Scientific American Supplement, No. 458, October 11, 1884 by Various
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Various >> Scientific American Supplement, No. 458, October 11, 1884
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11 [Illustration]
Scientific American Supplement No. 458
NEW YORK, OCTOBER 11, 1884
Scientific American Supplement. Vol. XVIII, No. 458.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
TABLE OF CONTENTS.
I. CHEMISTRY AND METALLURGY.--Chemical Nature of Starch
Grains.
The Amalgamation of Silver Ores.--Description of the Francke
tina, or vat process for amalgamation of silver ores.--By E.P.
RATHBONE.--6 figures.
Interesting Facts about Platinum.--Draw stones used for drawing
wire of precious metals.
II. ENGINEERING, MINING, ETC.--Modern Locomotive Practice.--Paper
read before the Civil and Mechanical Engineers' Society.--By
H. MICHELL WHITLEY--10 figures.
New Screw Steam Collier, Frostburg.--1 figure.
Destruction of the Tardes Viaduct by Wind.--With engraving.
Joy's Reversing and Expansion Valve Gear.--1 figure.
The Steam Bell for Locomotives.--2 figures.
Diamond Mining in Brazil.--With engravings showing the dam
on the Ribeirao Inferno at Portao de Ferro, and the arrangement
of the machinery.
III. ELECTRICITY, ETC.--The Frankfort and Offenbach Electric
Railway.--With 3 engravings.
Possibilities of the Telephone.--Its use by vessels at sea.
Pyrometers.--The inventions of Siemens and others.
IV. ARCHAEOLOGY.--The Cay Monument at Uxmal.--Discovered by
Dr. Le Plongeon on June 1, 1881.--With engraving.
V. ASTRONOMY.--The Temperature of the Solar Surface Corresponding
with the Temperature Transmitted to the Sun Motor.--By
J. ERICSSON.--With 2 engravings of the sun motor.
VI. HORTICULTURE.--Halesia Hispida, a Hardy Shrub.--With engraving.
Windflowers or Anemone.--With engraving.
VII. MEDICINE, HYGIENE. ETC.--What we Really Know about
Asiatic Cholera.--By J.C. PETERS, M.D.
Dr. Koch on the Cholera.
Malaria.--The natural production of malaria and the means of
making malarial countries healthier.--By C.T. CRUDELI, of Rome.
Story of Lieut. Greely's Recovery.--Treatment by Surgeon
Green.
VIII. MISCELLANEOUS.--Bayle's New Lamp Chimney.--With engraving.
Lieut. Greely before the British Association.
* * * * *
THE FRANKFORT AND OFFENBACH ELECTRIC RAILWAY.
The electric railway recently set in operation between Frankfort and
Offenbach furnishes an occasion for studying the question of such roads
anew and from a practical standpoint. For elevated railways Messrs.
Siemens and Halske a long time ago chose rails as current conductors. The
electric railway from Berlin to Lichterfelde and the one at Vienna are in
reality only elevated roads established upon the surface.
Although it is possible to insulate the rails in a satisfactory manner in
the case of an elevated road, the conditions of insulation are not very
favorable where the railway is to be constructed on a level with the
surface. In this case it becomes necessary to dispense with the simple and
cheap arrangement of rails as conductors, and to set up, instead, a number
of poles to support the electric conductors. It is from these latter that
certain devices of peculiar construction take up the current. The simplest
arrangement to be adopted under these circumstances would evidently be to
stretch a wire upon which a traveler would slide--this last named piece
being connected with the locomotive by means of a flexible cord. This
general idea, moreover, has been put in practice by several constructors.
In the Messrs. Siemens Bros.' electric railway that figured at Paris in
1881 the arrangement adopted for taking up the current consisted of two
split tubes from which were suspended two small contact carriages that
communicated with the electric car through the intermedium of flexible
cables. This is the mode of construction that Messrs. Siemens and Halske
have adopted in the railway from Frankfort to Offenbach. While the Paris
road was of an entirely temporary character, that of Frankfort has been
built according to extremely well studied plans, and after much light
having been thrown upon the question of electric traction by three years
of new experiments.
Fig. 1 shows the electric car at the moment of its start from Frankfort,
Fig. 2 shows the arrangement of a turnout, and Fig. 3 gives a general plan
of the electric works.
