IMPROVEMENTS IN ELECTRO-MAGNETIC SIGNALLING APPARATUS
Year: 1872

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine
Lake, & Co., Patent Agents, Southampton Buildings, London, for
the Invention of “IMPROVEMENTS IN ELECTRO-MAGNETIC SIGNALLING
APPARATUS."-A communication from abroad by Frank Leonard
Pope, of Elizabeth, New Jersey, United States of America,
Electrical Engineer.
Sealed the 10th October 1872, and dated the 19th August 1872.
COMPLETE SPECIFICATION filed by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 19th August 1872, pursuant to the 9th
Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London, send greeting.
COMPLETE SPECIFICATION filed by the said William Robert Lake
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 19th August 1872, pursuant to the 9th
Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS
IN ELECTRO-MAGNETIC SIGNALLING APPARATUS," and have petitioned Her

page_text: Majesty to grant unto me, my executors, administrators, and assigns,
Her Royal Letters Patent for the same, and have made solemn
Declaration that it has been cominunicated to me from abroad by
Frank Leonard Pope, of Elizabeth, New Jersey, United States of
America, Electrical Engincer.
NOW KNOW YE, that I, the said William Robert Lake, do hereby.
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention,
and in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawing forming
a part of this Specification :
-
This Invention relates to improvements in the construction of sema-
phorio railway signals actuated by electro-magnetism, and to means for
operating the said signals or causing them to be operated.
The said improvements consist, first, in improved modes of con-
structing semaphoric railway signals, both for day and night service, so
that they may be made of sufficient size and distinctness to be visible at
a distance to the engine driver of an approaching locomotive, and yet
capable of being actuated by an electro-magnet of comparatively small
power.
'
Also in the combination with a signalling apparatus of an electro-
magnet constructed to be actuated wholly or partially by axial
magnetism, by means of which the effective length of stroke of the
armature of the said magnet is materially increased.
Also in means for utilizing the residual or permanent magnetism
remaining in an electro-magnet after the exciting current has been
interrupted for the purpose of retaining or continuing the signalling
apparatus in position or action until the said residual magnetism is
removed by a demagnetizing current of opposite polarity.
Also in an arrangement of electrical connections between two stations,
by which a signal, after having been set by a signalman at one station,
can only be released or taken off by a signalman at the other station.
Also in means for limiting the extent of an electrical circuit
wherein the rails of a railway and the axles and wheels of a passing
locomotive or carriage become a part of the circuit by placing the ends of

page_text: the abutting rails in separate metallic chairs or supports, either with or
without an insulating material between the said ends.
"
Also in the combination of a visual or semaphoric signal, so con-
structed and arranged as to be seen from a distance by the engine driver
of an approaching locomotive with the rails of a railway when the said
rails form a portion of an electrical circuit, which includes the electro-
magnet or magnets that operate or control the operation of the said
signal.
Also in the arrangement of a series of semaphoric signals operated by
electro-magnetism at suitable intervals along the line of a railway, in
combination with a corresponding series of circuit closers capable of
being operated automatically by the passage of a locomotive or train
over the track of the said railway, so that the closing of an electric
circuit at any given point or station by the passage of a locomotive or
train will cause the corresponding signal at that station to be displayed,
and will cause the signal previously displayed at the last station passed
by the said locomotive or train to be reversed or released.
Lastly, in the combination of a circuit closer of any suitable con-
struction with an electrical circuit composed of wire or other suitable
conductors, the rail or rails of a railway, and the axle and wheels of a
passing locomotive or carriage, whereby the position of the rails of a
switch siding or turn-out is correctly indicated to the engine driver of
an approaching locomotive by means of a suitable signal.

