Scientific American Supplement, No. 417
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Various >> Scientific American Supplement, No. 417
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Ordinarily one charge of liquid will serve for twenty-four hours
working, but this, of course, is entirely determined by the space
provided for it. It is sold at sevenpence a gallon, and each gallon is
sufficient, we are informed, to drive a cell while it generates 800
ampere hours of current, or, taking the electromotive force at 1.8
volts, it represents (800 x 1.8) / 746 = 1.93 horse-power hours. The
cost of the zinc is stated to be 35 per cent. of that of the fluid,
although it is difficult to see how this can be, for one horse-power
requires the consumption of 895.2 grammes of zinc per hour, or 1.96 lb.,
and this at 18_l_. per ton, would cost 1.93 pence per pound, or 3.8
pence per horse-power hour. This added to 3.6 pence for the fluid, would
give a total of 7.4 pence per horse-power per hour, and assuming twenty
lamps of ten candle power to be fed per horse-power, the cost would be
about one-third of a penny per hour per lamp.
Mr Holmes admits his statement of the consumption of zinc does not agree
with what might be theoretically expected but he bases it upon the
result of his experiments in the Pullman train, which place the cost at
one farthing per hour per light. At the same time he does not profess
that the battery can compete in the matter of cost with mechanically
generated currents on a large scale, but he offers it as a convenient
means of obtaining the electric light in places where a steam engine or
a gas engine is inadmissible, as in a private house, and where the cost
of driving a dynamo machine is raised abnormally high by reason of a
special attendant having to be paid to look after it.
But he has another scheme for the reduction of the cost, to which we
have not yet alluded, and of which we can say but little, as the details
are not at present available for publication. The battery gives off
fumes which can be condensed into a nitrogenous substance, valuable, it
is stated, as a manure, while the zinc salts in the spent liquid can be
recovered and returned to useful purposes. How far this is practicable
it is at present impossible to say, but at any rate the idea represents
a step in the right direction, and if the electricians can follow the
example of the gas manufacturers and obtain a revenue from the residuals
of galvanic batteries, they will greatly improve their commercial
position. There is nothing impossible in the idea, and neither is it
altogether novel, although the way of carrying it out may be. In 1848,
Staite, one of the early enthusiasts in electric lighting, patented a
series of batteries from which he proposed to recover sulphate, nitrate,
and chloride of zinc, but we never heard that he obtained any success.
* * * * *
NEW ELECTRIC RAILWAY.
The original electric railway laid down by Messrs. Siemens and Halske
at Berlin seems likely to be the parent of many others. One of the most
recent is the underground electric line laid down by the firm in the
mines of Zankerodain Saxony. An account of this railway has appeared in
_Glaser's Annalen_, together with drawings of the engine, which we are
able to reproduce. They are derived from a paper by Herr Fischer, read
on the 19th December, 1882, before the Electro-Technical Union of
Germany. The line in question is 700 meters long--770 yards--and has two
lines of way. It lies 270 meters--300 yards--below the surface of the
ground. It is worked by an electric locomotive, hauling ten wagons at a
speed of 12 kilometers, or 71/2 miles per hour. The total weight drawn is
eight tons. The gauge is a narrow one, so that the locomotive can be
made of small dimensions. Its total length between the buffer heads is
2.43 meters; its height 1.04 meters; breadth 0.8 meter; diameter of
wheels, 0.34 meter. From the rail head to the center of the buffers is a
height of 0.675 meter; and the total weight is only 1550 kilogrammes, or
say 3,400 lb. We give a longitudinal section through the locomotive. It
will be seen that there is a seat at each end for the driver, so that he
can always look forwards, whichever way the engine may be running. The
arrangements for connection with the electric current are very simple.
The current is generated by a dynamo machine fixed outside the mine, and
run by a small rotary steam engine, shown in section and elevation, at a
speed of 900 revolutions per minute. The current passes through a cable
down the shaft to a T-iron fixed to the side of the heading. On this
T-iron slide contact pieces which are connected with the electric engine
by leading wires. The driver by turning a handle can move his engine
backward or forward at will. The whole arrangement has worked extremely
well, and it is stated that the locomotive, if so arranged, could easily
do double its present work; in other words, could haul 15 to 16 tons of
train load at a speed of seven miles an hour. The arrangements for the
dynamo machine on the engine, and its connection with the wheels, are
much the same as those used in Sir William Siemens' electric railway now
working near the Giant's Causeway.--_The Engineer_.
