upon
    the Management of Cupolas, and the Melting of Iron. By T.
    D. WEST, Practical Iron Moulder and Foundry Foreman. Second
    edition, _with numerous illustrations_, crown 8vo, cloth,
    10_s._ 6_d._

    _The Maintenance of Macadamised Roads._ By T. CODRINGTON,
    M.I.C.E, F.G.S., General Superintendent of County Roads for
    South Wales. 8vo, cloth, 6_s._

    _Hydraulic Steam and Hand Power Lifting and Pressing
    Machinery._ By FREDERICK COLYER, M. Inst. C.E., M. Inst. M.E.
    _With 73 plates_, 8vo, cloth, 18_s._

    _Pumps and Pumping Machinery._ By F. COLYER, M.I.C.E., M.I.M.E.
    _With 23 folding plates_, 8vo, cloth, 12_s._ 6_d._

    _Tables of the Principal Speeds occurring in Mechanical
    Engineering_, expressed in metres in a second. By P. KEERAYEFF,
    Chief Mechanic of the Obouchoff Steel Works, St. Petersburg;
    translated by SERGIUS KERN, M.E. Fcap. 8vo, sewed, 6_d._

    _Girder Making and the Practice of Bridge Building in Wrought
    Iron_, illustrated by Examples of Bridges, Piers, and Girder
    Work, etc., constructed at the Skerne Iron Works, Darlington,
    by EDWARD HUTCHINSON, M. Inst. M.E. _With 35 plates_, demy 8vo,
    cloth, 10_s._ 6_d._

    _Spons’ Dictionary of Engineering, Civil, Mechanical,
    Military, and Naval_; with technical terms in French, German,
    Italian, and Spanish, 3100 pp., and _nearly 8000 engravings_,
    in super-royal 8vo, in 8 divisions, 5_l._ 8_s._ Complete
    in 3 vols., cloth, 5_l._ 5_s._ Bound in a superior manner,
    half-morocco, top edge gilt, 3 vols., 6_l._ 12_s._
                            _See page 15._

    _A Treatise on the Origin, Progress, Prevention, and Cure of
    Dry Rot in Timber_; with Remarks on the Means of Preserving
    Wood from Destruction by Sea-Worms, Beetles, Ants, etc. By
    THOMAS ALLEN BRITTON, late Surveyor to the Metropolitan Board
    of Works, etc., etc. _With 10 plates_, crown 8vo, cloth, 7_s._
    6_d._

    _Metrical Tables._ By G. L. MOLESWORTH, M.I.C.E. 32mo, cloth,
    1_s._ 6_d._

                               CONTENTS.

      General--Linear Measures--Square
      Measures--Cubic Measures--Measures of
      Capacity--Weights--Combinations--Thermometers.

    _A Handbook of Electrical Testing._ By H. R. KEMPE, Member of
    the Society of Telegraph Engineers. New edition, revised and
    enlarged, _with 81 illustrations_. Crown 8vo, cloth, 12_s._
    6_d._

    _Electro-Telegraphy._ By FREDERICK S. BEECHEY, Telegraph
    Engineer. A Book for Beginners. _Illustrated._ Fcap. 8vo,
    sewed, 6_d._

    _Handrailing: by the Square Cut._ By JOHN JONES, Staircase
    Builder. Fourth edition, _with seven plates_, 8vo, cloth, 3_s._
    6_d._

    _Handrailing: by the Square Cut._ By JOHN JONES, Staircase
    Builder. Part Second, with eight plates, 8vo, cloth, 3_s._ 6_d._

    _The Gas Consumer’s Handy Book._ By WILLIAM RICHARDS, C.E.
    _Illustrated._ 18mo, sewed, 6_d._

    _Steam Pleating for Buildings_; or, Hints to Steam Fitters,
    being a description of Steam Heating Apparatus for Warming and
    Ventilating Private Houses and large Buildings; with Remarks on
    Steam, Water, and Air in their relation to Heating; to which
    are added miscellaneous Tables. By J. W. BALDWIN, Steam Heating
    Engineer. _With many illustrations._ Second edition, crown 8vo,
    cloth, 10_s._ 6_d._

    _A Pocket-Book of Useful Formulæ and Memoranda for Civil and
    Mechanical Engineers._ By GUILFORD L. MOLESWORTH, Mem. Inst.
    C.E., Consulting Engineer to the Government of India for State
    Railways. _With numerous illustrations_, 744 pp. Twenty-first
    edition, revised and enlarged, 32mo, roan, 6_s._

                         SYNOPSIS OF CONTENTS:

      Surveying, Levelling, etc.--Strength and Weight of
      Materials--Earthwork, Brickwork, Masonry, Arches,
      etc.--Struts, Columns, Beams, and Trusses--Flooring,
      Roofing, and Roof Trusses--Girders, Bridges, etc.--Railways
      and Roads--Hydraulic Formulæ--Canals, Sewers, Waterworks,
      Docks--Irrigation and Breakwaters--Gas, Ventilation,
      and Warming--Heat, Light, Colour, and Sound--Gravity:
      Centres, Forces, and Powers--Millwork, Teeth of
      Wheels, Shafting, etc.--Workshop Recipes--Sundry
      Machinery--Animal Power--Steam and the Steam
      Engine--Water-power, Water-wheels, Turbines, etc.--Wind
      and Windmills--Steam Navigation, Ship Building,
      Tonnage, etc.--Gunnery, Projectiles, etc.--Weights,
      Measures, and Money--Trigonometry, Conic Sections, and
      Curves--Telegraphy--Mensuration--Tables of Areas and
      Circumference, and Arcs of Circles--Logarithms, Square
      and Cube Roots, Powers--Reciprocals, etc.--Useful
      Numbers--Differential and Integral Calculus--Algebraic
      Signs--Telegraphic Construction and Formulæ.

    _Spons’ Tables and Memoranda for Engineers_; selected and
    arranged by J. T. HURST, C.E., Author of ‘Architectural
    Surveyors’ Handbook,’ ‘Hurst’s Tredgold’s Carpentry,‘ etc.
    Fifth edition, 64mo, roan, gilt edges, 1_s._; or in cloth case,
    1_s._ 6_d._

      This work is printed in a pearl type, and is so small,
      measuring only 2½ in. by 1¾ in. by ¼ in. thick, that it may
      be easily carried in the waistcoat pocket.

      “It is certainly an extremely rare thing for a reviewer
      to be called upon to notice a volume measuring but 2½ in.
      by 1¾ in., yet these dimensions faithfully represent the
      size of the handy little book before us. The volume--which
      contains 118 printed pages, besides a few blank pages for
      memoranda--is, in fact, a true pocket-book, adapted for
      being carried in the waistcoat pocket, and containing a
      far greater amount and variety of information than most
      people would imagine could be compressed into so small
      a space.... The little volume has been compiled with
      considerable care and judgment, and we can cordially
      recommend it to our readers as a useful little pocket
      companion.”--_Engineering._

    _Analysis, Technical Valuation, Purification and Use of Coal
    Gas._ By the Rev. W. R. BOWDITCH, M.A. _With wood engravings_,
    8vo, cloth, 12_s._ 6_d._

      Condensation of Gas--Purification of
      Gas--Light--Measuring--Place of Testing Gas--Test
      Candles--The Standard for Measuring Gas-light--Test
      Burners--Testing Gas for Sulphur--Testing Gas for
      Ammonia--Condensation by Bromine--Gravimetric Method
      of taking Specific Gravity of Gas--Carburetting or
      Naphthalizing Gas--Acetylene--Explosions of Gas--Gnawing of
      Gaspipes by Rats--Pressure as related to Public Lighting,
      etc.

    _A Practical Treatise on Natural and Artificial Concrete, its
    Varieties and Constructive Adaptations._ By HENRY REID, Author
    of the ‘Science and Art of the Manufacture of Portland Cement.’
    New Edition, _with 59 woodcuts and 5 plates_, 8vo, cloth, 15_s._

    _Hydrodynamics_: Treatise relative to the Testing of
    Water-Wheels and Machinery, with various other matters
    pertaining to Hydrodynamics. By JAMES EMERSON. _With numerous
    illustrations_, 360 pp. Third edition, crown 8vo, cloth, 4_s._
    6_d._

    _The Gas Analyst’s Manual._ By F. W. HARTLEY, Assoc. Inst.
    C.E., etc. _With numerous illustrations._ Crown 8vo, cloth,
    6_s._

    _Gas Measurement and Gas Meter Testing._ By F. W. HARTLEY.
    Fourth edition, revised and extended. _Illustrated_, crown 8vo,
    cloth, 4_s._

    _The French-Polishers Manual._ By a French-Polisher; containing
    Timber Staining, Washing, Matching, Improving, Painting,
    Imitations, Directions for Staining, Sizing, Embodying,
    Smoothing, Spirit Varnishing, French-Polishing, Directions for
    Repolishing. Third edition, royal 32mo, sewed, 6_d._

    _Hops, their Cultivation, Commerce, and Uses in various
    Countries._ By P. L. SIMMONDS, Crown 8vo, cloth, 4_s._ 6_d._

    _A Practical Treatise on the Manufacture and Distribution of
    Coal Gas._ By WILLIAM RICHARDS. Demy 4to, with _numerous wood
    engravings and 29 plates_, cloth, 28_s._

                         SYNOPSIS OF CONTENTS:

      Introduction--History of Gas Lighting--Chemistry of Gas
      Manufacture, by Lewis Thompson, Esq., M.R.C.S.--Coal,
      with Analyses, by J. Paterson, Lewis Thompson, and
      G. R. Hislop. Esqrs.--Retorts, Iron and Clay--Retort
      Setting--Hydraulic Main--Condensers--Exhausters--Washers
      and Scrubbers--Purifiers--Purification--History
      of Gas Holder--Tanks, Brick and Stone,
      Composite, Concrete, Cast-iron, Compound Annular
      Wrought-iron--Specifications--Gas Holders--Station
      Meter--Governor--Distribution--Mains--Gas
      Mathematics, or Formulæ for the Distribution of
      Gas, by Lewis Thompson, Esq.--Services--Consumers’
      Meters--Regulators--Burners--Fittings--Photometer--Carburization
      of Gas--Air Gas and Water Gas-Composition of Coal Gas,
      by Lewis Thompson, Esq.--Analyses of Gas--Influence of
      Atmospheric Pressure and Temperature on Gas--Residual
      Products--Appendix--Description of Retort Settings,
      Buildings, etc., etc.

