IMPROVEMENTS IN ELECTRICAL CONDUCTORS APPLICABLE TO ELECTRIC RAILWAYS AND TO ELECTRIC SIGNALLING, AND IN APPARATUS CONNECTED THEREWITH
Year: 1881

page_text: LETTERS PATENT to John Perry, of Talgarth Road, in the County of
Middlesex, Electrician, and William Edward Ayrton, of Cowper Street, in the
County of Middlesex, Professor of Technical Physics; for an Invention of
"IMPROVEMENTS IN ELECTRICAL CONDUCTORS APPLICABLE TO ELECTRIC
RAILWAYS AND TO ELECTRIC SIGNALLING, AND IN APPARATUS CONNECTED
THEREWITH."
PROVISIONAL SPECIFICATION left by the said John Perry and William
Edward Ayrton at the Office of the Commissioners of Patents on the 24th
February 1881.
JOHN PERRY, of Talgarth Road, in the County of Middlesex, Electrician,
and WILLIAM EDWARD AYRTON, of Cowper Street, in the County of Middlesex,
Professor of Technical Physics. "IMPROVEMENTS IN ELECTRICAL CONDUCTORS
APPLICABLE TO ELECTRIC RAILWAYS AND TO ELECTRIC SIGNALLING, AND IN
APPARATUS CONNECTED THEREWITH."
Our Invention is designed for the better and more convenient isolation of the
electric conductor for the transmission of power in electric railways, and further, by
that method of insulation to give an easy and simple indication to the signalman
of the position of a train or carriage at any point of its travel, and thus a simple
means of electrical signalling throughout the line.
In electrical railways it is usual to attempt to insulate a rail to conduct the
necessary electricity, either one of the two rails on which the carriage or carriages
rest, or a third rail, and to collect electricity for the motive power from this so
called insulated rail by rollers or brushes of wire fixed to the carriage. It is
extremely difficult to properly insulate a rail of this kind as it must have many
supports, and at each support there is a leakage, hence such a rail as at present in
use cannot be satisfactorily employed for long distances.
Our improved apparatus consists of an insulated wire cable or other conductor
or conductors placed either alongside, above, or underneath the railway or in any
other suitable position where it can be perfectly insulated by a suitable bitumenous
[Price 811

page_text: cloth or other nou conducting covering, and if uncovered on the fewest possible
number of supports above ground perfectly insulated, as in the case of telegraph
wires. We use also by preference an auxiliary rail which does not carry the
rolling traffic, but which is fairly well insulated on elastic supports, such as spiral
springs. This rail is also divided into sections which are fairly well insulated 5
one from another. Contact between any section of this elastic rail and the
before described carefully insulated conducting wire or cable is effected by the
pressure of a roller or brush from any carriage pressing upon the elastic rail,
and thereby causing a projecting button or stud thereon to touch a projecting
contact piece connected to the said conducting and insulated wire or cable.
These projecting studs and contact pieces are fixed at short intervals along the
line so that at least two or three simultaneous contacts are ensured in the length
of an ordinary train. The contact between the insulated section of the elastic
rail and the prime insulated conductor, so effected by the roller, brush, or
other device causing pressure upon the elastic rail serves to transmit the motive
current of electricity from a stationary generator to any electric machine employed
for propulsion of a carriage or train. The electricity leaves the said carriage at
any suitable point of contact of wheels with an uninsulated rail. It is evident
that the fairly insulated elastic rail is only made use of for the conduction of
the main current at such insulated sections over or near which the travelling
carriage may happen to be. We thus avoid the very considerable leakage
consequent upon the use of an imperfectly insulated rail of considerable length with
a corresponding large number of points of support through each of which some
leakage of the motive electric current must pass. In making contact between the
sectionally insulated rubbing rail and the well insulated wire cable or other
conductor of the motive electric current we may employ any modification of stud
and contact piece that may be suitable.
We may modify our apparatus by dispensing with a third elastic rubbing rail
as before described, insulating instead by the best known means one of the carrying
rails, dividing and insulating the said rail at the usual fish plate or other joint into
sections of suitable length insulated from one another as perfectly as may be.
Contact between such sectionally insulated rail and the main well insulated con-
ductor may be made by the wheel tire or special roller pressing upon long rods
parallel to the rail with contact pieces at their ends.
We do not restrict ourselves only to the specified means of effecting contact
between the rubbed rail and well insulated independent conductor, inasmuch as
our improvement consists essentially in employing only a short part or parts of
the sectionally insulated rubbed rail as conductors at any one time, viz., those to
which the travelling carriages are nearest, the electricity being conveyed from the
terminal generator to the required points of contact through a well insulated
independent condutor.
We may use one well insulated conductor only for the whole length of railway,
or we may employ a number of detached well insulated conductors over various
sections of the railways as desired, which may be placed in contact automatically by
electric or mechanical means or by the signalman, with the main continuous con-
ductor to serve the particular section over which the train is passing. The contact,
as before described, with the rubbed rail would in this latter case be made with
those auxiliary sectional well insulated conductors.
Our improved apparatus, as before described, of a sectional insulated rubbed rail
making successive contacts with the main insulated conductor enables as to apply
a most efficient means of information to the signalman as to the exact position of
the train or trains on either side of his station. This may be effected conveniently
by a recording galvanometer in the signal box, showing visibly the increase or
decrease of resistance in an independent circuit, and short circuited by the same
contact buttons continuously operated by the electrical circuit caused by the moving
train. This portion of our Invention is applicable to signalling purposes on ordinary
railways operated by steam or other locomotives, provided our improved apparatus

