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Title: Scientific American Supplement, No. 633,  February 18, 1888
Author: Various
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 "Scientific American Supplement, No. 633,  February 18, 1888" ***

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Scientific American Supplement. Vol. XXV., No. 633.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

       *       *       *       *       *


I.    ARCHITECTURE.--Elements of Architectural Design.--By H.H.
      STATHAM.--The commencement of a series of lectures
      delivered before the London Society of Arts, giving the line
      of development of the different styles and the aspirations
      of their originators. 34 illustrations.                      10106

II.   ASTRONOMY.--A Fivefold Comet.--A curious astronomical
      deduction; the probable division of one comet into five by
      the disturbing effects of the sun. 1 illustration.           10116

III.  BIOGRAPHY.--Linnæus.--By C.S. HALLBERG.--The life and
      work of the great botanist, his portrait and birthplace.
      2 illustrations.                                             10114

IV.   CHEMISTRY.--An Apparatus for Preparing Sulphurous, Carbonic,
      and Phosphoric Anhydrides.--By H.N. WARREN.--A simple
      apparatus for this purpose described and illustrated.
      1 illustration.                                              10117

      The Arrangement of Atoms in Space in Organic Molecules.--A
      review of Prof. JOHANNES WISLICENUS' recent theories
      on this abstract subject.                                    10117

      The Isolation of Fluorine.--Note on this last isolation of
      an element, with the properties of the gas. 1 illustration.  10117

V.    ELECTRICITY.--Observations on Atmospheric Electricity.--By
      Prof. L. WEBER.--Abstract of a British Association paper
      on this important subject.                                   10114

      The Menges Thermo-Magnetic Generator and Motor.--The direct
      conversion of electricity into heat; the generator fully
      described. 5 illustrations.                                  10113

VI.   ENGINEERING.--An Investigation into the Internal Stresses
      Occurring in Cast Iron and Steel.--By General NICHOLAS
      KALAKOUTZKY.--First installment of an elaborate paper,
      giving theoretical and experimental examination of this
      subject. 2 illustrations.                                    10105

      Hargreaves' Thermo-Motor.--A new caloric engine.--Its
      construction, theory, and cylinder diagrams.
      6 illustrations.                                             10104

      The Compound Steam Turbine.--A description and discussion
      of this motor, in which a series of forty-five turbines are
      acted on by the current of steam. 2 illustrations.           10103

VII.  MISCELLANEOUS.--Cold Storage for Potatoes.--The application
      of artificial cold to preserving potatoes.--Results obtained
      in actual experience.--A practical paper by Mr. EDWIN
      TAYLOR.                                                      10115

VIII. PHYSICS.--On a Method of Making the Wave Length of Sodium
      Light the Actual and Practical Standard of Length.--By ALBERT
      A. MICHELSON and EDWARD W. MORLEY.--Description of the
      new standard of length and outlines of the practical method for
      its determination.--The question of check determinations.
      1 illustration.                                              10115

IX.   TECHNOLOGY.--Progress of the Sorghum Sugar Industry.--
      Elaborate report on the diffusion process as developed at
      the Fort Worth, Kan., station. 2 illustrations.              10110

      The Lowe Incandescent Gas Burner.--The well known advanced
      type of gas burner described and illustrated. 1
      illustration.                                                10110

       *       *       *       *       *


Last year the whole of the lighting of the Newcastle Exhibition was
effected by the agency of seventeen of these motors, of which four were
spare, giving in the aggregate 280 electrical horse power. As the steam
was provided by the authorities of the exhibition, it was good proof to
the public that they had satisfied themselves that the consumption would
not be extravagant, as however favorable might be the terms on which the
manufacturers would be willing to lend their engines, they could
scarcely be sufficiently tempting to compensate for an outrageous
consumption of coal, even in Newcastle. At the time we gave an account
of the result of the test, showing that the steam used was 65 lb. per
electrical horse power, a very satisfactory result, and equal to 43 lb.
per indicated horse power if compared with an ordinary engine driving a
generator through a belt. Recently Mr. Parsons has given an account of
the theory and construction of his motor before the Northeast Coast
Institution, and has quoted 52 lb. of steam per electric horse power as
the best result hitherto attained with a steam pressure of 90 lb. As now
made there are forty-five turbines through which the steam passes in
succession, expanding in each, until it is finally exhausted.


The theoretical efficiency of a motor of this kind is arrived at by Mr.
Parsons in the following manner:

The efflux of steam flowing from a vessel at 15.6 lb. per square inch
absolute pressure through an orifice into another vessel at 15 lb.
pressure absolute is 366 ft. per second, the drop of pressure of 0.6 lb.
corresponding to a diminution of volume of 4 per cent. in the opposite
direction. The whole 45 turbines are so proportioned that each one,
starting from the steam inlet, has 4 per cent. more blade area or
capacity than that preceding it. Taking the pressure at the exhaust end
to be 15 lb. absolute, that at the inlet end will be 69 lb. above the
atmosphere. The steam enters from the steam pipe at 69 lb. pressure, and
in passing through the first turbine it falls 2.65 lb. in pressure, its
velocity due to the fall being 386 ft. per second, and its increase of
volume 3.85 per cent. of its original volume. It then passes through the
second turbine, losing 2.55 lb. in pressure, and gaining 3.85 per cent.
in volume, and so on until it reaches the last turbine, when its
pressure is 15.6 lb. before entering, and 15 lb. on leaving. The
velocity due to the last drop is 366 ft. per second. The velocity of the
wheels at 9,200 revolutions per minute is 150 ft. per second, or 39.9
per cent. of the mean velocity due to the head throughout the turbines.
Comparing this velocity with the results of a series of experiments made
by Mr. James B. Francis on a Tremont turbine at Lowell, Mass., it
appears that there should be an efficiency of 72 per cent. if the
blades be equally well shaped in the steam as in the water turbine, and
that the clearances be kept small and the steam dry. Further, as each
turbine discharges without check into the next, the residual energy
after leaving the blades is not lost as it is in the case of the water
turbine, but continues into the next guide blades, and is wholly
utilized there. This gain should be equal to 3 to 5 per cent.

As each turbine of the set is assumed to give 72.5 per cent. efficiency,
the total number may be assumed to give the same result, or, in other
words, over 72 per cent. of the power derived from using the steam in a
perfect engine, without losses due to condensation, clearances,
friction, and such like. A perfect engine working with 90 lb. boiler
pressure, and exhausting into the atmosphere, would consume 20.5 lb. of
steam per hour for each horse power. A motor giving 70 per cent.
efficiency would, therefore, require 29.29 lb. of steam per horse power
per hour. The best results hitherto attained have been 52 lb. of steam
per hour per electrical horse power, as stated above, but it is
anticipated that higher results will be attained shortly. Whether that
be so or not, the motor has many advantages to recommend it, and among
these is the increased life of the lamps due to the uniform rotation of
the dynamo. At the Phoenix Mills, Newcastle, an installation of 159
Edison-Swan lamps has been running, on an average, eleven hours a day
for two years past, yet in that time only 94 lamps have failed, the
remaining 65 being in good condition after 6,500 hours' service. Now,
if the lamps had only lasted 1,000 hours on the average, as is commonly
assumed, the renewals would have amounted to double the year's cost of
fuel, as at present consumed.

The present construction of the motor and dynamo is shown in the

[Illustration: Fig. 1 though 6]

Fig. 2 shows the arrangement of 90 complete turbines, 45 lying on each
side of the central steam inlet. The guide blades, R, are cut on the
internal periphery of brass rings, which are afterward cut in halves and
held in the top and bottom halves of the cylinder by feathers. The
moving blades, S, are cut on the periphery of brass rings, which are
afterward threaded and feathered on to the steel shaft, and retained
there by the end rings, which form nuts screwed on to the spindle. The
whole of this spindle with its rings rotate together in bearings, shown
in enlarged section, Fig. 3. Steam entering at the pipe, O, flows all
round the spindle and passes along right and left, first through the
guide blades, R, by which it is thrown on to the moving blades, S, then
back on to the next guide blades, and so on through the whole series on
each hand, and escapes by the passages, P, at each end of the cylinder
connected to the exhaust pipe at the back of cylinder. The bearings,
Fig. 3, consist of a brass bush, on which is threaded an arrangement of
washers, each successive washer alternately fitting to the bush and the
block, while being alternately 1/32 smaller than the block outside and
1/32 larger than the bush in the hole. One broad washer at the end holds
the bearings central. These washers are pressed together by a spiral
spring, N, and nut, and, by friction against each other, steady or damp
any vibration in the spindle that may be set up by want of balance or
other cause at the high rate of speed that is necessary for economical

The bearings are oiled by a small screw propeller, I, attached to the
shaft. The oil in the drain pipes, D and F, and the oil tank, D, lies at
a lower level than the screw, but the suction of the fan, K, raises it
up into the stand pipe, H, over and around the screw, which gripes it
and circulates it along the pipes to the bearings. The course of the oil
is as follows: The oil is forced by the propeller, I, and oils the
bearing, A. The greater part passes along the pipe, E, to the end
bearing, C; some after oiling the bearing, C, drains back by the pipe,
F, to the reservoir, D; the remaining oil passes along through the
armature spindle, oils the bearings, B, and drains into the reservoir,
D, from which the oil is again drawn along the pipe, G, into the stand
pipe, H, by the suction of the fan, K. The suction of the fan is also
connected to the diaphragm, L, and forms, with it and the spring, M, the
principal part of the governor which actuates the throttle valve, V.
Fig. 4 is the electrical control governor, which will be further
described in connection with the dynamo. It acts directly upon the
controlling diaphragm, L, by admitting or closing a large access of air
to it, and thus exercises a controlling influence upon it.

The dynamo which forms the other portion of the electric generator, Fig.
1, is coupled to the motor spindle by a square tube coupling fitted on
to the square spindle ends. The armature is of the drum type. The body
is built up of thin iron disks threaded on to the spindle and insulated
from each other by tracing paper. This iron body is turned up and
grooves milled out to receive the conducting wires. For pressures of 60
to 80 volts there are fifteen convolutions of wire, or 30 grooves. The
wire starting at b, Fig. 6, is led a quarter of a turn spirally, c,
round the cylindrical portion, a, then passing along a groove
longitudinally is again led a quarter turn spirally, d, round the
cylindrical portion, a, then through the end washer, and back
similarly a quarter turn, e, then led along the diametrically opposite
groove, and lastly a little over a quarter turn, f, back to g, where
it is coupled to the next convolution. The commutator is formed of rings
of sections. Each section is formed of short lengths. Each length is
dovetailed and interlocked between conical steel rings. The whole is
insulated with asbestos, and, when screwed up by the end nut, forms,
with the steel bush, a compact whole. There are fifteen sections in the
commutator, and each coupling is connected to a section. The whole
armature is bound externally from end to end with brass or pianoforte
steel wire. The magnets are of soft cast iron and of the horseshoe type.
They are shunt-wound only.

On the top of the magnet yoke is the electrical control governor, Fig.
4. It consists of one moving spindle on which are keyed a small soft
iron bar, and also a double finger, T. There is also a spiral spring, X,
attached at one end to the spindle, and at the other to an adjustable
top head and clamping nut, Y. The double finger, T, covers or opens a
small hole in the face, U, communicating by the pipe, W, to the
diaphragm, L. The action of the magnet yoke is to attract the needle
toward the poles of the magnet, while by turning the head the spiral
spring, X, is brought into tension to resist and balance this force, and
can be set and adjusted to any degree of tension. The double finger, T,
turns with the needle, and, by more or less covering the small air inlet
hole, U, it regulates the access of air to the regulating diaphragm, L.
The second finger is for safety in case the brushes get thrown off, or
the magnet circuit be broken, in which case the machine would otherwise
gain a considerable increase of speed before the diaphragm would act. In
these cases, however, the needle ceases to be attracted, falls back, and
the safety finger closes the air inlet hole.

There is no resistance to the free movement of this regulator. A
fraction of a volt increase or decrease of potential produces a
considerable movement of the finger, sufficient to govern the steam
pressure, and in ordinary work it is found possible to maintain the
potential within one volt of the standard at all loads within the
capacity of the machine, excepting only a slight momentary variation
when a large portion of the load is switched on or off.

The resistance of the armature from brush to brush is only 0.0032 ohm,
the resistance of the field magnets is only 17.7 ohms, while the normal
output of the dynamo is 200 amperes at 80 volts. This, excluding other
losses, gives an efficiency of 97 per cent. The other losses are due to
eddy currents throughout the armature, magnetic retardation, and bearing
friction. They have been carefully measured. By separately exciting the
field magnets from another dynamo, and observing the increased steam
pressure required to maintain the speed constant, the corresponding
power was afterward calculated in watts.

The commercial efficiency of this dynamo, after allowing for all losses,
is a little over 90 per cent. In the larger sizes it rises to 94 per
cent. Assuming the compound steam turbine to give a return of 70 per
cent. of the total mechanical energy of the steam, and the dynamos to
convert 90 per cent of this into electrical output, gives a resulting
efficiency of 63 per cent. As steam at 90 lb. pressure above the
atmosphere will with a perfect non-condensing engine give a horse power
for every 20.5 lb. of steam consumed per hour, it follows that an
electrical generator of 63 per cent. efficiency will consume 32.5 lb. of
steam for every electrical horse power per hour.

Again, with steam at 150 lb. pressure above the atmosphere, a generator
of the same efficiency would consume only 22.2 lb. of steam per
electrical horse power per hour.

The results so far actually obtained are a consumption of 52 lb. per
hour of steam for each electrical horse power with a steam pressure of
90 lb. above the atmosphere.--_Engineering._

       *       *       *       *       *


From the researches and investigations of Carnot, Joule, Rankine,
Clausius, and Sir William Thomson, the science of thermo-dynamics has
not only been brought into existence, but fully matured. We learn from
it that whereas in the steam engine, on account of the limited range of
temperature in the working cylinder and the rapid conduction of steam
during condensation, no combination of cylinders can materially affect
its present efficiency, internally fired engines, such as gas and
caloric engines--being, as it were, less fettered--can have their
already high efficiency increased by simply overcoming mechanical
difficulties. To this fact is no doubt due the recent remarkable
development of gas and caloric engines. The first caloric or hot air
engine was invented by Sir George Cayley in 1807, and in 1827 Dr. Robert
Stirling, a Scotch minister, took out his first patent for a hot air
engine, which was the foundation of many subsequent machines, and by the
invention of the regenerator he converted what was practically a
scientific toy into an efficient machine.

One of the most ardent workers in this field at the present time is Mr.
James Hargreaves, of Widnes, who, with a thorough theoretical knowledge
of the subject has, after many years of patient perseverance, over come
many of the mechanical difficulties, and designed the engine of which
the above is an illustration.

The sectional elevation, shown in Fig. 1, is an expanded view of the
machine, shown thus to enable the action of the machine to be more
clearly understood; the relative position of the different parts, as
actually made, is shown in the side elevation (Fig. 4). The principal
working parts of the machine are the combustion chamber, D, which is of
the form shown, lined with fire brick, and having an entrance, with the
door screwed down like a manhole lid; the working cylinder, A,
surrounded by the water casing, K; the piston, B, with a water lining,
and coupled to the end of the working beam by a parallel motion, the
beam being supported by two rocking columns, Z, as in engines of the
"grasshopper" type; the air compressor, C, coupled directly to the
piston of the working cylinder; the injection pump, F, for supplying the
fuel--creosote or coal tar--to the combustion chamber; the regenerator
E; the receiver and separator, V Y; the feed and exhaust valves, M.


[Illustration: Fig. 2.]

The action of the machine is as follows: Assuming the engine to be in
condition for starting, the sides of the combustion chamber, D, are red
hot, the chamber charged with air, and the spray of creosote, injected
by the pump, F, is ignited; the expansion of the gases produced by the
combustion acts upon the bottom of the piston, B, forcing it to the top
of the cylinder, and thus, by intermediate mechanism, causing the crank
shaft to revolve. By the same stroke a charge of air is forced by the
compressor, C, into the receiver through the pipe, R. The cylinder is,
of course, single acting, and on the down stroke of the piston, B--which
falls by its own weight and the momentum of the fly wheel--the exhaust
gases are forced through the regenerator, E, which absorbs most of their
heat; they then pass through the exhaust valve, placed immediately under
the feed valve, M, along the pipe, Q, up through the pipes, T, fitted
into the receiver, V, down the pipes, T, fitted into the saturator, Y,
and out of the funnel fixed to the bottom of Y.

[Illustration: Fig 3.]

[Illustration: Fig. 4.]

The charge of air for supplying the combustion chamber is forced by the
compressor, C, through the pipe, R, _outside_ the tubes, T, in the
chambers, V and Y, along the pipe, P, through the feed valve, M, and the
regenerator, E, into the combustion chamber. In its passage from the
compressor, it first picks up the residual heat of the exhaust gases in
the tubes, T, and finally the heat absorbed by the regenerator, E, thus
entering the combustion chamber in a highly heated state. Having
described generally the passage of the air from the compressor to the
working cylinder, and back again to the funnel, we will now describe the
details. The working cylinder, A, is fitted into the casting which forms
the water casing, K, a space being left between the bottom of the
cylinder and the casing, which is filled with a non-conducting mixture
of asbestos to protect it from the heat of combustion; the bottom of the
piston, B, has a similar protection, and the regenerator has a lining
of the same mixture, to prevent any heat from escaping through the
casting which holds it. The water in the casing, K, and in the piston,
B, is supplied by a small pump, G, which forces the water through the
pipe, P4, into the telescopic pipe, L either into the piston, B, or
through the pipe, P6, into the casing, K--the bottom of the casing
being connected by the pipe, P10, with the auxiliary boiler, W. The
steam generated in the casing, K, is carried to the boiler, W, by the
pipe, P3, and from the boiler it passes along the pipe, P2,
through the valve, A2, into the chamber, V, thus giving up its heat
to the incoming air, with which it mixes. The vapor gradually condenses
at the bottom of the vessel, Y, and the water so formed is drawn by the
pump, J, along the suction pipe, P9, and forced through the pipe,
P8, back to the chamber, Y, through the valve, A1, and in the form
of spray plays on the tubes, T, and absorbing any residual heat. The
heat generated by compression in the cylinder, C, is absorbed by a spray
of water from the pump, H, the vapor being carried along with the air
through the pipe, R, to the chamber, Y, where it is separated, and
falling to the bottom is circulated, as just described, by the pump, J.
X is a small auxiliary air compressor, to obtain the necessary
compression to start the engine, and is worked from the boiler, W. In
future engines this compressor will be superseded by a specially
designed injector, which will produce the necessary pressure at a
considerable reduction in cost. When once the engine is started, the
fire of the auxiliary boiler can, of course, be drawn, as the main
engine afterward makes its own steam. The regenerator, E, has circular
ends of fire clay perforated, the body being filled with fire clay
spirals of the shape clearly shown in elevation in Fig. 2. The injector
valve for the creosote is shown to a larger scale in Fig. 3. This valve
has, however, been since considerably modified and improved. The feed
and exhaust valves, M, are actuated by cams keyed to a countershaft
driven by bevel wheels from the main shaft. The creosote pump, F, is
also worked by a cam on the same shaft, but the pumps, G H J, are worked
by eccentrics. A stop valve, N, is fixed to the supply pipe, P, under
which is place a back pressure valve to retain the pressure in the
combustion chamber. The engine is regulated by an ordinary Porter
governor actuating the throttle valve, O. An engine, as described, has
been constructed by Messrs. Adair & Co., engineers, Waterloo Road,
Liverpool, and has been running most satisfactorily for several weeks,
the results being clearly shown by the indicator diagrams (Figs. 5 and
6). The results obtained by this motor are very remarkable, and are a
long way in advance of any previous performance, as only a little over ½
lb. of fuel is used per i.h.p. per hour. It may be mentioned that the
temperature of the combustion chamber is calculated to be about
2,500°F., and that of the exhaust gases does not exceed

[Illustration: Diagram from cylinder--25 in. diam, 18 in. stroke.
I.H.P., 63. Scale, 1/30 in. Mean pressure, 28.2 lb. FIG. 5.]

[Illustration: Diagram from air pump--15 in. diam., 18 in. stroke.
I.H.P., 23. Scale, 1/30 in--Mean pressure, 28.5 lb. FIG. 6.


Net indicated horse power, 40; revolutions per minute, 100; coal tar
consumed per hour, 20.5 lb.; coal tar per I.H.P. per hour, 0.512 lb.]

       *       *       *       *       *



NO. I.

_Determination of the Influence of Internal Stresses on the Strength of
Materials._--We call internal stresses those which exist within the mass
of any hollow cylinder or other body, when it appears to be in a state
of repose, or not under the influence of external forces. When pressure
is applied to a hollow cylinder, either externally or internally, the
interior layers into which its walls may be conceived to be divided are
subjected to a new series of stresses, the magnitude of which is
independent of those already existing. These additional stresses combine
with the former in such a manner that at every point of the thickness of
the cylinder they have common resultants acting in various directions.
Thus, if we call t the internal stress existing at a distance r_x
from the axis of the cylinder, and in a direction tangential to its
cross section, and T the additional stress due to pressure inside the
cylinder acting at the same point and in the same direction, then the
newly developed stress will be t + T.