    _Practical Geometry and Engineering Drawing_; a Course of
    Descriptive Geometry adapted to the Requirements of the
    Engineering Draughtsman, including the determination of cast
    shadows and Isometric Projection, each chapter being followed
    by numerous examples; to which are added rules for Shading,
    Shade-lining, etc., together with practical instructions as
    to the Lining, Colouring, Printing, and general treatment of
    Engineering Drawings, with a chapter on drawing Instruments.
    By GEORGE S. CLARKE, Lieut. R.E., Instructor in Mechanical
    Drawing, Royal Indian Engineering College. _20 plates_, 4to,
    cloth, 15_s._

    _The Elements of Graphic Statics._ By Professor KARL VON OTT,
    translated from the German by G. S. CLARKE, Lieut. R.E.,
    Instructor in Mechanical Drawing, Royal Indian Engineering
    College. _With 93 illustrations_, crown 8vo, cloth, 5_s._

    _The Principles of Graphic Statics._ By GEORGE SYDENHAM CLARKE,
    Lieut. Royal Engineers. _With 112 illustrations._ 4to. cloth,
    12_s._ 6_d._

    _The New Formula for Mean Velocity of Discharge of Rivers and
    Canals._ By W. R. KUTTER. Translated from articles in the
    ‘Cultur-Ingenieur,’ by LOWIS D’A. JACKSON, Assoc. Inst. C.E.
    8vo, cloth, 12_s._ 6_d._

    _Practical Hydraulics_; a Series of Rules and Tables for the
    use of Engineers, etc., etc. By THOMAS BOX. Fifth edition,
    _numerous plates_, post 8vo, cloth, 5_s._

    _A Practical Treatise on the Construction of Horizontal
    and Vertical Waterwheels_, specially designed for the use
    of operative mechanics. By WILLIAM CULLEN, Millwright and
    Engineer. _With 11 plates._ Second edition, revised and
    enlarged, small 4to, cloth, 12_s._ 6_d._

    _Aid Book to Engineering Enterprise Abroad._ By EWING
    MATHESON, M. Inst. C.E. The book treats of Public Works and
    Engineering Enterprises in their inception and preliminary
    arrangement; of the different modes in which money is
    provided for their accomplishment; and of the economical
    and technical considerations by which success or failure
    is determined. The information necessary to the designs of
    Engineers is classified, as are also those particulars by which
    Contractors may estimate the cost of works, and Capitalists the
    probabilities of profit. _Illustrated_, 2 vols., 8vo, 12_s._
    6_d._ each.

    _The Essential Elements of Practical Mechanics; based on the
    Principle of Work_, designed for Engineering Students. By
    Oliver Byrne formerly Professor of Mathematics, College for
    Civil Engineers. Third edition, _with 148 wood engravings_,
    post 8vo, cloth, 7_s._ 6_d._

                               CONTENTS:

      Chap. I. How Work is Measured by a Unit, both with and
      without reference to a Unit of Time--Chap. 2. The Work of
      Living Agents, the Influence of Friction, and introduces
      one of the most beautiful Laws of Motion--Chap. 3. The
      principles expounded in the first and second chapters are
      applied to the Motion of Bodies--Chap. 4. The Transmission
      of Work by simple Machines--Chap. 5. Useful Propositions
      and Rules.

    _The Practical Millwright’s and Engineer’s Ready Reckoner_;
    or Tables for finding the diameter and power of cog-wheels,
    diameter, weight, and power of shafts, diameter and strength of
    bolts, etc. By Thomas Dixon. Fourth edition, 12mo, cloth, 3_s._

    _Breweries and Maltings_: their Arrangement, Construction,
    Machinery, and Plant. By G. Scamell, F.R.I.B.A. Second edition,
    revised, enlarged, and partly rewritten By F. Colyer, M.I.C.E.,
    M.I.M.E. _With 20 plates_, 8vo, cloth, 18_s._

    _A Practical Treatise on the Manufacture of Starch, Glucose,
    Starch-Sugar, and Dextrine_, based 011 the German of L. Von
    Wagner, Professor in the Royal Technical School, Buda Pesth,
    and other authorities. By Julius Frankel; edited by Robert
    Hutter, proprietor of the Philadelphia Starch Works. _With 58
    illustrations_, 344 pp., 8vo, cloth, 18_s._

