IMPROVEMENTS IN ELECTRIC DISTANT SIGNAL APPARATUS FOR RAILWAYS, TO CWCMANTANROM A TRAIN AS IT APPROACHES A STATION
Year: 1872

page_text: LETTERS PATENT to David Alexander Carr and Crawford Peter Barlow,
both of No. 2, Old Palace Yard, Westminster, for the Invention of
"IMPROVEMENTS IN ELECTRIC DISTANT SIGNAL APPARATUS FOR RAILWAYS, TO
CWCMANTAN "
PROVISIONAL SPECIFICATION left by the said David Alexander Carr
and Crawford Peter Barlow at the Office of the Commissioners of
Patents, with their Petition, on the 18th May 1872.
We, DAVID ALEXANDER CARR and CRAWFORD PETER BARLOW, both
of No. 2, Old Palace Yard, Westminster, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN ELECTRIC DISTANT SIGNAL APPARATUS
FOR RAILWAYS, TO SIGNAL TO AND FROM A TRAIN AS IT APPROACHES A SIGNAL
STATION:
"
Our Invention has for its object to enable a signalman at a station,
junction, or other part of the line to cause a signal to be exhibited upon
the engine or any carriage in an approaching train, and also to record in
the signal station that such signal has been duly received..

page_text: The electrical apparatus is arranged so that, 1st., the train announces
its approach to the man at the signal station; 2nd., a signal is tele-
praphed on to the train by the signalman at the signal station; and, 3rd.,
the signal there received is repeated back in the signal station.
In order to carry out this arrangement we have first a warning signal
in the signal station that the train may announce its approach. This
warning signal is a self-acting arrangement, which is put in action by
means of a trigger or spring (or it may be worked by rollers and bars)
placed by the side of one of the rails on the line on which the train is
approaching, and situated a mile or any other suitable distance from the
signal station. The spring or trigger is pressed down by each wheel of
the train as the train passes over it and thereby moves a contact maker.
An insulated wire is laid from this contact maker to the signal station,
and there connected with an electro-magnetic instrument so arranged
that the passage of each wheel over the trigger or spring causes one
stroke to be given on a gong or bell. The signalman being thus warned
of the train's approach transmits a signal to a signal instrument on the
train. To enable this to be effected we have in the signal station an
instrument for transmitting the required signal to the train. This
instrument is a simple arrangement by which the signalman by a contact
maker of the ordinary construction can break or couple up the current
from a battery in the station to an insulated wire. This wire is laid from
the signal station to a pair of rollers placed in the line between the rails
at a suitable distance from the signal station. The pair of rollers is
placed and fixed on springs which are supported by the sleepers, or
otherwise, in such a manner as to retain the same relative position with
reference to the rails between which they are placed. The pair of rollers
is acted upon by a pair of curved metal bars placed beneath a convenient
part of the engine or other convenient part of the train, but for the sake
of clearness of description we will suppose the instrument to be on the
engine. Below each of the rollers is a contact maker enclosed in a
suitable casing. One of these contact makers has the insulated wire
before mentioned connected to it; the other contact maker is coupled
up with an earth plate, so that when the pair of rollers is pressed down
by the bars the bars will be electrically in connection with the signal
station, and from the bars insulated wires are connected to the signal
instrument on the engine. The contact maker also connects the two
extremities of wires for ringing the gong in the signal station; an