page_text: are
of a sectionally insulated rod or rail and continuous insulated conductor
short circuited by a wheel, roller, or suitable means attached to any moving train.
In some cases instead of using sectional well insulated conducting wires, cables,
or rods connected automatically or at will with the main insulated wire, cable, or
conductor we may use lapping insulated conducting cables or wires of different
lengths to serve the different successive portions of the railway.
We may further simplify our contact apparatus by using sectional insulated
lengths of rubbing rail considerably longer than the length of the moving train,
and in such case the contact with the independent well insulated conductor is
effected by the automatic action of an electric magnet at each end making contact
for the section just to be entered upon, and simultaneously breaking contact with
that just left.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Perry and William Edward Ayrton in the Great Seal
Patent Office on the 24th August 1881.
JOHN PERRY, of Talgarth Road, in the County of Middlesex, Electrician,
and WILLIAM EDWARD AYRTON, of Cowper Street, in the County of Middlesex,
Professor of Technical Physics. "IMPROVEMENTS IN ELECTRICAL CONDUCTORS
APPLICABLE TO ELECTRIC RAILWAYS AND TO ELECTRIC SIGNALLING, AND IN
APPARATUS CONNECTED THEREWITH."
Our Invention is designed for the better and more convenient insulation of the
electric conductor for the transmission of power in electric railways, and for
furnishing an automatic block system without the use of signalmen, and further by
that method of insulation to give an easy and simple indication of the position of
a train or carriage at any point of its travel, or simultaneously of any number of
trains or carriages, and thus to furnish a simple means of electric warning
throughout the line.
In electric railways it is usual to attempt to insulate either one of the two rails
on which the carriage or carriages rest, or a third rail, and to collect electricity for
the motive power from this so called insulated rail by rollers or brushes of wire
fixed to the carriage. It is extremely difficult to properly insulate a rail of this
kind as it must have many supports, and at each support there is a leakage. Hence
such a rail as at present in use cannot be satisfactorily employed for long distances.
Another plan recently adopted is to insulate by means of posts and telegraph
insulators the wire conveying the current for propelling the train, and to maintain
a continuous sliding connection between this wire and the moving train by means
of a secondary wire, one end of which is attached to the train or carriage, and the
other to a small jockey running on the wire insulated on the posts and pulled on by
the moving train. But in summer, when the main wire is slack, it will be difficult
to carry out this system for trains moving at high speeds.
Our improved apparatus consists of an insulated wire cable or other conductor
or conductors, placed either alongside, above, or underneath the railway, or in any
other suitable position, and the insulation of which is maintained by gutta percha,
india rubber, &c., or by paraffin or other oils, or by its being supported on
insulators. This conductor, or conductors, is automatically, or at will by a signal-
man or other person, electrically connected successively to one or more sections of
a rail in the neighborhood of the moving train. This rail, which may or may not
be that on which the train runs, and which may be rigid or somewhat elastic, is
divided into sections fairly well insulated from one another and from the earth by
the methods described further on. Since then leakage to the earth of the current
which propells the train can only take place from that section or sections of the
rail which are at any moment electrically connected with the continuous insulated
conductor, the loss of power by leakage of electricity to the ground will be very
much less than in the case of a single imperfectly insulated rail, such as been
hitherto employed for electric railways, and which if of considerable length, with
its corresponding large number of points of support, would possess a very large
number of points at which leakage of the motive electric current would continually
take place.
Our method will be best understood from the following examples of its applica-
tion. In Figures 1 and 2, Sheet 1, A B is a copper or other metallic rod resting on
the top of and fastened to a corrugated tempered steel disk DD (of the nature of
but much stronger than the corrugated top of the vacuum box in an aneroid

page_text: barometer), and which is carried by and fastened to a thick ring E E, made of
ebonite or other insulating material, either by a metal ring or by six screws and
washers. The ebonite ring is itself screwed to the top of the circular cast iron box,
which latter is fastened to the ordinary sleepers by wooden or iron pins or screws.
In these and in all the other Figures, sections of insulating material are indicated
by the shading lines being closer together than in the case of the metallic sections.
The Figures are drawn to scale, and the scale employed is shown from a foot rule
drawn on each Sheet. The rail A B and the corrugated steel disks DD, have
sufficient flexibility that two or more of the latter are simultaneously depressed by
an insulated collecting brush or roller carried on one or all of the carriages com-
posing the train, or on the single carriage if there be not more than one. Depressing
any one of the corrugated steel disks brings the stud E, which is mechanically and
electrically connected with the rod or rail A B, into contact with the stud G, which
is electrically connected with the main iusulated cable previously referred to, or
with one of them if there be more than one. This connection is made either by
means of a gutta percha or other insulated wire HHH, or by HH being the
main cable itself brought up into the box. To prolong the contact the stud G is
supported by a spiral spring as shown in the Drawing, so as to be depressed
somewhat by F.
In the neighbourhood of a train the rail A B is then electrically connected with
the well insulated cable or conductor at two or more points or contact boxes, and
the train receives electric power through the brushes or rollers under the carriages
or under some of them, and the current after passing through a suitable
electro moter on one or all of the carriages returns by means of one or both
of the ordinary uninsulated rails of the line, good electric contact between
the successive pieces of rail forming the ordinary permanent way and used
as the return wire being ensured by pieces of flexible wire being attached
if necessary in addition to the ordinary fish plates. The mode of insulating
one section of our auxiliary rail or conductor is shown in Figures 3 and
4, Sheet 1. It will be seen that as only a short piece of the auxiliary rail A. B is
at any moment in connection with the main cable the insulation of the ring E E
will be quite sufficient even in very wet weather, especially if the ring be made
with a circular lip, as shewn in the Figures, and similar to that forming the cup of
a telegraph insulator. But the insulation of G, which is always connected with the
main cable, or with one of them if there be more than one, must be much more
perfect, and hence the arrangements shewn in the Figures have been adopted by us.
In Figure 1 a rod composed of rigid insulating material, such as ebonite, porcelain,
earthenware, &c., and of comparatively small section, supports G, and as the inside
of the cast iron box is always fairly dry and clean the surface insulation of such a
rod will be very considerable. Surfice leakage down the outside of the gutta
percha or other insulated wire HH is prevented by cutting the end portion of the
insulating coating in the form of a pointed pencil according to the manner well
known to and used by electricians. Or the surface of the insulating rod and of the
end of the wire may be smeared over with paraffin or other oil as employed by
Mr. Cromwell Varley. Or the cast iron boxes themselves may be filled with paraffin
or other suitable oil to prevent the possibility of moisture entering from outside,
and this may be done without impairing the efficiency of the contact between E
and G when the rail A B is depressed by a neighbouring train or carriage, for we
have experimentally proved that although two pieces of metal separated by a very
small visible distance in paraffin oil are very well insulated from one another, there
is but a very small resistance between them if they are pressed together in the oil
even with a comparatively small force. When the boxes are thus filled with oil
there is attached to each box a small stand pipe used for filling, and by means of
which the level of the oil may be seen at any time, or all the boxes may communicate
by means of tubes, each of which has a stop cock kept open except when repairs
are being carried on.
Another plan we employ for securing very high insulation, and which does not