    _A Practical Treatise on Mill-gearing, Wheels, Shafts, Riggers,
    etc._; for the use of Engineers. By Thomas Box. Third edition,
    _with 11 plates_. Crown 8vo, cloth, 7_s._ 6_d._

    _Mining Machinery_: a Descriptive Treatise on the Machinery,
    Tools, and other Appliances used in Mining. By G. G. André,
    F.G.S., Assoc. Inst. C.E., Mem. of the Society of Engineers.
    Royal 4to, uniform with the Author’s Treatise on Coal Mining,
    containing _182 plates_, accurately drawn to scale, with
    descriptive text, in 2 vols., cloth, 3_l._ 12_s._

CONTENTS:

    Machinery for Prospecting, Excavating, Hauling, and
    Hoisting--Ventilation--Pumping--Treatment of Mineral Products,
    including Gold and Silver, Copper, Tin, and Lead, Iron, Coal,
    Sulphur, China Clay, Brick Earth, etc.

    _Tables for Setting out Curves for Railways, Canals, Roads,
    etc._, varying from a radius of five chains to three miles.
    By A. Kennedy and R. W. Hackwood. _Illustrated_, 32mo, cloth,
    2_s._ 6_d._

    _The Science and Art of the Manufacture of Portland Cement_,
    with observations on some of its constructive applications.
    _With 66 illustrations_. By Henry Reid, C.E., Author of ‘A
    Practical Treatise on Concrete,’ etc., etc. 8vo, cloth, 18_s._

    _The Draughtsman’s Handbook of Plan and Map Drawing_; including
    instructions for the preparation of Engineering, Architectural,
    and Mechanical Drawings. _With numerous illustrations in the
    text, and 33 plates (15 printed in colours)._ By G. G. André,
    F.G.S., Assoc. Inst. C.E. 4to, cloth, 9_s._

                               CONTENTS:

      The Drawing Office and its Furnishings--Geometrical
      Problems--Lines, Dots, and their Combinations--Colours,
      Shading, Lettering, Bordering, and North
      Points--Scales--Plotting--Civil Engineers’ and Surveyors’
      Plans--Map Drawing--Mechanical and Architectural
      Drawing--Copying and Reducing Trigonometrical Formulæ,
      etc., etc.

    _The Boiler-maker’s and Iron Ship-builder’s Companion_,
    comprising a series of original and carefully calculated
    tables, of the utmost utility to persons interested in the iron
    trades. By James Foden, author of ‘Mechanical Tables,’ etc.
    Second edition revised, _with illustrations_, crown 8vo, cloth,
    5_s._

    _Rock Blasting_: a Practical Treatise on the means employed in
    Blasting Rocks for Industrial Purposes. By G. G. André, F.G.S.,
    Assoc. Inst. C.E. _With 56 illustrations and 12 plates_, 8vo,
    cloth, 10_s._ 6_d._

    _Surcharged and different Forms of Retaining Walls._ By J. S.
    Tate. _Illustrated_, 8vo, sewed, 2_s._

    _A Treatise on Ropemaking as practised in public and private
    Rope-yards_, with a Description of the Manufacture, Rules,
    Tables of Weights, etc., adapted to the Trade, Shipping,
    Mining, Railways, Builders, etc. By R. Chapman, formerly
    foreman to Messrs. Huddart and Co., Limehouse, and late Master
    Ropemaker to H.M. Dockyard, Deptford. Second edition, 12mo,
    cloth, 3_s._

    _Laxton’s Builders’ and Contractors’ Tables_; for the use of
    Engineers, Architects, Surveyors, Builders, Land Agents, and
    others. Bricklayer, containing 22 tables, with nearly 30,000
    calculations. 4to, cloth, 5_s._

    _Laxton’s Builders’ and Contractors’ Tables._ Excavator, Earth,
    Land, Water, and Gas, containing 53 tables, with nearly 24,000
    calculations. 4to, cloth, 5_s._

    _Sanitary Engineering_: a Guide to the Construction of Works
    of Sewerage and House Drainage, with Tables for facilitating
    the calculations of the Engineer. By Baldwin Latham, C.E., M.
    Inst. C.E., F.G.S., F.M.S., Past-President of the Society of
    Engineers. Second edition, _with numerous plates and woodcuts_,
    8vo, cloth, 1_l._ 10_s._

    _Screw Cutting Tables for Engineers and Machinists_, giving the
    values of the different trains of Wheels required to produce
    Screws of any pitch, calculated by Lord Lindsay, M.P., F.R.S.,
    F.R.A.S., etc. Royal 8vo, cloth, oblong, 2_s._

    _Screw Cutting Tables_, for the use of Mechanical Engineers,
    showing the proper arrangement of Wheels for cutting the
    Threads of Screws of any required pitch, with a Table for
    making the Universal Gas-pipe Threads and Taps. By W. A.
    Martin, Engineer. Second edition, royal 8vo, oblong, cloth,
    1_s._, or sewed, 6_d._