page_text: insulated wire from this contact maker to the wire from the warning
gong (already described), being all that is necessary for this purpose.
Thus when the engine is in such a position that the bars are pressing on
the rollers the instrument on the engine is in electrical connection with
the transmittor at the signal station, and the gong in the signal station
is at the same time rung. The instrument on the engine is made with a
movable signal disc, arm, or other contrivance, which remains in its
normal position until an electric current passing from the signal station
through the rollers and bars, and thence by the insulated wires to an
electro-magnet, moves it. When the signal disc or arm is in its normal
position it represents the signal "stop," and when it has been removed to
the other it represents another, "go on." If when the pair of rollers is
depressed by the bars a current passes through the instrument on the
engine the signal is moved to " go on;" if no current passes through,
the signal remains in its normal position and represents the signal
"stop." The "stop" signal, carried by the disc or arm, is a red glass,
and the "go on" signal, a white glass. When the signal disc or arm is
in its normal position the red glass will be seen through an aperture in
the front of the casing of the instrument. If the signal disc or arm is
moved to "go on," the red glass is moved away and the white glass
comes behind the aperture. The instrument is made so that a lamp may
be placed behind the signal disc or arm in order that at night a red or a
white signal light may be shewn.
"
In front of the signal disc or arm is a screen which is moved away
mechanically or electrically by a trigger or spring fixed on the engine as
it passes over the pair of rollers just described, and at the same time and
in the same manner a bell is rung (to attract the attention of the driver
to the signal exhibited). As soon as the driver has seen the signal he
by depressing a finger key replaces the screen in front of it, and in so
doing puts back the signal disc or arm (if it has been moved). This
putting back the screen may be done either by the engine driver or by
an automatic arrangement; but we prefer that the engine driver should
as a part of his duty be required to put the screen back into its normal
position.
By the means above described the signalman in the station is able to
give the signal of "stop" or "go on" to the engine driver of the
approaching train, and he knows by the gong when the train has come
to his distant signal.

page_text: For repeating the signal received in the instrument on the train back
to the signal station, we have in the instrument on the engine
(described above), an arrangement that when the disc or arm is moved a
contact is by the movement of such disc or arm caused to be made
between the extremities of two other insulated wires. These two wires
proceed to another pair of bars, similar in every respect to the ones
already described, and fixed in a similar manner so as not to affect the
working of the former ones. This pair of bars acts upon another pair of
rollers, similar in every respect to the ones already described, fixed in a
similar manner but 20 yards or thereabouts nearer the station to which
the train is approaching. From this pair of rollers is laid an insulated
wire to the signal station, where it is attached to a similar instrument to
that on the engine, so that if the disc in the instrument on the engine is
moved the disc in the instrument at the signal station will be moved
when the engine arrives at the second pair of rollers (which will be
almost instantaneous), and vice versa. Thus the signalman at the
station knows what signal the engine has received.
In connection with the instruments in the signal station is a register,
which is so arranged as to register the signal given by the gong, the
signal given by the signalman, and the signal repeated back from the
train. This may be a time register worked by the clock in the signal
station. The instrument on the engine may be fitted with a similar
register.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said David Alexander Carr and Crawford Peter Barlow
in the Great Seal Patent Office on the 18th November 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, DAVID
ALEXANDER CARR and CRAWFORD PETER BARLOW, both of No. 2, Old
Palace Yard, Westminster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her:
Letters Patent, bearing date the Eighteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said David Alexander Carr and Crawford
Peter Barlow, Her special license that we, the said David Alexander

page_text: Carr and Crawford Peter Barlow, our executors, administrators, and
assigns, or such others as we, the said David Alexander Carr and
Crawford Peter Barlow, our executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and
at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN ELECTRIC DISTANT SIGNAL APPARATUS FOR
RAILWAYS, TO SIGNAL TO AND PROM A TRAIN AS IT APPROACHES A SIGNAL STATION,”
upon the condition (amongst others) that we, the said David Alexander
Carr, and Crawford Peter Barlow, our executors or administrators, by an
instrument in writing under our or their hands and seals, or under the
hand and seal of one of us or them, should particularly describe and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said David Alexander Carr, on behalf of
myself and the said Crawford Peter Barlow, do hereby declare the nature
of the said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
Our Invention has for its object to enable a signalman at a station,
junction, or other part of the line to cause a signal to be exhibited
upon the engine or any carriage in an approaching train, and also
to record in the signal station that such signal has been duly received.
The electrical apparatus is arranged so that first the train announces
its approach to the man at the signal station; second, a signal is
telegraphed on to the train by the signalman at the signal station;
and third, the signal there received is repeated back in the signal
station.
In order to carry out this arrangement we have first a warning
signal in the signal station that the train may announce its approach.
This warning signal is given by the wheels of a train acting upon a
contact making apparatus situated a mile or any other suitable distance
from the signal station. The contact making apparatus is formed by
preference of a spring which is pressed down by each wheel of the train