[Illustration: FIG. 1.--THE ELECTRIC RAILWAY, FRANKFORT, GERMANY.]
The two grooved tubes are suspended from insulators fixed upon external
cast iron supports. As for the conductors, which have their resting points
upon ordinary insulators mounted at the top of the same supports, these
are cables composed of copper and steel. They serve both for leading the
current and carrying the tubes. The same arrangement was used by Messrs.
Siemens and Halske at Vienna in 1883.
The motors, which are of 240 H.P., consist of two coupled steam engines of
the Collmann system. The one shaft in common runs with a velocity of 60
revolutions per minute. Its motion is transmitted by means of ten hempen
cables, 3.5 cm. in diameter. The flywheel, which is 4 m. in diameter,
serves at the same time as a driving pulley. As the pulley mounted upon
the transmitting shaft is only one meter in diameter, it follows that the
shafting has a velocity of 240 revolutions per minute. The steam
generators are of the Ten Brink type, and are seven in number. The normal
pressure in them is four atmospheres. There are at present four
dynamo-electric machines, but sufficient room was provided for four more.
The shafts of the dynamos have a velocity of 600 revolutions per minute.
The pulleys are 60 cm. in diameter, and the width of the driving belts is
18 cm. The dynamos are mounted upon rails so as to permit the tension of
the belting to be regulated when necessity requires it. This arrangement,
which possesses great advantages, had already been adopted in many other
installations.
The electric machines are 2 meters in height. The diameter of the rings is
about 45 cm. and their length is 70 cm. The electric tension of the
dynamos measures 600 volts.
[Illustration: FIG. 2.--TURNOUT TRACK OF THE ELECTRIC RAILWAY, FRANKFORT,
GERMANY.]
The duty varies between 80 and 50 per cent., according to the arrangement
of the cars. The total length of the road is 6,655 meters. Usually, there
are four cars _en route_, and two dynamos serve to create the current.
When the cars are coupled in pairs, three dynamos are used--one of the
machines being always held in reserve. All the dynamos are grouped for
quantity.
[Illustration: FIG. 3.--GENERAL PLAN OF THE ELECTRIC WORKS.]
The company at present owns six closed and five open cars. In the former
there is room for twenty-two persons. The weight of these cars varies
between 3,500 and 4,000 kilos.--_La Lumiere Electrique._
* * * * *
By the addition of ten parts of collodion to fifteen of creasote (says the
_Revue de Therap._) a sort of jelly is obtained which is more convenient
to apply to decayed teeth than is creasote in its liquid form.
* * * * *
POSSIBILITIES OF THE TELEPHONE.
The meeting of the American Association was one of unusual interest and
importance to the members of Section B. This is to be attributed not only
to the unusually large attendance of American physicists, but also to the
presence of a number of distinguished members of the British Association,
who have contributed to the success of the meetings not only by presenting
papers, but by entering freely into the discussions. In particular the
section was fortunate in having the presence of Sir William Thomson, to
whom more than to any one else we owe the successful operation of the
great ocean cables, and who stands with Helmholtz first among living
physicists. Whenever he entered any of the discussions, all were benefited
by the clearness and suggestiveness of his remarks.
Professor A. Graham Bell, the inventor of the telephone, read a paper
giving a possible method of communication between ships at sea. The simple
experiment that illustrates the method which he proposed is as follows:
Take a basin of water, introduce into it, at two widely separated points,
the two terminals of a battery circuit which contains an interrupter,
making and breaking the circuit very rapidly. Now at two other points
touch the water with the terminals of a circuit containing a telephone. A
sound will be heard, except when the two telephone terminals touch the
water at points where the potential is the same. In this way the
equipotential lines can easily be picked out. Now to apply this to the
case of a ship at sea: Suppose one ship to be provided with a dynamo
machine generating a powerful current, and let one terminal enter the
water at the prow of the ship, and the other to be carefully insulated,
except at its end, and be trailed behind the ship, making connection with
the sea at a considerable distance from the vessel; and suppose the
current be rapidly made and broken by an interrupter; then the observer on
a second vessel provided with similar terminal conductors to the first,
but having a telephone instead of a dynamo, will be able to detect the
presence of the other vessel even at a considerable distance; and by
suitable modifications the direction of the other vessel may be found.