    _A Treatise on a Practical Method of Designing Slide-Valve
    Gears by Simple Geometrical Construction_, based upon the
    principles enunciated in Euclid’s Elements, and comprising
    the various forms of Plain Slide-Valve and Expansion Gearing;
    together with Stephenson’s, Gooch’s, and Allan’s Link-Motions,
    as applied either to reversing or to variable expansion
    combinations. By Edward J. Cowling Welch, Memb. Inst.
    Mechanical Engineers. Crown 8vo, cloth, 6_s._

    _Cleaning and Scouring_: a Manual for Dyers, Laundresses, and
    for Domestic Use. By S. Christopher. 18mo, sewed, 6_d._

    _A Handbook of House Sanitation_; for the use of all persons
    seeking a Healthy Home. A reprint of those portions of Mr.
    Bailey-Denton’s Lectures on Sanitary Engineering, given
    before the School of Military Engineering, which related
    to the “Dwelling,” enlarged and revised by his Son, E. F.
    Bailey-Denton, C.E., B.A. _With 140 illustrations_, 8vo, cloth,
    8_s._ 6_d._

    _Treatise on Valve-Gears_, with special consideration of the
    Link-Motions of Locomotive Engines. By Dr. Gustav Zeuner. Third
    edition, revised and enlarged, translated from the German,
    with the special permission of the author, by Moritz Müller.
    _Plates_, 8vo, cloth, 12_s._ 6_d._

    _A Pocket-Book for Boiler Makers and Steam Users_, comprising
    a variety of useful information for Employer and Workman,
    Government Inspectors, Board of Trade Surveyors, Engineers in
    charge of Works and Slips, Foremen of Manufactories, and the
    general Steam-using Public. By Maurice John Sexton. Second
    edition, royal 32mo, roan, gilt edges, 5_s._

    _The Strains upon Bridge Girders and Roof Trusses_, including
    the Warren, Lattice, Trellis, Bowstring, and other Forms of
    Girders, the Curved Roof, and Simple and Compound Trusses. By
    Thos. Cargill, C.E.B.A.T., C.D., Assoc. Inst. C.E., Member of
    the Society of Engineers. _With 64 illustrations, drawn and
    worked out to scale_, 8vo, cloth, 12_s._, 6_d._

    _A Practical Treatise on the Steam Engine_, containing Plans
    and Arrangements of Details for Fixed Steam Engines, with
    Essays on the Principles involved in Design and Construction.
    By Arthur Rigg, Engineer, Member of the Society of Engineers
    and of the Royal Institution of Great Britain. Demy 4to,
    _copiously illustrated with woodcuts and 96 plates_, in one
    Volume, half-bound morocco, 2_l._ 2_s._; or cheaper edition,
    cloth, 25_s._

      This work is not, in any sense, an elementary treatise, or
      history of the steam engine, but is intended to describe
      examples of Fixed Steam Engines without entering into the
      wide domain of locomotive or marine practice. To this end
      illustrations will be given of the most recent arrangements
      of Horizontal, Vertical, Beam, Pumping, Winding, Portable,
      Semi-portable, Corliss, Allen, Compound, and other similar
      Engines, by the most eminent Firms in Great Britain and
      America. The laws relating to the action and precautions
      to be observed in the construction of the various details,
      such as Cylinders, Pistons, Piston-rods, Connecting-rods,
      Cross-heads, Motion-blocks, Eccentrics, Simple, Expansion,
      Balanced, and Equilibrium Slide-valves, and Valve-gearing
      will be minutely dealt with. In this connection will be
      found articles upon the Velocity of Reciprocating Parts and
      the Mode of Applying the Indicator, Heat and Expansion of
      Steam Governors, and the like. It is the writer’s desire
      to draw illustrations from every possible source, and give
      only those rules that present practice deems correct.

    _Barlow’s Tables of Squares, Cubes, Square Roots, Cube Roots,
    Reciprocals of all Integer Numbers up to 10,000._ Post 8vo,
    cloth, 6_s._

    _Camus (M.) Treatise on the Teeth of Wheels_, demonstrating
    the best forms which can be given to them for the purposes of
    Machinery, such as Mill-work and Clock-work, and the art of
    finding their numbers. Translated from the French, with details
    of the present practice of Millwrights, Engine Makers, and
    other Machinists, by Isaac Hawkins. Third edition, _with 18
    plates_, 8vo, cloth, 5_s._


    _A Practical Treatise on the Science of Land and Engineering
    Surveying, Levelling, Estimating Quantities, etc._, with a
    general description of the several Instruments required for
    Surveying, Levelling, Plotting, etc. By H. S. Merrett. Third
    edition, _41 plates with illustrations and tables_, royal 8vo,
    cloth, 12_s._ 6_d._

                          PRINCIPAL CONTENTS:

      Part 1. Introduction and the Principles of Geometry.
      Part 2. Land Surveying; comprising General
      Observations--The Chain--Offsets Surveying by the
      Chain only--Surveying Hilly Ground--To Survey an
      Estate or Parish by the Chain only--Surveying with
      the Theodolite--Mining and Town Surveying--Railroad
      Surveying--Mapping--Division and Laying out of
      Land--Observations on Enclosures--Plane Trigonometry.
      Part 3. Levelling--Simple and Compound Levelling--The
      Level Book--Parliamentary Plan and Section--Levelling
      with a Theodolite--Gradients--Wooden Curves--To Lay
      out a Railway Curve--Setting out Widths. Part 4.
      Calculating Quantities generally for Estimates--Cuttings
      and Embankments--Tunnels--Brickwork--Ironwork--Timber
      Measuring. Part 5. Description and Use of
      Instruments in Surveying and Plotting--The
      Improved Dumpy Level--Troughton’s Level--The
      Prismatic Compass--Proportional Compass--Box
      Sextant--Vernier--Pantagraph--Merrett’s Improved
      Quadrant--Improved Computation Scale--The Diagonal
      Scale--Straight Edge and Sector. Part 6. Logarithms
      of Numbers--Logarithmic Sines and Co-Sines, Tangents
      and Co-Tangents--Natural Sines and Co-Sines--Tables
      for Earthwork, for Setting out Curves, and for various
      Calculations, etc., etc., etc.

    _Saws: the History, Development, Action, Classification, and
    Comparison of Saws of all kinds._ By Robert Grimshaw. _With 220
    illustrations_, 4to, cloth, 12_s._ 6_d._

    _A Supplement to the above_; containing additional practical
    matter, more especially relating to the forms of Saw Teeth for
    special material and conditions, and to the behaviour of Saws
    under particular conditions. _With 120 illustrations_, cloth,
    9_s._

    _A Guide for the Electric Testing of Telegraph Cables._
    By Capt. V. Hoskiœr, Royal Danish Engineers. _With
    illustrations_, second edition, crown 8vo, cloth, 4_s._ 6_d._

    _Laying and Repairing Electric Telegraph Cables._ By Capt. V.
    Hoskiœr, Royal Danish Engineers. Crown 8vo, cloth, 3_s._
    6_d._

    _A Pocket-Book of Practical Rules for the Proportions of Modern
    Engines and Boilers for Land and Marine purposes._ By N. P.
    Burgh. Seventh edition, royal 32mo, roan, 4_s._ 6_d._

    _Table of Logarithms of the Natural Numbers, from 1 to
    108,000._ By Charles Babbage, Esq., M.A. Stereotyped edition,
    royal 8vo, cloth, 7_s._ 6_d._

      To ensure the correctness of these Tables of Logarithms,
      they were compared with Callett’s, Vega’s, Hutton’s,
      Briggs’, Gardiner’s, and Taylor’s Tables of Logarithms,
      and carefully read by nine different readers; and further,
      to remove any possibility of an error remaining, the
      stereotyped sheets were hung up in the Hall at Cambridge
      University, and a reward offered to anyone who could find
      an inaccuracy. So correct are these Tables, that since
      their first issue in 1827 no error has been discovered.

    _The Steam Engine considered as a Heat Engine_: a Treatise
    on the Theory of the Steam Engine, illustrated by Diagrams,
    Tables, and Examples from Practice. By Jas. H. Cotterill, M.A.,
    F.R.S., Professor of Applied Mechanics in the Royal Naval
    College. 8vo, cloth, 12_s._ 6_d._

    _The Practice of Hand Turning in Wood, Ivory, Shell, etc._,
    with Instructions for Turning such Work in Metal as maybe
    required in the Practice of Turning in Wood, Ivory, etc.; also
    an Appendix on Ornamental Turning. (A book for beginners.) By
    Francis Campin. Second edition, _with wood engravings_, crown
    8vo, cloth, 6_s._

                               CONTENTS:

      On Lathes--Turning Tools--Turning Wood--Drilling--Screw
      Cutting--Miscellaneous Apparatus and Processes--Turning
      Particular Forms--Staining--Polishing--Spinning
      Metals--Materials--Ornamental Turning, etc.

    _Health and Comfort in House Building, or Ventilation with Warm
    Air by Self-Acting Suction Power_, with Review of the mode
    of Calculating the Draught in Hot-Air Flues, and with some
    actual Experiments. By J. Drysdale, M.D., and J. W. Hayward,
    M.D. Second edition, with Supplement, _with plates_, demy 8vo,
    cloth, 7_s._ 6_d._

    _Treatise on Watchwork, Past and Present._ By the Rev. H. L.
    Nelthropp, M.A., F.S.A. _With 32 illustrations_, crown 8vo,
    cloth, 6_s._ 6_d._

                               CONTENTS:

      Definitions of Words and Terms used in
      Watchwork--Tools--Time--Historical Summary--On
      Calculations of the Numbers for Wheels and Pinions;
      their Proportional Sizes, Trains, etc.--Of Dial Wheels,
      or Motion Work--Length of Time of Going without Winding
      up--The Verge--The Horizontal--The Duplex--The Lever--The
      Chronometer--Repeating Watches--Keyless Watches--The
      Pendulum, or Spiral Spring--Compensation--Jewelling
      of Pivot Holes--Clerkenwell--Fallacies of the
      Trade--Incapacity of Workmen--How to Choose and Use a
      Watch, etc.