page_text: necessitate the steel disc DD or the insulating ring EE fitting perfectly water
tight into the top of the cast iron box, is shewn in Figure 2, and consists in bunging
up the insulated wire HH connecting G with the main cable through the centre
of an insulator shaped somewhat like an ordinary telegraph insulator, and causing
the outer surface of the insulated wire HH to adhere to the inside of the tube of
the insulator by the employment of a proper adherent. There will be then no
surface leakage along HH but only along the outside of the insulator I, I, which
latter may be rendered as small as we please by the insertion of a layer of insulating
oil according to the manner described by Mr. Varley in bis Patent No. 206, of
1860. Small taps J, which may be closed with an ordinary stop cock, as shewn in
the Figures, or by means of a key, may be fixed to the cast iron boxes to allow any
water being run out of them should by chance any get in from the line being
flooded for a lengthened period, during which time however our system of electric
railway will not, like the system hitherto employed of using one continuous badly
insulated rail, cease to work efficiently. When using either our form of contact
box shown in Figure 1 or that shewn in Figure 2 we place them at distances from
one another varying with circumstances, but usually 20 to 50 feet is an average
distance between the neighboring ones.
Another application of our method is shewn in Figure 5, Sheet 1, and differs only
from that shewn in Figure 2 in that the auxiliary insulated rail instead of
extending all along the line and being carried by the boxes is merely an insulated
bar the length of each carriage and carried under the carriage. All the bars under
the carriages comprising any one train are electrically connected together and with
one terminal of the electro-moters and one or more of the carriages. On the top of
the corrugated tempered steel disk DD Figure 5, is fixed an elastic fork K K
which is bent slightly sideways by the rod L carried by the moving carriage, but
which is sufficiently rigid to depress the steel disk and make contact between E
and G and therefore between the rod L and the main cable.
Figure 6, plate 1, shows a contact box we employ, when, instead of the main
cable being insulated with gutta percha, india rubber, or other such material, it is,
in the manner successfully employed by Mr. Brooks, merely covered with dried
cotton, hemp, or other fibrous substance, and immersed in a pipe filled with
anhydrous paraffin oil under pressure. In this case our contact boxes, which are,
as before, from 20 to 50 feet apart, and fastened to the sleepers with wooden or
iron screws or pins passing through holes in the casting, as shewn in plan
Figure 7, Sheet 1, are connected together with iron gas pipes. We employ a special
form of coupling, as shewn in Figure 6, to connect these pipes with the boxes, and
of such a length that on unscrewing the coupling, we can remove a defective piece
of pipe, and replace it with a good piece, or we can cut out a defective piece of the
cable and pull in a good piece, sufficient slack being coiled up in the boxes to enable
the joints to be easily made. The fibrous covering, which is wrapped for a thickness
of about a quarter of an inch on the conductor to mechanically protect it from
touching the iron pipes, we remove for a short distance inside each contact box and
screw, or solder, or screw and solder, a piece of metal P onto the conductor of the
cable, so as to make good electric contact with it. P is also electrically connected
by means of the wire Q with the metallic spring R, supporting the metallic stud G,
both being carried by the bracket S rigidly attached to the collar EE, made of
ebonite or other suitable insulating material. As the flow of liquid through the
iron gas pipes is very slow, even under considerable difference of pressure, since the
cable covered with cotton, hemp, jute, or other fibrous material nearly fills up
the pipes, there will be but little leakage even when a pipe is open. To avoid
however the oil, which is practically confined in each contact box, bursting open
the box when the corrugated steel top is suddenly pressed down by the presence of
a train, an air-spring T is attached to every coupling, and into which the oil is
temporarily pressed during the depression of the top of the box. Or the air spring
may be made in the form of an elastic compressible metal vessel, filled with air and

page_text: entirely closed, placed in each contact box and weighted so as not to float up and
make accidental contact between G and D. To allow all the air to escape when
filling the boxes with oil, we remove a small screw plug 6 which closes a small tube
bored through the pin attaching the auxiliary insulated rail A B to the steel disks,
and when the oil is observed to ooze out through the small tube, the screw b is
fastened in tightly. As the insulation of the main cable is with the arrangement
shown in Figure 6 extremely perfect, even when the whole contact box is covered
with water, the auxiliary rail A B may be nearly on a level with the ground.
Figures 8 and 9, Sheet 1, show the longitudinal and transverse section of a
different mode which we employ in carrying out our method of dividing our
insulated conductor or rail into sections fairly well insulated from the earth and
from one another, and connecting with the main cable only that section or sections
which is in the immediate neighbourhood at any moment of the moving train.
A B is a slightly flexible metallic tube fastened to to the top of the corrugated steel
disks D, D, in the manner to be described, and supported in position as shewn.
This metal tube contains the main cable CC, which may be insulated with gutta
percha, india rubber, &c., or simply lapped with cotton or other fibrous material,
and the tube kept full of paraffin or other oil under a slight pressure. A hole is
first bored in the metal tube, either before the tube is sent out from the factory, or
in the field, and the cable having been drawn into the tube, is at the position of
the hole pushed away from the hole to the opposite side of the tube, but kept
symmetrical with reference to the hole. A solidifying insulating cement a a is
then formed around the cable so as to fix its position.
A smaller hole is now bored through the insulating coating and into the metallic
conductor for a certain distance, after which the rod PG is rigidly screwed in. A
small quantity more of the insulating compound is now poured around the rod,
the special form of insulator II shewn in Figures 8 and 9, slid over the rod and
fastened rigidly to the metallic tube A. B by means of the tightening pieces T, T.
The tube, the cable, the rod, and the insulator, as well as the centre of the corru-
gated steel disk, are thus all rigidly fastened, and are depressed as one when the
collecting brush or wheel which is under one or more of the carriages composing
the train presses on the tube in the neighbourhood of the particular contact box in
question. But the conductor of the cable is, by the method of fixing just described,
but to which we do not restrict ourselves for fulfilling this object, well insulated
from AB and D D. Depressing the tube brings the stud G in contact with F,
which latter is connected by a slightly flexible metal band SS connecting F
electrically with the metal collar QQ, the disk DD, and the metallic tube Å B.
But while it is necessary that the insulation of the rod PG should be very good,
as this rod is always in connection with the main cable, the insulation of the outer
tube and disk need not be nearly as perfect, since leakage from it can only occur
when the the train is in the immediate neighborhood of a contact box; it is
sufficient therefore to support the tube on jars EE, made of earthenware, porcelain,
or other rigid insulating material, the efficiency of which we increase by shaping
this jar with a conical lip, as shown, similar to the cup of an ordinary telegraph
insulator. The insulating jar which carries the metal collar QQ, as shown, is
itself fastened to the sleeper by a pin or screw, a wooden waster being inserted to
prevent damage to the jar. Figures 10 and 11 show the transverse and horizontal
longitudinal section of one of our forms of insulated joint which we insert between
two portions of the pipe, the parts sbaded with closer lines being, as before, made
of ebonite, or other insulating substance, while the remainder is composed of metal..
If the tube contains oil under pressure then we add a stuffing box at each insulated
joint, but in either case the top of the tube at a junction is quite smooth to allow
of the contact brush or roller running easily over it.
When carrying out our system of improved electric railway by using any one of
the preceding contact boxes we add, if desired, the following means for enabling
the signalman or other person at the terminus or elsewhere to see at any moment