[Illustration: THE SIEMENS ELECTRIC RAILWAY AT ZANKERODA MINES.]
* * * * *
THE EARLIEST GAS-ENGINE.
Lebon, in the certificate dated 1801, in addition to his first patent,
described and illustrated a three-cylinder gas-engine in which an
explosive mixture of gas and air was to have been ignited by an electric
spark. This is a curious anticipation of the Lenior system, not brought
out until more than fifty years later; but there is no evidence that
Lebon ever constructed an engine after the design referred to. It is an
instructive lesson to would-be patentees, who frequently expect to reap
immediate fame and fortune from their property in some crude ideas which
they fondly deem to be an "invention," to observe the very wide interval
that separates Lebon from Otto. The idea is the same in both cases; but
it has required long years of patient work, and many failures, to embody
the idea in a suitable form. It is almost surprising, to any one who has
not specially studied the matter, to discover the number of devices
that have been tried with the object of making an explosion engine, as
distinguished from one deriving its motive power from the expansion of
gaseous fluids. A narrative of some of these attempts has been presented
to the Societe des Ingenieurs Civils; mostly taken in the first place
from Stuart's work upon the origin of the steam engine, published in
1820, and now somewhat scarce. It appears from this statement that so
long ago as 1794, Robert Street described and patented an engine in
winch the piston was to be driven by the explosion of a gaseous mixture
whereof the combustible element was furnished by the vaporization of
_terebenthine_ (turpentine) thrown upon red hot iron. In 1807 De Rivaz
applied the same idea in a different manner. He employed a cylinder
12 centimeters in diameter fitted with a piston. At the bottom of the
cylinder there was another smaller one, also provided with a piston.
This was the aspirating cylinder, which drew hydrogen from an inflated
bag, and mixed it with twice its bulk of air by means of a two-way cock.
The ignition of the detonating mixture was effected by an electric
spark. It is said that the inventor applied his apparatus to a small
locomotive.
In 1820 Mr. Cecil, of Cambridge, proposed the employment of a mixture of
air and hydrogen as a source of motive power; he gave a detailed account
of his invention in the _Transactions_ of the Cambridge Philosophical
Society, together with some interesting theoretical considerations.
The author observes here that an explosion may be safely opposed by
an elastic resistance--that of compressed air, for example--if such
resistance possesses little or no inertia to be brought into play;
contrariwise, the smallest inertia opposed to the explosion of a mixture
subjected to instantaneous combustion is equivalent to an insurmountable
obstacle. Thus a small quantity of gunpowder, or a detonating mixture of
air and hydrogen, may without danger be ignited in a large closed vessel
full of air, because the pressure against the sides of the vessel
exerted by the explosion is not more than the pressure of the air
compressed by the explosion. If a piece of card board, or even of paper,
is placed in the middle of the bore of a cannon charged with powder, the
cannon will almost certainly burst, because the powder in detonating
acts upon a body in repose which can only be put in motion in a period
of time infinitely little by the intervention of a force infinitely
great. The piece of paper is therefore equivalent to an insurmountable
obstacle. Of all detonating mixtures, or explosive materials, the most
dangerous for equal expansions, and the least fitted for use as motive
power, are those which inflame the most rapidly. Thus, a mixture
of oxygen and hydrogen, in which the inflammation is produced
instantaneously, is less convenient for this particular usage than a
mixture of air and hydrogen, which inflames more slowly. From this point
of view, ordinary gunpowder would make a good source of motive
power, because, notwithstanding its great power of dilatation, it is
comparatively slow of ignition; only it would be necessary to take
particular precautions to place the moving body in close contact with
the powder. Cecil pointed out that while a small steam engine could not
be started in work in less than half an hour, or probably more, a gas
engine such as he proposed would have the advantage of being always
ready for immediate use. Cecil's engine was the first in which the
explosive mixture was ignited by a simple flame of gas drawn into the
cylinder at the right moment. In the first model, which was that of
a vertical beam engine with a long cylinder of comparatively small
diameter, the motive power was simply derived from the descent of the
piston by atmospheric pressure; but Mr. Cecil is careful to state that
power may also be obtained directly from the force of the explosion. The
engine was worked with a cylinder pressure of about 12 atmospheres, and
the inventor seems to have recognized that the noise of the explosions
might be an objection to the machine, for he suggests putting the end of
the cylinder down in a well, or inclosing it in a tight vessel for the
purpose of deadening the shock.
