IMPROVEMENTS IN AUTOMATIC SIGNALS MORE ESPECIALLY ADAPTED FOR USE ON RAILWAYS WHERE THE BLOCK' SYSTEM OF SIGNALLING IS EMPLOYED."
Year: 1874

page_text: LETTERS PATENT to Henry James Barr, of Culter House, near
Aberdeen, North Britain, a General in Her Majesty's Army, for the
Invention of "IMPROVEMENTS IN AUTOMATIC SIGNALS MORE ESPECIALLY
ADAPTED FOR USE ON RAILWAYS WHERE THE BLOCK' SYSTEM OF SIGNALLING
IS EMPLOYED."
PROVISIONAL SPECIFICATION left by the said Henry James Barr at
the Office of the Commissioners of Patents, with his Petition, on
the 16th May 1874.
I, HENRY JAMES BARR, of Culter House, near Aberdeen, North
Britain, a General in Her Majesty's Army, do hereby declare the naturo
of the said Invention for "IMPROVEMENTS IN AUTOMATIC SIGNALS, MORE
ESPECIALLY ADAPTED FOR USE ON RAILWAYS WHERE THE BLOCK SYSTEM OF
SIGNALLING IS EMPLOYED," to be as follows:-
My Invention of improvements in railway signals has for its object
the working of such signals by automatic machinery so that the line of

page_text: railway may be absolutely "blocked" at certain well defined intervals
without the intervention of a signalman, which I accomplish by so con-
structing and arranging the working parts of my improved signal
apparatus that each train in passing a signal post sets the danger signal,
which remains exposed until the train reaches the next post which may
be any required distance in advance when the danger signal is exposed
from this post, and that belonging to the preceding post is withdrawn to
"all clear." In this way each train sets the danger signal for the
following train, which signal cannot be withdrawn until the train has
reached the next signal post, thereby ensuring a certain interval between
the trains. Besides setting the danger signal I make my improved
apparatus acts upon a system of levers in such a manner as to project on
to the rails a fog signal or case of detonating powder, so that in the
event of an engine driver failing to see the danger signal projecting
from the signal post and allowing his train to pass the powder would be
exploded and he would hear the second signal if he did not see the

page_text: iron forming a keeper for the magnet by which to withdraw the bolt
from the slot when the electrical circuit is completed.
Working into the rack at the bottom of the sliding bar is a small spur
wheel keyed to a horizontal shaft working in two uprights; on the outer
end of this shaft is keyed a drum covered with leather or other tough
and yielding material, this drum is placed in such a position as to be
covered by the footboard of a passing train. Attached to the footboard
of the last carriage of the train is a projecting bar which comes in
contact with the drum in passing, by which means the spur wheel is
turned and the rack and sliding bar raised so as to move the semaphore
arm to the danger position, where it is held by the sliding bolt; this bar
is fixed by springs to the foot board so as to prevent any sudden jar to
the apparatus, or instead of working the danger signal in the abovo
manner a circular vertical bar may be used with a lever projecting so as
to be caught by the advancing train, the bar having a spiral groove cut
in it, which on being turned traverses upwards through a rifled bearing,
turning at the same time a disc which would indicate danger. Or levers
may be used actuated by a cam.
To complete the circuit of electricity through the galvanic battery and
electro-magnet a galvanic needle instrument is supplied; the needle of
this instrument is placed horizontally and moves on an ivory pivot or
other non-conducting material, as horn, ebonite, or wood. This pivot
protrudes above the carriage of the needle and has a copper wire fixed at
right angles to the needle, this copper wire is bent at the extremities,
and two small cups of mercury are placed so that the divergence of the
needle causes the ends of the copper wire to come in contact with the
mercury. The wires of the electro-magnet are fixed in constant contact
with the mercury, and the motion of the needle bringing the copper
wire into the cups of mercury the circuit between the battery and
magnet is completed and the magnet momentarily becomes excited.
One wire of the needle instrument and its galvanic battery is carried
from the first signal post by the danger signal to the next distant signal
post, while the other wire is buried in the earth for the earth circuit.
At the second signal post the line wire coming from the needle instru-
ment of the first signal is attached to the sliding bar of the second
signal, and on the post of this signal is a copper band in connection
with the earth; the raising of the sliding bar then at the second signal
brings the line wire into connection with the earth circuit for a moment