page_text: the exact position on a map of every train on every line:-Figure 12, Sheet 1,
shows fitted to the contact box last described the arrangement necessary to be
added according to one of the methods which we employ for carrying out our
system of graphically showing the position of a train. Each line is as usual
divided into sections which are blocked, varying in length from a few hundred
yards to several miles, depending on the amount of traffic. For each section one
thin insulated wire goes from the terminus, signal box, or other place where is the
map of the line and where it is desired to see the motions of the trains, and enters
into each of the contact boxes in that particular section. W.W, Figure 12, Sheet 1,
shows this insulated wire led up through a tube made of porcelain or other insulated
material, and made to adhere to the inside of this tube for the greater part of its
length, partly that the wire may be held rigidly in position, and partly to avoid surface
leakage down the outside of the gutta percha, india rubber, or other coating of the
wire. Rigidly attached to the end of the conductor of this thin insulated wire is a
metallic spring T, and an upright piece of metal UV expanded at the bottom and
fastened under the head of the bolt which goes into the sleeper, carries at its top a
small spring U bent at right angles to the upright portion so that U comes just
over T.
A small horizontal pin, of ebonite, R carried by the rod PG presses the
spring U into contact with T when the disk DD is depressed by the passing train,
and so puts T to earth, since UV is, by means of an uninsulated wire, connected
with the uninsulated rail or rails of the permanent way used as the return circuit
for the main current driving the train. As a train or carriage passes over each
contact box, it not only connects the tube A. B electrically with the cable inside it
in the manner previously described, but it, in addition, puts an earth on the fine
insulated wire belonging to the particular section of the block system in which the
train is at the time. Although the insulation of the small ebonite pin R will be
fairly good since it is kept tolerably clean and dry from being in the inside of the
contact box, it may be noticed that a little surface leakage along this small
insulating pin is of no consequence, first, because the pin is only in connection with
the earth when the main cable conveying the current driving the train so in
connection with the tube AB during which short time there will be greater
surface leakage down the sides of the insulating jars supporting the tube than
along the pin R; secondly, as the ebonite pin first touches the earth contact V
before the spring T attached to the end of the auxiliary wire W W no leakage of
the main current along the pin can enter this auxiliary wire and interfere with the
current made to flow along this wire in the manner about to be described. We
have seen that while the train or carriage passes each contact box it puts on earth on
the auxiliary fine insulated wire, but just as the position of an earth fault on an
otherwise well insulated wire can be accurately determined by electrical testing
from either end, so we arrange in the following way, that the varying position of
the earth fault, that is, if the moving train, shall be automatically recorded. In
one of our plans we place at the spot where the progress of the trains is to be
graphically shown on the map of the line, a galvanic cell or cells of sufficiently
constant electromotive force that the current flowing from this cell or cells through
the auxiliary thin wire measures and automatically records on a special form of
galvanscope about to be described the resistance of the wire up to the place where
the earth contact is at the moment put on, that is, the distance up to the train.
When, however, the map is at a place where there is an engine for driving the
dynamo electric machine or machines used for generating the current propelling
the train, then we fix a small magneto electric machine so as to be driven at a
perfectly constant speed by this stationary engine, and so therefore as to produce a
perfectly constant electromotive force.
In the map there is cut a slit of the same shape as the railway line, or simply
straight if it be preferred, with the names of the stations, distances, &c., marked
along it, such as is shown in Figure 13, Sheet 1. Behind the map a light pointer
c, p, turns about the centre c, and which can be seen only where it crosses the