This conception Professor Bell has actually tried on the Potomac River
with two small boats, and found that at a mile and a quarter, the furthest
distance experimented upon, the sound due to the action of the interrupter
in one boat was distinctly audible in the other. The experiment did not
succeed quite so well in salt water. Professor Trowbridge then mentioned a
method which he had suggested some years ago for telegraphing across the
ocean without a cable, the method having been suggested more for its
interest than with any idea of its ever being put in practice. A conductor
is supposed to be laid from Labrador to Patagonia, ending in the ocean at
those points, and passing through New York, where a dynamo machine is
supposed to be included in the circuit. In Europe a line is to extend from
the north of Scotland to the south of Spain, making connections with the
ocean at those points, and in this circuit is to be included a telephone.
Then any change in the strength of the current in the American line would
produce a corresponding change in current in the European line; and thus
signals could be transmitted. Mr. Preece, of the English postal telegraph,
then gave an account of how such a system had actually been put into
practice in telegraphing between the Isle of Wight and Southampton during
a suspension in the action of the regular cable communication. The
instruments used were a telephone in one circuit, and in the other about
twenty-five Leclanche cells and an interrupter. The sound could then be
heard distinctly; and so communication was kept up until the cable was
again in working order. Of the two lines used in this case, one extended
from the sea at the end of the island near Hurst Castle, through the
length of the island, and entered the sea again at Rye; while the line on
the mainland ran from Hurst Castle, where it was connected with the sea,
through Southampton to Portsmouth, where it again entered the sea. The
distance between the two terminals at Hurst Castle was about one mile,
while that between the terminals at Portsmouth and Rye amounted to six
miles.--_Science._
* * * * *
PYROMETERS.
The accurate measurement of very high temperatures is a matter of great
importance, especially with regard to metallurgical operations; but it is
also one of great difficulty. Until recent years the only methods
suggested were to measure the expansion of a given fluid or gas, as in the
air pyrometer; or to measure the contraction of a cone of hard, burnt
clay, as in the Wedgwood pyrometer. Neither of these systems was at all
reliable or satisfactory. Lately, however, other principles have been
introduced with considerable success, and the matter is of so much
interest, not only to the practical manufacturer but also to the
physicist, that a sketch of the chief systems now in use will probably be
acceptable. He will thus be enabled to select the instrument best suited
for the particular purpose he may have in view.
The first real improvement in this direction, as in so many others, is due
to the genius of Sir William Siemens. His first attempt was a calorimetric
pyrometer, in which a mass of copper at the temperature required to be
known is thrown into the water of a calorimeter, and the heat it has
absorbed thus determined. This method, however, is not very reliable, and
was superseded by his well-known electric pyrometer. This rests on the
principle that the electric resistance of metal conductors increases with
the temperature. In the case of platinum, the metal chosen for the
purpose, this increase up to 1,500 deg.C. is very nearly in the exact
proportion of the rise of temperature. The principle is applied in the
following manner: A cylinder of fireclay slides in a metal tube, and has
two platinum wires one one-hundredth of an inch in diameter wound round it
in separate grooves. Their ends are connected at the top to two
conductors, which pass down inside the tube and end in a fireclay plug at
the bottom. The other ends of the wires are connected with a small
platinum coil, which is kept at a constant resistance. A third conductor
starting from the top of the tube passes down through it, and comes out at
the face of the metal plug. The tube is inserted in the medium whose
temperature is to be found, and the electric resistance of the coil is
measured by a differential voltameter. From this it is easy to deduce the
temperature to which the platinum has been raised. This pyrometer is
probably the most widely used at the present time.
Tremeschini's pyrometer is based on a different principle, viz., on the
expansion of a thin plate of platinum, which is heated by a mass of metal
previously raised to the temperature of the medium. The exact arrangements
are difficult to describe without the aid of drawings, but the result is
to measure the difference of temperature between the medium to be tested
and the atmosphere at the position of the instrument. The whole apparatus
is simple, compact, and easy to manage, and its indications appear to be
correct at least up to 800 deg.C.