If R and r0 be the external and internal radii of the cylinder, and
if we suppose the external pressure _nil_, then, if the pressure inside
the bore be P0, the stress on the radius r_x is determined by the
following expression deduced from the well-known fundamental formulæ of

           r0²      R² + (r_x)²
  T = P0 ------- · -------------
          R²-r0²      (r_x)²

From which we see that T is a maximum when r_x = r0, i.e., for
the layer immediately next to the bore of the cylinder. Calling t0
the internal stress in this layer, and T0 the stress resulting from
the action inside the bore of the pressure P0, and allowing that the
sum of both these quantities must not exceed the elastic limit U of the
material, we have--T0 = U - t0. And for this value of T0, the
corresponding pressure inside the bore will be

                R² - r0²
  P = (U - t0) ----------.
                R² + r0²

This pressure increases with the term (U - t0). With t0 positive,
i.e., when the internal stresses in the thickness of the hollow
cylinder are such that the metal of the layers nearest to the bore is
in a state of tension and that of the outer layers in a state of
compression, then the cylinder will have the least strength when t0
has the greatest numerical value. Such stresses are termed injurious
or detrimental stresses. With t0 negative, the strength of the
cylinder increases with the numerical value of t0, and those stresses
which cause compression in the layers nearest to the bore of the
cylinder and tension in the outer layers are termed beneficial or
useful stresses.

   [Footnote 1: Lame holds that in a homogeneous tube subjected to
   the action of two pressures, external and internal, the
   difference between the tension and the compression developed at
   any point of the thickness of the tube is a constant quantity,
   and that the sum of these two stresses is inversely proportional
   to the square of the radius of the layer under consideration. Let
   r0, R, and r_x be the respective radii, p0, p¹, and p_x the
   corresponding pressures, and T0, T¹, and T_x, the tensions, then
   we have:

                T0 - p0 = T_x - p_x              (1)
          (T0 + p0) r0² = (T_x + p_x) (r_x)²     (2)
              T_x - p_x = T¹ - p¹                (3)
      (T_x + p_x)(r_x)² = (T¹ + P¹)R²            (4)

   if the radii are known and p and p¹ be given, then deducing from
   the above equations the values T0 and T¹, and also the variable
   pressure p_x, we determine--

            p0 r0²(R² + (r_x)²) - p¹ R²((r_x)² + r0²)
      T_x = ------------------------------------------
                        (R² + r0²) (r_x)²

   This is the formula of Lame, from which, making p¹ = 0, we obtain
   the expression in the text.]

For these reasons, and in order to increase the power of resistance of a
cylinder, it is necessary to obtain on the inner layer a state of
initial compression approaching as nearly as possible to the elastic
limit of the metal. This proposition is in reality no novelty, since it
forms the basis of the theory of hooped guns, by means of which the
useful initial stresses which should be imparted to the metal throughout
the gun can be calculated, and the extent to which the gun is thereby
strengthened determined. The stresses which arise in a hollow cylinder
when it is formed of several layers forced on one upon another, with a
definite amount of shrinkage, we call the stress of built-up cylinders,
in order to distinguish them from natural stresses developed in
homogeneous masses, and which vary in character according to the
conditions of treatment which the metal has undergone. If we conceive a
hollow cylinder made up of a great number of very thin layers--for
instance, of wire wound on with a definite tension--in which case the
inner layer would represent the bore of the gun, then the distribution
of the internal stresses and their magnitude would very nearly approach
the ideally perfect useful stresses which should exist in a homogeneous
cylinder; but in hollow cylinders built up of two, three, and four
layers of great thickness, there would be a considerable deviation from
the conditions which should be aimed at.

The magnitude of the stresses in built-up cylinders is determined by
calculation, on the presumption that initial stresses do not exist in
the respective layers of the tube and of the hoops which make up the
walls of the cylinder. Nevertheless, Rodman, as early as the year 1857,
first drew attention to the fact that when metal is cast and then
cooled, under certain conditions, internal stresses are necessarily
developed; and these considerations led him, in the manufacture of cast
iron guns, to cool the bore with water and to heat the outside of the
moulds after casting. Although Rodman's method was adopted everywhere,
yet up to the present time no experiments of importance have been made
with the view of investigating the internal stresses which he had drawn
attention to, and in the transition from cast iron to steel guns the
question has been persistently shelved, and has only very lately
attracted serious attention. With the aid of the accepted theory
relating to the internal stresses in the metal of hooped guns, we can
form a clear idea of the most advantageous character for them to assume
both in homogeneous and in built-up hollow cylinders. In proof of this,
we can adduce the labors of Colonels Pashkevitch and Duchene, the former
of whom published an account of his investigations in the _Artillery
Journal_ for 1884--St. Petersburg--and the latter in a work entitled
"Basis of the Theory of Hooped Guns," from which we borrow some of the
following information.

The maximum resistance of a tube or hollow cylinder to external stresses
will be attained when all the layers are expanded simultaneously to the
elastic limit of the material employed. In that case, observing the same
notation as that already adopted, we have--

              R - r0
      P0 = T --------        (1)

But since the initial internal stresses before firing, that is previous
to the action of the pressure inside the bore, should not exceed the
elastic limit,[2] the value of R will depend upon this condition.

   [Footnote 2: We must, however, remark that in a built-up hollow
   cylinder the compression of the metal at the surface of the bore
   may exceed the elastic limit. This cannot occur in the case of
   natural stresses.]

In a hollow cylinder which in a state of rest is free from initial
stresses, the fiber of which, under fire, will undergo the maximum
extension, will be that nearest to the internal surface, and the amount
of extension of all the remaining layers will decrease with the increase
of the radius. This extension is thus represented--

                   (r0)²        (r_x)² + R²
    (t_x)¹ = P0 ------------ . ------------
                 R² - (r0)²       (r_x)²

Therefore, to obtain the maximum resistance in the cylinder, the value
t_x of the initial stress will be determined by the difference (T - t'_x),[*need to check the prime with library or work out the equations]
and since P0 is given by Equation (1), then

             /        r0        (r_x)² + R² \
    t_x = T ( 1 - ---------- · ------------- )     (2)
             \     R0 + r0         (r_x)²   /

The greatest value t_x = t0 corresponds to the surface of the bore
and must be t0 = -T, therefore

       r0² + R²
    --------------- = 2
      r0 (R + r0)

whence P0 = T sqrt(2) = 1.41 T.

From the whole of the preceding, it follows that in a homogeneous
cylinder under fire we can only attain simultaneous expansion of all the
layers when certain relations between the radii obtain, and on the
assumption that the maximum pressure admissible in the bore does not
exceed 1.41 U.

Equation (2) may be written thus--

                 R       r_x - Rr
     t_x = T -------- . ----------        (3)
               R + r0     (r_x)²

Substituting successively r_x = r0 and r_x = R, we obtain
expressions for the stresses on the external and internal radii--

               R - r0                     R   R - r0
     t_R  = T --------  and  t_r0  = -T ---- --------
               R + r0                    r0   R + r0

Therefore, in a homogeneous hollow cylinder, in which the internal
stresses are theoretically most advantageous, the layer situated next to
the bore must be in a state of compression, and the amount of
compression relative to the tension in the external layer is measured by
the inverse ratio of the radii of these layers. It is further evident
that the internal stresses will obey a definite but very simple law,
namely, there will be in the hollow cylinder a layer whose radius is
sqrt(R r0), in which the stress is _nil_; from this layer the
stresses increase toward the external and the internal radii of the
cylinder, where they attain a maximum, being in compression in the
internal layers and in tension in the external ones.

The internal pressures corresponding to these stresses may be found by
means of very simple calculations. The expression for this purpose,
reduced to its most convenient form, is as follows:

                 R      /  R     \   /      r0 \
      p_x = T -------- (  --- - 1 ) ( 1 - ----- )     (4)
               R + r0   \ r_x    /   \     r_x /

In order to represent more clearly the distribution of stresses and
pressures in the metal of a homogeneous ideally perfect hollow cylinder,
let us take, as an example, the barrel of a 6 in. gun--153 mm. Let us
suppose T = 3,000 atmospheres; therefore, under the most favorable
conditions, P0 = 1.41 T, or 4,230 atmospheres. From Equation (1) we
determine R = 184.36 mm. With these data were calculated the internal
stresses and the pressures from which the curve represented in Fig. 1 is
constructed. The stresses developed under fire with a pressure in the
bore of 4,230 atmospheres are represented by a line parallel to the axis
of the abscissæ, since their value is the same throughout all the layers
of metal and equal to the elastic limit, 3,000 atmospheres. If, previous
to firing, the metal of the tube were free from any internal stresses,
then the resistance of the tube would be

               R² - r²_0
      P0 = U ----------- ,
               R² + r²_0

or 2,115 atmospheres--that is, one-half that in the ideally perfect
cylinder. From this we perceive the great advantage of developing useful
initial stresses in the metal and of regulating the conditions of
manufacture accordingly. Unless due attention be paid to such
precautions, and injurious stresses be permitted to develop themselves
in the metal, then the resistance of the cylinder will always be less
than 2,115 atmospheres; besides which, when the initial stresses exceed
a certain intensity, the elastic limit will be exceeded, even without
the action of external pressures, so that the bore of the gun will not
be in a condition to withstand any pressure because the tensile stress
due to such pressure, and which acts tangentially to the circumference,
will increase the stress, already excessive, in the layers of the
cylinder; and this will occur, notwithstanding the circumstance that the
metal, according to the indications of test pieces taken from the bore,
possessed the high elastic limit of 3,000 atmospheres.

[Illustration: Fig. 1]

In order to understand more thoroughly the difference of the law of
distribution of useful internal stresses as applied to homogeneous or to
built-up cylinders, let us imagine the latter having the external and
internal radii of the same length as in the first case, but as being
composed of two layers--that is to say, made up of a tube with one hoop
shrunk on under the most favorable conditions--when the internal radius
of the hoop = sqrt(R v0) or 118.7 mm., Fig. 2, has been traced,
after calculating, by means of the usual well known formulæ, the amount
of pressure exerted by the hoop on the tube, as well as the stresses and
pressures inside the tube and the hoop, before and after firing. A
comparison of these curves with those on Fig. 1 will show the difference
between the internal stresses in a homogeneous and in a built-up
cylinder. In the case of the hooped gun, the stresses in the layers
before firing, both in the tube and in the hoop, diminish in intensity
from the inside of the bore outward; but this decrease is comparatively
small. In the first place, the layer in which the stresses are = 0 when
the gun is in a state of rest does not exist. Secondly, under the
pressure produced by the discharge, all the layers do not acquire
simultaneously a strain equal to the elastic limit. Only two of them,
situated on the internal radii of the tube and hoop, reach such a
stress; whence it follows that a cylinder so constructed possesses less
resistance than one which is homogeneous and at the same time endowed
with ideally perfect useful initial stresses. The work done by the
forces acting on a homogeneous cylinder is represented by the area _a b
c d_, and in a built-up cylinder by the two areas _a' b' c' d'_ and _a"
b" c" d"_. Calculation shows also that the resistance of the built-up
cylinder is only 3,262 atmospheres, or 72 per cent. of the resistance of
a homogeneous cylinder. By increasing the number of layers or rows of
hoops shrunk on, while the total thickness of metal and the caliber of
the gun remains the same, we also increase the number of layers
participating equally in the total resistance to the pressure in the
bore, and taking up strains which are not only equal throughout, but are
also the greatest possible. We see an endeavor to realize this idea in
the systems advocated by Longridge, Schultz, and others, either by
enveloping the inner tubes in numerous coils of wire, or, as in the
later imitations of this system, by constructing guns with a greater
number of thin hoops shrunk on in the customary manner. But in wire
guns, as well as in those with a larger number of hoops--from four to
six rows and more--the increase in strength anticipated is acknowledged
to be obtained in spite of a departure from one of the fundamental
principles of the theory of hooping, since in the majority of guns of
this type the initial compression of the metal at the surface of the
bore exceeds its elastic limit.[3] We have these examples of departure
from first principles, coupled with the assumption that initial stresses
do not exist in any form in the metal of the inner tube previous to the
hoops having been shrunk on; but if the tube happen to be under the
influence of the most advantageous initial stresses, and we proceed
either to hoop it or to envelope it with wire, according to the
principles at present in vogue, then, without doubt, we shall injure the
metal of the tube; its powers of resistance will be diminished instead
of increased, because the metal at the surface of the bore would be
compressed to an amount exceeding twice its elastic limit. An example of
injury inflicted in this way is to be found in the method adopted for
hooping cast iron tubes cast by Rodman's process. If we take into
consideration the undoubted fact of the existence to a considerable
extent of useful initial stresses in these tubes, then the hoops should
be put on them either with very little shrinkage or none at all, whereas
ordnance authorities everywhere have applied to this case methods which
are only correct for tubes which are free from initial stresses.

   [Footnote 3: In certain cases this, of course, may be an
   advantage, as, for instance, when the inner tube is under
   injurious initial stresses; but then, in order to be able to
   apply the necessary shrinkage, we must know the magnitude of
   these stresses.]

[Illustration: Fig. 2]

During the process of hooping guns it is very important to know how to
take into account the value and mode of distribution of the prejudicial
stresses in the inner tube, should such exist. Knowing these stresses,
it is possible, by regulating the tension of the hoops, to reduce the
compression of the metal at the surface of the bore to the proper
extent, thus doing away with the previously existing tension, and by
that means removing a source of weakness in the tube. In precisely the
same way in the shrinkage of gun hoops attention must be paid to the
character and value of the stresses which arise in the course of their
manufacture; otherwise it will be impossible to hoop the barrel
throughout in a proper manner. If prejudicial stresses exist in the
metal of a hoop before it is put in its place, then, when the gun is
fired, if it had been shrunk on with the degree of tension usually
allowed, the layer situated in the internal radius will be extended
beyond admissible limits, thereby causing the resistance of the gun to
be less than that prescribed.[4]

   [Footnote 4: When the inner tube is strengthened by means of
   wire, the initial or natural stresses in the latter may be
   neglected on account of its thinness; but when the thickness of
   the hoops is reduced, and the number of layers thereby increased,
   then the value of the initial stresses in these hoops is a very
   important factor with respect to the decrease or increase Of the
   powers of resistance of the gun.]

It is evident, from what has been said, that in order to determine
precisely the resistance of hollow cylinders to internal pressures, and
to make the correct calculations for hooping tubes, it is absolutely
necessary to know whether internal initial stresses exist in the tube
and in the hoops, and to ascertain what their nature and intensity may
be--that is to say, whether they are useful or detrimental; yet it is
incontestable that in the construction of modern ordnance no attention
has been paid to the investigations indicated. If it be possible to
ignore these considerations in the manufacture of guns of small caliber,
and where the thickness of metal is not sufficiently great to admit of
strongly developed internal stresses, such is by no means the case with
the colossal and costly weapons of the present day. In these the
thickness of metal in the tube and hoops is very great; hence the
extreme probability of very considerable internal stresses developing
themselves. That the strength of large guns is often far below that
anticipated is demonstrated, year by year, by the repeated cases of
failure. Consciousness as to the want of strength in such guns is made
evident by the precautionary measures as to their use everywhere
adopted. The heavy artillery produced in the gun factories of Europe is
constructed with all the skill, science, and experience which engineers
and artillerists can command, and therefore it would seem that instances
of defective strength should not arise. Such cases, however, do occur
everywhere, and irresistibly give rise to the suspicion that not only is
the system of construction of guns of large caliber faulty, but also
that the conditions of their manufacture must be considered as
defective. Bearing in mind the enormous sums of money expended by every
nation in order to secure an armament of completely trustworthy guns,
this question demands speedy and searching investigation. The first step
in this direction is the study of the internal stresses inherent in the
metal; because, if such exist, and are capable of attaining, under
certain conditions, considerable magnitudes, then it is absolutely
necessary to take advantage of them in order to increase the resistance
of the metal, instead of allowing them to act to its detriment.

The study of natural internal stresses is of importance, not only with
reference to gun making, but also in respect of other structures where
great resistance is required. All have heard of the sudden failure of
crank shafts and piston rods, of the bursting of boiler shells and
tubes, of the breaking of tires, etc. In the majority of cases the
investigations into the causes of such sudden failures have not led to
any definite results. It has usually been found that the metal possessed
a satisfactory elastic resistance, and satisfied all the conditions set
down in the specifications. Had attention been paid during these
investigations to the state of the internal stresses in the metal, the
cause of unlooked-for accidents might have been explained, and steps
would consequently have been taken to avoid them in future.

We are also familiar with the development of considerable internal
stresses in various kinds of steel articles which are subjected to
hardening and tempering; for example, as dies, tools of various
description, sword blades, and thin plates rolled at a low temperature
or subjected to cold hammering. In the foundry the appearance of
internal stresses is of still more frequent occurrence. The neglect of
certain practical rules in casting, and during the subsequent cooling,
leads to the spontaneous breakage of castings after a few hours or days,
although taken out of the sand apparently perfectly sound. Projectiles
for penetrating armor plate, and made of cast steel, as well as shells
which have been forged and hardened, and in which the metal possessed an
ultimate resistance of over twelve thousand (12,000) atmospheres, with
an elastic limit of more than six or seven thousand atmospheres, will
crack to a serious extent, and even break up in the lathe, while the
recess for the copper ring is being turned out. In shell of this nature,
as well as in chilled cast iron shell, the heads are apt to fly off
spontaneously either while they are lying in store or during transport.
Such phenomena, it seems to me, demonstrate the existence of internal
stresses of considerable magnitude in the metal of the projectiles, and
it is highly probable that the manufacture of many articles would have
approached nearer to perfection had more attention been bestowed upon
the study of the internal stresses which they were liable to. Having
thus explained the nature and importance of the subject, I will proceed
to describe the experiments which I have made with a view to its
illustration.--_London Engineer._

       *       *       *       *       *


   [Footnote 1: Delivered before the Society of Arts, London,
   November 28, 1887. From the _Journal_ of the Society.]



Judging from the nature of the correspondence on architecture and the
duty of architects which is frequently seen in the columns of the daily
papers, the _Times_ especially, it would seem that the popular notion of
architecture now is that it is a study mainly of things connected with
sanitary engineering--of the best forms of drain pipes and intercepting
traps. This is indeed a very important part of sound building, and it is
one that has been very much neglected, and has been, in fact, in a
comparatively primitive state until very recent times; and therefore it
is not surprising that there should be a reaction in regard to it, and
that newspapers which follow every movement of public opinion, and try
to keep pace with it, should speak as if the drain pipe were the true
foundation of architecture. I have a great respect for the drain pipe,
and wish to see it as well laid and "intercepted" as possible; but I
think, for all that, that there is something in architecture higher than
sanitary engineering. I wish to consider it in these lectures as what I
think it essentially is, what it has evidently been in the eyes of all
those of past days who have produced what we now regard as great
architectural monuments, namely, as an intellectual art, the object of
which is to so treat the buildings which we are obliged to raise for
shelter and convenience as to render them objects of interest and
beauty, and not mere utilitarian floors, walls, and roofs to shelter a
race who care nothing for beauty, and who only want to have their
physical comfort provided for.

Architecture, then, from the point of view from which I am asking you to
regard it--and the only point of view in which it is worth the serious
regard of thoughtful people--is the art of erecting expressive and
beautiful buildings. I say expressive _and_ beautiful, and I put
expressive first, because it is the characteristic which we can at least
realize even when we cannot realize what can fairly be called beauty,
and it is the characteristic which comes first in the order of things. A
building may be expressive and thereby have interest, without rising
into beauty; but it can never be, architecturally speaking, beautiful
unless it has expression. And what do we mean by expression in a
building? That brings us to the very pith of the matter.

We know pretty well what we mean when we say that a painted or
sculptured figure is expressive. We mean that, while correctly
representing the structure of the human figure, it also conveys to our
minds a distinct idea of a special emotion or sentiment, such as human
beings are capable of feeling and expressing by looks and actions.
Expression in this sense a building cannot be said to have. It is
incapable of emotion, and it has no mobility of surface or feature. Yet
I think we shall see that it is capable of expression in more senses
than one. It may, in the first place, express or reflect the emotion of
those who designed it, or it may express the facts of its own internal
structure and arrangement. The former, however, can only, I think, be
said to be realized in the case of architecture of the highest class,
and when taken collectively as a typical style. For instance, we can all
pretty well agree that the mediæval cathedral expresses an emotion of
aspiration on the part of its builders. The age that built the
cathedrals longed to soar in some way, and this was the way then open to
it, and it sent up its soul in spreading vaults, and in pinnacles and
spires. So also we can never look at Greek architecture without seeing
in it the reflection of a nature refined, precise, and critical; loving
grace and finish, but content to live with the graces and the muses
without any aspirations that spurned this earth. We can hardly go
further than this in attributing emotional expression to architecture.
But in a more restricted sense of the word _expression_, a building may
express very definitely its main constructive facts, its plan and
arrangement, to a certain extent even its purpose, so far at least that
we may be able to identify the class of structure to which it belongs.
It not only may, but it ought to do this, unless the architecture is to
be a mere ornamental screen for concealing the prosaic facts of the
structure. There is a good deal of architecture in the world which is in
fact of this kind--an ornamental screen unconnected with the
constructional arrangement of the building. Nor is such architecture to
be entirely scouted. It may be a very charming piece of scenery in
itself, and you may even make a very good theoretical defense for it,
from a certain point of view. But on the whole, architecture on that
principle becomes uninteresting. You very soon tire of it. It is a mask
rather than a countenance, and tends to the production of a dull
uniformity of conventional design.

For we must remember that architecture, although a form of artistic
expression, is not, like painting and sculpture, unfettered by practical
considerations. It is an art inextricably bound up with structural
conditions and practical requirements. A building is erected first for
convenience and shelter; secondly only for appearance, except in the
case of such works as monuments, triumphal arches, etc., which represent
architectural effect pure and simple, uncontrolled by practical
requirements. With such exceptions, therefore, a building ought to
express in its external design its internal planning and arrangement; in
other words, the architectural design should arise out of the plan and
disposition of the interior, or be carried on concurrently with it, not
designed as a separate problem. Then a design is dependent on structural
conditions also, and if these are not observed, the building does not
stand, and hence it is obvious that the architectural design must
express these structural conditions. It must not appear to stand or be
constructed in a way in which it could not stand (like the modern shops
which are supposed to stand on sheets of plate glass), and its whole
exterior appearance ought to be in accordance with, and convey the idea
of, the manner and principle on which it is constructed. The most
important portions of the interior must be shown as such externally by
the greater elaboration and emphasis of their architectural treatment.
If the general arrangement of the plan is symmetrical, on either side of
a center (which, however, it cannot often be except in the largest type
of monumental or public buildings), the architectural treatment must be
symmetrical. If the building is necessarily arranged, in accordance with
the requirements of the plan, unsymmetrically, the architectural
treatment must follow suit, and the same principle must be carried out
through all the details.