page_text: slit since the map, which is made of cardboard, thin wood, or other suitable
material is opaque. The pointer is attached to the needle of a galvanoscope, and
which is more or less deflected by the current sent by the galvanic cell or magnet
electric machine through the thin auxiliary insulated wire. For each section of
the block, which of course may contain any number of sections of our insulated
rail, or conductor, or tube A B, there is one thin insulated auxiliary wire and ore
galvanoscope, hence as a train moves, stops, or backs on any one of the sections of
the block, an observer sees a spot on that portion of the slit corresponding with
the section in question moving, stopping, or backing at exactly the same relative
rate. The map, Figure 13, shows three sections of the block system, a train being
on the middle section, and none on the first and third, so that the pointers of the
first and third galvanoscopes are quite out of sight, corresponding with no earth
contact on the thin insulated wires belonging to either the first or third sections.
In Figure 1, a, b, c, represent also respectively the insulating pin, the earth spring,
and the spring attached to the end of the thin auxiliary wire used for graphically
recording the position of the trains. It is to be observed that this system of
automatically recording on a map the position at every moment of every train,
and which cannot be accomplished with any system of railway, electric or other-
wise hitherto employed, is an addition to our main Invention for diminishing the
loss of power hitherto experienced in electric railways, and may or may not be
added without affecting our main arrangement of apparatus.
In all our arrangements previously described the distance between each contact
box and the next varies from about 20 to 50 feet, so that there are several contact
boxes in each section of our insulated rail, and several sections of an insulated rail
in one section of the line blocked, but the following illustrates one of our methods
for making each section of our insulated rail or conductor, which is rubbed by
passing train a mile or more in length, in fact as long as the goodness of the
particular system employed to insulate the rubbed conductor will allow. In this
case we arrange that the electric connection between the main cable and the
rubbed conductor of any section shall be automatically, or by a signalman at will,
made when the train enters the section, and automatically, or at will by a signal-
man, broken as the train leaves the section. It has to be noticed that the reason
wby all electric contacts hitherto devised for being worked automatically by the
rapid passage of a train have failed, is because they have been designed apparently
in ignorance either of the laws of dynamics or of electricity. They might perhaps
bave worked with slow trains running in a dry country, but must necessarily have
failed for express trains passing them at the rate of sixty miles an hour, or in
countries where there was much damp, rain, or possible flooding of the line. We
however after due consideration of the shock and strains produced by a rapidly
moving train of the possible swaying from side to side, which occasionally occurs
in trains from the rails being worn uneven or from other causes, as well as after
careful consideration of the methods of electric insulation necessitated from con-
tinued rain, accumulation of melting snow, and possible flooding of the permanent way
(W. E. A.) have devised in detail systems which will work automatically for electric
railways in the dampest country and for trains running at the highest speeds.
The automatic method of contact we employ when the sections of our rubbed
insulated conductor are long will be best understood from the following examples
of its application:-
1-2, 2-3, 3-4, 4-5, Figure 14, Sheet 2, are four long sections of our insulated
rubbed conductor, each half a mile or a mile more in length, and which are
passed over successively by a moving train, the ordinary direction of motion of
which is shown by the arrows. In Figure 14 the line has been bent round to
enable a length of some miles to be symbolically represented in the Drawing.
The insulated conductor, of which 1, 2, 3, 4, 5, are the insulated joints separating
the sections, may be the nail bearing the weight of the train, indicated by the
double line in the symbolical Drawing, Figure 14, in which case the main current

page_text: will be led into the electro-motor or electro-motors on one or more of the carriages,
by means of the wheels or a wheel on one side of the carriages, and which wheel
or wheels must therefore be insulated from the wheels on the other side, and
through which the return current passes to the other rail, uninsulated, carrying
the train; or the uninsulated conductor may be distinct from the rails of the
permanent way, and placed in any convenient position so as to be rubbed by a
brush or roller on one or more of the carriages. 3, Figure 14, represents our
nornial contact box, one of which may be placed at each of the distant insulated
junctions of our rubbed rail; or if it be desired to add our automatic absolute
block system, then at certain of the insulated junctions of the rubbed rail we
employ our block contact box, represented symbolically by 1 and 4, and at the
insulated junction next passed over by the carriage or train moving in its ordinary
direction, indicated in the Figure by the arrows, we place a form of contact box,
représented symbolically by 2 and 5. The mechanical and electrical details of all
these different forms of contact box are shewn in Figure 15, 16, and 17, 15 being
a longitudinal section parellel to the rails, and 16 a vertical section of 15
through X X, and 17 through Y Y. It is to be remembered that the com-
parative complexity of Figure 15 is due not to any complexity in our normal
contact box, 3, Figure 14, and which alone may be used, if it be desired, at all the
distant insulated junctions of this form of our electric railway, since it contains all
the mechanism necessary for automatically supplying motive power to each section
as entered on by a train, and for automatically cutting off the power from each
section as left by a train, and so diminishing the loss of electric power arising from
leakage, but the comparative complexity of Figure 15 arises from its showing in
addition the mechanism we employ in our automatic absolute block system for
rendering collisions impossible, since, as will be seen further on, this system not
only automatically deprives an otherwise colliding train of all motive power, but
in addition automatically puts on a powerful electric brake. Contact boxes 1, 3,
and 4 we have designed so as to act when run over by a train going in either
direction so as to allow of a train in section 25 or a train in the section before 2
backing if necessary; but contact boxes 2 and 5 are only intended to be run over
in the direction of the arrow; for a train after passing 2 or 5 must not stop and
back into the section 21 or 54, since, as will be seen further on, although the mere
passage of a train over 2 automatically makes it impossible for a train following
to pass 2 until the first train has passed 5, it does not prevent a train entering the
section 12, and which might be run into were the first train to back past 2.
Indeed this is carrying out the rule already followed on double line ordinary
railways, viz., that a train after passing a signal box must not stop and back into
the section just left, since a following train has probably been allowed to enter this
section on the first train quitting it, and unblocking thereby the section.
Let us now consider the actions which take place when a carriage or train passes
over our normal contact box 3, Figure 14. The two plungers shown in detail
AB, a b, Figures 15 and 17, are in succession pressed down by the flange on each
wheel of a carriage, and instantly fly up again after the passage of the wheel, as
they are attached to very stiff spring plates, one of which is shown in section CH,
Figure 16, fastened by means of nuts H to the top of the back of the cast iron box
containing the apparatus, and which box is let into a hole dug in the ballast of the
permanent way. The rapidity of action of the depressing force is diminished by
the pieces of steel JK, jk, which come into contact with the flange of the wheel
being somewhat rounded, as shown in the Figure, and in calculating the amount
of downward motion of the plungers we have allowed for the wearing away of the
tires of the wheels. The plate CH shown in the Drawing is so proportioned that
the impact given by the flange to C is reflected from the fixed bearing at the back.
of the cast iron box to the plunger AB without causing it to jam. The lower ends
of the plungers B, b, are attached by pivots to the tops of two corrugated tempered
steel disks DD, dd, closing two holes in the top of the cast iron box, and to the