    _Spons’ Engineers’ and Contractors Illustrated Book of Prices
    of Machines, Tools, Ironwork, and Contractors’ Material; and
    Engineers’ Directory._ Third edition, 4to, cloth, 6_s._

    _Algebra Self-Taught._ By W. P. Higgs, M.A., D.Sc., LL.D.,
    Assoc. Inst. C.E., Author of ‘A Handbook of the Differential
    Calculus,’ etc. Second edition, crown 8vo, cloth, 2_s._ 6_d._

                               CONTENTS:

      Symbols and the Signs of Operation--The Equation
      and the Unknown Quantity--Positive and Negative
      Quantities--Multiplication--Involution--Exponents--Negative
      Exponents--Roots, and the Use of Exponents as
      Logarithms--Logarithms--Tables of Logarithms and
      Proportionate Parts--Transformation of System of
      Logarithms--Common Uses of Common Logarithms--Compound
      Multiplication and the Binomial Theorem--Division,
      Fractions, and Ratio--Continued Proportion--The Series and
      the Summation of the Series--Limit of Series--Square and
      Cube Roots--Equations--List of Formulæ, etc.



                            JUST PUBLISHED.

     In super-royal 8vo, 1168 pp., _with 2400 illustrations_, in 3
     Divisions, cloth, price 13_s._ 6_d._ each; or 1 vol., cloth,
                  2_l._; or half-morocco, 2_l._ 8_s._


                             A SUPPLEMENT

                                  TO

                   SPONS’ DICTIONARY OF ENGINEERING,

                Civil, Mechanical, Military and Naval.

             Edited by ERNEST SPON, Memb. Soc. Engineers.

The success which has attended the publication of ‘SPONS’ DICTIONARY OF
ENGINEERING’ has encouraged the Publishers to use every effort tending
to keep the work up to the standard of existing professional knowledge.
As the Book has now been some years before the public without addition
or revision, there are many subjects of importance which, of necessity,
are either not included in its pages, or have been treated somewhat
less fully than their present importance demands. With the object,
therefore, of remedying these omissions, this Supplement is now being
issued. Each subject in it is treated in a thoroughly comprehensive
way; but, of course, without repeating the information already included
in the body of the work.

The new matter comprises articles upon

  Abacus, Counters, Speed Indicators, and Slide Rule.
  Agricultural Implements and Machinery.
  Air Compressors.
  Animal Charcoal Machinery.
  Antimony.
  Axles and Axle-boxes.
  Barn Machinery.
  Belts and Belting.
  Blasting.
  Boilers.
  Brakes.
  Brick Machinery.
  Bridges.
  Cages for Mines.
  Calculus, Differential and Integral.
  Canals.
  Carpentry.
  Cast Iron.
  Cement, Concrete, Limes, and Mortar.
  Chimney Shafts.
  Coal Cleansing and Washing.
  Coal Mining.
  Coal Cutting Machines.
  Coke Ovens.
  Copper.
  Docks.
  Drainage.
  Dredging Machinery.
  Dynamo-Electric and Magneto-Electric Machines.
  Dynamometers.
  Electrical Engineering, Telegraphy, Electric Lighting and its
    practical details, Telephones.
  Engines, Varieties of.
  Explosives.
  Fans.
  Founding, Moulding and the practical work of the Foundry.
  Gas, Manufacture of.
  Hammers, Steam and other Power.
  Heat.
  Horse Power.
  Hydraulics.
  Hydro-geology.
  Indicators.
  Iron.
  Lifts, Hoists, and Elevators.
  Lighthouses, Buoys, and Beacons.
  Machine Tools.
  Materials of Construction.
  Meters.
  Ores, Machinery and Processes employed to Dress.
  Piers.
  Pile Driving.
  Pneumatic Transmission.
  Pumps.
  Pyrometers.
  Road Locomotives.
  Rock Drills.
  Rolling Stock.
  Sanitary Engineering.
  Shafting.
  Steel.
  Steam Navvy.
  Stone Machinery.
  Tramways.
  Well Sinking.



                             NOW COMPLETE.

      _With nearly 1500 illustrations_, in super-royal 8vo, in 5
    Divisions, cloth. Divisions 1 to 4, 13_s._ 6_d._ each; Division
             5, 17_s._ 6_d._; or 2 vols., cloth, £3 10_s._


                          SPONS’ ENCYCLOPÆDIA

                                OF THE

        INDUSTRIAL ARTS, MANUFACTURES, AND COMMERCIAL PRODUCTS.

                 Edited by C. G. WARNFORD LOCK, F.L.S.