Now this dependence of architectural design upon plan and construction
is one of the conditions which is often overlooked by amateurs in
forming a judgment upon architectural design; and the overlooking of
this is one reason of the uncertainty of opinion about architecture as
compared with such arts as sculpture and painting. Few people know or
care much about the structure and planning of buildings except those
whose business it is to care about this; and consequently they do not
realize what it is which they should look for in the architectural
design. They like it or do not like it, and they regard this as what is
called a mere question of taste, which, according to the proverb, is not
to be disputed about. In fact, however, the good or bad taste of an
architectural design, say, if you like, its correctness or
incorrectness, is to a considerable extent a matter of logical
reasoning, of which you must accurately know the premises before you can
form a just conclusion. But there is another reason for this prevalent
uncertainty and vagueness of opinion, arising out of the very nature of
architectural art itself, as compared with the imitative arts. A
painting of a figure on a landscape is primarily a direct imitation of
the physical facts of nature. I do not for a moment say it is only that,
for there is far more involved in painting than the imitation of nature;
but the immediate reference to nature does give a standard of comparison
which to a certain extent every eye can appreciate. But architecture is
not an art which imitates natural forms at all, except as minor
decorations, and it then does so, or should do so, only in a
conventionalized manner, for reasons which we shall consider later on.
Architecture is, like music, a metaphysical art. It deals with the
abstract qualities of proportion, balance of form, and direction of
line, but without any imitation of the concrete facts of nature. The
comparison between architecture and music is an exercise of the fancy
which may indeed be pushed too far, but there is really a definite
similarity between them which it is useful to notice. For instance, the
regular rhythm, or succession of accentuated points in equal times,
which plays so important a part in musical form, is discernible in
architecture as a rhythm in space. We may treat a cottage type of
design, no doubt, with a playful irregularity, especially if this
follows and is suggested by an irregularity, of plan. But in
architecture on a grand scale, whether it be in a Greek colonnade or a
Gothic arcade, we cannot tolerate irregularity of spacing except where
some constructive necessity affords an obvious and higher reason for it.
Then, again, we find the unwritten law running throughout all
architecture that a progress of line in one direction requires to be
stopped in a marked and distinct manner when it has run its course, and
we find a similarly felt necessity in regard to musical form. The
repetition so common at the close of a piece of music of the same chord
several times in succession is exactly analogous to the repetition of
cross lines at the necking of a Doric column to stop the vertical lines
of the fluting, or to the strongly marked horizontal lines of a cornice
which form the termination of the height or upward progress of an
architectural design. The analogy is here very close. A less close
analogy may also be felt between an architectural and a musical
composition regarded as a whole. A fugue of Bach's is really a built-up
structure of tones (as Browning has so finely put it in his poem, "Abt
Vogler"), in accordance with certain ideas of relation and proportion,
just as a temple or a cathedral is a built-up structure of lines and
spaces in accordance with ideas of relation and proportion. Both appeal
to the same sense of proportion and construction in the brain; the one
through the ear, the other through the eye. Then, in regard to
architecture again, we have further limiting conditions arising not only
out of the principle of construction employed, but out of the physical
properties of the very material we employ. A treatment that is suitable
and expressive for a stone construction is quite unsuitable for a timber
construction. Details which are effective and permanent in marble are
ineffective and perishable in stone, and so; on and the outcome of all
this is that all architectural design has to be judged, not by any easy
and ready reference to exterior physical nature, with which it has
nothing to do, but by a process of logical reasoning as to the relation
of the design to the practical conditions, first, which are its basis,
and as to the relation of the parts to each other. Of course beyond all
this there is in architecture, as in music, something which defies
analysis, which appeals to our sense of delight we know not how or why,
and probably we do not want to know; the charm might be dissolved if we
did. But up to this point architectural design and expression are based
on reasoning from certain premises. The design is good or bad as it
recognizes or ignores the logic of the case, and the criticism of it
must rest on a similar basis. It is a matter of thought in both cases,
and without thought it can neither be designed nor appreciated to any
purpose, and this is the leading idea which I wish to urge and to
illustrate in these lectures.

You may say: May not a design satisfy all these logical conditions, and
yet be cold and uninteresting, and give one no pleasure? Certainly it
may. Indeed, we referred just now to that last element of beauty which
is beyond analysis. But, if we cannot analyze the result, I rather think
we can express what it is which the designer must evince, beyond clear
reasoning, to give the highest interest to his architecture. He must
have taken an interest in it himself. That seems a little thing to say,
but much lies in it. As Matthew Arnold has said of poetry:

    "What poets feel not, when they make
      A pleasure in creating,
    The world, in its turn, will not take
      Pleasure in contemplating."

The truth runs through all art. There are, alas, so many people who do
not seem to have the faculty of taking pleasure, and there is so much
architecture about our streets which it is impossible to suppose any one
took "pleasure in creating." When a feature is put into a design, not
because the designer liked it, but because it is the usual thing and it
saves trouble, it always proclaims that melancholy truth. But where
something is designed because the designer liked doing it, and was
trying to please his own fancy instead of copying what a hundred other
men have done before, it will go hard but he will give some pleasure to
the spectator. It is from this blessed faculty that a design becomes
inspired with what is best described as "character." It is not the same
thing as style. I have something to say in my next lecture as to what I
think _style_ means, but it is certain that a building may have _style_
and yet want _character_, and it may have a good deal of _character_ and
yet be faulty or contradictory in _style_. We cannot define "character,"
but when we feel that it is present we may rely upon it that it is
because the designer took interest and pleasure in his work, was not
doing it merely scholastically--in short, he put something of his own
character into it, which means that he had some to put.

[Illustration: Figs. 1 through 3]

Now, coming back to the axiom before mentioned, that architectural
design should express and emphasize the practical requirements and
physical conditions of the building, let us look a little more in detail
into the manner in which this may be done. We will take, to begin with,
the very simplest structure we can possibly build--a plain wall (Fig.
1).[2] Here there is no expression at all; only stones piled one on
another, with sufficient care in coursing and jointing to give stability
to the structure. It is better for the wall, constructively, however,
that it should have a wider base, to give it more solidity of
foundation, and that the coping should project beyond the face of the
wall, in order to throw the rain off, and these two requirements may be
treated so as to give architectural expression to our work (Fig. 2). It
now consists of three distinct portions--a plinth, or base, a
superficies of wall, and a coping. We will mark the thickening at the
base by a moulding, which will give a few horizontal lines (at B), and
the coping in the same way. The moulding of the coping must also be so
designed as to have a hollow throating, which will act as a drip, to
keep the rain from running round the under side of the coping and down
the wall. We may then break up the superficies by inserting a band of
single ornament in one course of this portion of the wall--not half way,
for to divide any portion of a building into mere "halves" has usually a
weak and monotonous effect, but about two thirds of the distance from
the base line; and this band of ornament not only breaks up the plain
surface a little, but also, by carrying another horizontal line along
the wall, emphasizes its horizontality. Always emphasize that which is
the essential characteristic of your structure. A wall of this kind is
essentially a long horizontal boundary. Emphasize its length and

   [Footnote 2: The dark shaded portion in this and the next two
   diagrams show the "section" of the wall as seen if we cut it
   through and look at it endwise.]

If we are millionaires, and can afford to spend a great deal on a wall,
we may not only (Fig. 3) carry further the treatment of the coping and
base, by giving them ornamental adjuncts as well as mouldings, but we
might treat the whole wall superficies as a space for surface carving,
not mechanically repeated, but with continual variation of every
portion, so as to render our wall a matter of interest and beauty while
retaining all its usefulness as a boundary, observing that such surface
ornament should be designed so as to fulfill a double object: 1, to give
general relief to the surface of the wall; 2, to afford matter of
interest to the eye on close inspection and in detail.

That is the double function of nearly all architectural ornament. It is,
in the first place, to aid the general expression and balance of the
building, and give point and emphasis where needed; and, in the second
place, to furnish something to the eye for study on its own account when
viewed more closely.

[Illustration: Figs. 4 through 9]

We will take another typical and simple erection, a stone pillar to
support the ends of two lintels or beams. This may be simply a long
squared piece set on end (Fig. 4), and will perform its constructive
functions perfectly well in that form; but it is not only absolutely
expressionless, but is in one sense clumsy and inconvenient, as taking
up more space than need be, presenting an unwieldy-looking mass when
viewed at an angle, and shutting out a good deal of light (if that
happen to be a matter of practical consequence in the case). Cutting off
the angles (Fig. 5) does not weaken it much, and renders it much less
unwieldy-looking, besides giving it a certain degree of verticality of
expression, and rendering it more convenient as taking up less room and
obstructing less light. But though the column is quite strong enough,
the octagonal top does not make so good a seat or bearing for the ends
of the lintels. We will therefore put a flat square stone on the top of
it (Fig. 6), which will serve as a bed for the lintels to rest on
securely. But the angles of this bed plate, where they project beyond
the face of the column, appear rather weak, and are so actually to some
extent--a double defect, for it is not enough in architecture that a
thing should be strong enough, it is necessary that it should appear so,
architecture having to do with expression as well as with fact. We will,
therefore, strengthen this projecting angle, and correct the abruptness
of transition between the column and the bed plate, by brackets (Fig. 7)
projecting from the alternate faces of the column to the angles of the
bed plates. As this rather emphasizes four planes of the octagon column
at the expense of the other four, we will bind the whole together just
under the brackets by a thin band of ornament constituting a necking,
and thus we have something like a capital developed, a definitely
designed finish to our column, expressive of its purpose. This treatment
of the upper end, however, would make the lower end rising abruptly from
the ground seem very bare. We will accordingly emphasize the base of the
column, just as we emphasized the base of the wall, by a projecting
moulding, not only giving expression to this connection of the column
with the ground, but also giving it the appearance, and to some extent
the reality, of greater stability, by giving it a wider and more
spreading base to rest on. We have here still left the lines of one
column vertically parallel, and there is no constructive reason why they
should not remain so. There is, however, a general impression to the eye
both of greater stability and more grace arising from a slight
diminution upward. It is difficult to account for this on any
metaphysical principle, but the fact has been felt by most nations which
have used a columnar architecture, and we will accept it and diminute
(so to speak) our column (Fig. 8). We have here taken a further step by
treating the shaft of the column in two heights, keeping the lower
portion octagonal and reducing the upper portion to a circle, and we now
find it easier to treat the capital so as to have a direct and complete
connection with the column, the capital being here merely a spreading
out of the column into a bracket form all round, running it into the
square of the bed plate.[3] The spreading portion is emphasized by
surface ornament, and the necking is again emphasized, this time more
decisively, by a moulding, forming a series of parallel rings round the
column. If we wish to give our column an expression of more grace and
elegance, we can further reduce the thickness of it (Fig. 9), and give
more spread to the capital, always taking care to be sure that the
strength of the column is not reduced below what the weight which it has
to carry requires. In this case a bracket is shown above the capital,
projecting longitudinally only (in the direction of the lintel bearing),
a method of giving a larger bearing surface for the ends of the lintels,
shortening their actual bearing[4] (in other words, widening the space
which can be bridged between column and column) and giving a workmanlike
appearance of stability to the construction at this point. The idea of
the division of the column into two sections, suggested in Fig. 8, is
kept up in Fig. 9 by treating the lower portion up to the same height
with incised decorative carving. The dotted lines on each side in Fig. 9
give the outline of the original square column as shown in Fig. 4. The
finished column was within that block; it is the business of the
architectural designer to get it out.[5]

   [Footnote 3: This is the feature called "abacus" (i.e., "tile")
   in Greek architecture, but I am here considering it apart from
   any special style or nomenclature.]

   [Footnote 4: "Bearing," in building language, is used in a double
   sense, for the distance between the points of support, and the
   extent to which the beam rests on the walls. Thus a beam which
   extends 20 feet between the points of support is a beam of 20
   feet bearing. If the beam is 22 feet long, so that 1 foot rests
   on the walls at each end, it has "1 foot bearing on the wall."]

   [Footnote 5: None of the forms of column sketched here have any
   existence in reality. They are purposely kept apart from
   imitation of accepted forms to get rid of the idea that
   architecture consists in the acceptance of any particular form
   sanctioned by precedent.]

Let us see if we can apply the same kind of process of evolving
expression in regard to a building. We will take again the very simplest
form of building (Fig. 10), a square house with a door in the center and
uniform rows of windows. There cannot be said to be any architectural
expression in this. There is no base or plinth at all, no treatment of
the wall. The slight projection at the eaves is only what is necessary
to keep the rain from running down the walls, and facilitate the
emptying of the gutters, and the even spacing of the windows is
essential for constructive reasons, to keep the masses of wall over each
other, and keep the whole in a state of equally balanced pressure. The
first thing we should do in endeavoring to give some expression to the
building would be to give it a base or plinth (Fig. 11), and to mark
that and the cornice a little more decidedly by mouldings and a line of
paneling at the plinth.

[Illustration: Figs. 10 and 11]

The house being obviously in three stories, we should give it some echo
externally of this division into horizontal stages by horizontal
mouldings, or what are called in architectural phraseology "string
courses," not necessarily exactly at the floor levels, but so as to
convey the idea of horizontal division; observing here, as in the case
of the wall and column, that we should take care not to divide the
height into equal parts, which is very expressionless. In this case we
will keep the lower string close down on the ground floor windows, and
keep these rather low, thus showing that the ground floor apartments are
not the most important; while the fact that the first floor ones are so
is conversely made apparent by keeping these windows rather higher,
putting a double string course over them, and a slight extra depth of
moulding, forming a kind of cornice over each.

The space left between these and the roof, in which the attic windows
are placed, is treated with a series of mullions and panelings, into
which the attic windows are worked, as part of the series of openings;
this gives a little richness of effect to the top story, and a
continuity of treatment, which binds the whole series of windows
together. To have treated the whole of the walls and windows in this way
would have been merely throwing away labor; what little effect it has
consists in the "character" given by the contrast of this top story
treatment with the plain wall surfaces below.

The last thing is to emphasize the door, as the principal opening in the
walls, and quite distinct in use and meaning from the other openings, by
giving it a little architectural frame or setting, which may be done in
many ways, but in this case is done by the old fashioned device (not
very logical certainly) of putting a little entablature over it, and a
column on either side; there is, however, this to be said for it, that
the projecting tablature forms a semi-porch, protecting those at the
door somewhat from rain; it must be carried in some way, and columns are
the readiest and most seemly manner of doing it, and they also form,
practically, something of a weather screen; the bases on which they
stand also form a framework or inclosing wall for the steps, which are
thus made part of the architectural design, instead of standing out as
an eyesore, as on Fig. 10. We have now given the house a little general
expression, but it still is vague in its design as far as regards the
distribution of the interior; we do not know whether the first floor,
for instance, is one large room, or two or more rooms, or how they are
divided; and the little house is very square and prim in effect.

Let us try grouping the windows a little, and at the same time breaking
up the flat surface of the front wall (Fig. 12). Here, as before, we
have divided the building by a horizontal string, but only by one main
one on the first floor level, keeping the same contrast, however,
between a richer portion above and a plainer portion below; we have
divided the building vertically, also, by two projecting bays finishing
in gables, thus breaking also the skyline of the roof, and giving it a
little picturesqueness, and we have grouped the windows, instead of
leaving them as so many holes in the wall at equal distances. The
contrast between the ground and first floor windows is more emphatic;
and it is now the more evident that the upper floor rooms are the best
apartments, from their ample windows; it is also pretty evident that the
first floor is divided into two main rooms with large bay windows, and a
smaller room or a staircase window, between them; the second floor
windows are also shifted up higher, the two principal ones going in to
the gables, showing that the rooms below them have been raised in
height. Windows carried up the full height of these rooms, however,
might be too large either for repose internally or for appearance
externally, so the wall intervening between the top of these and the
sill of the gables is a good field for some decorative treatment,
confined to the bays, so as to assist in separating them from the
straight wall which forms the background to them.

[Illustration: Fig. 12]

So far we have treated our building only as a private house. Without
altering its general scale and shape we may suggest something entirely
different from a private house. On Fig. 13, we have tried to give a
municipal appearance to it, as if it were the guild hall of a small
country town. The plain basement and the wide principal doorway, and the
row of three very large equal-spaced windows above, render it
unquestionable that this is a building with a low ground story, and one
large room above. A certain "public building" effect is given to it by
the large and enriched cornice with balustrade above and paneling below,
and by the accentuation of the angles by projecting piers, and by the
turrets over them, which give it quite a different character from that
of a private house.

[Illustration: Fig. 13]

If, on the other hand, the building were the free library and reading
room of the same small country town, we should have little doubt of this
if we saw it as in Fig. 14, with the walls all blank (showing that they
are wanted for ranging something against, and cannot be pierced for
windows), and windows only in the upper portion. Similarly, if we want
to build it as the country bank, we should have to put the large windows
on the ground floor, bank clerks wanting plenty of light, and the ground
story being always the principal one; and we might indulge the humor of
giving it a grim fortress-like strength by a rusticated plinth (i.e.,
stones left or worked rough and rock-like) and by very massive piers
between the windows, and a heavy cornice over them; the residential
upper floor forming a low story subordinate to the bank story. It is
true this would not satisfy a banker, who always wants classic pilasters
stuck against the walls, that being his hereditary idea of bank
expression in architecture.

[Illustration: Figs. 14 and 15]

Now if we proceed to take to pieces the idea of architectural design,
and consider wherein the problem of it consists, we shall find that it
falls into a fourfold shape. It consists first in arranging the plan;
secondly, in carrying up the boundary lines of this plan vertically in
the shape of walls; thirdly, in the method of covering in the space
which we have thus defined and inclosed; and, fourthly, in the details
of ornamentation which give to it the last and concluding grace and
finish. All building, when it gets beyond the mere wall with which we
began, is really a method of covering in a space, or, if we may put it
so, a collection of spaces, marked out and arranged for certain
purposes. The first thing that the architect has to do is to arrange
these spaces on the ground so that they may conveniently meet the
necessary requirements of the building. Convenience and practical
usefulness come first; but in any building which is worth the name of
architecture something more than mere convenience has to be kept in
mind, even in the arrangement of the plan upon the site. It is to be a
combination of convenience with effectiveness of arrangement. We shall
probably find that some one compartment of the plan is of paramount
importance. We have to arrange the interior so that this most important
compartment shall be the climax of the plan.

The entrance and the other subsidiary compartments must be kept
subordinate to it, and must lead up to it in such a manner that the
spectator shall be led by a natural gradation from the subsidiary
compartments up to the main one, which is the center and _raison
d'etre_ of the whole--everything in the lines of the plan should point
to that. This is the great _crux_ in the planning of complicated public
buildings. A visitor to such a building, unacquainted with it
previously, ought to have no difficulty in finding out from the
disposition of the interior which are the main lines of route, and when
he is on the line leading him up to the central feature of the plan.
There are public buildings to be found arranged on what may be called
the rabbit warren system, in which perhaps a great number of apartments
are got upon the ground, but which the visitor is obliged laboriously to
learn before he can find his way about them. That is not only
inconvenient but inartistic planning, and shows a want of logic and
consideration, and, in addition to this, a want of feeling for artistic
effect. I saw not long ago, for instance, in a set of competitive
designs for an important public building, a design exhibiting a great
deal of grace and elegance in the exterior architectural embellishment,
but in which the principal entrance led right up to a blank wall facing
the entrance, and the spectator had to turn aside to the left and then
to the right before finding himself on the principal axis of the plan.
That is what I should call inartistic or unarchitectural planning. The
building may be just as convenient when you once know its dodges, but it
does not appear so, and it loses the great effect of direct vista and

An able architect, who had given much thought to a plan of a large
building of this kind, said to me, in showing me his plan, with a
justifiable gratification in it, "It has cost me endless trouble, but it
is a satisfaction to feel that you have got a plan with backbone in it."
That is a very good expression of what is required in planning a
complicated building, but few outsiders have any notion of the amount of
thought and contrivance which goes to the production of a plan "with
backbone;" a plan in which all the subordinate and merely practical
departments shall be in the most convenient position in regard to each
other, and yet shall all appear as if symmetrically and naturally
subordinate to the central and leading feature; and if the public had a
little more idea what is the difficulty of producing such a plan, they
would perhaps do a little more justice to the labors of the man who
contrives the plan, which they think such an easy business; and no doubt
it may appear an easy business, because the very characteristic of a
really good plan is that it should appear as if it were quite a natural
and almost inevitable arrangement.

Just as it is said in regard to literature that easy writing is hard
reading, so, in regard to planning, it is the complicated and rabbit
warren plans that are the easiest to make, because it is just doing what
you please; it is the apparently perfectly simple and natural plan which
springs from thought and contrivance. Then there is the next step of
raising the walls on the plan, and giving them architectural expression.
This must not be thought of as an entirely separate problem, for no
truly architectural intellect will ever arrange a plan without seeing
generally, in his mind's eye, the superstructure which he intends to
rear upon it; but the detailed treatment of this forms a separate branch
of the design. Then comes the third and very important problem--the
covering in of the space. Next to the plan, this is the most important.
All building is the covering over of a space, and the method of covering
it over must be foreseen and provided for from the outset. It largely
influences the arrangement of the plan. If there were no roofing, you
could arrange the walls and carry them up pretty much as you chose, but
the roofing of a large space is another matter. It requires extra
strength at certain points, where the weight of the roof is
concentrated, and it has to be determined whether you will employ a
method of roofing which exercises only a vertical pressure on the walls,
like the lid of a box, or one which, like an arch, or a vault, or a
dome, is abutting against the walls, and requires counterforts to resist
the outward thrust of the roof. We shall come upon this subject of the
influence of the roof on the design of the substructure more in detail
later on. Then, if the plan is convenient and effective, the walls
carried up with the architectural expression arising from the placing
and grouping of the openings, and the proper emphasizing of the base and
the cornice, and the horizontal stages (if any) of the structure, and
the roof firmly and scientifically seated on the walls; after all these
main portions of the structure are designed logically and in accordance
with one another and with the leading idea of the building, then the
finishing touches of expression and interest are given by well designed
and effective ornamental detail. Here the designer may indulge his fancy
as he pleases, as far as the nature of the design is concerned, but not,
if you please, as far as its position and distribution are concerned.
There the logic of architecture still pursues us.