page_text: as the train passes over it, and thereby moves a contact maker. An
insulated wire is laid from this contact maker to the signal station, and
there connected with an electro-magnetic instrument so arranged that
the passage of each wheel over the spring causes one stroke to be given
on a gong or bell. The signalman being thus warned of the train's
approach transmits a signal to a signal instrument on the train. To
enable this to be effected we have in the signal station an instrument
for transmitting the required signal to the train. This instrument is
a simple arrangement by which the signalman by a contact maker of
the ordinary construction can break or couple-up the current from a
battery in the station to an insulated wire. This wire is laid from the
signal station up to an insulated metal surface placed in the line
between the rails at a suitable distance from the signal station. The
insulated metal surface is not permanently in electric connection with
the insulated wire from the signal station, but is thus connected at the
time that a train moves past it. This may be effected in various ways.
The insulated metal surface may be a roller supported by a spring, and
having a contact maker below it enclosed in a suitable box and coupled
up with the insulated wire from the signal station. In this case a
curved metal bar carried by the engine (or it might be other convenient
part of a train) may act upon the roller and depress it so as to put the
roller and bar on the engine in electric connection with the insulated
wire, or the insulated metal surface may be a bar fixed parallel with the
rail, and a roller or spring be mounted on the engine so that it shall
come into contact with it. In this case in order to put the insulated
bar in electric connection with the insulated wire at the time when a
train is moving past it, we prefer to cause the wheels of the train to
act upon and depress another metal bar placed close alongside of one
of the rails. This bar is mounted on a number of short links, and is
held up by a weight or springs. The axis of one of the links forms part
of a contact maker enclosed in a suitable box. The contact maker is
constructed so that when the bar is held up the insulated wire and
insulated bar are not in electric connection with one another, but when
the bar is depressed by the wheels of a train passing over it the contact
maker completes the connection between the wire and insulated bar.
The spring or roller which is mounted on the engine and which comes
into contact with the insulated bar is coupled by an insulated wire to
one end of the coil of an electro-magnet forming part of the signal
instrument upon the engine. The opposite end of the coil may either

page_text: be coupled to any suitable part of the engine, so that the connection to
earth may be completed through the lines of rail, or the return current
may be conveyed back to the signal station by a second insulated
wire connected like the other wire to a contact maker to be moved
simultaneously with the other contact maker and by similar means.
The instrument on the engine is made with a movable signal disc arm
or other contrivance which remains in its normal position until an
electrc current passing from the signal station to the electro-magnet
above mentioned moves it. When the signal disc or arm is in its
normal position it represents the signal "stop," and when it has been
moved to the other it represents another, "go on." If a current passes
through the instrument on the engine the signal is moved to "go on ;"
if no current passes through, the signal remains in its normal position
and represents the signal "stop." The stop signal carried by the
disc or arm is a red glass, and the go on signal a white glass. When
the signal disc or arm is in its normal position the red glass will be seen.
through an aperture in the front of the casing of the instrument.
the signal disc or arm is moved to "go on the red glass is moved away
and the white glass comes behind the aperture. The instrument is
made so that a lamp may be placed behind the signal disc or arm in
order that at night a red or a white signal light may be shewn.
"
If
In front of the signal disc or arm is a screen which as the engine
passes the insulated metal surface herein-before mentioned is moved
away mechanically or electrically by a trigger or spring fixed on the
engine, and at the same time and in the same manner a bell is rung to
attract the attention of the driver to the signal exhibited. As soon as
the driver has seen the signal, he by depressing a finger key replaces the
screen in front of it, and in so doing puts back the signal disc or arm (if
it has been moved). This putting back the screen may be done either by
the engine driver or by an automatic arrangement, but we prefer that
the engine driver should, as a part of his duty, be required to put the
screen back into its normal position.
By the means above described, the signalman in the station is able to
give the signal of "stop" or "go on" to the engine driver of the
approaching train, and he knows by the gong when the train has come
to his distant signal.
For repeating the signal received in the instrument on the train back
to the signal station, we have in the instrument on the engine (described

