Scientific American Supplement, No. 417
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Various >> Scientific American Supplement, No. 417
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If the galvanometer be replaced by a telephone, no matter how the spiral
be moved, no sound will be heard, simply because the induced currents
produced consist of comparatively slow undulations, and not of sharp
variations suitable for a telephone. But by placing in circuit this
mechanical make and break arrangement the interruptions of the current
are at once audible, and by regulating the movement of the spiral I can
send signals, which, if they had been prearranged, might have enabled
us to communicate intelligence to each other by means of the earth's
magnetism. I show this experiment more with a view to illustrate the
fact that for experiments on induction both instruments are necessary,
as each makes manifest those currents adapted to itself.
The lines of force of light, heat, and sound can be artificially
produced and intensified, and the more intense--they are the more we
perceive their effects on our eyes, ears, or bodies. But it is not so
with the lines of magnetic force, for it matters not how much their
power is increased--they appear in no way to affect us. Their presence
can, however, be made manifest to our eyes or ears by mechanical
appliances. I have already shown you how this can be done by means of
either a galvanometer or a telephone in circuit with a spiral wire.
I have already stated that while engaged in these experiments I found
that as far as the telephone was concerned it was immaterial whether it
was in circuit with a spiral or not, as in either case it accurately
reproduced the same sounds; therefore, much in the same way as lenses
assist the sight or tubes the hearing, so does the telephone make
manifest the lines of intermittent inductive energy. This was quite a
new phenomenon to me, and on further investigation of the subject I
found that it was not necessary to have even a telephone, for by simply
holding a piece of iron to my ear and placing it close to the center
of the spiral I could distinctly hear the same sounds as with the
telephone, although not so loud. The intensity of the sound was greatly
increased when the iron was placed in a magnetic field. Here is a small
disk of iron similar to those used in telephones, firmly secured in this
brass frame; this is a small permanent bar magnet, the marked end of
which is fixed very closely to, but not touching, the center of the iron
disk. Now, by applying the disk to my ear I can hear the same sounds
that were audible to all of you when the telephone in circuit with a
small spiral was placed in front of and close to the large spiral. To me
the sound is quite as loud as when you heard it; but now you are one and
all totally deaf to it. My original object in constructing two large
spirals was to ascertain whether the inductive lines of force given out
from one source would in any way interfere with those proceeding from
another source. By the aid of this simple iron disk and magnet it can be
ascertained that they do in no way interfere with each other; therefore,
the direction of the lines proceeding from each spiral can be distinctly
traced. For when the two spirals are placed parallel to each other at
a distance of 3 ft. apart, and connected to independent batteries and
transmitters, as shown in Plate 7, each transmitter having a sound
perfectly distinct from that of the other, when the circuits are
completed the separate sounds given out by the two transmitters can be
distinctly heard at the same time by the aid of a telephone; but, by
placing the telephone in a position neutral to one of the spirals, then
only the sound proceeding from the other can be heard. These results
occur in whatever position the spirals are placed relatively to each
other, thus proving that there is no interference with or blending of
the separate lines of force. The whole arrangement will be left in
working order at the close of the meeting for any gentlemen present to
verify my statements or to make what experiments they please.
In conclusion, I would ask, what can we as practical men gather from
these experiments? A great deal has been written and said as to the best
means to secure conductors carrying currents of very low tension,
such as telephone circuits, from being influenced by induction from
conductors in their immediate vicinity employed in carrying currents of
comparatively very high tension, such as the ordinary telegraph wires.
Covering the insulated wires with one or other of the various metals has
not only been suggested but said to have been actually employed with
marked success. Now, it will found that a thin sheet of any known metal
will in no appreciable way interrupt the inductive lines of force
passing between two flat spirals; that being so, it is difficult to
understand how inductive effects are influenced by a metal covering as
described.
Telegraph engineers and electricians have done much toward accomplishing
the successful working of our present railway system, but still there
is much scope for improvements in the signaling arrangements. In foggy
weather the system now adopted is comparatively useless, and resource
has to be had at such times to the dangerous and somewhat clumsy method
of signaling by means of detonating charges placed upon the rails.