page_text: Figure 6 shews the method of insulating the extremities of two
abutting rails from each other.
Figure 7 shews the manner of operating a series of signals automati-
cally by a passing locomotive or train.
Figure 8 shews the manner of arranging the connections to cause a
signal to be displayed by the passage of a train when the line is
displaced or interrupted at a point in advance of the position of the
train.
In Figures 1 and 2 E, E, designate the helices of the electro-magnet
that moves the signal apparatus. The soft-iron cores e, e, are of the
usual cylindrical form, and are connected together by the soft-iron
yoke e', which is securely fastened in any suitable manner to the frame
or support D, D. The cores e, e, extend about half the length of the
helices E, E, and within them, as shewn in Figure 2. A second yoke f¹
also provided with cores f. f, which are moveable longitudinally within
the helices E, E, constitutes the armature. This armature is supported
by a vertical rod F pivoted to an angular lever G, which turns upon an
arbor g, and the opposite extremity of which is pivoted to the pitman
rod G of the crank G². The crank Gis secured to an arbor or shaft G³,
which is provided with suitable bearings.
radial
The signal is composed of four circular discs or targets H, H, H¹, H³,
constructed of some light and thin material, such, for instance, as paper
or oiled silk stretched upon hoops, or any suitable diameter, as shewn.
These discs should be of such size that when used as railway signals for
example, they may be plainly visible to an engine driver at a distance of
several hundred yards. By constructing the discs of some semi-transparent
material they may be illuminated at night by lamps placed directly
behind them. These discs or targets are mounted upon
arms h, h, h, h, projecting from the arbor or shaft G³. The alternating
discs are of contrasting colours, for example, I and H may be white,
while II' and 'may Le black, as represented in the Drawing, or of any
other suitable colour. In the Drawing the covering of the lowermost
disc H' is supposed to be removed in order to show the mechanism more
clearly. The signal is shown as enclosed in an opaque box L, which is
to be provided with two circular openings corresponding in size and
position with the discs I, H, and permitting the latter to be visible from
the exterior of the box when the apparatus is in its normal position.

page_text: It will readily be understood that if the arbor or shaft G³ is moved
the distance of one-fourth of a revolution, the coloured discs H³, H³, will
be brought in front of the openings in the box, while the white discs H, H,
will be concealed and a reversal of this movement will cause the white
5 discs to be again displayed and the coloured discs concealed. It may be
here remarked that only two discs or targets, each of a different colour
may be employed instead of four; but in this case it would be proper
to counterbalance such discs by a weight or weights, or otherwise. It
is generally preferable however to exhibit a double signal, as it is more
> distinctly visible at a distance, especially when illuminated at night.
When a current of electricity is sent through the helices E, E, the
axial magnetic force developed thereby tends to draw the coros f, ƒ, into
the helices, while at the same time both sets of cores f,f, and e, e,
become powerfully magnetized, and their mutual attraction acts in con-
junction with the first-named force to bring them into contact with each
other.. The employment of the force of axial magnetism in this manner
is found to materially increase the effective length of stroke .in. the
apparatus. The movement of the cores f.f, is transmitted through the
vertical rod F, angular lever G, and pitman G, to the crank G³, which
is so adjusted that the arbor or shaft G will he moved thereby through
the distance of one-fourth of a revolution, and the coloured discs or
targets H³, H', will then be exhibited through the openings in the signal
box L instead of the white discs H, H, shown in the Drawing.
A pulley P provided with a cord P' and weight P is also fixed 'upon
the shaft G³, the weight P being sufficiently heavy to cause the. appa-
ratus to return to its normal position whenever the attraction between
e, e, and ff, ceases. But inasmuch as the said cores are permitted to
come into absolute contact with cach other the residual magnetism, which
by a well-known law of magnetic action always remains in the soft iron
under these conditions after the exciting current has ceased, prevents
them from being separated by the action of the weight På after the circuit
is broken. In practice it is generally preferred to construct the cores ƒƒ,
and yoke f of hardened steel, by which means the permanent or residual
magnetism may be greatly increased.. If now a somewhat weaker
electric current of opposite polarity is sent through the helices E, E, the
residual magnetism will be neutralized, and the attraction between e, e,
and entirely destroyed, and the signal will at once return to its
normal position by the action of the weight P³ upon the pulley P.

page_text: Thus it will be understood that a current sent through the helices D, E,
in one direction, will cause a colored signal to be shown through the
openings in the signal box L, which will remain in position after the
said current has ceased, and until a current of opposite polarity is sent
through the said helices, when a white signal will be again displayed.
If desired I may use an electro-magnet of the ordinary form, in which
the cores e, e, extend entirely through the helices E, E, and their
attraction is exerted upon a simple armature similar to f¹, and the latter,
if necessary, may be guided in any suitable manner, so as to come
directly in contact with the ends of both cores e, e. Or the movable
cores ff, shown in Figure 2, may be extended nearly or quite through
the helices E, E, and the cores e, e, and the yoke e¹ may be dispensed
with, in which case the movement of the apparatus will be effected solely
by axial magnetism.
Figure 3 is an elevation partly in section illustrating another mode
of constructing the signal box and signal mechanism, and Figure 4 is a
horizontal section of the same taken in the plane indicated by the
line x, x, of Figure 3. In this case but one disc or target is employed
as the signal. The electro-magnet C acts upon the armature O' attached
to the lever C³, having a fulcrum at c³. The extremity of the lever C³
carries a toothed segment C³, which engages with a pinion C³ upon an
upright spindle C'. The disc or target H³ is fixed upon this spindle, the
apparatus being so adjusted that when the electro-magnet C exerts its
attraction upon
its armature the disc H will be brought in front of the
corresponding opening in the signal box L', which is in the position
shown in Figures 3 and 4. When the armature of the electro-
magnet C is released, the spring c¹ withdraws it from the poles of tho
magnet, at the same time causing the spindle C³ to turn for the distance
of one-fourth of a revolution, removing the disc H from its position in
front of the opening 1, and causing it to assume a position at right angles
to the front of the box, so as to be concealed from view. For a night
signal a lantern J is placed upon the top of the spindle C, said lantern
being preferably of a rectangular shape, and provided with coloured
glasses, so that when turned the distance of one-fourth of a revolution,
it exhibits a light of a different colour from the one shown by it when
in its normal position. Either of the two above described forms of
signal apparatus may be employed in any of the different applications
herein-after described.