page_text: above) an arrangement, that when the disc or arm is moved, a contact
is by the movement of such disc or arm caused to be made between the
extremities of two wires, one coupled to "earth" and the other put into
electric connection with an insulated wire leading to the signal station
by means of apparatus similar to that already described, and situated at
a distance of about twenty yards or thereabouts from it and nearer to
the signal station to which the train is approaching. In the signal
station the insulated wire above mentioned is attached to a similar
instrument to that on the engine, so that if the signal disc in the
instrument on the engine is moved, the disc in the instrument at the
signal station will be moved also, and vice versa. Thus the signalman
at the station knows what signal the engine driver has received.
In connection with the instruments in the signal station there may
be a register, so arranged as to register the signal given by the gong,
the signal given by the signalman, and the signal repeated back from
the train. This may be a time register worked by the clock in the
signal station. The instrument on the engine may be fitted with a
similar register.
-
Having thus described the nature of our Invention, we will proceed to
describe more fully the manner in which we prefer to carry it into effect,
and for this purpose we have in the Drawings hereunto annexed, shewn
various views of signal apparatus arranged as above described.
At Figure 1, Sheet 2, of the Drawings is shewn a diagram view of the
combined arrangement of signal apparatus. In this Figure, A, A, are
the lines of rails; B, a signal station; C, the point, at which is placed
the apparatus for sounding the warning bell in the signal station; D, the
point at which is placed the apparatus for transmitting a signal to
the instrument on the engine; and E, the point at which is placed the
apparatus for transmitting back to the signal station the signal that has
been exhibited on the engine.
On Sheet I. of the Drawings are shewn various views of the apparatus
placed at the point C upon the line for announcing to the signal station
the approach of a train. Figure 2 is a plan view partly in section, and
Figure 3 a side view also partly in section of the apparatus. The
apparatus is supported by the sleepers, as shewn, and consists simply of a
spring a placed close alongside of one of the rails and fixed at its end a¹,
whilst the opposite end of the spring is coupled to a metal rod b passing

page_text: through the stuffing box c into the box d, in which is a terminal spring e
connected to the insulated wire C*; this wire passes to the signal station,
and is there connected to one end of the coil of an electro-magnet,
forming part of the signal apparatus, whilst the opposite end of the coil
is permanently connected to one pole of a battery, the other pole of
which is connected to "earth." When a train passes the point C on the
line of railway, the flanges of the wheels act successively on the top of
the curved spring a and depress it, thereby moving endwise the rod b
and bringing its end into contact with the terminal spring e, the circuit
through the insulated wire C* is thus completed as the rod 6 is connected
to earth, and the gong of the signal instrument herein-after described in
the signal station is thereby sounded.
On Sheet 2 of the Drawings are shewn various views of the contact
making apparatus, which is situated at the point D on the line of railway,
and which is for enabling the signalman at the signal station to transmit
a signal to the instrument on the engine.
Figure 4 is a plan view, and Figure 5 a side view of the apparatus;
Figures 6 and 7 are transverse sections of part of the same. In these
Figures, is a bar of angle iron, supported by the side of one of the rails
by the links f¹, and held up so as to be level with the face of the rail
or nearly so by a counterbalance weight, as shewn at Figure 7, the axis f³
of one of these links f forms part of a contact maker, shewn separately
at Figure 7*, it consists of an enlargement upon the axis f³, which is
received between two insulated metal plates g, one connected to an insu-
lated wire D* leading to the signal station, the other to an insulated wire
leading to the metal bar h mounted between the lines of rail, as shewn
at Figure 4. When the angle iron bar f is in its raised position, there
is no electric connection between the two plates g, but when the bar is
depressed by the flanges of the wheels of a passing train, the enlargement
on the spindle f³ comes into contact with the plates g and puts them into
electric connection with one another, and so puts the insulated bar h
into electric connection with the insulated wire D* leading to the signal
station. The bar fis by preference made of a length greater than the
distance between the wheels of the carriages, so that during the time a
train is passing there shall always be one of the wheels holding the bar
down. The spring k, shewn in Figure 5, is carried by the engine (or as
before stated it might be the guard's van or other suitable part of a
train), and is connected by the insulated wire k* with one end of the coil