Now, it has occurred to me that volta induction might be employed with
advantage in various ways for signaling purposes. For example, one or
more wire spirals could be fixed between the rails at any convenient
distance from the signaling station, so that when necessary intermittent
currents could be sent through the spirals; and another spiral could be
fixed beneath the engine or guard's van, and connected to one or more
telephones placed near those in charge of the train. Then as the train
passed over the fixed spiral the sound given out by the transmitter
would be loudly reproduced by the telephone and indicate by its
character the signal intended.
One of my experiments in this direction will perhaps better illustrate
my meaning. The large spiral was connected in circuit with twelve
Leclanche cells and the two make and break transmitters before
described. They were so connected that either transmitter could be
switched into circuit when required, and this I considered the signaling
station. This small spiral was so arranged that it passed in front of
the large one at the distance of 8 in. and at a speed of twenty-eight
miles per hour. The terminals of the small spiral were connected to
a telephone fixed in a distant room, the result being that the sound
reproduced from either transmitter could be clearly heard and recognized
every time the spirals passed each other. With a knowledge of this fact
I think it will be readily understood now a cheap and efficient adjunct
to the present system of railway signaling could be obtained by such
means as I have ventured to bring to your notice this evening.
Thus have I given you some of the thoughts and experiments which have
occupied my attention during my leisure. I have been long under the
impression that there is a feeling in the minds of many that we are
already in a position to give an answer to almost every question
relating to electricity or magnetism. All I can say is, that the more
I endeavor to advance in a knowledge of these subjects, the more am I
convinced of the fallacy of such a position. There is much yet to be
learnt, and if there be present either member, associate, or student to
whom I have imparted the smallest instruction, I shall feel that I have
not unprofitably occupied my time this evening.
* * * * *
ON TELPHERAGE.
[Footnote: Introductory address delivered to the Class of Engineering,
University of Edinburgh, October 30, 1883.]
By Professor FLEEMING JENKIN, LL.D., F.R.S.
"The transmission of vehicles by electricity to a distance,
independently of any control exercised from the vehicle, I will call
Telpherage." These words are quoted from my first patent relating to
this subject. The word should, by the ordinary rules of derivation, be
telphorage; but as this word sounds badly to my ear, I ventured to adopt
such a modified form as constant usage in England for a few centuries
might have produced, and I was the more ready to trust to my ear in the
matter because the word telpher relieves us from the confusion which
might arise between telephore and telephone, when written.
I have been encouraged to choose Telpherage as the subject of my address
by the fact that a public exhibition of a telpher line, with trains
running on it, will be made this afternoon for the first time.
You are, of course, all aware that electrical railways have been run,
and are running with success in several places. Their introduction has
been chiefly due to the energy and invention of Messrs. Siemens. I do
not doubt of their success and great extension in the future--but when
considering the earliest examples of these railways in the spring of
last year, it occurred to me that in simply adapting electric motors to
the old form of railway and rolling stock, inventors had not gone far
enough back. George Stephenson said that the railway and locomotive were
two parts of one machine, and the inference seemed to follow that when
electric motors were to be employed a new form of road and a new type of
train would be desirable.
When using steam, we can produce the power most economically in large
engines, and we can control the power most effectually and most cheaply
when so produced. A separate steam engine to each carriage, with its own
stoker and driver, could not compete with the large locomotive and heavy
train; but these imply a strong and costly road and permanent way. No
mechanical method of distributing power, so as to pull trains along at a
distance from a stationary engine, has been successful on our railways;
but now that electricity has given us new and unrivaled means for the
distribution of power, the problem requires reconsideration.