Among the more important of the subjects treated of, are the
following:--

  Acids, 207 pp. 220 figs.
  Alcohol, 23 pp. 16 figs.
  Alcoholic Liquors, 13 pp.
  Alkalies, 89 pp. 78 figs.
  Alloys.
  Alum.
  Asphalt.
  Assaying.
  Beverages, 89 pp. 29 figs.
  Blacks.
  Bleaching Powder, 15 pp.
  Bleaching, 51 pp. 48 figs.
  Candles, 18 pp. 9 figs.
  Carbon Bisulphide.
  Celluloid, 9 pp.
  Cements.
  Clay.
  Coal-tar Products, 44 pp. 14 figs.
  Cocoa, 8 pp.
  Coffee, 32 pp. 13 figs.
  Cork, 8 pp. 17 figs.
  Cotton Manufactures, 62 pp. 57 figs.
  Drugs, 38 pp.
  Dyeing and Calico Printing, 28 pp. 9 figs.
  Dyestuffs, 16 pp.
  Electro-Metallurgy, 13 pp.
  Explosives, 22 pp. 33 figs.
  Feathers.
  Fibrous Substances, 92 pp. 79 figs.
  Floor-cloth, 16 pp. 21 figs.
  Food Preservation, 8 pp.
  Fruit, 8 pp.
  Fur, 5 pp.
  Gas, Coal, 8 pp.
  Gems.
  Glass, 45 pp. 77 figs.
  Graphite, 7 pp.
  Hair, 7 pp.
  Hair Manufactures.
  Hats, 26 pp. 26 figs.
  Honey.
  Hops.
  Horn.
  Ice, 10 pp. 14 figs.
  Indiarubber Manufactures, 23 pp. 17 figs.
  Ink, 17 pp.
  Ivory.
  Jute Manufactures, 11 pp. 11 figs.
  Knitted Fabrics--Hosiery, 15 pp. 13 figs.
  Lace, 13 pp. 9 figs.
  Leather, 28 pp. 31 figs.
  Linen Manufactures, 16 pp. 6 figs.
  Manures, 21 pp. 30 figs.
  Matches, 17 pp. 38 figs.
  Mordants, 13 pp.
  Narcotics, 47 pp.
  Nuts, 10 pp.
  Oils and Fatty Substances, 125 pp.
  Paint.
  Paper, 26 pp. 23 figs.
  Paraffin, 8 pp. 6 figs.
  Pearl and Coral, 8 pp.
  Perfumes, 10 pp.
  Photography, 13 pp. 20 figs.
  Pigments, 9 pp. 6 figs.
  Pottery, 46 pp. 57 figs.
  Printing and Engraving, 20 pp. 8 figs.
  Rags.
  Resinous and Gummy Substances, 75 pp. 16 figs.
  Rope, 16 pp. 17 figs.
  Salt, 31 pp. 23 figs.
  Silk, 8 pp.
  Silk Manufactures, 9 pp. 11 figs.
  Skins, 5 pp.
  Small Wares, 4 pp.
  Soap and Glycerine, 39 pp. 45 figs.
  Spices, 16 pp.
  Sponge, 5 pp.
  Starch, 9 pp. 10 figs.
  Sugar, 155 pp. 134 figs.
  Sulphur.
  Tannin, 18 pp.
  Tea, 12 pp.
  Timber, 13 pp.
  Varnish, 15 pp.
  Vinegar, 5 pp.
  Wax, 5 pp.
  Wool, 2 pp.
  Woollen Manufactures, 5s pp. 39 figs.


London: E. & F. N. SPON, 16, Charing Cross.

New York: 44, Murray Street.





*** End of this Doctrine Publishing Corporation Digital Book "Philipp Reis: Inventor of the Telephone - A Biographical Sketch" ***

Doctrine Publishing Corporation provides digitized public domain materials.
Public domain books belong to the public and we are merely their custodians.
This effort is time consuming and expensive, so in order to keep providing
this resource, we have taken steps to prevent abuse by commercial parties,
including placing technical restrictions on automated querying.

We also ask that you:

+ Make non-commercial use of the files We designed Doctrine Publishing
Corporation's ISYS search for use by individuals, and we request that you
use these files for personal, non-commercial purposes.

+ Refrain from automated querying Do not send automated queries of any sort
to Doctrine Publishing's system: If you are conducting research on machine
translation, optical character recognition or other areas where access to a
large amount of text is helpful, please contact us. We encourage the use of
public domain materials for these purposes and may be able to help.

+ Keep it legal -  Whatever your use, remember that you are responsible for
ensuring that what you are doing is legal. Do not assume that just because
we believe a book is in the public domain for users in the United States,
that the work is also in the public domain for users in other countries.
Whether a book is still in copyright varies from country to country, and we
can't offer guidance on whether any specific use of any specific book is
allowed. Please do not assume that a book's appearance in Doctrine Publishing
ISYS search  means it can be used in any manner anywhere in the world.
Copyright infringement liability can be quite severe.

About ISYS® Search Software
Established in 1988, ISYS Search Software is a global supplier of enterprise
search solutions for business and government.  The company's award-winning
software suite offers a broad range of search, navigation and discovery
solutions for desktop search, intranet search, SharePoint search and embedded
search applications.  ISYS has been deployed by thousands of organizations
operating in a variety of industries, including government, legal, law
enforcement, financial services, healthcare and recruitment.



Home