page_text: of an electro-magnet forming part of the instrument on the engine, the
other end of such coil being connected to any metal work of the engine,
and so to the metal rail. As the engine passes over the bar the
spring comes into contact with it, and as the bar is at this time in
electrical connection with the insulated wire D* from the signal station,
a current is free to pass from it to the signal instrument on the engine.
Various views of this signal instrument are shewn at Figures 8, 9, 10,
11, 12, 13, 14, and 15 on Sheets 3 and 4 of the Drawings. is the
electro-magnet above mentioned; m is the signal arm; and n a screen in
front of such arm; o is the front plate of the case of the apparatus,
having a central aperture o¹ through which the signals are to be seen.
When the screen n is raised into its normal position, as shewn at
Figure 9, it comes behind the orifice o¹ and shuts out from view the
signal arm m, and it is held up by the spring catch p catching over a
pin n¹ on the screen. Coincident with the axis of the catch p is another
axis p¹, upon which is an arm p*, which by a wire or cord is to be
connected to a bell crank lever coupled to the rod q (see Figure 5
Sheet 2). When the rod q is moved upwards by the insulated bar hit
turns the axis p¹, and by arm p³ upon it lifts the catch p and allows the
screen n to fall, an aperture in the screen then coincides with the
aperture o¹ and discloses the signal behind it. At the same time in
order to attract the attention of the engine driver the bell r is sounded.
Any suitable arrangement may be adopted for this purpose. In the
arrangement shewn in the Drawing it is effected by the end of an arm p³
on the axis p¹ coming against the end of a rod * and moving it back
until the arm p³ has been carried round clear of the end of the rod ** ;
this rod is then thrown quickly forward by the coiled spring around it,
and the hammer 2 which it carries is caused to strike the bell. So soon
as the engine has passed over and beyond the insulated bar h the coiled
spring ps turns back the axis p¹ to its former position, the end of the
arm p³ which acts upon the rod r* is pivoted, so that as the arm moves
back to its former position it may turn on its pivot and move freely past
the end of the rod r*, and so soon as it has been moved past the end
of this rod it is by the spring p turned into a position to drive back the
rod when again brought against it. When the attention of the driver
has thus been called to the signal exhibited through the aperture o¹ of
the front casing o and he has attended to the signal shewn, he brings
back the screen n to its former position by depressing the spring thumb

page_text: piece s. The lower end of the stem of this thumb piece then acts upon
a tail piece n² of the screen n, and so raises this screen until the pin n¹
is caught by the spring catch p. The signal arm m when in its normal
position is held up by the upper end of a lever t, being held by a
spring ¹ below a projection on the signal arm. The lower arm of the
levert carries an armature in front of the electro-magnet l; when a
current is passed through the coils of this electro-magnet the armature is
drawn towards it, and the signal arm is so released and drops, the signal
"go on is thereby brought in front of the orifice o¹, whereas if no
current is passed through the coils of the magnet the signal arm remains
in its normal position, with the signal "stop" in rear of this aperture.
If the signal arm has been allowed to drop it is again brought back by
the engine driver as soon as he has attended to the signal by the act of
depressing the thumb piece 8. The depressing of this thumb piece, as
before described, raises the outer screen n, and a pin upon this screen
raises the signal arm m until it is again supported by the lever t, and
subsequently the outer screen is itself laid hold of by the spring catch p
as before described.
As before stated the signal "stop" is painted on a piece of red glass
and the signal "go on" on white glass, and the frame of the apparatus
is suitably made for a signal lamp to be inserted into the case in rear of
the signal arm. For this purpose an aperture z is formed in the top of
the case to allow of the insertion of a lamp into the case.
means the signals can readily be seen both by night and day.
By this
The transmission back to the signal station of the signal exhibited on
the engine is effected by a metal projection m¹ on the signal arm m
dropping down between two insulated terminals u, and forming an
electric connection between them whenever the signal arm drops. One
of these terminals is by an insulated wire connected to a spring similar
to the spring k below the engine, and the other to the metal work of the
engine and so to " earth." When the engine arrives at the point E this
spring comes into contact with one or other of two insulated metal bars
similar to the bar h (according to which end of the engine is leading),
and at this time both these bars are by apparatus, similar to that before
described with respect to the bar h, put into electric connection with an
insulated wire E* leading to the signal station. The contact maker for
putting these insulated bars into electric connection with the wire Ex
may also be arranged to connect the two extremities of wires for ringing