With the help of an electric current as the transmitter of power, we
can draw off, as it were, one, two, or three horse-power from a hundred
different points of a conductor many miles long, with as much ease as we
can obtain 100 or 200 horse-power at any one point. We can cut off the
power from any single motor by the mere break of contact between two
pieces of metal; we can restore the power by merely letting the two
pieces of metal touch; we can make these changes by electro magnets with
the rapidity of thought, and we can deal as we please with each of
one hundred motors without sensibly affecting the others. These
considerations led me to conclude, in the first place, that when using
electricity we might with advantage subdivide the weight to be carried,
distributing the load among many light vehicles following each other in
an almost continuous stream, instead of concentrating the load in heavy
trains widely spaced, as in our actual railways. The change in the
distribution of the load would allow us to adopt a cheap, light form
of load. The wide distribution of weight, entails many small trains in
substitution for a single heavy train; these small trains could not be
economically run if a separate driver were required for each. But, as
I have already pointed out, electricity not only facilitates the
distribution of power, but gives a ready means of controlling that
power. Our light, continuous stream of trains can, therefore, be
worked automatically, or managed independently of any guard or driver
accompanying the train--in other words, I could arrange a self-acting
block for preventing collisions. Next came the question, what would be
the best form of substructure for the new mode of conveyance? Suspended
rods or ropes, at a considerable height, appeared to me to have great
advantages over any road on the level of the ground; the suspended rods
also seemed superior to any stiff form of rail or girder supported at a
height. The insulation of ropes with few supports would be easy; they
could cross the country with no bridges or earth-works; they would
remove the electrical conductor to a safe distance from men and cattle;
cheap small rods employed as so many light suspension bridges would
support in the aggregate a large weight. Moreover, I consider that a
single rod or rail would present great advantages over any double rail
system, provided any suitable means could be devised for driving a train
along a single track. (Up to that time two conductors had invariably
been used.) It also seemed desirable that the metal rod bearing the
train should also convey the current driving it. Lines such as I
contemplated would not impede cultivation nor interfere with fencing.
Ground need not be purchased for their erection. Mere wayleaves would
be sufficient, as in the case of telegraphs. My ideas had reached this
point in the spring of 1882, and I had devised some means for carrying
them into effect when I read the account of the electrical railway
exhibited by Professors Ayrton and Perry. In connection with this
railway they had contrived means rendering the control of the vehicles
independent of the action of the guard or driver; and this absolute
block, as they called their system, seemed to me all that was required
to enable me at once to carry out my idea of a continuous stream of
light, evenly spaced trains, with no drivers or guards. I saw, moreover,
that the development of the system I had in view would be a severe tax
on my time and energy; also that in Edinburgh I was not well placed for
pushing such a scheme, and I had formed a high opinion of the value of
the assistance which Professors Ayrton and Perry could give in designs
and inventions.
Moved by these considerations, I wrote asking Professor Ayrton to
co-operate in the development of my scheme, and suggesting that he
should join with me in taking out my first Telpher patent. It has been
found more convenient to keep our several patents distinct, but my
letter ultimately led to the formation of the Telpherage Company
(limited), in which Professor Ayrton, Professor Perry, and I have equal
interests. This company owns all our inventions in respect of electric
locomotion, and the line shown in action to-day has been erected by this
company on the estate of the chairman--Mr. Marlborough R. Pryor, of
Weston. Since the summer of last year, and more especially since the
formation of the company this spring, much time and thought has been
spent in elaborating details. We are still far from the end of our work,
and it is highly probable what has been done will change rapidly by a
natural process of evolution. Nevertheless, the actual line now working
does in all its main features accurately reproduce my first conception,
and the general principles I have just laid down will, I think, remain
true, however great the change in details may be.
The line at Weston consist of a series of posts, 60 ft. apart, with two
lines of rods or ropes, supported by crossheads on the posts. Each of
these lines carries a train; one in fact is the up line, and the other
the down line. Square steel rods, round steel rods, and steel wire ropes
are all in course of trial. The round steel rod is my favorite road at
present. The line is divided into sections of 120 ft. or two spans, and
each section is insulated from its neighbor. The rod or rope is at the
post supported by cast-iron saddles, curved in a vertical plane, so as
to facilitate the passage of the wheels over the point of support.