page_text: lower sides of these disks are fastened two short plungers L, l, one of which, with
the steel disks, &c., is shown enlarged in Figure 18. The depression of each of the
plungers fulfills two distinct objects, the one to depress the ends M, m, of the levers
MN, mn, which are pulled up by springs S, s, the other to break the electric
contact between R and V or r and v, and make contact between R and E or r and e.
The depression of the levers brings E or f into contact with GF, which is a flat
metallic spring supported, as shown in Figure 15, from a piece of ebonite or other
insulating material fixed to the bearing of the spring M N, and also attached by
a piece of ebonite to the end of this lever is forked at the end, as shown in section
Figure 16, so as to make good contact with G. The fixed end of the spring F is
electrically connected with the insulated section of the rubbed conductor in advance
of the contact box, and the spring f, constructed like F but carried by the lever mn,
is electrically connected with the insulated section of the rubbed conductor behind
the contact box; thus at contact box 3, F is connected with the section 34, and ƒ
with the section 2-3. G is a metallic cap cemented onto the top of the insulator I,
Figures 15, 16, and at a normal contact box is, by means of a screw or solder, or
both, connected with the main cable or with a suitable insulated wire, which is
itself connected with the main cable 22.
The train T, Figure 14, then moving in the direction of the arrow, depresses the
plunger AL first, and connects the main cable with the insulated rubbed conductor
of section 34, while on the other hand if the train be moving in the opposite direction
it first depresses plunger al, and makes contact between the main cable and the
insulated conductor of the section 23, in either case supplying electric power to the
section the train or carriage is about to enter. But as both plungers are depressed
whichever way the train be moving we employ the following method among others
to prevent the depression of the second plunger whichever one it may happen to be,
depending on the direction of motion of the train producing the effect above referred
to-Let a be depressed first, then as the end n of the lever mm rises it is caught by
the spring catch p, which tends to fly inwards, and n is locked, as shown in Figure 19;
but the end of p is not quite home under the head of n, that is, p would go further
in were it not for the elbowed shape piece of metal between the springs, which
(W. E. A.) turns on a horizontal axes through o, and which is prevented from being
deflected partly from the action of a small spring, not shown in the Figure, tending
to keep it in its normal symmetrical position, but mainly from the pressure of the
spring P, which, like p, also presses inwards; but on the flange of a wheel of a
carriage pressing down the plunger AL, the spring P is deflected outwards, and its
pressure on the elbowed shaped piece of metal is thereby (W. E. A.) removed, p then
flies home under the head of n, and turns the elbow until its left hand side is at
right angles to P, as shown in Figure 20; P then cannot fly back, and the head of
the lever M N cannot be locked in its upper position. Although then every time a
wheel passes over the plunger AL, the train going from right to left, a contact is
made between the main cable and the section 34, which the train is leaving, this
contact is but momentary, and is not maintained like that between the main
cable and the section 3-2, which the train is entering.
In addition to the operation performed by the depression of each plunger above
described, there is another previously referred to, viz., the breaking of the electric
contact between r and u combined with the making of the contact between r
and e, and it is this latter action which automatically disconnect the main cable
from each section of the insulated rubbed rail or conductor as the train or carriage
enters the next section. Qq, Figures 15 and 16, and shown in contact boxes
1, 2, 3, 4, 5, Figure 14, are the pole-pieces of a horse shoe electro magnet so placed
that on a current being sent through it, the springs P, p, are both attracted
outwards, and thereby unlock that one of the levers MN, mn, which was
previously locked, and which is pulled sharply back against the stop V, shown in
Figures 15, 16, by the spring s, Figure 18, thereby breaking the electric contact
between F or f and G. One terminal Q of each of these electro magnets is, by

page_text: means of the insulated wire Q W, joined with the main cable, represented by the
thick line Z Z, Figure 14, and the other terminal q is, by means of the piece of
insulated wire qw, x, joined to the pin r, fastened to the second of the two
plungers depressed by the passing train or carriage at the contact box next in
advance of that containing the electro magnet in question. Consequently, as e is in
contact with the earth or return circuit, the depression of the second plunger sends
a current for a short time from the main cable through the liberating electro-
magnet Qq, of the lost contact box passed, and so takes off the current from the
section the train is leaving. It will be observed that whichever way a train or
carriage be proceeding this action occurs at each of the contact boxes, excepting
1 and 4, where there is no pin r on the plunger AL, which would be the second
plunger depressed by a train, that is, running against the arrows; but as a
train, as already explained, never backs over 2 or 5, it follows that if it backs
over 1 or 4, then sections 2-1 or 5-4, which it is leaving, must be receiving
current through contact box 1, or contact box 4 respectively, and not through the
contact boxes 2 or 5; hence, although the motion of the plunger al of 2 and of 5
act respectively on the electro magnet Q 9 of 1 and 4, there is no necessity for the
plunger a 1, of 1 and of 4 to act on the liberating electro magnet Qq of 2 and 5
respectively. It will be further observed that when the second plunger of any
particular contact box is depressed, no current is sent through the liberating
electro magnet of that contact box since the connection between R and V, or
between and u is broken by the depression of the plungers; hence the motions
given mechanically to the springs P p are not interfered with by electro magnetic
attractions. At a normal contact box 3 the end q of the electro magnet Qq is
connected by a wire with both U and u, whereas at the other forms of contact
box is only connected with V or u. This produces the result that whereas the
contact of r with e in contact box 5 sends currents through the electro magnets of
all the contact boxes 4, 3, and 2 (the current however flowing through the
electro magnet of the nearest contact box 4 being the strongest of them all), it
produces no effect on the electro magnet of any contact box, such as 1 in the rear
of 2. Similarly the contact of R with E at 2 acts on the electro magnet of 3 and 4,
but produces no effect on any electro magnet in advance of contact box 4.
we carry out the necessary condition that a train passing over any contact box
included in one of the block sections of the line produces no effects on the electro-
magnets of the contact boxes in any other block section behind or in front.
Thus
The pin referred to above is, as shown in Figure 18, a piece of metal at the end
of an ebonite arm, carried by the smaller plunger fixed to the bottom of the
corrugated disk dd, which we have previously spoken of as being made of tempered
steel, but which may be made of any sufficiently strong elastic substance.
end of an insulated spring attached by a piece of ebonite or other insulating
material not shown in the Drawing to the cast iron box, and e being an uninsulated
spring is attached direct to the cast iron box.
u is the
When a train or carriage is going forwards or backwards, it finds the levers M N
mn of all the contact boxes in their normal position, as shown in Figure 15,
except at the first contact box passed over after the train or carriage has stopped
and backed. We have devised an arrangement by which the train automatically
restores the levers to their normal position, even at the first contact box it meets
after backing, but as the introduction of this arrangement into all the contact
boxes would introduce unnecessary complication, we prefer that previous to
the train passing over the first contact box it meets after stopping and commencing
to back, contact should be made by hand between V and E, or between
u and c by a special form of key possessed by the driver, it being of course
remembered that the employment of this key would be only occasional, since the
stopping and backing of a train for any distance is itself only occasionally done.
Hence, the necessity of using such a hand key would not in any way affect the
main traffic.