We may not place ornament anywhere at haphazard on a building simply
because it looks pretty. At least, to do so is to throw away great part
of its value. For everything in architectural design is relative; it is
to be considered in relation to the expression and design of the whole,
and ornament is to be placed where it will emphasize certain points or
certain features of the building. It must form a part of the grouping of
the whole, and be all referable to a central and predominating idea. A
building so planned, built, and decorated becomes, in fact, what all
architecture--what every artistic design in fact should be--an organized
whole, of which every part has its relation to the rest, and from which
no feature can be removed without impairing the unity and consistency of
the design. You may have a very good, even an expressive, building with
no ornament at all if you like, but you may not have misplaced ornament.
That is only an excrescence on the design, not an organic portion of it.

I have thought that it would be of use to those who are unacquainted
with architectural procedure in delineating architecture by geometrical
drawings if I took the opportunity of illustrating very briefly the
philosophy of elevations, plans, and sections, which many
non-professional people certainly do not understand.

[Illustration: Figs. 16 through 25]

A simple model of a building, like that in Fig. 16, will serve the
purpose, as the principle is the same in the most complicated as in the
simplest building. It must be remembered that the object of
architectural drawings on the geometrical system is not to show a
picture of the building, but to enable the designer to put together his
design accurately in all its parts, according to scale, and to convey
intelligible and precise information to those who have to erect the
building. A perspective drawing like Fig. 16 is of no use for this
purpose. It shows generally what the design is, but it is impossible to
ascertain the size of any part by scale from it, except that if the
length of one line were given it would be possible, by a long process of
projection and calculation, to ascertain the other sizes. The
_rationale_ of the architect's geometrical drawings is that on them each
plane of the building (the front, the side, the plan, etc.) is shown
separately and without any distortion by perspective, and in such a
manner that every portion is supposed to be opposite to the eye at once.
Only the width of any object on one side can be shown in this way at one
view; for the width of the return side you have to look to another
drawing; you must compare the drawings in order to find out those
relative proportions which the perspective view indicates to the eye at
a glance; but each portion of each side can be measured by reference to
a scale, and its precise size obtained, which can only be guessed at
roughly from the perspective drawing. Thus the side of the model is
shown in Fig. 19, the end in Fig. 17; the two together give the precise
size and proportions of everything outside to scale, except the
projection of the pilasters. This has to be got at from the plan and
section. Everything being drawn on one plane, of course surfaces which
are sloping on one elevation are represented as flat in the other. For
instance, on No. 17 the raking line of the sloping roof is shown at N.
So we know the slope of the roof, but we do not know to what length it
extends the other way. This is shown on Fig. 19, where the portion
showing the roof is also marked N, and it will be seen that the surface
which is sloping in Fig. 17 is seen in the side elevation only as a
space between a top and bottom line. We see the length of the roof here,
and its height, but for its slope we go to the end elevation. Neither
elevation tells us, however, what is inside the building; but the
section (Fig. 18) shows us that it has an arched ceiling, and two
stories, a lower and a higher one. The section is the building cut in
half, showing the end of the walls, the height and depth of the window
openings, the thickness of the floor, etc., and as all parts which are
opposite the eye are shown in the drawing, the inside of the cross wall
at the end of the building is shown as a part of the section drawing,
between the sectional walls. In Fig. 23 the section is sketched in
perspective, to show more clearly what it means. Another section is made
lengthwise of the building (Fig. 20). It is customary to indicate on
the plan by dotted lines the portion through which the section is
supposed to be made. Thus on the plans the lines A B and C D are drawn,
and the corresponding sections are labeled with the same lines. As with
the elevation, one section must be compared with another to get the full
information from them. Thus in Fig. 18, the ceiling, M, is shown as a
semicircle; in Fig. 20, it is only a space between the top and bottom
lines. It is, certainly, shaded here to give the effect of rotundity,
but that is quite a superfluity. On Fig. 18 the height of the side
windows is shown at F, and the thickness of the wall in which they are
made. In Fig. 20 (F) their width and spacing are shown. In Fig. 18 some
lines drawn across, one over the other, are shown at H. These are the
stairs, of which in this section we see only the fronts, or risers, so
that they appear merely as lines (showing the edge of each step) drawn
one over the other. At H on the plan, Fig. 21, we again see them
represented as a series of lines, but here we are looking down on the
top of them, and see only the upper surfaces, or "treads," the edges
again appearing as a series of lines. At H on the longitudinal section,
we see the same steps in section, and consequently their actual slope,
which, however, could have been calculated from Figs. 18 and 21, by
putting the heights shown in section with the width shown in plan. The
plan, Fig. 21, shows the thickness and position on the floor of the
pillars, G G. Their height is shown in the sections. The plan of a
building is merely a horizontal section, cutting off the top, and
looking down on the sectional top of the walls, so as to see all their
thicknesses. I have drawn (Fig. 24) a perspective sketch of one end of
the plan (Fig. 22) of the building, on the same principle as was done
with the section (Fig. 23), in order to show more intelligibly exactly
what it is that a plan represents--the building with the upper part
lifted off.

Returning for a moment to the subject of the relation between the plan
and the exterior design, it should be noted that the plan of a building
being practically the first consideration, and the basis of the whole
design, the latter should be in accordance with the principle of
disposition of the plan. For example, if we have an elevation (shown in
diagram) showing two wings of similar design on either side of a center,
designed so as to convey the idea of a grand gallery, with a suite of
apartments on either side of similar importance--if the one side only of
the plan contains such a suite, and the opposite side is in reality
divided up into small and inferior rooms, filled in as well as may be
behind the architectural design--the whole design is in that case only
a blind or screen, giving a false exterior symmetry to a building which
is not so planned. This is an extreme case (or might be called so if it
were not actually of pretty frequent occurrence); but it illustrates in
a broad sense a principle which must be carried out in all cases, if the
architecture is to be a real expression of the facts of the building.

In this lecture, which is concerned with general principles, a word may
fittingly be said as to the subject of _proportion_, concerning which
there are many misapprehensions. The word may be, and is, used in two
senses, first in regard to the general idea suggested in the words "a
well proportioned building." This expression, often vaguely used, seems
to signify a building in which the balance of parts is such as to
produce an agreeable impression of completeness and repose. There is a
curious kind of popular fallacy in regard to this subject, illustrated
in the remark which used to be often made about St. Peter's, that it is
so well proportioned that you are not aware of its great size, etc.--a
criticism which has been slain over and over again, but continues to
come to life again. The fact that this building does not show its size
is true. But the inference drawn is the very reverse of the truth. One
object in architectural design is to give full value to the size of a
building, even to magnify its apparent size; and St. Peter's does not
show its size, because it is _ill_ proportioned, being merely like a
smaller building, with all its parts magnified. Hence the deception to
the eye, which sees details which it is accustomed to see on a smaller
scale, and underrates their actual size, which is only to be ascertained
by deliberate investigation. This confusion as to scale is a weakness
inherent in the classical forms of columnar architecture, in which the
scale of all the parts is always in the same proportion to each other
and to the total size of the building so that a large Doric temple is in
most respects only a small one magnified. In Gothic architecture the
scale is the human figure, and a larger building is treated, not by
magnifying its parts, but by multiplying them. Had this procedure been
adopted in the case of St. Peter's, instead of merely treating it with a
columnar order of vast size, with all its details magnified in
proportion, we should not have the fault to find with it that it does
not produce the effect of its real size. In another sense, the word
"proportion" in architecture refers to the system of designing buildings
on some definite geometrical system of regulating the sizes of the
different parts. The Greeks certainly employed such a system, though
there are not sufficient data for us to judge exactly on what principle
it was worked out. In regard to the Parthenon, and some other Greek
buildings, Mr. Watkiss Lloyd has worked out a very probable theory,
which will be found stated in a paper in the "Transactions of the
Institute of Architects."

Vitruvius gives elaborate directions for the proportioning of the size
of all the details in the various orders; and though we may doubt
whether his system is really a correct representation of the Greek one,
we can have no doubt that some such system was employed by them. Various
theorists have endeavored to show that the system has prevailed of
proportioning the principal heights and widths of buildings in
accordance with geometrical figures, triangles of various angles
especially; and very probably this system has from time to time been
applied, in Gothic as well as in classical buildings. This idea is open
to two criticisms, however. First, the facts and measurements which have
been adduced in support of it, especially in regard to Gothic buildings,
are commonly found on investigation to be only approximately true. The
diagram of the section of the building has nearly always, according to
my experience, to be "coaxed" a little in order to fit the theory; or it
is found that though the geometrical figure suggested corresponds
exactly with some points on the plan or section, these are really of no
more importance than other points which might just as well have been
taken. The theorist draws our attention to those points in the building
which correspond with his geometry, and leaves on one side those which
do not. Now it may certainly be assumed that any builders intending to
lay out a building on the basis of a geometrical figure would have done
so with precise exactitude, and that they would have selected the most
obviously important points of the plan or section for the geometrical
spacing. In illustration of this point, I have given (Fig. 25) a
skeleton diagram of a Roman arch, supposed to be set out on a
geometrical figure. The center of the circle is on the intersection of
lines connecting the outer projection of the main cornice with the
perpendiculars from those points on the ground line. This point at the
intersection is also the center of the circle of the archway itself. But
the upper part of the imaginary circle beyond cuts the middle of the
attic cornice. If the arch were to be regarded as set out in reference
to this circle, it should certainly have given the most important
line--the top line, of the upper cornice, not an inferior and less
important line; and that is pretty much the case with all these
proportion theories (except in regard to Greek Doric temples); they are
right as to one or two points of the building, but break down when you
attempt to apply them further. It is exceedingly probable that many of
these apparent geometric coincidences really arise, quite naturally,
from the employment of some fixed measure of division in setting out
buildings. Thus, if an apartment of somewhere about 30 feet by 25 feet
is to be set out, the builder employing a foot measure naturally sets
out exactly 30 feet one way and 25 feet the other way. It is easier and
simpler to do so than to take chance fractional measurements. Then comes
your geometrical theorist, and observes that "the apartment is planned
precisely in the proportion of six to five." So it is, but it is only
the philosophy of the measuring-tape, after all. Secondly, it is a
question whether the value of this geometrical basis is so great as has
sometimes been argued, seeing that the results of it in most cases
cannot be judged by the eye. If, for instance, the room we are in were
nearly in the proportion of seven in length to five in width, I doubt
whether any of us here could tell by looking at it whether it were truly
so or not, or even, if it were a foot out one way or the other, in which
direction the excess lay; and if this be the case, the advantage of such
a geometrical basis must be rather imaginary than real.

[Illustration: Figs. 26 through 28]

Having spoken of plan as the basis of design, I should wish to conclude
this lecture by suggesting also, what has never to my knowledge been
prominently brought forward, that the plan itself, apart from any
consideration of what we may build up upon it, is actually a form of
artistic thought, of architectural poetry, so to speak. If we take three
such plans as those shown in Figs. 26, 27, and 28, typical forms
respectively of the Egyptian, Greek, and Gothic plans, we certainly can
distinguish a special imaginative feeling or tendency in each of them.
In the Egyptian, which I have called the type of "mystery," the plan
continually diminishes as we proceed inward. In the third great
compartment the columns are planted thick and close, so as to leave no
possibility of seeing through the building except along a single avenue
of columns at a time. The gloom and mystery of a deep forest are in it,
and the plan finally ends, still lessening as it goes, in the small and
presumably sacred compartment to which all this series of colonnaded
halls leads up. In the Greek plan there is neither climax nor
anti-climax, only the picturesque feature of an exterior colonnade
encircling the building and surrounding a single oblong compartment. It
is a rationalistic plan, aiming neither at mystery nor aspiration. In
the plan of Rheims (Fig. 28) we have the plan of climax or aspiration;
as in the Egyptian, we approach the sacred portion through a long avenue
of piers; but instead of narrowing, the plan extends as we approach the
shrine. I think it will be recognized, putting aside all considerations
of the style of the superstructure on these plans, that each of them in
itself represents a distinct artistic conception. So in the plan of the
Pantheon (Fig. 29), this entrance through a colonnaded porch into a vast
circular compartment is in itself a great architectural idea,
independently of the manner in which it is built up.

[Illustration: Figs. 29 through 34]

We may carry out this a little further by imagining a varied treatment
on plan of a marked-out space of a certain size and proportion, on which
a church of some kind, for instance, is to be placed. The simplest idea
is to inclose it round with four walls as a parallelogram (Fig. 30),
only thickening the walls where the weight of the roof principals comes.
But this is a plan without an idea in it. The central or sacred space at
the end is not expressed in the plan, but is merely a railed-off portion
of the floor. The entrance is utterly without effect as well as without
shelter. If we lay out our plan as in Fig. 31, we see that there is now
an idea in it. The two towers, as they must evidently be, form an
advanced guard of the plan, the recessed central part connecting them
gives an effective entrance to the interior; the arrangement in three
aisles gives length, the apse at the end incloses and expresses the
_sacrarium_, which is the climax and object of the plan. The shape of
the ground, however, is not favorable to the employment of a long or
avenue type of plan, it is too short and square; let us rather try a
plan of the open area order, such as Fig 32. This is based on the
short-armed Greek cross, with an open center area; again there is an
"advanced guard" in the shape of an entrance block with a porch; and the
three apses at the end give architectural emphasis to the _sacrarium_.
Fig. 35 is another idea, the special object of which is to give an
effect of contrast between the entrance, approached first through a
colonnaded portico, then through an internal vestibule, lighted from
above, and flanked by rows of small coupled columns; then through these
colonnaded entrances, the inner one kept purposely rather dark, we come
into an interior expanding in every direction; an effect of strong
contrast and climax. If our plot of ground again be so situated that one
angle of it is opposite the vista of two or more large streets, there
and nowhere else will be the salient angle, so to speak, of the plan,
and we can place there a circular porch--which may, it is evident, rise
into a tower--and enter the interior at the angle instead of in the
center; not an effective manner of entering as a rule, but quite
legitimate when there is an obvious motive for it in the nature and
position of the site. A new feature is here introduced in the circular
colonnade dividing the interior into a central area and an aisle. Each
of these plans might be susceptible of many different styles of
architectural treatment; but quite independently of that, it will be
recognized that each of them represents in itself a distinct idea or
invention, a form of artistic arrangement of spaces, which is what
"plan," in an architectural sense, really means.

       *       *       *       *       *


This burner is in the form of a cylinder made of a composition in which
magnesium predominates, and gives a light of 210 candle power with a
consumption of three and one-half cubic feet of gas per hour.


The cylinder to be heated to incandescence is firmly held in place on a
metal spindle, which is slowly revolved by means of an ingenious
clock-work in the base of the fixture. The arrangement is such that by
turning off the gas the clock-work is stopped, and by the turning on of
the gas, it is again set in motion. The movement of the spindle is so
slow that a casual observer would not notice it, there being only one
revolution made in twenty-four hours. The object of this movement is to
continually present new surface to be heated, as that which is exposed
to the high temperature wears away, similarly to the carbons used in
electric lighting, though much more slowly.

These burners can be made of 2,000 candle power, down to fifty candle

Pure oxygen can now be obtained from the atmosphere at a cost of about
twenty-five cents per 1,000 cubic feet, and the small amount required to
supplement the fuel water gas in producing this light can be supplied
under proper pressure from a very small pipe, which can be laid in the
same trench with the fuel gas pipe, at much less cost than is required
to carry an electric wire to produce an equal amount of light.

The oxygen pipe necessary to carry the gas under pressure need not
exceed an inch and a half in diameter to supply 5,000 lamps of 2,000
candle power each. The only reason why this burner has not been further
perfected and placed upon the market is because of the continual
preoccupation of Prof. Lowe in other lines of invention, and the amount
of attention required by his large business interests. Besides, the
field for its usefulness has been limited, as cheap fuel gas has only
just begun to be generally introduced. Now, however, that extensive
preparations are being made for the rapid introduction of the Lowe fuel
gas system into various cities, this burner will receive sufficient
attention to shortly complete it for general use in large quantities. It
is a more powerful and at the same time a softer light than is the
electric incandescent or the arc light. The light-giving property of a
burner of 1,000 candle power would not cost more than one cent for ten
hours' lighting, and the cylinder would only require to be changed once
a week; whereas the carbons of arc lights are changed daily. The cost of
the gas required to maintain such a lamp ten hours would be six cents,
allowing the same profit on the gas as when it is sold for other heating
purposes. The lamps complete will cost much less than the present
electric lamps, and after allowing a large profit to companies supplying
them, will not cost consumers more than one-fourth as much as arc lamps,
and will give a much clearer and steadier light.

Since Prof. Lowe perfected his first incandescent burner great progress
has been made in this line of invention, and it is no wonder that the
attention of the whole gas fraternity of the country has been drawn to
the subject of cheap fuel water gas, which is so admirably adapted to
all purposes of heat, light, and power.

While there is no doubt that light can be more cheaply produced by
incandescence obtained by the use of fuel water gas than by any other
means, still a large amount of electric lighting will continue to hold
its position, and the electric system will gain ground for many uses.
But the electric light also can be more economically produced when fuel
water gas is used as power to revolve the dynamos. Therefore, we believe
it to be for the best interests of every gas company that would move in
the line of progress to commence without delay to make preparations for
the introduction of fuel water gas, if, at first, only as supplementary
to their present illuminating gas business.-_Progressive Age._

       *       *       *       *       *


We are indebted to Prof. E.B. Cowgill, of Kansas, for a copy of his
recent report to the Kansas State Board of Agriculture concerning the
operations of the Parkinson Sugar Works, at Fort Scott, Kansas. The
report contains an interesting historical sketch of the various efforts
heretofore made to produce sugar from sorghum, none of which proved
remunerative until 1887, when the persevering efforts of a few energetic
individuals, encouraged and assisted by a small pecuniary aid from
government, were crowned with success, and gave birth, it may justly be
said, to a new industry which seems destined shortly to assume gigantic
proportions and increase the wealth of the country.

We make the following abstracts from the report:

The sorghum plant was introduced into the United States in 1853-54, by
the Patent Office, which then embraced all there was of the United
States Department of Agriculture. Its juice was known to be sweetish,
and chemists were not long in discovering that it contained a
considerable percentage of some substance giving the reactions of cane
sugar. The opinion that the reactions were due to cane sugar received
repeated confirmations in the formation of true cane sugar crystals in
sirups made from sorghum. Yet the small amounts that were crystallized,
compared with the amounts present in the juices as shown by the
analyses, led many to believe that the reactions were largely due to
some other substance than cane sugar.

During the years 1878 to 1882, inclusive, while Dr. Peter Collier was
chief chemist of the Department of Agriculture, much attention was given
to the study of sorghum juices from canes cultivated in the gardens of
the department at Washington. Dr. Collier became an enthusiastic
believer in the future greatness of sorghum as a sugar producing plant,
and the extensive series of analyses published by him attracted much

As a result large sugar factories were erected and provided with costly
appliances. Hon. John Bennyworth erected one of these at Larned, in
Kansas. S.A. Liebold & Co. subsequently erected one at Great Bend.

Sterling and Hutchinson followed with factories which made considerable
amounts of merchantable sugar at no profit.

The factory at Sterling was erected by R.M. Sandy & Co., of New Orleans,
and while the sirup produced paid the expenses of the factory, not a
crystal of sugar was made. The factory then, in 1883, changed hands, and
passed under the superintendency of Prof. M.A. Scovell, then of
Champaign, Illinois, who, with Prof. Webber, had worked out, in the
laboratories of the Illinois Industrial University, a practical method
for obtaining sugar from sorghum in quantities which at prices then
prevalent would pay a profit on the business. But prices declined, and
after making sugar for two years in succession, the Sterling factory

The Hutchinson factory at first made no sugar, but subsequently passed
under the management of Prof. M. Swenson, who had successfully made
sugar in the laboratory of the University of Wisconsin. Large amounts of
sugar were made at a loss, and the Hutchinson factory closed its doors.
In 1884, Hon. W.L. Parkinson fitted up a complete sugar factory at
Ottawa, and for two years made sugar at a loss. Mr. Parkinson was
assisted during the first year by Dr. Wilcox, and during the second year
by Prof. Swenson.

Much valuable information was developed by the experience in those
several factories, but the most important of all was the fact that, with
the best crushers, the average extraction did not exceed half of the
sugar contained in the cane. It was known to scientists and well
informed sugar makers in this country that the process of diffusion was
theoretically efficient for the extraction of sugar from plant cells,
and that it had been successfully applied by the beet sugar makers of
Europe for this purpose.

In 1883, Prof. H.W. Wiley, chief chemist of the Department of
Agriculture, made an exhaustive series of practical experiments in the
laboratories of the department on the extraction of the sugars from
sorghum by the diffusion process, by which the extraction of at least 85
per cent. of the total sugars present was secured.

The Kansas delegation in Congress became interested. Senator Plumb made
a thorough study of the entire subject, and, with the foresight of
statesmanship, gave his energies to the work of securing an
appropriation of $50,000 for the development of the sugar industry,
which was granted in 1884, and fifty thousand dollars more was added in
1885 to the agricultural appropriation bill. This was expended at
Ottawa, Kansas, and in Louisiana.