Each alternate section is insulated from the ground; all the insulated
sections are in electrical connection with one another--so are all the
uninsulated sections. The train is 120 ft. long--the same length as that
of a section. It consists of a series of seven buckets and a locomotive,
evenly spaced with ash distance pieces--each bucket will convey, as a
useful load, about 21/2 cwt., and the bucket or skep, as it has come to be
called, weighs, with its load, about 3 cwt. The locomotive also weighs
about 3 cwt. The skeps hang below the line from one or from two V
wheels, supported by arms which project out sideways so as to clear the
supports at the posts; the motor or dynamo on the locomotive is also
below the line. It is supported on two broad flat wheels, and is driven
by two horizontal gripping wheels; the connection of these with the
motor is made by a new kind of frictional gear which I have called nest
gear, but which I cannot describe to-day. The motor on the locomotive
as a maximum 11/2 horse-power when so much is needed. A wire connects one
pole of the motor with the leading wheel of the train, and a second wire
connects the other pole with the trailing wheel; the other wheels are
insulated from each other. Thus the train, wherever it stands, bridges a
gap separating the insulated from the uninsulated section. The insulated
sections are supplied with electricity from a dynamo driven by a
stationary engine, and the current passing from the insulated section
to the uninsulated section through the motor drives the locomotive. The
actual line is quite short, and can only show two trains, one on the up
and one on the down line; but with sufficient power at the station any
number of trains could be driven in a continuous stream on each line.
The appearance is that of a line of buckets running along a single
telegraph wire of large size. A block system is devised and partly made,
but is not yet erected. It differs from the earlier proposals in having
no working parts on the line. This system of propulsion is called by us
the Cross Over Parallel Arc. Other systems of supplying the currents,
devised both by Professors Ayrton and Perry and myself, will be tried on
lines now being erected; but that just described gives good results. The
motors employed in the locomotives were invented by Messrs. Ayrton and
Perry. They are believed to have the special advantage of giving a
larger power for a given weight than any others. One weighing 99 lb.
gave 11/2 horse-power in some tests lately made. One weighing 36 lb. gave
0.41 horse-power.
No scientific experiments have yet been made on the working of the line,
and matters are not yet ripe for this--but we know that we can erect a
cheap and simple permanent way, which will convey a useful load of say
15 cwt. on every alternate span of 130 feet. This corresponds to 161/2
tons per mile, which, running at five miles per hour, would convey 921/2
tons of goods per hour. Thus if we work for 20 hours, the line will
convey 1850 tons of goods each way per diem, which seems a very fair
performance for an inch rope. The arrangement of the line with only one
rod instead of two rails diminishes friction very greatly. The carriages
run as light as bicycles. The same peculiarity allows very sharp curves
to be taken, but I am without experimental tests as yet of the limit
in this respect. Further, we now know that we can insulate the line
satisfactorily, even if very high potentials come to be employed. The
grip of the locomotive is admirable and almost frictionless, the gear is
silent and runs very easily. It is suited for the highest speeds, and
this is very necessary, as the motors may with advantage, run at 2,000
revolutions per minute.
* * * * *
MACHINE FOR MAKING ELECTRIC LIGHT CARBONS.
One of the hinderances to the production of a regular and steady light
in electric illumination is the absence of perfect uniformity in the
carbons. This defect has more than once been pointed out by us, and we
are glad to notice any attempt to remedy an admitted evil. To this end
we illustrate above a machine for manufacturing carbons, invented by
William Cunliffe. The object the inventor has in view is not only the
better but the more rapid manufacture of carbons, candles, or electrodes
for electric lighting or for the manufacture of rods or blocks of carbon
or other compressible substances for other purposes, and his invention
consists in automatic machinery whereby a regular and uniform pressure
and compression of the carbon is obtained, and the rods or blocks are
delivered through the formers, in a state of greater density and better
quality then hitherto. The machine consists of two cylinders, A A',
placed longitudinally, as shown at Fig. 1, and in reversed position in
relation to each other. In each cylinder works a piston or plunger, a,
with a connecting rod or rods, b; in the latter case the ends of the
rods have right and left handed threads upon which a sleeve, c, with
corresponding threads, works. This sleeve, c, is provided with a hand
wheel, so that by the turning it the stroke of the plungers, a a, and
the size of the chambers, A A', is regulated so that the quantity of
material to be passed through the dies or formers is thereby determined
and may be indicated. In front of the chambers, A A', are fixed the dies
or formers, d d, which may have any number of perforations of the size
or shape of the carbon it is intended to mould. The dies are held in
position by clamp pieces, e e, secured to the end of the chambers A
A', by screws, and on each side of these clamp pieces are guides, with
grooves, in which moves a bar with a crosshead, termed the guillotine,
and which moves across the openings of the dies, and opening or closing
them. Near the front end of the cylinders are placed small pistons or
valves, f f, kept down in position by the weighted levers, g g (see Fig.