page_text: '
For the use of single track railways, tunnels, bridges, and, the like, the
following mode of working the signals is applicable:-A and B, Figure.5
represent two stations at opposite ends of a bridge, tunnel, or any
section of a single line railway. Each station is provided with a
semaphoric signal constructed and arranged as herein-before described
and shown in Figures 1 and 2. A tell-tale or repeating signal, a voltaic
battery and two finger keys of any suitable construction are also placed
at each station. The manner in which the apparatus is operated is as
follows:-
-
Let it be assumed that a train is about to enter at A upon the section
of track between A and B. The operator at A depresses the black key K,
which closes the circuit at k, as shown in Figure 5. An electrical current
from the negative or pole of the battery S (its positive or. + pole
being already in connection with the earth at Z), will pass through the
wires 1 and 2 to the key K, thence over the line wire 3 to station B,
thence through the rear contact of key K³ and wire 4 to the helices E*
of the semaphoric signal, and thence to the earth by the wires 5 and
6. This current by its action upon the helices E³ as herein-before
explained will cause the coloured discs of the signal to be displayed at
B, as shown, thereby warning any train approaching B in the opposite
direction that the right of way is held by the train going from A
towards B.
In order that the operator or signalman at A may know whether the
signal at B is properly displayed, the latter is made to work a repeating
signal or tell-tale at A. This is done in the following manner :-
The metallic levers N and N', Figure 5, are kept in contact with the
stops i and ¹ by the springs m and m³. Adjustable screw stops g and g¹
are placed upon the angular levers G, G, and so arranged that when the
signal is in position to display the coloured discs, as shown at B in
Figure 5, the stop 7" comes in contact with the lever N', and at the
same instant interrupts the contact between the latter and . A
current of electricity from the battery S₁ will then traverse the wire 7,
lever G, stop g', lever N, line wire 8, arm N, stop i, and wire 9 to the
helices Q of the repeating signal at station A, and thence by wire 10 to
the earth at 7.
.
The helices QQ, may be employed to operate any suitable form of
tell-tale repeating signal or alarm bell, the particular arrangement adopted

page_text: being immaterial, as the object of the device is merely to inform the
operator or signalman at A that the signal at B is in the desired
position. It is necessary to construct the repeating signal in such a
manner that it will only remain in position as long as a continuous
electric current is flowing through the helices Q or Q', and will return
to its normal position upon the cessation of the current. This is accom-
plished by preventing the armature from coming into absolute contact
with the poles of the magnet in a manner well understood by electricians.
As soon as the operator or signalman at A has received the return
signal from B, he allows the train to proceed on its way to B. The
signal at B is held in position after the operator at A breaks the circuit
at the key K, by the action of the residual magnetism as herein-before
explained. When the train reaches B the signalman at that station
depresses the white key K³. This causes a current to pass from tho
positive pole of the battery S¹ through the wires 12 and 13 to the key:
K³, thence through the wires 14 and 4 to the helices of the signal
magnet E³, and thence returning by the wires 5 and 15 to the other
pole of the battery. This current being of a polarity opposite to that by
which the signal magnet was originally charged, neutralizes the residual
magnetism remaining in the cores, and permits the signal to resume its
normal position. This latter operation breaks the contact between g¹
and N', and thereby releases the repeating signal connected with Q at
station A, and notifies the signal man at A that the train has arrived