The Trampler pyrometer is based upon the difference in the coefficients of
dilatation for iron and graphite, that of the latter being about
two-thirds that of the former. There is an iron tube containing a stick of
hard graphite. This is placed in the medium to be examined, and both
lengthen under the heat, but the iron the most of the two. At the top of
the stick of graphite is a metal cap carrying a knife-edge, on which rests
a bent lever pressed down upon it by a light spring. A fine chain attached
to the long arm of this lever is wound upon a small pulley; a larger
pulley on the same axis has wound upon it a second chain, which actuates a
third pulley on the axis of the indicating needle. In this way the
relative dilatation of the graphite is sufficiently magnified to be easily
visible.
A somewhat similar instrument is the Gauntlett pyrometer, which is largely
used in the north of England. Here the instrument is partly of iron,
partly of fireclay, and the difference in the expansion of the two
materials is caused to act by a system of springs upon a needle revolving
upon a dial.
The Ducomet pyrometer is on a very different principle, and only
applicable to rough determinations. It consists of a series of rings made
of alloys which have slightly different melting-points. These are strung
upon a rod, which is pushed into the medium to be measured, and are
pressed together by a spiral spring. As soon as any one of the rings
begins to soften under the heat, it is squeezed together by the pressure,
and, as it melts, it is completely squeezed out and disappears. The rod is
then made to rise by the thickness of the melted ring, and a simple
apparatus shows at any moment the number of rings which have melted, and
therefore the temperature which has been attained. This instrument cannot
be used to follow variations of temperature, but indicates clearly the
moment when a particular temperature is attained. It is of course entirely
dependent on the accuracy with which the melting-points of the various
alloys have been fixed.
Yet another principle is involved in the instrument called the
thalpotasimeter, which may be used either with ether, water, or mercury.
It is based on the principle that the pressure of any saturated vapor
corresponds to its temperature. The instrument consists of a tube of metal
partly filled with liquid, which is exposed to the medium which is to be
measured. A metallic pressure gauge is connected with the tube, and
indicates the pressure existing within it at any moment. By graduating the
face of the gauge when the instrument is at known temperatures, the
temperature can be read off directly from the position of the needle. From
100 deg. to 220 deg.F. ether is the liquid used, from thence to 680 deg. it is water,
and above the latter temperature mercury is employed.
Another class of pyrometers having great promise in the future is based on
what may be called the "water-current" principle. Here the temperature is
determined by noting the amount of heat communicated to a known current of
water circulating in the medium to be observed. The idea, which was due to
M. De Saintignon, has been carried out in its most improved form by M.
Boulier. Here the pyrometer itself consists of a set of tubes one inside
the other, and all inclosed for safety in a large tube of fireclay. The
central tube or pipe brings in the water from a tank above, where it is
maintained at a constant level. The water descends to the bottom of the
instrument, and opens into the end of another small tube called the
explorer (_explorateur_). This tube projects from the fireclay casing into
the medium to be examined, and can be pushed in or out as required. After
circulating through this tube the water rises again in the annular space
between the central pipe and the second pipe. The similar space between
the second pipe and the third pipe is always filled by another and much
larger current of water, which keeps the interior cool. The result is that
no loss of heat is possible in the instrument, and the water in the
central tube merely takes up just so much heat as is conducted into it
through the metal of the explorer. This heat it brings back through a
short India-rubber pipe to a casing containing a thermometer. This
thermometer is immersed in the returning current of water, and records its
temperature. It is graduated by immersing the instrument in known and
constant temperatures, and thus the graduations on the thermometer give at
once the temperature, not of the current of water, but of the medium from
which it has received its heat. In order to render the instrument
perfectly reliable, all that is necessary is that the current of water
should be always perfectly uniform, and this is easily attained by fixing
the size of the outlet once for all, and also the level of water in the
tank. So arranged, the pyrometer works with great regularity, indicating
the least variations of temperature, requiring no sort of attention, and
never suffering injury under the most intense heat; in fact the tube, when
withdrawn from the furnace, is found to be merely warm. If there is any
risk of the instrument getting broken from fall of materials or other
causes, it may be fitted with an ingenious self-acting apparatus shutting
off the supply. For this purpose the water which has passed the
thermometer is made to fall into a funnel hung on the longer arm of a
balanced lever. With an ordinary flow the water stands at a certain height
in the funnel, and, while this is so, the lever remains balanced; but if
from any accident the flow is diminished, the level of the water in the
funnel descends, the other arm of the lever falls, and in doing so
releases two springs, one of which in flying up rings a bell, and the
other by detaching a counterweight closes a cock and stops the supply of
water altogether.