2, which is drawn to an enlarged scale), which, when the pressure in
the chamber exceeds that of the weighted levers connected to the safety
valve, f, the latter is raised and the guillotine bar, h, moved across
the openings of the dies by the connecting rods, h', thereby allowing
the carbon to be forced through the dies. In the backward movement
of the piston, a, a fresh supply of material is drawn by atmospheric
pressure through the hoppers, B B', alternately. At the end of the
stroke the arms of the rocking levers (which are connected by tension
rods with the tappet levers) are struck by the disk wheel or regulator,
the guillotine is moved back and replaced over the openings of the
dies, ready for the next charge, as shown. The plungers are operated by
hydraulic, steam, compressed air, or other power, the inlet and outlet
of such a pressure being regulated by a valve, an example of which is
shown at Fig. 1, and provided with the tappet levers, i i, hinged to the
valve chest, C, as shown, and attached to spindles, i' i', operating the
slide valves, and struck alternately at the end of each stroke, thus
operating the valves and the guillotine connections, i squared and i cubed. The
front ends of the cylinders may be placed at an angle for the more
convenient delivery of the moulded articles.--_Iron_.
[Illustration: MACHINE FOR MAKING ELECTRIC LIGHT CARBONS]
* * * * *
NEW ELECTRIC BATTERY LIGHTS.
There has lately been held, at No. 31 Lombard Street, London, a private
exhibition of the Holmes and Burke primary galvanic battery. The chief
object of the display was to demonstrate its suitability for the
lighting of railway trains, but at the same time means were provided
to show it in connection with ordinary domestic illumination, as it is
evident that a battery will serve equally as well for the latter as for
the former purpose. Already the great Northern express leaving London at
5:30 P.M. is lighted by this means, and satisfactory experiments have
been made upon the South-western line, while the inventors give a long
list of other companies to which experimental plant is to be supplied.
The battery shown, in Lombard Street consisted of fifteen cells arranged
in three boxes of five cells each. Each box measured about 18 in. by
12 in. by 10 in., and weighed from 75 lb. to 100 lb. The electromotive
force of each cell was 1.8 volts and its internal resistance from 1/40
to 1/50 of an ohm, consequently the battery exhibited had, under the
must favorable circumstances, a difference of potential of 27 volts at
its poles, and a resistance of 0.3 ohm.
When connected to a group of ten Swan lamps of five candle power,
requiring a difference of potential of 20 volts, it raised them to vivid
incandescence, considerably above their nominal capacity, but it failed
to supply eighteen lamps of the same kind satisfactorily, showing that
its working capacity lay somewhere between the two. A more powerful lamp
is used in the railway carriages, but as there was only one erected it
was impossible to judge of the number that a battery of the size shown
would feed. _Engineering_ says the trial, however, demonstrated that
great quantities of current were being continuously evolved, and if,
as we understood, the production can be maintained constant for about
twenty-four hours without attention, the new battery marks a distinct
step in this kind of electric lighting. Of the construction of the
battery we unfortunately can say but little, as the patents are not yet
completed, but we may state that the solid elements are zinc and
carbon, and that the novelty lies in the liquid, and in the ingenious
arrangement for supplying and withdrawing it.
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