page_text: siderably weaker than the primary current. This result is accomplished
by inserting rheostats or artificial resistances R, R', into the releasing or
reversing circuits, by the aid of which the strength of the current can be
modified or regulated at pleasure. The same result may be accomplished
by using a smaller separate battery of the required power, or by including
only a small portion, say one-fourth, of the main battery in the reversing
circuit at each station. Or the battery may be dispensed with, and the
demagnetizing current derived from a magneto-electric apparatus of any
well-known and suitable construction.
A bell signal may be used for communicating between the stations A
and B, using the wire 3 and a weaker current, which though strong
enough to operate a magnet for striking a bell will not be sufficient to
affect the signal magnets. This current may be derived from a separate
battery, or from the main battery, or a portion thereof, and weakened
by being made to pass through a rheostat.
When it is desired to operate the signals through a long line a relay
magnet of any suitable construction is employed in place of the helices
E, E, and their appurtenances. The said relay is caused, in a manner
well understood by those skilled in the art, to close the circuit of a local
battery, thus actuating the magnet that moves the signal. The arma-
ture of the relay is held in position after the circuit is broken by means
of the residual magnetism, as herein-before explained, and thus the
local circuit remains closed and the signal displayed until a de-
magnetizing current is sent through the helices of the relay.
Figure 7. represents an arrangement for operating automatically, by
the passage of a train, a series of signals placed at intervals along the
line of a railway. This arrangement is more particularly designed for
use upon railways having double tracks. M, M, represent one of the
tracks of a double track railway, and O, O, O, a locomotive and train of
carriages running upon the said track. E is the electro-magnet of a
semaphoric signal arranged as shown in Figures 1 and 2. This signal is
supposed to be one of a sèries placed at suitable and convenient intervals,
say two miles, or more or less apart, along the railway. V is a rail of the
track insulated from the adjoining rails in both directions in a manner
herein-after explained. This rail is situated at a distance in advance of the
position of the signal, somewhat greater than the length of an ordinary
train. A wire 20 is connected with the insulated rail V, which includes

page_text: 0
in the circuit the battery S³ and the electro-magnet of the relay T, at or
near the signal, its other extermity being connected at to the opposite
line of rails from that which contains the insulated section V. The two
lines of rails being insulated from each other by the wooden ties or
sleepers which support the same, the current from the battery S³ will
only transverse the wire 20 when a continuous metallic connection is
formed between the insulated rail V and the opposite line of rails.
When the train O, O, passes over the rail V its metallic wheels and
axles complete the circuit and operate the relay T. To the lever of this
relay is attached the wire 19 from the battery S*, the other pole of which
is connected to the earth at Z'. The movement of the
the wire 19 simultaneously with the two wires 16 and 17.
entering the wire 16 operates the signal magnet E³ and displays a
coloured signal, returning to the battery by the wire 18. Another
portion of the current goes by the wire 17 back to the next signal
in the rear, reversing or releasing it, as will herein-after be explained.
relay connects
The current
The signal connected with E³ having thus been displayed by the
passage of the train, will remain in that position until the train arrives
at the next signal in advance, when a current will be sent back over the
wire 16, passing through Es and demagnetizing its cores, and thence
going to the earth at Z' by the wire 18. It is necessary that the polarity
of the battery S² connected with each signal magnet should be opposite
to that of the battery of the next adjacent signal in each direction.
By arranging the insulated rail at a distance of more than a train's
length in advance of the signal, the train is protected by each signal in
turn until the next one in advance has been reached and set, when the
last one is released, thus preventing any danger of collision from one
train following another too closely. Thus it will be understood that the
engine driver of a train upon arriving at a signal station and finding the
signal displayed will be made aware that a preceding train is occupying
the track of the section in advance of him, but he will be notified by
the changing of the signal when the preceding train shall have passed
beyond the limits of the section in advance, thereby enabling him to
proceed with safety.
A convenient method of insulating the abutting ends of two rails from
each other without essentially impairing the stability of the track is