In that year Judge Parkinson, at Fort Scott, organized the Parkinson
Sugar Company. Taking up the work when all others had failed, this
company has taken a full share of the responsibilities and losses, until
it has at last seen the Northern sugar industry made a financial

The report of 1895 showed such favorable results that in 1886 the House
made an appropriation of $90,000, to be used in Louisiana, New Jersey,
and Kansas. A new battery and complete carbonatation apparatus were
erected at Fort Scott. About $60,000 of the appropriation was expended
here in experiments in diffusion and carbonatation.

Last year (1887) the Fort Scott management made careful selection of
essential parts of the processes already used, omitted non-essential and
cumbrous processes, availed themselves of all the experience of the past
in this country, and secured a fresh infusion of experience from the
beet sugar factories of Germany, and attained the success which finally
places sorghum sugar making among the profitable industries of the

The success has been due, first, to the almost complete extraction of
the sugars from the cane by the diffusion process; second, the prompt
and proper treatment of the juice in defecating and evaporating; third,
the efficient manner in which the sugar was boiled to grain in the
strike pan.

  Total number tons of cane bought     3,840
    "     "     "   seed tops bought     437
  Total number tons of field cane      4,277

There was something over 500 acres planted. Some of it failed to come at
all, some "fell upon the rocky places, where they had not much earth,
and when the sun was risen they were scorched;" so that, as nearly as we
can estimate, about 450 acres of cane were actually harvested and
delivered at the works. This would make the average yield of cane 9½
tons per acre, or $19 per acre in dollars and cents.


  Sugar, 235,826 lb., @ 5¾c            $13,559 98
    "    State bounty, @ 2c              4,716 53
                                        ---------   $17,276 50
  Sirups, 51,000 gals,(estimated) @ 20c.             10,200 00
  Seed (estimated)                                    7,000 00
  Value of total product                            $34,476 50


  Cane, 3,840 tons,@ $2                    $7,680
  Seed, 967 tons, @ $3                      1,934
                                          -------    $9,614 00
  Labor bill from August 15 to October 15,
    including labor for department experiments        5,737 16
  Coal, including all experiments                     1,395 77
  Salaries, etc.                                      3,500 00
  Insurance, sundries, etc.                           1,500 00
  Total                                             $21,746 93
  Total value                                       $34,476 50
  Total cost                                         31,248 93
  Net                                               $13,329 57
  To be paid by the department                        6,534 75
  Total profit for season's work, 1887              $19,764 32


As now developed, the processes of making sugar from sorghum are as

 _First_, The topped cane is delivered at the factory by the farmers
 who can grow it.

 _Second_, The cane is cut by a machine into pieces about one and a
 quarter inches long.

 _Third_, The leaves and sheaths are separated from the cut cane by
 fanning mills.

 _Fourth_, The cleaned cane is cut into fine bits called chips.

 _Fifth_, The chips are placed in iron tanks, and the sugar
 "diffused," soaked out with hot water.

 _Sixth_, The juice obtained by diffusion has its acids nearly or
 quite neutralized with milk of lime, and is heated and skimmed.

 _Seventh_, The defecated or clarified juice is boiled to a
 semi-sirup in vacuum pans.

 _Eighth_, The semi-sirup is boiled "to grain" in a high vacuum in
 the "strike pan."

 _Ninth_, The mixture of sugar and molasses from the strike pan is
 passed through a mixing machine into centrifugal machines which
 throw out the molasses and retain the sugar.

The process of the formation of sugar in the cane is not fully
determined, but analyses of canes made at different stages of growth
show that the sap of growing cane contains a soluble substance having a
composition and giving reactions similar to starch. As maturity
approaches, grape sugar is also found in the juice. A further advance
toward maturity discloses cane sugar with the other substances, and at
full maturity perfect canes contain much cane sugar and little grape
sugar and starchy matter.

In sweet fruits the change from grape sugar to cane sugar does not take
place, or takes place but sparingly. The grape sugar is very sweet,

Cane sugar, called also sucrose or crystallizable sugar, when in dilute
solution is changed very readily into grape sugar or glucose, a
substance which is much more difficult than cane sugar to crystallize.
This change, called inversion, takes place in over-ripe canes. It sets
in very soon after cutting in any cane during warm weather; it occurs in
cane which has been injured by blowing down, or by insects, or by frost,
and it probably occurs in cane which takes a second growth after nearly
or quite reaching maturity.

To insure a successful outcome from the operations of the factory, the
cane must be so planted, cultivated and matured as to make the sugar in
its juice. It must be delivered to the factory very soon after cutting,
and it must be taken care of before the season of heavy frosts.


The operations of the factory are illustrated in the large diagram. The
first cutting is accomplished in the ensilage or feed cutter at E. This
cutter is provided with three knives fastened to the three spokes of a
cast iron wheel which makes about 250 revolutions per minute, carrying
the knives with a shearing motion past a dead knife. By a forced feed
the cane is so fed as to be cut into pieces about one and a quarter
inches long. This cutting frees the leaves and nearly the entire sheaths
from the pieces of cane. By a suitable elevator, F, the pieces of cane,
leaves and sheaths are carried to the second floor.

The elevator empties into a hopper, below which a series of four or five
fans, G, is arranged one below the other. By passing down through these
fans the cane is separated from the lighter leaves, much as grain is
separated from chaff. The leaves are blown away, and finally taken from
the building by an exhaust fan. This separation of the leaves and other
refuse is essential to the success of the sugar making, for in them the
largest part of the coloring and other deleterious matters are
contained. If carried into the diffusion battery, these matters are
extracted (see reports of Chemical Division, U.S. Department of
Agriculture), and go into the juice with the sugar. As already stated,
the process of manufacturing sugar is essentially one of separation. The
mechanical elimination of these deleterious substances at the outset at
once obviates the necessity of separating them later and by more
difficult methods, and relieves the juice of their harmful influences.
From the fans the pieces of cane are delivered by a screw carrier to an
elevator which discharges into the final cutting machine on the third
floor. This machine consists of an eight inch cast iron cylinder, with
knives like those of a planing machine. It is really three cylinders
placed end to end in the same shaft, making the entire length eighteen
inches. The knives are inserted in slots and held in place with set
screws. The cylinder revolves at the rate of about twelve hundred per
minute, carrying the knives past an iron dead knife, which is set so
close that no cane can pass without being cut into fine chips. From this
cutter the chips of cane are taken by an elevator and a conveyer, K, to
cells, MM, of the diffusion battery. The conveyer passes above and at
one side of the battery, and is provided with an opening and a spout
opposite each cell of the battery. The openings are closed at pleasure
by a slide. A movable spout completes the connection with any cell which
it is desired to fill with chips.


The condition in which the sugars and other soluble substances exist in
the cane is that of solution in water. The sweetish liquid is contained,
like the juices of plants generally, in cells. The walls of these cells
are porous. It has long been known that if a solution of sugar in water
be placed in a porous or membraneous sack, and the sack placed on water,
an action called osmosis, whereby the water from the outside and the
sugar solution from the inside of the sack each pass through, until the
liquids on the two sides of the membrane are equally sweet. Other
substances soluble in water behave similarly, but sugar and other
readily crystallizable substances pass through much more readily than
uncrystallizable or difficultly crystallizable. To apply this properly
to the extraction of sugar, the cane is first cut into fine chips, as
already described, and put into the diffusion cells, where water is
applied and the sugar is displaced.



as used at the Parkinson factory, consists of twelve iron tanks. (See
diagram.) They are arranged in a line, as shown in diagram, Fig. 1. Each
has a capacity of seventy-five cubic feet, and by a little packing holds
a ton of cane chips. The cells are supported by brackets near the
middle, which rest on iron joists. Each cell is provided with a heater,
through which the liquid is passed in the operation of the battery. The
cells are so connected by pipes and valves that the liquid can be passed
into the cells, and from cell to cell, at the pleasure of the operator.
The bottom of each cell consists of a door, which closes on an annular
rubber hose placed in a groove, and filled with water, under a pressure
greater than that ever given to the liquids in the cell. This makes a
water tight joint whenever the trap door bottom is drawn up firmly
against it. The upper part is of cast iron and is jug shaped, and is
covered with a lid which is held with a screw on rubber packing. In the
jug neck and near the bottom the sides are double, the inner plates
being perforated with small holes to let water in and out. The bottoms
are double, the inner plates being perforated like the neighboring
sides, and for the same purpose. The cells, of whose appearance a fair
idea may be had from diagram, Fig. 2, are connected with a water pipe, a
juice pipe, a compressed air pipe, and the heaters, by suitable valves.
The heaters are connected with a steam pipe. This, and the compressed
air pipe, are not shown in the diagram. The water pipe is fed from an
elevated tank, which gives a pressure of twelve pounds per square inch
The valve connections enable the operator to pass water into the cells
at either the top or the bottom; to pass the liquid from any cell to the
next, or to the juice pipe through the heater; to separate any cell from
any or all others, and to turn in compressed air.

Now let the reader refer to Fig. 2.


The cutters are started, and cell 1 is filled with chips. This done, the
chips from the cutters are turned into cell 2; cell 1 is closed, and cut
off from the others, and water is turned into it by opening valve, c,
of cell 1 (see Fig. 2) until it is filled with water among the chips.
When 2 is filled with chips, its valve, a, is raised to allow the
liquid to pass down into the juice pipe. Valve a of 3 is also raised.
Now the juice pipe fills, and when it is full the liquid flows through
valve, a, of 3, and into the heater between 2 and 3, and into the
bottom of 2, until 2 is full of water among the chips. (This may be
understood by following the course of the arrows shown in the diagrams
of 9 and 10). Valve a of 2 is now screwed down; c is down and b is
opened. It will be readily seen by attention to the diagram that this
changes the course of the flow so that it will no longer enter at the
bottom, but at the top of 2, as shown by the arrows at cell 2.

It is to be observed that the water is continually pressing in at the
top of 1, and driving the liquid forward whenever a valve is opened to
admit it to another cell, heater, or pipe. When cell 3 is full of chips,
its valves are manipulated just as were those of 2. So as each
succeeding cell is filled, the manipulation of valves is repeated until
cell 6 is filled with liquid. After passing through six cells of fresh
chips, this liquid is very sweet, and is drawn off into the measuring
tank shown at p in diagram, Fig. 1, and is thence conveyed for
subsequent treatment in the factory. To draw this juice from 6, valve
a of 7 is raised to connect the heater between 6 and 7 with the juice
pipe. A gate valve in the juice pipe is opened into the measuring tank,
and the pressure of water into the top of 1 drives the liquid forward
through the bottom of 1, through the heater, into the top of 2, out from
the bottom of 2, through the heater into the top of 3, out from the
bottom of 3, through the heater into the top of 4, out from the bottom
of 4, through the heater, into the top of 5, out from the bottom of 5,
through the heater, into the top of 6, and now out from the bottom of 6,
through the heater, into the juice pipe, and from the juice pipe into
the measuring tank. It will be understood that the liquid which is drawn
from 6 is chiefly that which was passed into 1 when it was filled with
chips. There is doubtless a little mixing as the pressure drives the
liquid forward. But the lighter liquid is always pressed in at the top
of the cells, so that the mixing is the least possible. The amount of
liquid, now called juice, which is drawn from 6 is 1,110 liters, or 291
gallons. When this quantity has been drawn into the measuring tank, the
gate valve is closed, and the valves connecting with 7 are manipulated
as were those of 6, a measure of juice being drawn in the same way. All
this time the water has been passed into the top of 1, and this is
continued until the juice has been drawn from 9. Valve c to cell 1 is
now closed, and compressed air is turned into the top of 1 to drive the
liquid forward into 10. After the water has thus been nearly all
expelled from 1, valve a of cell 2 is lowered so as to shut off
communication with the juice pipe, and b, of cell 2 is closed. a and
b of cell 1 have, it will be observed, been closed or down from the
beginning. Cell 1 is now isolated from all others. Its chips have been
exhausted of sugar, and are ready to be thrown out. The bottom of 1 is
opened, and the chips fall out into the car, o (see diagram, Fig. 1),
and are conveyed away. Immediately on closing valves a and b of cell
2, c is opened, and the water presses into the top of 2, as before
into the top of 1, and the circulation is precisely similar to that
already described, 2 having taken the place of 1, 3 of 2, and so on.

When 2 is emptied, 3 takes the first place in the series and so on. When
12 has been filled, it takes the l3th place. (The juice pipe returns
from the termination of the series, and connects with 1, making the
circuit complete.) The process is continuous, and the best and most
economical results are obtained if there is no intermission.

One cell should be filled and another emptied every eight minutes, so
that in twenty-four hours the number of cells diffused should be one
hundred and eighty.


For the purpose of illustration, let us assume that when it has been
filled with chips just as much water is passed into the cell as there
was juice in the chips. The process of osmosis or diffusion sets in, and
in a few minutes there is as much sugar in the liquid outside of the
cane cells as in the juice in these cane cells; i.e., the water and
the juice have divided the sugar between them, each taking half.

Again, assume that as much liquid can be drawn from 1 as there was water
added. It is plain that if the osmotic action is complete, the liquid
drawn off will be half as sweet as cane juice. It has now reached fresh
chips in 2, and again equalization takes place. Half of the sugar from 1
was brought into 2, so that it now contains one and a half portions of
sugar, dissolved in two portions of liquid, or the liquid has risen to
three quarters of the strength of cane juice. This liquid having three
fourths strength passes to 3, and we have in 3 one and three fourths
portions of liquid, or after the action has taken place the liquid in 3
is seven eighths strength. One portion of this liquid passes to 4, and
we have one and seven eighths portions of sugar in two portions of
liquid, or the liquid becomes 15/16 strength. One portion of this liquid
passes to 5, and we have in 5 one and fifteen sixteenths portions of
sugar in two portions of liquid, or the liquid is 31/32 strength. It is
now called _juice_. From this time forward a cell is emptied for every
one filled.

Throughout the operation, the temperature is kept as near the boiling
point as can be done conveniently without danger of filling some of the
cells with steam. Diffusion takes place more rapidly at high than at low
temperatures, and the danger of fermentation, with the consequent loss
of sugar, is avoided.


By the first action of water in 1, ½ of the sugar was left in cell 1; by
the second ¼ was left, by the third 1/8 was left, by the fourth 1/16 was
left, by the fifth 1/32 was left, by the sixth 1/64 was left, by the
seventh 1/128 was left, by the eighth 1/256 was left, by the ninth 1/512
was left. The fractions representing the strength of the juice on the
one hand and the sugar left in each cell on the other hand, after the
battery is fully in operation, are not so readily deduced. The theory is
easily understood, however, although the computation is somewhat
intricate. Those who desire to follow the process by mathematical
formula are referred to pages 9 and 10, Bulletin No. 2, Chemical
Division U.S. Department of Agriculture, where will be found the formula
furnished by Professor Harkness, of the U.S. Naval Observatory.

For the sake of simplifying the explanation, it was assumed that the
water added is equal in volume to the juice in a cellful of cane chips.
In practice more water is added, to secure more perfect exhaustion of
the chips, and with the result of yielding about thirteen volumes of
juice for every nine volumes as it exists in the cane, and of extracting
92.04 per cent. of all the sugars from the cane, as shown by the report
of Dr. C.A. Crampton, Assistant Chemist of the U.S. Department of


In the experiments at Fort Scott in 1886, much difficulty was
experienced on account of inversion of the sugar in the diffusion
battery. The report shows that this resulted from the use of soured cane
and from delays in the operation of the battery on account of the
imperfect working of the cutting and elevating machinery, much of which
was there experimental. Under the circumstances, however, it became a
matter of the gravest importance to find a method of preventing this
inversion without in any manner interfering with the other processes. On
the suggestion of Prof. Swenson, a portion of freshly precipitated
carbonate of lime was placed with the chips in each cell.[1] In the
case of soured cane, this took up the acid which otherwise produced
inversion. In case no harmful acids were present, this chalk was
entirely inactive. Soured canes are not desirable to work under any
circumstances, and should be rejected by the chemist, and not allowed to
enter the factory. So, also, delays on account of imperfect machinery
are disastrous to profitable manufacturing, and must be avoided. But for
those who desired to experiment with deteriorated canes and untried
cutting machines, the addition of the calcium carbonate provides against
disastrous results which would otherwise be inevitable.

   [Footnote 1: For this improvement Prof. Swenson obtained a patent
   Oct. 11, 1887, the grant of which was recently made the subject
   of congressional inquiry.]

Immediately after it is drawn from the diffusion battery the juice is
taken from the measuring tanks into the defecating tanks or pans. These
are large, deep vessels, provided with copper steam coils in the bottom
for the purpose of heating the juice. Sufficient milk of lime is added
here to nearly or quite neutralize the acids in the juice, the test
being made with litmus paper. The juice is brought to the boiling point,
and as much of the scum is removed as can be taken quickly. The scum is
returned to the diffusion cells, and the juice is sent by a pump to the
top of the building, where it is boiled and thoroughly skimmed. These
skimmings are also returned to the diffusion cells.

This method of disposing of the skimmings was suggested by Mr.
Parkinson. It is better than the old plan of throwing them away to
decompose and create a stench about the factory. Probably a better
method would be to pass these skimmings through some sort of filter, or,
perhaps better still, to filter the juice and avoid all skimming. After
this last skimming the juice is ready to be boiled down to a thin sirup


These consist of two large closed pans provided within with steam pipes
of copper, whereby the liquid is heated. They are also connected with
each other and with pumps in such a way as to reduce the pressure in the
first to about three fifths and in the second to about one fifth the
normal atmospheric pressure.

The juice boils rapidly in the first at somewhat below the temperature
of boiling water, and in the second at a still lower temperature. The
exhaust steam from the engines is used for heating the first pan, and
the vapor from the boiling juice in the first pan is hot enough to do
all the boiling in the second, and is taken into the copper pipes of the
second for this purpose. In this way the evaporation is effected without
so great expenditure of fuel as is necessary in open pans, or in single
effect vacuum pans, and the deleterious influences of long continued
high temperature on the crystallizing powers of the sugar are avoided.

From the double effects the sirup is stored in tanks ready to be taken
into the strike pan, where the sugar is crystallized.


At this point the juice has just reached a condition in which it will
keep. From the moment the cane is cut in the fields until now, every
delay is liable to entail loss of sugar by inversion. After the water is
put into the cells of the battery with the chips, the temperature is
carefully kept above that at which fermentation takes place most
readily, and the danger of inversion is thereby reduced. But with all
the precautions known to science up to this point the utmost celerity is
necessary to secure the best results. There is here, however, a natural
division in the process of sugar making, which will be further
considered under the heading of "Auxiliary Factories." Any part of the
process heretofore described may be learned in a few days by workmen of
intelligence and observation who will give careful attention to their
respective duties.


This operation is the next in course, and is performed in what is known
at the sugar factory as the strike pan, a large air tight iron vessel
from which the air and vapor are almost exhausted by means of a suitable
pump and condensing apparatus. As is the case with the saccharine juices
of other plants, the sugar from sorghum crystallizes best at medium

The process of boiling to grain may be described as follows: A portion
of the sirup is taken into the pan, and boiled rapidly _in vacuo_ to the
crystallizing density. If in a sirup the molecules of sugar are brought
sufficiently near to each other through concentration--the removal of
the dissolving liquid--these molecules attract each other so strongly as
to overcome the separating power of the solvent, and they unite to form
crystals. Sugar is much more soluble at high than at low temperatures,
the heat acting in this as in almost all cases as a repulsive force
among the molecules. It is therefore necessary to maintain a high vacuum
in order to boil at a low temperature, in boiling to grain. When the
proper density is reached the crystals sometimes fail to appear, and a
fresh portion of cold sirup is allowed to enter the pan. This must not
be sufficient in amount to reduce the density of the contents of the pan
below that at which crystallization may take place. This cold sirup
causes a sudden though slight reduction in temperature, which may so
reduce the repulsive forces as to allow the attraction among the
molecules to prevail, resulting in the inception of crystallization. To
discover this requires the keenest observation. When beginning to form,
the crystals are too minute to show either form or size, even when
viewed through a strong magnifying glass. There is to be seen simply a
very delicate cloud. The inexperienced observer would entirely overlook
this cloud, his attention probably being directed to some curious
globular and annular objects, which I have nowhere seen explained. Very
soon after the sample from the pan is placed upon glass for observation,
the surface becomes cooled and somewhat hardened. As the cooling
proceeds below the surface, contraction ensues, and consequently a
wrinkling of the surface, causing a shimmer of the light in a very
attractive manner. This, too, is likely to attract more attention than
the delicate, thin cloud of crystals, and may be even confounded with
the reflection and refraction of light, by which alone the minute
crystals are determined. The practical operator learns to disregard all
other attractions, and to look for the cloud and its peculiarities. When
the contents of the pan have again reached the proper density, another
portion of sirup is added. The sugar which this contains is attracted to
the crystals already formed, and goes to enlarge these rather than to
form new crystals, provided the first are sufficiently numerous to
receive the sugar as rapidly as it can crystallize.

The contents of the pan are repeatedly brought to the proper density,
and fresh sirup added as above described until the desired size of grain
is obtained, or until the pan is full. Good management should bring
about these two conditions at the same time. If a sufficient number of
crystals has not been started at the beginning of the operation to
receive the sugar from the sirup added, a fresh crop of crystals will be
started at such time as the crystallization becomes too rapid to be
accommodated on the surfaces of the grain already formed. The older and
larger crystals grow more rapidly, by reason of their greater attractive
force, than the newer and smaller ones on succeeding additions of sirup,
so that the disparity in size will increase as the work proceeds. This
condition is by all means to be avoided, since it entails serious
difficulties on the process of separating the sugar from the molasses.
In case this second crop of crystals, called "false grain" or "mush
sugar" has appeared, the sugar boiler must act upon his judgment, guided
by his experience as to what is to be done. He may take enough thin
sirup into the pan to dissolve all of the crystals and begin again, or,
if very skillful, he may so force the growth of the false grain as to
bring it up to a size that can be worked.