It will be seen that these instruments are not adapted for shifting about
from place to place in order to observe different temperatures, but rather
for following the variations of temperature at one and the same place. For
many purposes this is of great importance. They have been used with great
success in porcelain furnaces, both at the famous manufactories at Sevres
and at another porcelain works in Limoges. From both these establishments
very favorable reports as to their working have been received.--_W.R.
Browne, in Nature_.
* * * * *
[NATURE.]
THE TEMPERATURE OF THE SOLAR SURFACE.
I have, during the summer solstice of 1884, carried out an experimental
investigation for the purpose of demonstrating the temperature of the
solar surface corresponding with the temperature transmitted to the sun
motor. Referring to the illustrations previously published, it will be
seen that the cylindrical heater of the sun motor, constructed solely for
the purpose of generating steam or expanding air, is not well adapted for
an exact determination of the amount of surface exposed to the action of
the reflected solar rays. It will be perceived on inspection that only
part of the bottom of the cylindrical heater of the motor is acted upon by
the reflected rays, and that their density diminishes _gradually_ toward
the sides of the vessel; also that owing to the imperfections of the
surface of the reflecting plates the exact course of the terminal rays
cannot be defined. Consequently, the most important point in the
investigation, namely, the area acted upon by the reflected radiant heat,
cannot be accurately determined. I have accordingly constructed an
instrument of large dimensions, a polygonal reflector (see Fig. 1),
composed of a series of inclined mirrors, and provided with a central
heater of conical form, acted upon by the reflected radiation in such a
manner that each point of its surface receives an equal amount of radiant
heat in a given time. The said reflector is contained within two regular
polygonal planes twelve inches apart, each having ninety-six sides, the
perimeter of the upper plane corresponding with a circle of eight feet
diameter, that of the lower plane being six feet. The corresponding sides
of these planes are connected by flat taper mirrors composed of thin glass
silvered on the outside. When the reflector faces the sun at right angles,
each mirror intercepts a pencil of rays of 32.61 square inches section,
hence the entire reflecting surface receives the radiant heat of an
annular sunbeam of 32.61 x 96 = 3,130 square inches section. It should be
observed that the area thus stated is 0.011 less than the total
foreshortened superficies of the ninety-six mirrors if sufficiently wide
to come in perfect contact at the vertices. Fig. 2 represents a transverse
section of the instrument as it appears when facing the sun; the direct
and reflected rays being indicated by dotted lines. The reflector and
conical heater are sustained by a flat hub and eight radial spokes bent
upward toward the ends at an angle of 45 deg.. The hub and spokes are
supported by a vertical pivot, by means of which the operator is enabled
to follow the diurnal motion of the sun, while a horizontal axle, secured
to the upper end of the pivot, and held by appropriate bearings under the
hub, enables him to regulate the inclination to correspond with the
altitude of the luminary. The heater is composed of rolled plate iron
0.017 inch thick, and provided with bead and bottom formed of
non-conducting materials. By means of a screw-plug passing through the
bottom and entering the face of the hub the heater may be applied and
removed in the course of five minutes, an important fact, as will be seen
hereafter. It is scarcely necessary to state that the proportion of the
ends of the conical heater should correspond with the perimeters of the
reflector, hence the diameter of the upper end, at the intersection of the
polygonal plane, should be to that of the lower end as 8 to 6, in order
that every part may be acted upon by reflected rays of equal density. This
condition being fulfilled, the temperature communicated will be perfectly
uniform. A short tube passes through the upper head of the heater, through
which a thermometer is inserted for measuring the internal temperature.
The stem being somewhat less than the bore of the tube, a small opening is
formed by which the necessary equilibrium of pressure will be established
with the external atmosphere. It should be mentioned that the indications
of the thermometer during the experiment have been remarkably prompt, the
bulb being subjected to the joint influence of radiation and convection.
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