page_text: spikes in the usual manner to the longitudinal sleeper V. The ends of
the rails are separated by a small space, and placed upon separate
"chairs" or supports w, 20. A bar of some suitable hard wood Y is then
bolted upon the rails by suitable bolts y, y, y, y, the rails being by this
means kept in line with each other. The space between the rails may be
filled with some insulating substance.
Figure 8 illustrates the manner in which this Invention is applied for
the purpose of indicating the position of a switch or drawbridge to the
engine driver of an approaching train. The Drawing shows the apparatus
applied to a switch. I, I, are the rails of the main track, and I', I', the
rails of a branch track. M', M', are the moveable rails of the switch,
which are capable of being adjusted in line with the main track I, I, or
with the branch track I, I, by means of a hand lever U, which is pivoted
at u³, and connected with the.movable rails by a suitable connecting rod.
A section of the main track V, V, which may be at any desired distance
from the switch and of any suitable length, is insulated from the adjacent
portions of the track in the manner herein-before described. A circuit
closing arm z projects from the hand lever U of the switch, and is
so arranged in reference to the metallic stud "' as to be in contact
therewith when the moveable rails M, M'; are adjusted in line with the
rails of the main track I, I, but if moved into line with the rails 1', I', of
the sliding or branch track, the arm u will be moved away from contact
with the stud u¹.
The voltaic battery S* has one of its poles permanently connected with
the earth Z' by the wire 21. From the other pole the wire 21 extends
to the circuit closing arm u.
From the stud u the wire 22 extends in
a direction parallel with the main track, or nearly so, to the electro-
magnet E, to which a suitable signal is attached as herein-before
explained, and thence to the insulated rail V*. The opposite rail V³ is
connected to the earth at Z by the wire 23.
The signal connected with the magnet E' is arranged in this case to
indicate "danger" when in its normal position, that is to say, when no
current is passing through the magnet while the passage of a current
will exhibit an indication of " safety." It is also so arranged as to
5 return to its normal position indicating "danger" as soon as the current
ceases, which is accomplished by preventing the armature of E' from
coming in absolute contact with its poles.

page_text: If now the switch is adjusted to its normal position in line with the
main track, as shown in Figure 8, the circuit between u and u¹ will be
uninterrupted, and the closing of the circuit between V and V by the
advancing train (represented by O'), will cause the signal to assume the
position shown in the Drawing indicating "safety," but at all times.
when no train is passing over the insulated rails V and V the circuit
will be broken at that point, and the signal will remain in a position
indicating "danger," but if the switch is adjusted in line with the
branch track I¹, I', the circuit between u and u¹ will be interrupted, and
the closing of the circuit between V² and V³ by an approaching train
will therefore have no effect upon the signal, which will continue to
indicate "danger" until the circuit is closed at m, n, when it will again
assume the position shown in the Drawing, and indicating "safety."
A return wire may be substituted for the earth as a part of the circuit
in any or all of the herein-before desoribed arrangements of circuits for 1
operating the signals, if preferred.
Having thus fully described the said Invention as communicated to
me by my foreign correspondent, and shown how the same is to be
performed, I claim,-
First. A semaphoric signal constructed with discs or targets of alter- 2
nate contrasting colours in combination with an electro-magnet, sub-
stantially as specified.
Second. A vertical rotating spindle provided with a suitable day or
night signal, either or both, in combination with an electro-magnet,
substantially as specified.
Third. An electro-magnet actuated wholly or in part by axial
magnetism in combination with a semaphoric signal, substantially as
and for the purposes specified.
2
Fourth. An electro-magnet having an armature so arranged as to
be held in contact with its poles by residual or permanent magnetism 3
until released by an opposing or demagnetizing current in combination
with a semaphoric signalling apparatus, substantially as specified.
Fifth, The combination of a semaphoric signal operated by electro-
magnetism, and a secondary or repeating signal actuated or controlled
by the said semaphoric signal with a reversing or releasing apparatus, so 3
arranged that when the signals have been set by an operator at one

page_text: point they can only be reversed or released by an operator at another
point, substantially as herein specified.
Sixth. The arrangement of the ends of two abutting rails of a
railway track in separate chairs or supports upon a sleeper, whereby
electrical conduction between the said rails is prevented, and the extent
of an electrical circuit limited, substantially as and for the purpose
herein specified.
Seventh. The combination of a visual or semaphoric signal with the
rail or rails of a railway track, when the said rail or rails form a portion
of the electrical circuit which operates or controls the said signal,
substantially as and for the purpose herein specified.
Eighth. The combination of the signal magnet E³, battery S³, relay T,
and wires 16, 17, and 18, substantially in the manner and for the pur-
pose specified.
Ninth. A circuit closing device in combination with a railway track
situated at the distance of a train's length, more or less, in advance of
the signal operated thereby, substantially as and for the purpose
specified.
Tenth. The combination of the circuit closer u, u³, with the battery S*
and the electrical circuit 24, u, u³, 22, V, O¹, V³, 23, Zº, Z', and 21,
substantially as and for the purpose specified.
In witness whereof, I, the said William Robert Lake, have here-
unto set my hand and seal, this Nineteenth day of August,
in the year of our Lord One thousand eight hundred and
seventy-two
13
Witness,
CHAS. J. Gooch.
W, ROB. LAKE. (L.S.)