It is interesting to rescue for a moment the account of Mr. Cecil's
invention from the obscurity into which it has fallen--obscurity which
the ingenuity of the ideas embodied in this machine does not merit. It
is probable that in addition to the imperfections of his machinery,
Mr. Cecil suffered from the difficulty of obtaining hydrogen at a
sufficiently low price for use in large quantities. It does not
transpire that the inventor ever seriously turned his attention to the
advantages of coal gas, which even at that time, although very dear,
must have been much cheaper than hydrogen. Knowing what we do at
present, however, of the consumption of gas by a good engine of the
latest pattern, it may be assumed that a great deal of the trouble of
the gas engine builders of 60 years ago arose from the simple fact of
their being altogether before their age. Of course, the steam engine of
1820 was a much more wasteful machine, as well as more costly to build
than the steam engine of to-day; but the difference cannot have been so
great as to create an advantage in favor of an appliance which required
even greater nicety of construction. The best gas-engine at present made
would have been an expensive thing to supply with gas at the prices
current in 1820, even if the resources of mechanical science at that
date had been equal to its construction; which we know was not the case.
Still, this consideration was not known, or was little valued, by Mr.
Cecil and his contemporaries. It was not long, however, before Mr. Cecil
had to give way before a formidable rival; for in 1823 Samuel Brown
brought out his engine, which was in many respects an improvement upon
the one already described. It will probably be right, however, to regard
the Rev. Mr. Cecil, of Cambridge, as the first to make a practicable
model of a gas-engine in the United Kingdom.--_Journal of Gas Lighting_.
* * * * *
Alabama has 2,118 factories, working 8,248 hands, with a capital
invested of $5,714,032, paying annually in wages $2,227,968, and
yielding annually in products $13,040,644.
* * * * *
THE MOVING OF LARGE MASSES.
[Footnote: For previous article see SUPPLEMENT 367.]
The moving of a belfry was effected in 1776 by a mason who knew neither
how to read nor write. This structure was, and still is, at Crescentino,
upon the left bank of the Po, between Turin and Cazal. The following is
the official report on the operation:
"In the year 1776, on the second day of September, the ordinary council
was convoked, ... as it is well known that, on the 26th of May last,
there was effected the removal of a belfry, 7 trabucs (22.5 m.) or
more in height, from the church called _Madonna del Palazzo_, with the
concurrence and in the presence and amid the applause of numerous people
of this city and of strangers who had come in order to be witnesses of
the removal of the said tower with its base and entire form, by means of
the processes of our fellow-citizen Serra, a master mason who took it
upon himself to move the said belfry to a distance of 3 meters, and to
annex it to a church in course of construction. In order to effect this
removal, the four faces of the brick walls were first cut and opened at
the base of the tower and on a level with the earth. Into the apertures
from north to south, that is to say in the direction that the edifice
was to take, there were introduced two large beams, and with these there
ran parallel, external to the belfry and alongside of it, two other rows
of beams of sufficient length and extent to form for the structure a bed
over which it might be moved and placed in position in the new spot,
where foundations of brick and lime had previously been prepared.
[Illustration: FIG. 1.--REMOVAL OF A BELFRY AT CRESCENTINO IN 1776]
"Upon this plane there were afterward placed rollers 31/2 inches in
diameter, and, upon these latter, there was placed a second row of beams
of the same length as the others. Into the eastern and western apertures
there were inserted, in cross-form, two beams of less length.
"In order to prevent the oscillation of the tower, the latter was
supported by eight joists, two of these being placed on each side and
joined at their bases, each with one of the four beams, and, at their
apices, with the walls of the tower at about two-thirds of its height.
"The plane over which the edifice was to be rolled had an inclination of
one inch. The belfry was hauled by three cables that wound around
three capstans, each of which was actuated by ten men. The removal was
effected in less than an hour.
"It should be remarked that during the operation the son of the mason
Serra, standing in the belfry, continued to ring peals, the bells not
having been taken out.
"Done at Crescentino, in the year and on the day mentioned."