The completion of the work in the strike pan leaves the sugar mixed with
molasses. This mixture is called _malada_ or _masscuite_. It may be
drawn off into iron sugar wagons and set in the hot room above
mentioned, in which case still more of the sugar which remains in the
uncrystallized state generally joins the crystals, somewhat increasing
the yield of "first sugars." At the proper time these sugar wagons are
emptied into a mixing machine, where the mass is brought to a uniform
consistency. If the sugar wagons are not used, the strike pan is emptied
directly into the mixer.


From the mixer the melada is drawn into the centrifugal machines. These
consist, first, of an iron case resembling in form the husk of mill
stones. A spout at the bottom of the husk connects with a molasses tank.
Within this husk is placed a metallic vessel with perforated sides. This
vessel is either mounted or hung on a vertical axis, and is lined with
wire cloth. Having taken a proper portion of the melada into the
centrifugal, the operator starts it to revolving, and by means of a
friction clutch makes such connection with the engine as gives it about
1,500 revolutions per minute. The centrifugal force developed drives the
liquid molasses through the meshes of the wire cloth, and out against
the husk, from which it flows off into a tank. The sugar, being solid,
is retained by the wire cloth. If there is in the melada the "false
grain" already mentioned, it passes into the meshes of the wire cloth,
and prevents the passage of the molasses. After the molasses has been
nearly all thrown out, a small quantity of water is sprayed over the
sugar while the centrifugal is in motion. This is forced through the
sugar, and carries with it much of the molasses which would otherwise
adhere to the sugar, and discolor it. If the sugar is to be refined,
this washing with water is omitted. When the sugar has been sufficiently
dried, the machine is stopped, the sugar taken out, and put into barrels
for market.

Simple as the operation of the centrifugals is, the direction of the
sugar boiler as to the special treatment of each strike is necessary,
since he, better than any one else, knows what difficulties are to be
expected on account of the condition in which the melada left the strike


A plant having a battery like that at Fort Scott, in which the cells are
each capable of containing a ton of cane chips, should have a capacity
of 180 tons of cleaned cane, or 200 tons of cane with leaves, or 240
tons of cane as it grows in the field, per day of twenty-four hours.
Those who have given most attention to the subject think that a battery
composed of one and a half ton cells may be operated quite as
successfully as a battery of one ton cells. Such a battery would have a
capacity of 360 tons of field cane per day.


This consists of modifications of appliances which have long been used.
Simple as it is, and presenting only mechanical problems, the cutting,
cleaning, and evaporating apparatus is likely to be the source of more
delays and perplexities in the operation of the sugar factory than any
other part.

The diffusion battery in good hands works perfectly; the clarification
of the juice causes no delays; the concentration to the condition of
semi-sirup may be readily, rapidly, and surely effected in apparatus
which has been brought to great perfection by long experience, and in
many forms; the work at the strike pan requires only to be placed in the
hands of an expert; the mixer never fails to do its duty; there are
various forms of centrifugal machines on the market, some of which are
nearly perfect. If, then, the mechanical work of delivering, cutting,
cleaning, and elevating the cane can be accomplished with regularity and
rapidity, the operation of a well adjusted sugar factory should proceed
without interruption or delay from Monday morning to Saturday night.


An acre of land cultivated in sorghum yields a greater tonnage of
valuable products than in any other crop, with the possible exception of
hay. Under ordinary methods of cultivation, ten tons of cleaned cane per
acre is somewhat above the average, but under the best cultivation the
larger varieties often exceed twelve, while the small early amber
sometimes goes below eight tons per acre. Let seven and a half tons of
cleaned cane per acre be assumed for the illustration. This corresponds
to a gross yield of ten tons for the farmer, and at two dollars per ton
gives him twenty dollars per acre for his crop. These seven and a half
tons of clean cane will yield:

  750 pounds of sugar.
  1,000 pounds of molasses.
  900 pounds of seed.
  1,500 pounds of fodder (green leaves).
  1,500 pounds of exhausted chips (dried). A total of 5,650 pounds.

The first three items, which are as likely to be transported as wheat or
corn, aggregate 2,650 pounds per acre.

Sorghum will yield seven and a half tons of cleaned cane per acre more
surely than corn will yield thirty bushels or wheat fifteen bushels per

In the comparison, then, of products which bear transportation, these
crops stand as follows:

  Sorghum, at 7½ tons, 2,650 pounds per acre.
  Corn, at 30 bushels, 1,680 pounds per acre.
  Wheat, at 15 bushels, 900 pounds per acre.

The sugar from the sorghum is worth say 5 cents per pound; the molasses,
1¾ cents per pound; the seed, ½ cent per pound.

The sorghum products give market values as follows:

  750 pounds sugar at say 5 cents,[2] $37.50.
  1,000 pounds molasses at say 1¾ cents,[2] $17.50.
  900 pounds seed at say ½ cent,[2] $4.50.
  Total value of sorghum, less fodder, $59.50.
  The corn crop gives 1,680 pounds, at ½ cent $8.40.
  The wheat crop gives 900 pounds, at 1 cent, $9.

   [Footnote 2: The sugar sold this year at 5¾ cents per pound, the
   molasses at 20 cents per gallon, and the seed at ---- per bushel
   of 56 pounds. The seed is of about equal value with corn for
   feeding stock.]

Thus it will be seen that the sorghum yields to the farmer more than
twice as much per acre as either of the leading cereals, and as a gross
product of agriculture and manufacture on our own soil more than six
times as much per acre as is usually realized from either of these
standard crops.

       *       *       *       *       *

A new process for producing iron and steel direct from the ore has been
brought out in Russia. Under the new process iron ore, after being
submitted to the smelting processes, is taken direct from the furnace to
the rolling mill and turned into thin sheets of the finest charcoal
iron. At present the process has only been commercially applied with
charcoal fuel, but experiments are stated to have shown that equal
success can be obtained with coke. The secret of the process lies in the
construction of the furnace, which is said to be simple and inexpensive.

       *       *       *       *       *


We have received from M. Menges (of the Hague) a most interesting
description of an apparatus on which he has been at work for some time
past, with the object of generating electricity by the direct conversion
of heat, or, as it might be more accurately described, by a more direct
conversion than that of an ordinary dynamo. M. Menges' apparatus
depends, like that of Edison, upon the fact that the magnetic metals
lose their magnetic permeability at a certain temperature.

It differs greatly, however, from its predecessor in important points,
especially in the fact that it does not require the aid of any external
source of motive power.

In Edison's pyromagnetic dynamo it will be remembered that it is
necessary to provide some small amount of motive power from an
extraneous source in order to revolve the shield by which the heat is
alternately directed on one half or the other of the armature cores. M.
Menges' apparatus is, on the contrary, wholly automatic.

We proceed to give a free translation of the description furnished us by
the inventor.

In attempting to employ the thermo-magnetic properties of iron or nickel
in the construction of machines for the generation of electricity upon
an industrial scale, we are met with the difficulty that the heating and
cooling of large masses of metal not only involves great loss of heat,
but also requires much time. Hence, to obtain a useful effect of any
importance, it would appear necessary to employ machines of dimensions
altogether impracticable. By the device and method of construction now
to be explained this difficulty has, however, been completely overcome.

The action of a magnetic pole diminishes so rapidly with the increase of
distance that it may suffice to remove the armature to a distance
relatively small compared with its own dimensions, or with those of the
magnet, in order to reduce the action to a negligible value. But if the
magnet, N S, and the armature, A, being at a certain distance, we bring
between them a piece of iron or nickel, d, then the magnetic force
upon A is immediately and very considerably increased. In modern
language, the resistance of the magnetic circuit has been reduced by the
introduction of a better magnetic conductor, and the number of lines of
force passing through A is proportionately increased. The mass of the
piece, d, may, moreover, be relatively small compared with that of N S
and A. If d be again withdrawn, the magnetic resistance is increased,
and the lines through A are again a minimum.

Now, it is evident that we can also obtain the same effect by
sufficiently heating and cooling the intermediate piece, d; and again,
with a broad field we can alter the distribution of the lines at will by
heating or cooling one side of this piece or the other. For this reason
we will call the piece d the _thermo-magnetic distributor_, or, briefly,
the distributor.

We will now describe the manner in which this principle has been
realized in the practical construction of both a thermo-magnetic
generator and motor.

[Illustration: Fig. 1.]

Fig. 1 shows an elevation and part section of one of the arrangements
employed. Fig. 2 is a plan of the same machine (in the latter the ring,
_a a_, appearing on a higher plane than it actually occupies).

[Illustration: Fig. 2.]

N S is an electro-magnet, _a a_ the armature, wound as a Gramme ring,
and fixed to a frame with four arms, which can turn freely upon a pivot
midway between the poles. The cross arms of the frame are attached at 1,
2, 3, 4, Fig. 2. Between the magnets and the armature is placed the
distributor, _d d_, where it occupies an annular space open above and
below. Both the magnets and the armature are coated on the sides facing
the distributor with mica or some other non-conductor of heat and
electricity. The distributor is attached to and supported by the cross
arms, so that it turns with the armature.

The distributor is composed of a ribbon of iron or nickel, bent into a
continuous zigzag. This form has the advantage of presenting, in the
cool part of the distributor, an almost direct road for the lines of
force between the poles and the armature, thus diminishing the magnetic
resistance as far as possible. At the same time the Foucault currents
are minimized. To the same end it is useful to slit the ribbon, as in
Fig. 3. This also facilitates the folding into zigzags.

[Illustration: Fig. 3.]

The distributor is heated at two opposite points on a diameter by the
burners, _b b_, above which are the chimneys, _e e_. The cooling of the
alternate section is aided by the circulation of cold air, which is
effected by means of the draught in the chimneys, _e e_. At the points
of lowest temperature a jet of air or water is maintained. The cross
arms are insulated with mica or asbestos at the points where they extend
from the armature to the distributor.

It will now be evident that while the distributor is entirely cool, many
of the lines of force pass from N to S without entering the armature
core; but if heat is applied at the points 1 and 2 in the figure, so as
to increase the magnetic resistance at these points, then a great
portion of the lines will leave the distributor, and pass through the
armature core. Under these conditions, so long as heat is applied at two
points equidistant from N and S, we might, if we so pleased, cause the
armature to be rotated by an external source of power, and we should
then have an E.M.F. generated in the armature coils--that is to say, the
machine would work as an ordinary dynamo, and the power expended in
driving the armature would be proportionate to the output.

Suppose next that the points of heating, and with them the alternate
points of cooling 90 deg. apart, are shifted round about 45 deg., so
that the two hot regions are no longer symmetrically situated in respect
to each pole of the field. The distribution of the magnetization has
therefore become unsymmetrical, and the iron core is no longer in
equilibrium in the magnetic field. We have, in fact, the conditions of
Schwedoff's experiment upon a larger scale, and if the forces are
sufficient to overcome the frictional resistance, a rotation of the ring
ensues in the endeavor to restore equilibrium. The regions of heating
and cooling being fixed in space, this rotation is continuous so long as
the difference of temperature is maintained. The ring in rotating
carries with it the armature coils, and of course an E.M.F. is generated
in the same way as if the motive power came from an external source. In
this respect the machine therefore resembles a motor generator, and the
rotation is entirely automatic.

The armature coils are connected with a commutator in the usual way, and
the field may, of course, be excited either in shunt or in series. M.
Menges says that the residual magnetization is sufficient in his machine
to start the rotation by itself.

When the machine is to be used as a motor, it is evident that the
windings on the armature core need only be sufficient to supply current
to excite the field, or by the use of permanent magnets they may be
dispensed with altogether.

M. Menges has further designed a large number of variations on the
original type, varying the arrangement of the several parts, and
employing armatures and fields of many different types, such as are
already in use for dynamos.

In Fig. 4 a machine is represented in which the field is external to the

[Illustration: Fig. 4.]

In Fig. 5 we have a thermo-magnetic generator, which corresponds to the
disk machine in dynamos. Similar parts are indicated by the same letters
in each of these figures, so that no further detailed description is

[Illustration: Fig. 5.]

In another modification M. Menges proposes to rotate the burners and
leave the armature and distributor at rest. But in this case it is
evident that the E.M.F. produced would be much less, because the
magnetization of the core would only undergo a variation of intensity,
and would nowhere be reversed, except, perhaps, just in front of the
poles. In machines modeled on the Brush type it is evident that the
distributor need not be continuous.

Enough has, however, been said to indicate the extent of the field upon
which the principle may be applied.--_The Electrician._

       *       *       *       *       *


   [Footnote 1: Abstract of a paper read before the British
   Association meeting at Manchester, September, 1887.]


I will try to give a short report of some experiments I have made during
the last year in regard to atmospheric electricity. It was formerly
uncertain whether the electrostatic potential would increase by rising
from the surface of the earth to more elevated region of the atmosphere
or not, and also whether the potential in a normal--that is,
cloudless--state of the atmosphere was always positive or sometimes
negative. Sir William Thomson found by exact methods of measuring that
the increase of the potential with elevation is very important, and
values about 100 volts per meter. That fact is proved by many other
observers, especially lately by Mr. F. Exner, at Vienna, who found an
increase of 60 to 600 volts per meter. The observations were made by
means of an electrometer. In respect of many inconveniences which are
connected with the use of an electrometer, I have tried the measurements
with a very sensitive galvanometer. In this case it is necessary to
apply a separating air exhaust apparatus, for example flame, or a system
of points at the upper end of the conductor, which is elevated in the
atmosphere. In order to get a constant apparatus, I have used 400 of the
finest needles inserted in a metallic ribbon. This system I have raised
in the air by means of a captive balloon, or by a kite, which was
attached to a conductor of twine or to a twisted line of the finest
steel wire. In this way I have attained a height of 100 to 300 meters.
When the lower end of the kite line was communicating with the
galvanometer whose other terminal was in contact with the earth, a
current passed through the galvanometer. For determining the strength of
this current I proposed to called a micro-ampere the 10^{-9} part of an
ampere. At the height of about 100 meters in the average the current
begins to be regular, and increases at the height of 300 meters to 4,000
or 5,000 of these units. The increase is very regular, and seems to be a
linear function of the height. I have, nevertheless, found the smallest
quantities of dust contained in the atmosphere or the lightest veil of
cirrus disturbed the measurement very materially, and generally made the
potential lower. In negative experiments of this nature I have made at
Breslau, at the Sohneekoppe, and at the "Reisengebirge," especially at
the last station, an increase of potential was observed, not only by
reason of the perpendicular height, but also by reaching such regions of
the atmosphere as were situated horizontally to about 200 meters from
the utmost steep of the same mountain, Sohneekoppe. Therefore it must,
according to Mr. Exner, be assumed that the surface of the air presents
a surface of equal potential, and that the falling surfaces of high
potential were stretched parallel over the plane contours of the air,
and more thinly or narrow lying over all the elevated points, as, for
example, mountains, church towers, etc. On the basis of these facts I
think it easy to explain the electricity of thunder storm clouds, in
fact every cloud, or every part of a cloud, may be considered as a
leading conductor, such clouds as have for the most part perpendicular
height. After being induced the change results by supposing the
conduction of electricity either from the upper or from the lower side,
according to greater or smaller speed of the air in the height. In the
first case the clouds will be charged positive, in the other negative. I
am inclined, therefore, to state that the electricity of thunder storm
clouds must be considered as a special but disturbed case of the normal
electric state of the atmosphere, and that all attempts to explain
thunder storm electricity must be based on the study of the normal
electric state of the atmosphere.

       *       *       *       *       *


   [Footnote 1: For the illustrations and many facts in the life of
   Linnæus we are indebted to the _Illustrated Tidning_, Stockholm.]


At intervals in the history of science, long periods of comparative
inertia have attended the death of its more distinguished workers. As
time progresses and the number of workers increases, there is a
corresponding increase in the number of men whose labors merit
distinction in the literature of every language; but as these accessions
necessitate in most cases further division of the honors, many names
conspicuously identified with modern science fail of their just relative
rank, and fade into unmerited obscurity. Thus the earlier workers in
science, like Scheele, Liebig, Humboldt, and others of that and later
periods, have won imperishable fame, to which we all delight to pay
homage, while others of more recent times, whose contributions have
perhaps been equally valuable for their respective periods, are given
stinted recognition of their services, if indeed their names are not
quite forgotten. Nothing illustrates so clearly the steps in the
evolution of science as a review of the relative status of its
representatives. As in the political history of the world an epoch like
that of the French revolution stands out like a mountain peak, so in the
history of science an epoch occurs rather by evolution than revolution,
when a hitherto chaotic, heterogeneous mass of knowledge is rapidly
given shape and systematized. Previous to the seventeenth century an
immense mass of facts had accumulated through the labors of
investigators working under the Baconian philosophy, but these facts had
been thrown together in a confused, unsystematic manner. A man of master
mind was then needed to grasp the wonders of nature and formulate the
existing knowledge of them into a scientific system with a natural
basis. Such a system was given by Linnæus, and so great were its merits
that it continues the foundation of all existing systems of

Charles Linnæus was born May 13, 1707, in a country place named Roshult
in Smaland, near Skane, Sweden. He was called Charles after the well
known Swedish knight errant, King Charles XII., then at the height of
his renown.

The natural beauty of his native place, with its verdure-clad hills, its
stately trees, and sparkling brooks fringed with mosses and flowers,
inspired the boy Linnæus with a love of nature and a devotion to her
teachings which tinged the current of his whole life. He was destined by
his parents for the ministry, and in accordance with their wish was sent
to the Vexio Academy ("gymnasium"). Here the dull theological studies
interfered so much with his study of nature that he would have felt lost
but for the sympathy of Dr. Rothman, one of his teachers, a graduate of
Harderwyk University, Holland, who had been a pupil of Boerhaave (the
most eminent physician and scientist of his day), and been much
impressed by his scientific teachings.


Dr. Rothman took a great interest in Linnæus, and assured his father
that he would prove a great success financially and otherwise as a
physician (an occupation whose duties then included a study of all
existing sciences). The father was satisfied, but dreaded the effect the
announcement of such a career would have on the mother, whose ambition
had been to see her son's name among the long list of clergymen of the
family who had been ministers to the neighboring church of Stentrohult.
She finally yielded, and the best possible use was made by Linnæus of
Dr. Rothman's tuition. Latin, then the mother tongue of all scientists
and scholars, he wrote and spoke fluently.

At the age of twenty Linnæus entered the University of Lund, and
remained there a year. Here he formed the acquaintance of a medical man,
a teacher in the university, who opened his home and his library to him,
and took him on his botanical excursions and professional visits. Some
time later, on Dr. Rothman's advice, Linnæus entered the University of
Upsala, then the most celebrated university of Northern Europe. His
parents were able to spare him but one hundred silver thalers for his
expenses. At the end of a year his money was spent, his clothing and
shoes were worn out, and he was without prospects of obtaining a
scholarship. When things were at their gloomiest he accidentally entered
into a discussion with a stranger in the botanical garden, who turned
out to be a clergyman scientist named Celsius. Celsius, while staying at
Upsala, had conceived the plan of given a botanical description of
biblical plants. Having learned that Linnæus had a herbarium of 600
plants, he took the young man under his protection, and opened up to him
his home and library.

While studying in this library, his observations regarding the sexes in
plants, hitherto in a chaotic state, took form, stimulated by an
abstract published in a German journal of Vaillant's views, and before
the end of 1729 the basis of the sexual system had appeared in
manuscript. This treatise having been seen by a member of the university
faculty, Linnæus was invited to fill a temporary vacancy, and lectured
with great success therein one and a half years. Meanwhile the
foundation of the celebrated treatises afterward published on the sexual
system of classification and on plant nomenclature had been laid.

As in the history of most great men, a seemingly great misfortune proved
to be a turning point in his career. The position he had temporarily
filled with such credit to himself and profit to the students was
claimed by its regular occupant, and, despite the opposition of the
faculty, Linnæus had to relinquish it. The two subsequent years were
spent in botanical investigations under the patronage of various eminent
men. During one of these he traveled through Lapland to the shores of
the Polar Sea, and the results of this expedition were embodied in his
"Lapland Flora," the first flora founded on the sexual system. He
delivered a peripatetic course of lectures, and during one of these he
formed the acquaintance of Dr. Moræus, a pupil of the great Boerhaave.
Dr. Moræus took Linnæus into partnership with him. Here again a seeming
misfortune proved to be a great advantage. Linnæus fell in love with the
eldest daughter of Dr. Moræus, but was denied her hand until he should
graduate in medicine. Linnæus, to complete his studies as a physician,
then entered the University of Harderwyk, Holland, the alma mater of his
first benefactor, Dr. Rothman, and of the great Boerhaave.

After two years' study he was graduated in medicine with high honors.
His thesis, "The Cause of Chills," received special commendation. He
visited all the botanical gardens and other scientific institutions for
which Holland was then renowned. A learned and wealthy burgomaster,
Gronovius, having read his "Systema Naturæ" in manuscript, not only
defrayed the cost of its publication, but secured him the high honor of
an interview with the great Boerhaave--an honor for which even the Czar
Peter the Great had to beg.

Boerhaave's interest was at once awakened, and he gave Linnæus so strong
a recommendation to Dr. Burman, of Amsterdam, that the influence of the
scientific circles of the Dutch metropolis was exerted in behalf of
Linnæus, and he was soon offered the position of physician
superintendent of a magnificent botanical garden owned by a millionaire
horticultural enthusiast, Clifford, a director of the Dutch East India
Company. Linnæus' financial and scientific future was now secure.
Publication of his works was insured, and his position afforded him
every opportunity for botanical research. After five years' residence in
Holland, during which he declined several positions of trust, he
determined to return to Sweden. His fame had become so widespread in
Western Europe that his system was already adopted by scientists and
made the basis of lectures at the Dutch universities. In the French
metropolis he was greatly esteemed, and during a visit thereto he was a
highly distinguished guest.