page_text: As already explained a train or carriage never requires to back over contact
boxes 2 or 5, consequently the levers m n of these contact boxes will never be
required respectively to connect the main cable with the sections 2-1 or 5-4; hence
the levers m n of these contact boxes 2 and 5, which are each the one next in
advance of a block contact box we have employed for a different purpose about to
be described. At contact boxes 2, 3, and 5, G is in permanent electric connection
with the main cable Z Z, but at the block contact box 4 the lower end of the rod
proceeding downwards from G is in connection with the bar X, which is itself in
connection with the main cable, while at 1 the contact between the lower end of
the rod proceeding downwards from G and X has been broken by X (which forms
the armature of the electro magnet Y) having been attracted down and caught
when down by the spring-catch y. Hence although a carriage or train passing
over the contact box 1 depresses the levers MN and mn and locks M N, the one
suitable for putting the main current onto the section 1-2 which it is entering,
still it can receive no current since the contact between G and X is broken. Now
when a carriage is receiving no current we arrange that the armature of an electro-
magnet on the carriage or carriages which are fitted with electro metors is released
and pulled by a spring against a stop, which has the immediate effect of short
circuiting the electro motor or electro motors, or connecting the terminals of the
electro motors through a certain resistance, in either case introducing a powerful
brake. Hence when a train enters a blocked section, not only is it automatically
deprived of its driving power, but it is automatically powerfully braked. Even
a runaway carriage (corresponding with a runaway engine on an ordinary non-
electric railway) would be automatically quickly stopped on entering a blocked
section. The momentary current which on passing through the electro magnet Y
of contact box (1) caused Y to attract down X and so blocked 1, was sent when the
train or carriage T pressed down the plunger al of contact box 2 when passing
over it. For the lever mn of contact box 2 when depressed puts as is shown the
main cable attached electrically to G momentarily into contact with the wire f2,
which is joined to one terminal of the electro magnet Y, and as the other terminal
of this electromagnet is at a contact box in the rear of 1 and not shown in the
tigure permanently to earth, it follows that when the lever m n of contact box 2
or the same lever of 5 is momentarily depressed, a strong current of short duration
is sent back magnetising Y and attracting down X. But we employ this current
sent back by 5 not only to magnetise the electro magnet Y of 4, but also, as shown
in the figure, the electro magnet t of 1, and the magnetisation of the latter attracts
the catch y which is attached to its armature, and so allows the X of 1 to spring
up into contact with G, and thus takes off the block at 1'; hence if a train had run
outo section 1-2 while X was down, and consequently in the manner already
explained been stopped, it would now receive current and proceed on, no matter
at what part of the section 1-2 the absence of driving power and the automatic
brake had pulled it up. And similarly the previous passage of the train over
contact box 2 not only blocked 1 but unblocked a contact box in the rear of 1,
placed as many boxes behind 1 as the traffic of the line requires.
When a carriage or train in the ordinary course passes from one section to the
next, whether going forwards or backing, the main current, as already explained, is
put onto the section the carriage or train is entering before it is taken off from the
section the carriage or train is leaving; indeed, it is not until after the carriage or
train has received the current on the section just entered that it is taken off from
the section being left, and for a short time while the carriage or train is partly on
one section and partly on the other it is receiving currents from both sections; and
we have adopted this arrangement partly in order that the induced sparks or flashes
that are usually produced in making or breaking an electric circuit, and which
rapidly burn away the contracts, shall not be produced by our form of contact
makers; but if a carriage or train runs on to a blocked section the current supplied
to the section just left will be cut off before the current is supplied to the train on