A note communicated to the Academie des Sciences at its session of May
9, 1831, added that the base of the belfry was 3.3 m. square. This
permits us to estimate its weight at about 150 tons.
[Illustration: FIG. 2.--MOVING THE WINGED BULLS FROM NINEVEH TO MOSUL IN
1854]
Fig. 1 shows the general aspect of the belfry with its stays. This is
taken from an engraving published in 1844 by Mr. De Gregori, who, during
his childhood, was a witness of the operation, and who endeavored to
render the information given by the official account completer without
being able to make the process much clearer.
In 1854 Mr. Victor Place moved overland, from Nineveh to Mosul, the
winged bulls that at present are in the Assyrian museum of the Louvre,
and each of which weighs 32 tons. After carefully packing these in boxes
in order to preserve them from shocks, Place laid them upon their side,
having turned them over, by means of levers, against a sloping bank of
earth That he afterward dug away in such a manner that the operation was
performed without accident. He had had constructed an enormous car with
axles 0.25 m. in diameter, and solid wheels 0.8 m. in thickness (Fig.
2). Beneath the center of the box containing the bull a trench was dug
that ran up to the natural lever of the soil by an incline. This trench
had a depth and width such that the car could run under the box while
the latter was supported at two of its extremities by the banks. These
latter were afterward gradually cut away until the box rested upon the
car without shock. Six hundred men then manned the ropes and hauled the
car with its load up to the level of the plain. These six hundred men
were necessary throughout nearly the entire route over a plain that
was but slightly broken and in which the ground presented but little
consistency.
The route from Khorsabad to Mosul was about 18 kilometers, taking into
account all the detours that had to be made in order to have a somewhat
firm roadway. It took four days to transport the first bull this
distance, but it required only a day and a half to move the other one,
since the ground had acquired more compactness as a consequence of
moving the first one over it, and since the leaders had become more
expert. The six hundred men at Mr. Place's disposal had, moreover, been
employed for three months back in preparing the route, in strengthening
it with piles in certain spots and in paving others with flagstones
brought from the ruins of Nineveh. In a succeeding article I shall
describe how I, a few years ago, moved an ammunition stone house,
weighing 50 tons, to a distance of 35 meters without any other machine
than a capstan actuated by two men.--_A. De Rochas, in La Nature_.
* * * * *
[NATURE.]
SCIENCE AND ENGINEERING.
In the address delivered by Mr. Westmacott, President of the Institution
of Mechanical Engineers to the English and Belgian engineers assembled
at Liege last August, there occurred the following passage: "Engineering
brings all other sciences into play; chemical or physical discoveries,
such as those of Faraday, would be of little practical use if engineers
were not ready with mechanical appliances to carry them out, and make
them commercially successful in the way best suited to each."
We have no objection to make to these words, spoken at such a time and
before such an assembly. It would of course be easy to take the converse
view, and observe that engineering would have made little progress in
modern times, but for the splendid resources which the discoveries of
pure science have placed at her disposal, and which she has only had to
adopt and utilize for her own purposes. But there is no need to quarrel
over two opposite modes of stating the same fact. There _is_ need on
the other hand that the fact itself should be fairly recognized and
accepted, namely, that science may be looked upon as at once the
handmaid and the guide of art, art as at once the pupil and the
supporter of science. In the present article we propose to give a few
illustrations which will bring out and emphasize this truth.
We could scarcely find a better instance than is furnished to our hand
in the sentence we have chosen for a text. No man ever worked with a
more single hearted devotion to pure science--with a more absolute
disregard of money or fame, as compared with knowledge--than Michael
Faraday. Yet future ages will perhaps judge that no stronger impulse was
ever given to the progress of industrial art, or to the advancement of
the material interests of mankind, than the impulse which sprang from
his discoveries in electricity and magnetism. Of these discoveries
we are only now beginning to reap the benefit. But we have merely to
consider the position which the dynamo-electric machine already occupies
in the industrial world, and the far higher position, which, as almost
all admit, it is destined to occupy in the future, in order to see
how much we owe to Faraday's establishment of the connection between
magnetism and electricity. That is one side of the question--the debt
which art owes to science. But let us look at the other side also. Does
science owe nothing to art? Will any one say that we should know as much
as we do concerning the theory of the dynamo-electric motor, and the
laws of electro-magnetic action generally, if that motor had never
risen (or fallen, as you choose to put it) to be something besides the
instrument of a laboratory, or the toy of a lecture room? Only a short
time since the illustrious French physicist, M. Tresca, was enumerating
the various sources of loss in the transmission of power by electricity
along a fixed wire, as elucidated in the careful and elaborate
experiments inaugurated by M. Marcel Deprez, and subsequently continued
by himself. These losses--the electrical no less than the mechanical
losses--are being thoroughly and minutely examined in the hope of
reducing them to the lowest limit; and this examination cannot fail to
throw much light on the exact distribution of the energy imparted to a
dynamo machine and the laws by which this distribution is governed.