His reception in Sweden was rather frigid, and but for the hearty
welcome by his family and betrothed he would probably have returned to
Holland. His _amour propre_ was also doubtless wounded, and he
determined to remain and fight his way into the magic circle of the
gilt-edged aristocracy which then monopolized all scientific honors in
Stockholm and the universities. He acquired a great reputation for the
treatment of lung disease, and was popularly credited with the ability
to cure consumption. This reached the ears of the queen (a sufferer from
the disease), who directed one of her councilors to send for Linnæus. He
soon recognized the name of Linnæus as one of great renown on the
Continent, and at once took him under his protection.

The star of Linnæus was now in the ascendant. He was soon delegated to
various pleasant duties, among which was the delivery of lectures on
botany and mineralogy in the "auditorium illustre" at Stockholm. He at
this time founded the "Swedish Scientific Academy," and was its first
president. In 1741 he was elected professor of medicine in Upsala
University, which chair he exchanged for that of botany and the position
of director of the botanical garden. This opened up a new era for
science in Sweden. He who was regarded as the world's greatest botanist
abroad had at last been similarly acknowledged in his native land.

With the indomitable courage and tact characteristic of the man, he set
on foot a gigantic scientific popular educational project. The
government, under his direction, established a system of exploring
expeditions into the fauna, flora, and mineralogy of the whole Swedish
peninsula, partly for the purpose of developing the resources of the
country, partly in the interest of science, but more especially to
interest the mass of the people in scientific research. The vast
majority of the people of Sweden, like those of other countries, were
dominated by fetichic superstitions and absurd notions about plants and
vegetables, which were indorsed to a certain extent by popular handbooks
devoted more to the dissemination of marvels than facts. A popular
clergyman, for instance, stated in a description of the maritime
provinces that "certain ducks grew upon trees." The vast stride which
was made by the populace in the knowledge of nature was due to these
efforts of Linnæus, who, in order to further popularize science,
established and edited, in conjunction with Salvius, a journal devoted
to the discussion of natural history.

During this period, on the first of May, semi-weekly excursions were
made from the university, the public being invited to attend. The people
came to these excursions by hundreds, and all classes were represented
in them--physicians, apothecaries, preachers, merchants, and mechanics,
all joined the procession, which left the university at seven in the
morning, to return at eve laden with zoological, botanical, and
mineralogical specimens.

A man who could thus arouse popular enthusiasm for science a century and
a half ago must have been a remarkable genius. Trusted students of
Linnæus were sent on botanical exploring expeditions throughout the
world. The high renown in which Linnæus was held was shown in the
significant title, almost universally bestowed upon him, of "The Flower
King."--_Western Druggist._

       *       *       *       *       *



The first actual attempt to make the wave length of sodium light a
standard of length was made by Peirce.[1] This method involves two
distinct measurements: first, that of the angular displacement of the
image of a slit by a diffraction grating, and, second, that of the
distance between the lines of the grating. Both of these are subject to
errors due to changes of temperature and to instrumental errors. The
results of this work have not as yet been published; but it is not
probable that the degree of accuracy attained is much greater than one
part in fifty or a hundred thousand. More recently, Mr. Bell, of the
Johns Hopkins University, using Rowland's gratings, has made a
determination of the length of the wave of sodium light which is claimed
to be accurate to one two hundred thousandth part[2]. If this claim is
justified, it is probably very near the limit of accuracy of which the
method admits. A short time before this, another method was proposed by
Mace de Lepinay.[3] This consists in the calculation of the number of
wave lengths between two surfaces of a cube of quartz. Besides the
spectroscopic observations of Talbot's fringes, the method involves the
measurement of the index of refraction and of the density of quartz, and
it is not surprising that the degree of accuracy attained was only one
in fifty thousand.

   [Footnote 1: Nature, xx, 99, 1879; this Journal, III, xviii, 51, 1879.]

   [Footnote 2: On the absolute wave lengths of light, this Journal,
   III, xxxiii, 167, 1887.]

   [Footnote 3: Comptes Rendus, cii, 1153, 1886; Journal, de Phys.,
   II, v, 411, 1886.]

Several years ago, a method suggested itself which seemed likely to
furnish results much more accurate than either of the foregoing, and
some preliminary experiments made in June have confirmed the
anticipation. The apparatus for observing the interference phenomena is
the same as that used in the experiments on the relative motion of the
earth and the luminiferous ether.

Light from the source at s (Fig. 1), a sodium flame, falls on the
plane parallel glass, a, and is divided, part going to the plane
mirror, c, and part to the plane mirror, b. These two pencils are
returned along _cae_ and _bae_, and the interference of the two is
observed in the telescope at e. If the distances, _ac_ and _ab_, are
made equal, the plane, c, made parallel with that of the image of b,
and the compensating glass, d, interposed, the interference is at once
seen. If the adjustment be exact, the whole field will be dark, since
one pencil experiences external reflection and the other internal.

If now b be moved parallel with itself a measured distance by means of
the micrometer screw, the number of alternations of light and darkness
is exactly twice the number of wave lengths in the measured distance.
Thus the determination consists absolutely of a measurement of a length
and the counting of a number.

The degree of accuracy depends on the number of wave lengths which it is
possible to count. Fizeau was unable to observe interference when the
difference of path amounted to 50,000 wave lengths. It seemed probable
that with a smaller density of sodium vapor this number might be
increased, and the experiment was tried with metallic sodium in an
exhausted tube provided with aluminum electrodes. It was found possible
to increase this number to more than 200,000. Now it is very easy to
estimate tenths or even twentieths of a wave length, which implies that
it is possible to find the number of wave lengths in a given fixed
distance between two planes with an error less than one part in two
millions and probably one in ten millions. But the distance
corresponding to 400,000 wave lengths is roughly a decimeter, and this
cannot be determined or reproduced more accurately than say to one part
in 500,000. So it would be necessary to increase this distance. This
can be done by using the same instrument together with a comparer.

The intermediate standard decimeter, lm (Fig. 2), is put in place of
the mirror, b. It consists of a prism of glass one decimeter long with
one end, l, plane, and the other slightly convex, so that when it
touches the plane, m, Newton's rings appear, and these serve to
control any change in the distance, lm, which has been previously
determined in wave lengths.

The end, l, is now adjusted so that colored fringes appear in white
light. These can be measured to within one-twentieth of a wave length,
and probably to within one-fiftieth. The piece, lm, is then moved
forward till the fringes again appear at m. Then the refractometer is
moved in the same direction till the fringes appear again at l, and so
on till the whole meter has been stepped off. Supposing that in this
operation the error in the setting of the fringes is always in the same
direction, the whole error in stepping off the meter would be one part
in two millions. By repetition this could of course be reduced. A
microscope rigidly attached to the carriage holding the piece, lm, would
serve to compare, and a diamond attached to the same piece would be used
to produce copies. All measurements would be made with the apparatus
surrounded by melting ice, so that no temperature corrections would be

Probably there would be considerable difficulty in actually counting
400,000 wave lengths, but this can be avoided by first counting the wave
lengths and fractions in a length of one millimeter and using this to
step off a centimeter. This will give the nearest whole number of
wave lengths, and the fractions may be observed directly. The centimeter
is then used in the same way to step off a decimeter, which again
determines the nearest whole number, the fraction being observed
directly as before.

The fractions are determined as follows: The fringes observed in the
refractometer under the conditions above mentioned can readily be shown
to be concentric circles. The center has the minimum intensity when the
difference in the distances, ab, ac, is an exact number of wave
lengths. The diameters of the consecutive circles vary as the square
roots of the corresponding number of waves. Therefore, if x is the
fraction of a wave length to be determined, and y the diameter of the
first dark ring, d being the diameter of the ring corresponding to one
wave length, then x = y²/d².


           -----    +---+
             |c     |   |
             |      |   |
             |      |   |+-------------------------+
             |      |   ||                         |
             |      |   ||                         |
             |      |   |+-------------------------+ l
             |      |   |            2.
             |      |   | m
             |      +---+
             |                           ______
             |            +-------------|      |---+
             | /\    /\   | +-----------|    __|-+ |   _
            a|/ /   / /   | |           | b |    | |  | |
  S----------/\/__d/ /    | |           | | |    | |  | |
            / /|  / /-----| |-----------|-| ||||||||||| |
               |  \/      | |           | | |    | |  | |
              _|_         | |           |   |    | |  |_|
             | : |        | +-----------|___|----+ |  m
            e| : |         +-----------------------+
             | : |
             |_ _|                  1.

There is a slight difficulty to be noted in consequence of the fact that
there are two series of waves in sodium light. The result of this
superposition of these is that as the difference of path increases, the
interference becomes less distinct and finally disappears, reappears,
and has a maximum of distinctness again, when the difference of path is
an exact multiple of both wave lengths. Thus there is an alternation of
distinct interference fringes with uniform illumination. If the length
to be measured, the centimeter for instance, is such that the
interference does not fall exactly at the maximum--to one side by, say,
one-tenth the distance between two maxima, there would be an error of
one-twentieth of a wave length requiring an arithmetical correction.

Among other substances tried in the preliminary experiments were
thallium, lithium, and hydrogen. All of these gave interference up to
fifty to one hundred thousand wave lengths, and could therefore all be
used as checks on the determination with sodium. It may be noted that in
case of the red hydrogen line, the interference phenomena disappeared at
about 15,000 wave lengths, and again at about 45,000 wave lengths; so
that the red hydrogen line must be a double line with the components
about one-sixtieth as distant as the sodium lines.--_Amer. Jour.

       *       *       *       *       *



Upon this subject I am able to speak with the freedom habitually enjoyed
by some voluminous agricultural writers--my imagination will not be
hampered by my knowledge.

In debatable climates, like Ohio, Illinois, Kansas and southward, it is
conceded that a great point would be gained by the discovery of some
plan--not too expensive--that would make it safe to put away potatoes in
the summer, as soon as ripe, so that they would go through the winter
without sprouting and preserve their eating qualities till potatoes come
again. As it is, digging must be deferred till late, for fear of rot;
the fields of early varieties grow up with weeds after they are "laid
by." In the spring a long interregnum is left between old potatoes fit
to eat and the new crop, and the seed stock of the country loses much of
its vigor through sprouting in cellars and pits. Most farmers have had
occasion to notice the difference between the yield from crisp,
unsprouted seed potatoes and that from the wilted, sprouted tubers so
often used. Some years ago Professor Beal made a test of this
difference. I speak from recollection, but think I am right in saying
that, according to the published account which I saw, he found one
sprouting of seed potatoes lowered the yield 10 per cent.; each
additional sprouting still further reduced the crop, till finally there
was no yield at all. Even a 10 per cent. shrinkage in all that portion
of the annual potato crop grown from sprouted seed would result in an
aggregate loss of millions of bushels. The question how to store
potatoes and not have them sprout I have seen answered in the papers by
recommending a "cold" cellar, of about 40 degrees temperature. If there
are cellars that are cold in warm weather, without the use of some
artificial process, I have not seen them. The temperature of well water
is about 45 degrees only, and anybody knows how much colder a well is
than a cellar. But the greatest difficulty comes in from the fact that
potatoes are such a prolific source of heat in themselves.

If a 40 degree cellar could be found and be filled with potatoes, the
temperature would at once begin to rise, and the later in the season,
the faster it would go up. I repeat that a cellar filled with potatoes
will have a much higher temperature than the same cellar would have if
empty. This I have learned as Nimbus learned tobacco growing--"by
'sposure." I hope I won't be asked "why." I don't know. The reason is
unimportant. The remedy is the thing. The only help for it that I know
of is to give the cellar plenty of ventilation, put the potatoes in as
clean as possible, and then shovel them over every month or two. This
will keep the sprouting tendency in check very largely; but it won't
make it practicable to begin storing potatoes in July or cause them to
keep in good flavor till June.

Several years ago I placed some barrels of early Ohio potatoes in the
Kansas City cold storage warehouses from March till July. They were kept
in a temperature of 38 degrees, and came out crisp and very little
sprouted. The plan of this structure was very simple: a three-story
brick building so lined with matched lumber and tarred paper as to make
three air-spaces around the wall. In the top story was a great bulk of
ice, which was freely accessible to the air that, when cooled, passed
through ducts to the different "cool rooms." The results were
satisfactory, but the system seemed too expensive for potatoes. I have
wondered whether it was necessary for potatoes to be kept as cold as 38
degrees. Would not a current of air passing through pipes showered with
well water keep them cold enough? Wine vaults, I believe, are sometimes
cooled by air currents forced through a cold water spray. If the air
blast of well water temperature would be sufficient, the apparatus for
producing it would be comparatively inexpensive--or at least much
cheaper than those plans of cold storage where ice is stored in quantity
over the cool room. However, any process that could be devised would
probably be unprofitable to the small cropper, and the larger the
business done, the less the cost per bushel. If it should be found that
individual operators could not reach such an improvement on a profitable
scale, why could not several of them pool their issues sufficiently to
build, jointly, a potato elevator? There are at least 50,000 bushels of
potatoes held in store by farmers within three miles of where I live. It
seems to me there would be many advantages and economies in having that
large stock under one roof, one insurance, one management; on a side
track where they could be loaded in any weather or state of the roads,
besides the great item that the temperature could be controlled, by
artificial means, in one large building much cheaper than in several
small ones.
                                                          EDWIN TAYLOR.
Edwardsville, Kans.

       *       *       *       *       *



The figure illustrating this article is taken from _L'Astronomie_, and
represents the remarkable southern comet of January, 1887, as drawn on
successive days by Mr. Finlay, of Cape Town.

The comet was first seen by a farmer and a fisherman of Blauwberg, near
Cape Town, on the night of January 18-19. The same night it was seen at
the Cordoba Observatory by M. Thome. On the next Mr. Todd discovered it
independently at the Adelaide Observatory, and watched it till the 27th.
On the 22d Mr. Finlay detected the comet, and was able to watch it till
the 29th. At Rio de Janeiro M. Cruls observed it from the 23d to the
25th; and at Windsor, New South Wales, Mr. Tebbutt observed the comet on
the 28th and 30th. Moonlight interfered with further observations.

The comet's appearance was remarkable. Its tail, long and straight,
extended over an arc of 30 degrees, but there was no appreciable
condensation which could be called the comet's head. The long train of
light, described as nearly equal in brightness to the Magellanic clouds,
seemed to be simply cut off at that end where in most comets a nucleus
and coma are shown.

This comet has helped to throw light on one of the most perplexing
puzzles which those most perplexing of all the heavenly bodies, comets,
have presented to astronomers.

In the year 1668 a comet was seen in the southern skies which attracted
very little notice at the time, and would probably have been little
thought of since had not attention been directed to it by the appearance
and behavior of certain comets seen during the last half century.
Visible for about three weeks, and discovered after it had already
passed the point of its nearest approach to the sun, the comet of 1668
was not observed so satisfactorily that its orbit could be precisely
determined. In fact, two entirely different orbits would satisfy the
observations fairly, though one only could be regarded as satisfying
them well.

This orbit, however, was so remarkable that astronomers were led to
prefer the other, less satisfactory though it was, in explaining the
observed motions of the comet. For the orbit which best explained the
comet's movements carried the comet so close to the sun as actually to
graze his visible surface.

Moreover, there was this remarkable, and, indeed, absolutely unique
peculiarity about the orbit thus assigned: the comet (whose period of
revolution was to be measured by hundreds of years) actually passed
through the whole of that part of its course during which it was north
of our earth's orbit plane in less than two hours and a half! though
this part of its course is a half circuit around the sun, so far as
direction (not distance of travel) is concerned. That comet, when at its
nearest to the sun, was traveling at the rate of about 330 miles per
second. It passed through regions near the sun's surface commonly
supposed to be occupied by atmospheric matter.

Now, had the comet been so far checked in its swift rush through those
regions as to lose one thousandth part of its velocity, it would have
returned in less than a year. But the way in which the comet retreated
showed that nothing of this sort was to be expected. I am not aware,
indeed, that any anticipations were ever suggested in regard to the
return of the comet of 1668 to our neighborhood. It was not till the
time of Halley's comet, 1682, that modern astronomy began to consider
the question of the possibly periodic character of cometic motions with
attention. (For my own part, I reject as altogether improbable the
statement of Seneca that the ancient Chaldean astronomers could
calculate the return of comets.) The comet of 1680, called Newton's, was
the very first whose orbital motions were dealt with on the principles
of Newtonian astronomy, and Halley's was the first whose periodic
character was recognized.

In 1843 another comet came up from the south, and presently returned
thither. It was, indeed, only seen during its return, having, like the
comet of 1668, been only discovered a day or two after perihelion
passage. Astronomers soon began to notice a curious resemblance between
the orbits of the two comets. Remembering the comparative roughness of
the observations made in 1668, it may be said that the two comets moved
in the same orbit, so far as could be judged from observation. The comet
of 1843 came along a path inclined at apparently the same angle to the
earth's orbit plane, crossed that plane ascendingly at appreciably the
same point, swept round in about two hours and a half that part of its
angular circuit which lay north of the earth's orbit plane, and,
crossing that plane descendingly at the same point as the comet of 1668,
passed along appreciably the same course toward the southern stellar
regions! The close resemblance of two paths, each so strikingly
remarkable in itself, could not well be regarded as a mere accidental

[Illustration: The Constellations, though unnamed, can readily be
identified, when it is noted that the Comet's course, as here
represented, began in the constellation of the Crane.]

However, at that time no very special attention was directed to the
resemblance between the paths of the comets of 1843 and 1668. It was not
regarded as anything very new or striking that a comet should return
after making a wide excursion round the sun; and those who noticed that
the two comets really had traversed appreciably the same path around the
immediate neighborhood of the sun, simply concluded that the comet of
1668 had come back in 1843, after 175 years, and not necessarily for the
first time.

It must be noticed, however, before leaving this part of the record,
that the comet of 1843 was suspected of behaving in a rather strange way
when near the sun. For the first observation, made rather roughly,
indeed, with a sextant, by a man who had no idea of the interest his
observation might afterward have, could not be reconciled by
mathematicians (including the well-known mathematician, Benjamin Pierce)
with the movement of the comet as subsequently observed. It seemed as
though when in the sun's neighborhood the comet had undergone some
disturbance, possibly internal, which had in slight degree affected its
subsequent career.

According to some calculations, the comet of 1843 seemed to have a
period of about thirty-five years, which accorded well with the idea
that it was the comet of 1668, returned after five circuits. Nor was it
deemed at all surprising that the comet, conspicuous though it is, had
not been detected in 1713, 1748, 1783, and 1818, for its path would
carry it where it would be very apt to escape notice except in the
southern hemisphere, and even there it might quite readily be missed.
The appearance of the comet of 1668 corresponded well with that of the
comet of 1843. Each was remarkable for its extremely long tail and for
the comparative insignificance of its head. In the northern skies,
indeed, the comet of 1843 showed a very straight tail, and it is usually
depicted in that way, whereas the comet of 1668 had a tail showing
curvature. But pictures of the comet of 1843, as seen in the southern
hemisphere, show it with a curved tail, and also the tail appeared
forked toward the end during that part of the comet's career.

However, the best observations, and the calculations based on them,
seemed to show that the period of the comet of 1843 could not be less
than 500 years.

Astronomers were rather startled, therefore, when, in 1880, a comet
appeared in the southern skies which traversed appreciably the same
course as the comets of 1668 and 1843. When I was in Australia, in 1880,
a few months after the great comet had passed out of view, I met several
persons who had seen both the comet of that year and the comet of 1843.
They all agreed in saying that the resemblance between the two comets
was very close. Like the comet of 1843, that of 1880 had a singularly
long tail, and both comets were remarkable for the smallness and dimness
of their heads. One observer told me that at times the head of the comet
of 1880 could barely be discerned.

Like the comets of 1668 and 1843, the comet of 1880 grazed close past
the sun's surface. Like them, it was but about two hours and a half
north of the earth's orbit place. Had it only resembled the other two in
these remarkable characteristics, the coincidence would have been
remarkable. But of course the real evidence by which the association
between the comets was shown was of a more decisive kind. It was not in
general character only, but in details, that the path of the comet of
1880 resembled those on which the other two comets had traveled. Its
path had almost exactly the same slant to the earth's orbit plane as
theirs, crossed that plane ascendingly and descendingly at almost
exactly the same points, and made its nearest approach to the sun at
very nearly the same place. To the astronomer such evidence is decisive.
Mr. Hind, the superintendent of the "Nautical Almanac," and as sound and
cautious a student of cometic astronomy as any man living, remarked, so
soon as the resemblance of these comets' paths had been ascertained,
that if it were merely accidental, the case was most unusual; nay, it
might be described as unique. And, be it noticed, he was referring only
to the resemblance between the comets of 1880 and 1843. Had he recalled
at the time the comet of 1668, and its closely similar orbit, he would
have admitted that the double coincidence could not possibly be merely

But this was by no means the end of the matter. Indeed, thus far,
although the circumstances were striking, there was nothing to prevent
astronomers from interpreting them as other cases of coincident, or
nearly coincident, cometic paths had been interpreted. Hind and others,
myself included, inferred that the comets of 1880, 1843, and 1668 were
simply one and the same comet, whose return in 1880 probably followed
the return in 1843 after a single revolution.

In 1882, however, two years and a half after the appearance of the comet
of 1880, another comet came up from the south, which followed in the
sun's neighborhood almost the same course as the comets of 1668, 1843,
and 1880. The path it followed was not quite so close to those followed
by the other three as these had been to each other, but yet was far too
close to indicate possibly a mere casual resemblance; on the contrary,
the resemblance in regard to shape, slope, and those peculiarities which
render this family of comets unique in the cometary system, was of the
closest and most striking kind.