page_text: the section entered, which latter will not take place until the section is auto-
matically unblocked by the preceding train having got sufficiently far ahead.
Consequently if the contact between X and the lower part of G were a simple
contact, as shown in 2 and 4, Figure 14, there would be risk of the contact being
burnt away. To avoid that we employ a special form of key, which we may also
employ, if found necessary, at the contacts between F and fand G. This key is
shown with the other details of the block contact box in Figures 15 and 23,
Sheet 2, and in Figures 21 and 22, Sheet 1, 21 being a section through A, B, of 22,
which is in plan. In all the Figures Y is the blocking electro magnet and t the
unblocking electro magnet. Figure 15 shows the main cable, or an insulated wire
attached to the main cable, joined by a screw or solder, or both, to the metal cap of
the right hand insulator i, which cap carries also the aromature y of t, the armature X
of Y, the guides for these armatures, the spiral spring pulling back y, and the flat
spring HH, Figures 15 and 23, Sheet 2, and 22, Sheet 1, which pulls up X. All
these are in electrical contact with the main cable, but being, with the end of the
main cable or the insulated wire from it, carried by the insulator i, they introduce
no extra leakage down their support. When the contact box is blocked H is
prevented from springing into contact with the end of h, Figure 23, since H, which
is attached to the armature X, is held down, as already seen, by X being caught
with the catch y. When, however, this contact box is unblocked H rises and first
comes into contact with the end of the metal spring h, which it pushes up against
the end of the metal spring 7, and lastly presses the ends of both h and against
the anvil piece T, which is part of the metal cap of the insulator I, Figures 15, 16,
and 23. The springs h and I are insulated from one another and from T by slips
of ebonite or of other suitable material, where they are fastened to G, but h is
permanently electrically connected with through a coil of wire of suitable
resistance, not shown in the Drawing, and to T through another similar coil.
Consequently, the first moment H springs up into contact with h the current flows
through the electro motors or motor under one or more of the carriages should a
train happen to have run onto and been stopped on the section blocked, but as the
two resistance coils above referred to are in circuit the current is proportionally
weak. On H rising a little further, the end of h coming into contact with L, the
first resistance coil is cut out of circuit and the current flowing through the
electromotors proportionately increased, and on H rising still farther comes into
contact with T, when the second resistance coil is cut out of circuit and the current
still more increased. By using then a key of this form the suddeness of closing or
opening an electric circuit is diminished and the consequent induced sparks or
flashes proportioned lessened in intensity and the burning away of the contact
points prevented. We do not limit ourselves to two springs h, l, and two resistance
coils, but we employ as many of each as are necessary to diminish the suddenness
of opening and closing the electric circuit. But in preference to employing a large
number of springs and resistance coils we prefer to make one contact spring slide
over the other and to tip one or both of them with a piece of semi-insulating
material shaped like a wedge, or of other convenient form, so that at the first instant
of contact a considerable thickness of the semi-insulator is in circuit, but which
thickness diminishes gradually until at last the metal springs are themselves in
contact as one is slid over the other. If the semi-insulating material employed be
comparatively soft like carbon, so that the surface of the piece attached to one
spring might be damaged by rubbing against the other, then we stud the surface
of the carbon with slightly projection metal pins insulated from one another
and from the spring to which the piece of carbon is rigidly attached, but which
serve to make contact between the spring rubbed over and the portion of the
carbon which would otherwise rub against this spring.
We make the resistances of the electro magnet Q, Y, t, sufficiently great that the
fraction of the main current momentarily shunted through any one or any number
of them that can act at one time is not large enough to interfere at all with the

page_text: propulsion of the various trains, while at the same time we make the resistances
sufficiently small that the temporary magnetic effect of each of these electro magnets
is large enough for the purpose required. If necessary we add to any one or all of
these electro magnets, according to a method well known, a shunt of suitable
resistance so that the induced current which occurs on breaking the circuit prolongs
the magnetic action.
Instead of the mechanical plungers shown on Sheet 2 for automatically con-
necting the main cable with the section just entered by the train and for
automatically disconnecting the main cable from the section the train is leaving, we
may use electric means for this purpose based on the wheels, rollers, or brushes on
one side of a carriage completing an electric circuit through the wheels, rollers, or
brushes on the other side, or based on the wheels, rollers, or brushes in the front of
a carriage or train being in connection with the insulated section just entered on
while the wheels, rollers, or brushes in the rear of a carriage or train are in contact
with the insulated section being left, and so connecting for a short time the two
insulated sections electrically together, or we may employ a magnetic arrangement
depending for its action not on the weight of the train but on its magnetic mass.
Our absolute automatic block system we can also add to an electric railway when
any of our forms of contact box, shown at Figures 1 to 12, Sheet 1, are employed;
but in that case the rubbed conductor, which only has its insulated junctures at
long distances apart, shown in Sheet 2, becomes a third insulated conductor not
rubbed by the passing train. This third insulated conductor is, instead of the main
cable, permanently connected with the studs G, shown in those Figures, and each
comparatively long section of it is automatically or at will by a signalman
electrically connected with the main cable as the train enters the section and
automatically or at will disconnected as the train or carriage leaves.
We can employ the contacts automatically made or broken by a passing carriage
or train in any of our forms of contact box to automatically make and break electric
currents working or controlling the working of visual signals placed at any
convenient distance from the contact boxes.
Having thus described the nature of our Invention, and the manner of performing
the same, we would have it understood that we claim,-
First. The division of an elastic rail, conductor, or tube, from which the carriage
or carriages of an electric railway receives, by means of wheels, rollers, or brushes,
the propelling electric current into comparatively short sections, each fairly well
imsulated from the next and from the earth, and furnishing these sections with
contact makers, substantially as shown in the Drawings, so that on a passage of a
carriage or train electric contact is made automatically at two or more of these
contact boxes between the section or sections in the neighbourhood of the carriage
or train and the main insulated wire, or with one of them if there be more than one
such wire used to conduct the main propelling electric current.
Second. The use of contact boxes, substantially as shown in Figure 5, Sheet 1,
placed at comparatively short distances along the line, and at each of which electric
contact is automatically made between the main conducting wire and a bar carried
under the carriage or carriages, when this bar presses on a brush or roller on each
of such contact boxes, and which roller or brush is itself only in contact with the
main conducting wire, or with one of them if there be more than one, when the
brush or roller is depressed by the passing carriage or carriages.
Third. The employment of our graphic method, worked substantially as shown,
for showing automatically the position of every train at every moment.
Fourth. The division of the rail, conductor, or tube rubbed by the brush, roller,
or wheel on the moving carriage or carriages into comparatively long sections, each
fairly well insulated from the earth and from one another, and the placing at each
insulated junction between two sections a contact box, substantially as shown, for
automatically or at will electrically connecting the main conducting wire, or one of
them if there be more than one, with the insulated section the carriage or train is

page_text: about to enter, and for automatically or at will disconnecting it from the insulated
section the carriage or train is just leaving.
Fifth. The employment of our absolute block system, in accordance with which
a carriage or train on entering a blocked section of the line is, independent of any
action on the part of the driver or guard, deprived of all motive power or deprived
of motive power and in addition powerfully braked.
In witness whereof, I, the said William Edward Ayrton, have hereunto on
my own behalf and on behalf of John Perry, set my hand and seal this
Twenty fourth day of August, in the year of our Lord One thousand
eight hundred and eighty one.
WILLIAM EDWARD AYRTON. (L.S.)