But would this examination ever have taken place--would the costly
experiments which render it feasible ever have been performed--if the
dynamo machine was still under the undisputed control of pure science,
and had not become subject to the sway of the capitalist and the
engineer?
Of course the electric telegraph affords an earlier and perhaps as good
an illustration of the same fact. The discovery that electricity would
pass along a wire and actuate a needle at the other end was at first a
purely scientific one; and it was only gradually that its importance,
from an industrial point of view, came to be recognized. Here again art
owes to pure science the creation of a complete and important branch of
engineering, whose works are spread like a net over the whole face
of the globe. On the other hand our knowledge of electricity, and
especially of the electrochemical processes which go on in the working
of batteries, has been enormously improved in consequence of the use of
such batteries for the purposes of telegraphy.
Let us turn to another example in a different branch of science.
Whichever of our modern discoveries we may consider to be the most
startling and important, there can I think be no doubt that the most
beautiful is that of the spectroscope. It has enabled us to do that
which but a few years before its introduction was taken for the very
type of the impossible, viz., to study the chemical composition of the
stars; and it is giving us clearer and clearer insight every day into
the condition of the great luminary which forms the center of our
system. Still, however beautiful and interesting such results may be,
it might well be thought that they could never have any practical
application, and that the spectroscope at least would remain an
instrument of science, but of science alone. This, however, is not the
case. Some thirty years since, Mr. Bessemer conceived the idea that
the injurious constituents of raw iron--such as silicon, sulphur,
etc.--might be got rid of by simple oxidation. The mass of crude metal
was heated to a very high temperature; atmospheric air was forced
through it at a considerable pressure; and the oxygen uniting with these
metalloids carried them off in the form of acid gases. The very act
of union generated a vast quantity of heat, which itself assisted the
continuance of the process; and the gas therefore passed off in a highly
luminous condition. But the important point was to know where to
stop; to seize the exact moment when all or practically all hurtful
ingredients had been removed, and before the oxygen had turned from them
to attack the iron itself. How was this point to be ascertained? It was
soon suggested that each of these gases in its incandescent state would
show its own peculiar spectrum; and that if the flame rushing out of the
throat of the converter were viewed through a spectroscope, the moment
when any substance such as sulphur, had disappeared would be known
by the disappearance of the corresponding lines in the spectrum. The
anticipation, it is needless to say, was verified, and the spectroscope,
though now superseded, had for a time its place among the regular
appliances necessary for the carrying on of the Bessemer process.
This process itself, with all the momentous consequences, mechanical,
commercial, and economical, which it has entailed, might be brought
forward as a witness on our side; for it was almost completely worked
out in the laboratory before being submitted to actual practice. In this
respect it stands in marked contrast to the earlier processes for the
making of iron and steel, which were developed, it is difficult to say
how, in the forge or furnace itself, and amid the smoke and din of
practical work. At the same time the experiments of Bessemer were
for the most part carried out with a distinct eye to their future
application in practice, and their value for our present purpose is
therefore not so great. The same we believe may be said with regard
to the great rival of the Bessemer converter, viz., the Siemens open
hearth; although this forms in itself a beautiful application of the
scientific doctrine that steel stands midway, as regards proportion of
carbon, between wrought iron and pig iron, and ought therefore to be
obtainable by a judicious mixture of the two. The basic process is
the latest development, in this direction, of science as applied to
metallurgy. Here, by simply giving a different chemical constitution
to the clay lining of the converter, it is found possible to eliminate
phosphorus--an element which has successfully withstood the attack of
the Bessemer system. Now, to quote the words of a German eulogizer of
the new method, phosphorus has been turned from an enemy into a friend;
and the richer a given ore is in that substance, the more readily and
cheaply does it seem likely to be converted into steel.
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