page_text: the gong in the signal station; all that is necessary for this purpose
being to connect one of the wires to the wire C* and the other to earth.
If the signal arm of the signal apparatus on the engine has not dropped
no current passes through the wire E*, but if the signal arm has dropped
a current passes and a similar signal arm in the apparatus in the signal
station is thereby caused to fall.
Various views of the signal apparatus in the signal station are shewn
at Sheet 5 of the Drawings hereunto annexed. Figure 16 represents a
front view of the apparatus with the face removed; Figure 17 shews a
transverse section, and Figure 18, a face view of the apparatus. In these
Figures a is the bell for giving notice of the approach of a train; b,
the hammer for striking the same; this hammer is carried from the
armature c of the electro-magnet d. One end of the coil of this magnet
is connected to the line wire C* herein-before mentioned, and the other
to one pole of a battery, the opposite pole of which is connected to earth.
The armature c also carries a point e to act upon a contact making
apparatus fso as to complete a circuit each time the bell is sounded, and
register the signal in a suitable electric registering apparatus.
enable the signalman to put the line wire D* in electrical connection
with one pole of a battery, and so transmit the "go on signal to a
passing train, a metal arm g is carried by an axis h which passes out
through the front of the casing, and has a handle h* upon it by which it
can be turned. When the axis is turned so as to bring the arm g into
the position shewn by the Drawings, the end of the arm comes between
two insulated metal plates i, one of which is connected to the line
wire D*, and the other to one pole of a battery, and so puts the line
wire into connection with the battery.
"
To
The arm also carries two signal plates corresponding to the signals on
the signal arm of the apparatus carried by the train. When the arm is
in the position shewn by the Drawings the signal "go on" is shewn
through the aperture k of the front casing. By turning the axis the
arm g can be moved away from between the plates i and so break the
electrical connection between them; the signal "stop" is then shewn
through the aperture, and the axis is compelled to be in either one or
other of these two positions by a spring acting against two flat surfaces
formed upon it as shewn.
Above the aperture k in the face of the apparatus is another aperture m
through which is exhibited the signal that has been received upon the

page_text: engine. This is effected by an arrangement of apparatus similar to that
in the instrument on the engine, and consists of a signal arm n and lever
catch o carrying an armature p which hangs in front of an electro-
magnet r as shewn. One end of the coil of this magnet is connected to
the line wire E*, the other to one pole of a battery the opposite pole of
which is connected to " earth."
If the signal screen of the instrument on the engine has been caused
to drop, a circuit will, as herein-before described, be completed through
the wire E*, and the electro-magnet will attract its armature p and
thereby release the signal arm and allow it to drop. The signal
exhibited through the upper aperture will then correspond with the
signal exhibited through the lower aperture, and the signalman in the
signal station will thereby know that the signal sent by him has been
correctly received and can at once move his signal to "stop," and so
immediately protect the train which has just passed the distance signal.
The shifting of the lower set of signals from "go on" to "stop" by
turning the axis h causes the upper signals simultaneously to change,
as the arm g has a pin upon it which then comes against the signal
arm n and raises it until it is again upheld by the lever catch o.
In order to record the movements of the signal arm n, this arm
carries a metal tongue n' which when the signal drops enters between
two plates s and allows a current to pass to the electrical recording
apparatus.
Having thus described the nature of our Invention, and the manner of
performing the same, we would have it understood that we claim,-
1. The combined arrangement of electric signal apparatus, sub-
stantially as herein described, consisting of apparatus for announcing
the approach of a train to a signal station, apparatus to signal from the
station to the train, and apparatus to repeat back to the station the
signal that has been received on the train.
2. The employment of automatic apparatus, substantially as herein
described, to enable a railway train as it is moving past an insulated
metal surface to put such surface into electrical connection with an
insulated wire leading to a signal station, in place of the insulated metal
surface being permanently in connection with the wire, as heretofore
proposed.

page_text: 3. The combined arrangement of apparatus, substantially as herein
described, and shewn on Sheet 2 of the Drawings, to enable a man at
the signal station to transmit a signal to the train, or to enable a signal
to be repeated back from the train to the signal station.
4. The combined arrangement of electric signal apparatus, sub-
stantially as herein described, and shewn on Sheets 3 and 4 of the
Drawings, to be carried on the engine or other part of a railway train.
5. The combined arrangement of electric signal apparatus to be placed
in the signal stations of railways, substantially as herein described, and
shewn on Sheet 5 of the Drawings.
In witness whereof, I, the said David Alexander Carr, have here-
unto set my hand and seal, this Sixteenth day of November, in
the year of our Lord One thousand eight hundred and seventy-
two.
DAVID A. CARR. (L.S.)