Many will remember the startling ideas which were suggested, by
Professor Piazzi Smyth respecting the portentous significance of the
comet of 1882. He regarded it as confirming the great pyramid's teaching
(according to the views of orthodox pyramidalists) respecting the
approaching end of the Christian dispensation. It was seen under very
remarkable circumstances, blazing close by the sun, within a fortnight
or three weeks of the precise date which had been announced as marking
that critical epoch in the history of the earth.

Moreover, even viewing the matter from a scientific standpoint,
Professor Smyth (who, outside his pyramidal paradoxes, is an astronomer
of well deserved repute) could recognize sufficient reason for regarding
the comet as portentous.

Many others, indeed, both in America and in Europe, shared his opinion
in this respect. A very slight retardation of the course of the comet of
1880, during its passage close by the surface of the sun, would have
sufficed to alter its period of revolution from the thirty-seven years
assigned on the supposition of its identity with the comet of 1843 to
the two and a half years indicated by its apparent return in 1882, and
if this had occurred in 1880, a similar interruption in 1832 would have
caused its return in less than two and a half years.

Thus, circling in an ever narrowing (or rather shortening) orbit, it
would presently, within a quarter of a century or so perhaps, have
become so far entangled among the atmospheric matter around the sun that
it would have been unable to resist absolute absorption. What the
consequences to the solar system might have been, none ventured to
suggest. Newton had expressed his belief that the effects of such
absorption would be disastrous, but the physicists of the nineteenth
century, better acquainted with the laws associating heat and motion,
were not so despondent. Only Professor Smyth seems to have felt assured
(not being despondent, but confident) that the comet portended, in a
very decisive way, the beginning of the end.

However, we were all mistaken. The comet of 1882 retreated on such a
course, and with such variation of velocity, as to show that its real
period must be measured, not by months, as had been supposed, nor even
by years, but by centuries. Probably it will not return till 600 or 700
years have passed. Had this not been proved, we might have been not a
little perplexed by the return of apparently the same comet in this
present year. A comet was discovered in the south early in January,
whose course, dealt with by Professor Kruger, one of the most zealous of
our comet calculators, is found to be partially identical with that of
the four remarkable comets we have been considering. Astronomers have
not been moved by this new visitant on the well-worn track as we were by
the arrival of the comet of 1882, or as we should have been if either
the comet of 1882 had never been seen or its path had not been shown to
be so wide ranging. Whatever the comet of the present year may be, it
was not the comet of 1882 returned. No one even supposes that it was the
comet of 1880, or 1843, or 1668. Nevertheless, rightly apprehended, the
appearance of a comet traveling on appreciably the same track as those
four other comets is of extreme interest, and indeed practically
decisive as to the interpretation we must place on these repeated

Observe, we are absolutely certain that the five comets are associated
together in some way; but we are as absolutely certain that they are not
one and the same comet which had traveled along the same track and
returned after a certain number of circuits. We need not trouble
ourselves with the question whether two or more of the comets may not
have been in reality one and the same body at different returns. It
suffices that they all five were not one; since we deduce precisely the
same conclusion whether we regard the five as in reality but four or
three or two. But it may be mentioned in passing as appearing altogether
more probable, when all the evidence is considered, that there were no
fewer than five distinct comets, all traveling on what was practically
the selfsame track when in the neighborhood of the sun.

There can be but one interpretation of this remarkable fact--a fact
really proved, be it noticed (as I and others have maintained since the
retreat of the comet of 1882), independently of the evidence supplied by
the great southern comet of the present year. These comets must all
originally have been one comet, though now they are distinct bodies. For
there is no reasonable way (indeed, no possible way) of imagining the
separate formation of two or more comets at different times which should
thereafter travel in the same path.

No theory of the origin of comets ever suggested, none even which can be
imagined, could account for such a peculiarity. Whereas, on the other
hand, we have direct evidence showing how a comet, originally single,
may be transformed into two or more comets traveling on the same, or
nearly the same, track.

The comet called Biela's, which had circuited as a single comet up to
the year 1846 (during a period of unknown duration in the past--probably
during millions of years), divided then into two, and has since broken
up into so many parts that each cometic fragment is separately
undiscernible. The two comets into which Biela's divided, in 1846, were
watched long enough to show that had their separate existence continued
(visibly), they would have been found, in the fullness of time,
traveling at distances very far apart, though on nearly the same orbit.
The distance between them, which in 1846 had increased only to about a
quarter of a million of miles, had in 1852 increased to five times that

Probably a few thousands of years would have sufficed to set these
comets so far apart (owing to some slight difference of velocity,
initiated at the moment of their separation) that when one would have
been at its nearest to the sun, the other would have been at its
farthest from him. If we could now discern the separate fragments of the
comet, we should doubtless recognize a process in progress by which, in
the course of many centuries, the separate cometic bodies will be
disseminated all round the common orbit. We know, further, that already
such a process has been at work on portions removed from the comet many
centuries ago, for as our earth passes through the track of this comet
she encounters millions of meteoric bodies which are traveling in the
comet's orbit, and once formed part of the substance of a comet
doubtless much more distinguished in appearance than Biela's.

There can be little doubt that this is the true explanation of the
origin of that family of comets, five of whose members returned to the
neighborhood of the sun (possibly their parent) in the years 1668, 1843,
1880, 1882, and 1887.[1]

   [Footnote 1: It may be interesting to compare the orbital elements
   of the five comets above dealt with. They may be presented as
   follows; but it should be noticed that the determinations must be
   regarded as rough in the case of Comets I. and V., as the
   observations were insufficient for exact determination of the

                   |    I.   |     II.    |    III.    |    IV.     |  V.
                   |  1668.  |    1843.   |    1880.   |   1882.    | 1887.
    Perih. Passage.| Feb. 29 |  Feb. 27   |  Jan. 27   |  Sep. 17   |Jan. 11
    Log. Per. Dist.|  7.6721 |   7.8395   |   7.7714   |   7.8895   | 8.1644
    Long. Per.     | 80° 15' | 73° 30' 46"| 74° 11' 13"| 55° 37' 29"| 89° 41'
    Long. Node.    | 357° 17'|355° 46' 48"|356° 17'  4"|346°  1' 27"|359° 41'
    Inclination.   | 125° 58'|143°  1' 31"|143°  7' 31"|141° 59' 40"|141° 16'
    Eccentricity.  | 0.9999  |   0.9991   |   0.9995   |   0.999    | ......
    Calculator.    |Henderson| Plantamour |   Meyer    |   Kreutz   | Finlay

But it is not merely as thus explaining what had been a most perplexing
problem that I have dealt with the evidence supplied by the practical
identity of these five comets' orbits. When once we recognize that this,
and this only, can be the explanation of the associated group of five
comets, we perceive that very interesting and important light has been
thrown on the subject of comets generally. To begin with: what an
amazing comet that must have been from which these five, and we know not
how many more, were formed by disaggregative processes--probably by the
divellent action of repulsive forces exerted by the sun! Those who
remember the comets of 1843 and 1882 as they appeared when at their full
splendor will be able to imagine how noble an appearance a comet would
present which was formed of these combined together in one. But the
comet of 1880 was described by all who saw it in the southern hemisphere
as most remarkable in appearance, despite the faintness of its head. The
great southern comet of the present year was a striking object in the
skies, though it showed the same weakness about the head. That of 1668
was probably as remarkable in appearance as even the comet of 1882. A
comet formed by combining all these together would certainly surpass in
magnificence all the comets ever observed by astronomers.

And then, what enormous periods of time must have been required to
distribute the fragments of a single comet so widely that one would be
found returning to its perihelion more than two centuries after another!
When I spoke of one member of the Biela group being in aphelion when
another would be in perihelion, I was speaking of a difference of only
three and one-third years in time; and even that would require thousands
of years. But the scattered cometic bodies which returned to the sun's
neighborhood in 1668 and 1887 speak probably of millions of years which
have passed since first this comet was formed. It would be a matter of
curious inquiry to determine what may have been the condition of our
sun, what even his volume, at that remote epoch in history.

       *       *       *       *       *


The element fluorine has at last been successfully isolated, and its
chief chemical and physical properties determined. Many chemists,
notably Faraday, Gore, Pflaunder, and Brauner, have endeavored to
prepare this element in the free state, but all attempts have hitherto
proved futile. M. Moissau, after a long series of researches with the
fluorides of phosphorus, and the highly poisonous arsenic trifluoride,
has finally been able to liberate fluorine in the gaseous state from
anhydrous hydrofluoric acid by electrolysis. This acid in the pure state
is not an electrolyte, but when potassium fluoride is dissolved in it, a
current from ninety Bunsen elements decomposes it, evolving hydrogen
from the negative and fluoride from the positive electrode.


                 (+)                 (-)
                  |                   |
                  |                   |
              __/_|_\_A           __/_|_\_A
             |    |    |         |    |    |
             |____|____|         |____|____|
              |   |   |           |   |   |
         _____|   |   |           |   |   |_____
        / ----    |   |           |   |    -----\
       //     |   |   |           |   |   |     \\
      || F    |===|===|           |===|===|    H ||
      ||      |- -|- -|           |- -|- -|      ||
      ||      | - | - |           | - | - |      ||
      ||      |- -|- - \_________/ - -|- -|      ||
      ||      | - | - - - - - - - - - | - |      ||
     //       \___________________________/      \\


The apparatus employed in this process is constructed of platinum, and
is made in the form of a U tube, as shown in the accompanying
illustration, with fluorspar stoppers, through which the battery
terminals, made of platinum iridium alloy, are led. The gas is liberated
at about the rate of two liters per hour, and has very powerful chemical
properties. It smells somewhat like hypochlorous acid, etches dry glass,
and decomposes water, liberating ozone, and forming hydrofluoric acid.
The non-metallic elements, with the exception of chlorine, oxygen,
nitrogen, and carbon, combine directly with it, evolving in most cases
both light and heat. It combines with hydrogen, even in the dark,
without the addition of any external energy, and converts most metals
into their fluorides. Gold and platinum are not attacked in the cold,
but when gently heated are easily corroded. Mercury readily dissolves
the gas, forming the protochloride; iron wire also completely absorbs
the gas, while powdered antimony and lead take fire in it. It is
necessary in the electrolysis of the liquid hydrofluoric acid to cool
the electrolytic cell by means of methyl chloride to -50° C. Fluorine
appears to thus fully confirm the predictions which have been made by
chemists concerning its properties. It is by far the, most energetic of
all the known elements, and its position in the halogen series is
established by its property of not liberating iodine from the iodides of
potassium, mercury, and lead, and also of setting free chlorine from
potassium chloride. With iodine it appears to form a fluoride. No
compound with oxygen has yet been obtained.--_Industries._

       *       *       *       *       *



Having had occasion to prepare a quantity of sulphurous anhydride, for
the purpose of reducing chromates previous to their analysis, I made use
of the following apparatus, as represented in the accompanying figure.
It consists of a glass vessel, A, provided with three tubulars,
otherwise resembling a large Wolff bottle, the large tube, B, being
provided with a stopper for the purpose of introducing pieces of sulphur
from time to time into the small dish, C, intended for its reception,
and fed with air by means of the delivery tube, D, thus allowing the
stream of gas caused by the consumption of the sulphur to escape by
means of the exit tube, E, to the vessel desired to receive it.


In using the apparatus the sulphur is first kindled by introducing a red
hot wire through the tube, B, and replacing the stopper that has been
momentarily removed for the introduction of the same. A slight blast is
now maintained from the bellows that are in connection with the pipe, D,
until the whole of the sulphur is thoroughly kindled, when a somewhat
more powerful blast may be applied. When the apparatus above described
is in full working order, from 2 to 3 lb. of sodium carbonate may be
converted into sodium sulphite in less than half an hour, or several
gallons of water saturated. I have also on connecting the apparatus with
a powerful refrigerator obtained in a short time a large quantity of
liquid SO2. It will be found advantageous, however, during the
preparation of sulphurous anhydride, to employ a layer of water covering
the bottom of the vessel to about 1 inch in depth. Carbonic anhydride
and phosphoric anhydride may also be readily obtained in any desired
quantity by slight alteration; but in case of phosphorus the air must be
allowed to enter only gently, since a rapid current would at all times
determine the fracture of the vessel.--_Chem. News_.

       *       *       *       *       *


   [Footnote 1: Ueber die raumliche Anordnung der Atome in
   organischen Molekulen, and ihre Bestimmung in
   geometrisch-isomeren ungesattigten Verbindungen. Von Johannes
   Wislicenus.--Abhandlungen der mathemalisch-physischen Klasse der
   Konigl. Sachsischen Gesellschaft der Wissenechaften. Band XIV.,
   No. 1.]

The expression "chemical structure," as commonly used by chemists, has,
as is well known, nothing to do with the arrangement of atoms in space.
The structural formula does not profess to represent spatial relations,
but simply the connections which, after a careful study of the
transformations and modes of formation of the compound represented, are
believed to exist between the atoms. Nevertheless, although we do not
commonly consider the question of space relations, it is clear that
atoms must have some definite positions in space in the molecules, and
the only reason why we do not represent these positions is because we
know practically nothing about them. The most definite suggestion
concerning space relations of atoms which has been made is that of Le
Bel and Van't Hoff. The well known hypothesis of these authors was put
forward to account for a certain kind of so-called physical isomerism
which shows itself in the action of substances upon polarized light.
Since this hypothesis was proposed, the number of cases of "abnormal
isomerism," that is to say, of cases of isomerism which cannot be
accounted for by the commonly accepted method of explaining structure,
has increased to a considerable extent, and the necessity for some new
hypothesis, or for some modification of the old ones, has come to be
pretty generally recognized. Among the cases of isomerism which it is at
least difficult to explain by the aid of the prevailing views are those
of maleic and fumaric acids; citraconic and mesaconic acids; certain
halogen derivatives of crotonic acid and of cinnamic acid; and coumaric
and coumarinic acids.

More than one hypothesis has been proposed to account for these cases of
isomerism, but no one has shown itself to be entirely satisfactory.
Quite recently Johannes Wislicenus, Professor of Chemistry in the
University of Liepsic, has made what has the appearance of being an
important contribution toward the solution of the problem referred to.
The author shows that many of the facts known in regard to the relations
between maleic and fumaric acids, and the other substances which
furnish examples of "abnormal isomerism," may be explained by the aid of
an extension of the Le Bel-Van't Hoff hypothesis. It is difficult
without the aid of models to give a clear idea concerning the hypothesis
of Wislicenus, but some idea of it may be gained from the following. If
we suppose a carbon atom to exert its affinities in the directions of
the solid angles of a tetrahedron, as is done in the Le Bel-Van't Hoff
hypothesis, then, when two carbon atoms unite, as in ethane, the union
will be between two solid angles of two tetrahedrons. If the two carbon
atoms unite by the ethylene kind of union, the union will be along a
line corresponding to one of the edges of each tetrahedron. In the
former case, in which single union exists, the two parts of the molecule
represented by the two tetrahedrons can be supposed to be capable of
revolving around an axis either in the same direction or in opposite
directions. This axis corresponds to the straight line joining the two
carbon atoms. In the case in which double union exists no such
revolution is possible. Again, if, by addition to an unsaturated
compound like ethylene, a saturated compound is formed, the kind of
union between the carbon atoms is changed, and the possibility of
revolution of the two parts of the compound is given. Whether such
revolution take place or not will be determined largely by the structure
of the compound. The tendency will be for those parts of the molecule
which have the greatest specific affinity for one another to take those
positions in which they are nearest to one another. Thus, suppose that
chlorine is added to ethylene. By following the change on the model, it
is seen that in the resulting figure the two chlorine atoms in ethylene
chloride are situated at angles of the two tetrahedrons which are
nearest each other. But chlorine has a stronger affinity for hydrogen
than it has for chlorine, and therefore each chlorine atom would tend to
get as near a hydrogen atom as possible. This involves a partial
revolution of the two tetrahedrons in opposite directions around their
common axis. So also hydrogen would tend to take a position as near as
possible to hydroxyl and to carboxyl, while hydroxyl would avoid
hydroxyl, and carboxyl would avoid carboxyl. These views are suggested
as a result of a careful application of the original Le Bel-Van't Hoff
hypothesis, and are, of course, of little value unless they can be shown
to be in accordance with the facts.

The chief merit of the work of Wislicenus consists in the fact that he
has shown that a large number of phenomena which have been observed in
the study of such cases of isomerism as were mentioned above find a
ready explanation in terms of the new hypothesis, whereas for most of
these phenomena no explanation whatever has thus far been presented. The
most marked case presented is that of maleic and fumaric acids. One by
one, the author discusses the transformations of these acids and their
substitution products, and becomes to this conclusion: "There is not to
my knowledge a single fact known in regard to the relations between
fumaric and maleic acids which is not explained by the aid of the above
geometrical considerations, not one which does not clearly support the
new hypothesis." Among the facts which he discusses in the light of the
hypothesis are these: The formation of fumaric and maleic acids from
malic acid; the quantitative transformation of maleic into fumaric acid
by contact with strong acids; the transformation of the ethereal salts
of maleic acid into those of fumaric acid by the action of a minute
quantity of free iodine; the formation of brommaleic acid and
hydrobromic acid from the dibromsuccinic acid formed by the addition of
two bromine atoms to fumaric acid; the formation of dibromsuccinic acid
from brommaleic acid and of isodibromsuccinic acid from bromfumaric acid
by the action of fuming hydrobromic acid; the conversion of brommaleic
acid into fumaric and then into succinic acid by the action of sodium
amalgam; the formation of one and the same tribromsuccinic acid by the
action of bromine on brommaleic and on bromfumaric acid; and finally,
the conversion of maleic into inactive tartaric acid, and of fumaric
into racemic acid by potassium permanganate. All these facts are shown
to find a ready explanation by the aid of the new hypothesis. Further,
it is shown that the decompositions of the salts of certain halogen
derivatives of organic acids, which give up halogen salt and carbon
dioxide, as well as the formation of lactones and of anhydrides of
dibasic acids, are in perfect harmony with the hypothesis. But the only
way to get a clear conception in regard to the mass of material which
the author has brought together and which he has shown to support his
hypothesis is by a careful study of the original paper, and the object
of this notice is mainly to call the attention of American chemists to

As to the question what value to attach to the speculations which
Wislicenus has brought to our notice, it is difficult to give any but a
general answer. No one can well have a greater fear of mere speculation,
which is indulged in independently of the facts, than the writer of this
notice. Great harm has been done chemistry, and probably every other
branch of knowledge, by unwarranted speculation, and every one who has
looked into the matter knows how extremely difficult it is to emancipate
one's self from the influence of a plausible hypothesis, even when it
can be shown that it is not in accordance with the facts. It behooves
every one, therefore, before accepting a new hypothesis, no matter how
fascinating it may appear at first sight, to look carefully into the
facts, and to endeavor to determine independently whether it is well
founded or not. On the other hand, there is some danger to be
apprehended from a tendency, sometimes observed, to denounce everything
speculative, no matter how broad the basis of facts upon which it rests
may be. Without legitimate speculation, it is clear that there could be
no great progress in any subject. As far as the hypothesis under
consideration is concerned, the writer is firmly of the opinion that it
is likely to prove of great value in dealing with a large number of
chemical facts, and that, as it suggests many lines of research, it will
undoubtedly in the course of a few years exert a profound influence on
chemistry. Whether the evidence which will be accumulated will or will
not confirm the view that the tetrahedron form is characteristic of the
simplest molecules of carbon compounds is not the most important
question to be asked under the circumstances. We should rather ask
whether the testing of the hypothesis is or is not likely to bring us
nearer to the truth. It is a proposition that admits of no denial that a
hypothesis which can be tested by experiment, and which suggests lines
of work and stimulates workers to follow them, is a gain to science, no
matter what the ultimate fate of the hypothesis may be.--_Amer. Chem.

       *       *       *       *       *


It should be thoroughly understood by all that any common paper, coarse
wrapping paper, new or old newspapers, etc., are admirable to keep out
cold or keep in warmth. The blood of _all_ domestic animals, as well as
of human beings, _must_ be always kept very near 98 degrees, just as
much in winter as in summer. And this heat always comes from _within_
the body, whenever the atmosphere is not above 98 degrees temperature.
So long as the air is cooler than this, the heat produced inside the
body is escaping. Heat seeks a level. If there is more in one of two
bodies or substances side by side, the heat will pass from the warmer
into the colder, until they are both of the same temperature.

Moving air carries away vastly more heat than still air. The thin film
of air next to the body soon gets warm from it. But if that air is moved
along, slowly or swiftly, by a breeze, be it ever so gentle, new cooler
air takes its place, and abstracts more heat from the body. Anything
that keeps the air next to the bodies of men and of animals from moving,
checks the escape of heat.

The thinnest paper serves to keep the air quiet. A newspaper laid on a
bed acts much as a coverlid to keep a film or layer of air quiet, and
thus less heat escapes from the bodies of the sleepers. If paper is
pasted up over the cracks of a house, or of a barn or stable, or under
the joists of a house floor, it has just the same effect. Every person
who keeps animals will find it a wonderful and paying protection to
them, to put against the walls one, two, three, or more layers of
newspapers during cold weather. If a person in riding finds his garments
too cool, a newspaper placed under the coat or vest, or under or over
the trousers, even if only on the side next the wind, will do a great
deal to check the outflow of heat, and keep him warm. Two or three
thicknesses of newspaper crumpled a little, and put under the coat or
overcoat, are almost as effective in keeping in warmth as an extra
garment. A slight crumpling keeps them a little separate, and makes
additional thin layers of air.

Further: Heat does not pass through films of _still_ air. Fibrous
woolens, furs, loosely woven cotton, down, and the like, contain a great
deal of air _confined_ in the meshes, and are therefore excellent
conservers of heat. Double walls of stone, brick, or wood, or even of
wall or roofing paper, double glass, double layers of anything that will
have thin layers of still air between them, prevent the escape of heat

       *       *       *       *       *



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