page_text: as the studs or bands connected with them come into contact by the
raising of the sliding bar, an arrangement being provided for preventing
contact as the sliding bar falls.
As the batteries both of the magnet and of the needle instrument are.
only brought into activity for a moment, on cach occasion the loss of
the elements of each is very small.
.
The apparatus by. which the detonating powder or fog signals are
worked is as follows:-A metal arm or lever is placed upon a wooden
board on the sleepers of the railway at the outer side of the rail; this arm
or lever works horizontally on a pivot and has a spring attached to it
which causes it to move in an outward direction from the rail when it is
released. To the other arm of the lever is attached a small chain or
wire rope, such as is used for working signals; this is carried over a
pulley or pulleys and is fixed to the lower end of the sliding bar of the
danger signal. The raising of the sliding bar draws back the end of the
lever and brings the other end forward towards the rail; on this latter is
fixed a thin piece of sheet metal, this carries the fog or detonating
signal, and when the arm of the lever to which it is attached is drawn
towards the rail the sheet of metal lies upon it, and if while in that
position a train passes the detonating signal upon it is exploded, when
the sliding bar is allowed to come down the arm of the lever which is,
attached to it is released and the spring forces back the arm carrying the.
detonating signal which is thus removed from the rail. A covered recess
is provided under which the lever and signal pass to be out of the way
of injury.
When a train passing along the line arrives at the first signal post it
causes the drum to revolve, which raises the sliding bar, and the sema-
phore arm is placed at danger and the detonating signals are placed on
the rail; as the train advances and arrives at the second signal post it
acts as before, but the act of throwing up the sliding bar of this second
post causes the bands or studs in connection with the line wire and
earth circuit to come into contact for a moment; this moves the needle
of the instrument at the first danger signal, causing the completion of
the galvanic current between the electro-magnet and its battery. The
electro-magnet is excited and draws back the spring bolt, allowing the
sliding bar to fall, removing in its fall the semaphore arm and the
detonating signal.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry James Barr in the Great Scal Patent Office
on the 16th November 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
JAMES BARR, of Culter House, near Aberdeen, North Britain, a General
in Her Majesty's Army, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Henry James Barr, Her special license
that I, the said Henry James Barr, my executors, administrators, and
assigns, or such others as I, the said Henry James Barr, my 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 Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for " IMPROVEMENTS IN
AUTOMATIC SIGNALS, MORE ESPECIALLY ADAPTED FOR USE ON RAILWAYS WHERE THE
'BLOCK' SYSTEM OF SIGNALLING IS EMPLOYED," upon the condition (amongst
others) that I, the said Henry James Barr, my executors or admini-
strators, by an instrument in writing under my, or their, or one of
their hands and scals, 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 Scal Patent
Office within six calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that I, the said Henry James Barr, do hereby declaro
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
1
My Invention of improvements in railway signals has for its object
the working of such signals by automatic machinery, so that the line of
railway may be absolutely "blocked" at certain well defined intervals
without the intervention of a signalman. I accomplish this by so con-

page_text: structing and arranging the working parts of my improved signal
apparatus that cach train in passing a signal post sets the danger signal
which remains exposed until the train reaches the next post, thus giving
any required distance between the two trains, according to the distance
apart of the signal posts. When the train reaches the second signal
post the danger signal is exposed from that post, at the same time the
preceding post is made to release its danger signal and exhibit the
signal "all clear," so that the driver of a following train may know
there is a clear distance between his train and the one in advance, equal
to the interval between the signal posts. In this way each train sets
the danger signal for the following train, which signal cannot be with-
drawn until the train has reached the next signal post. Besides setting
the danger signal I make my improved apparatus act upon a system of
levers in such a manner as to project on to the rails a fog signal or case
of detonating powder, so that in the event of an engine driver failing to
see the danger signal projecting from the signal post and allow his train
to pass, the powder would be exploded and he would hear the second
signal if he did not see the first.
The semaphore posts may be erected along each side of the railway,
so that one set of posts are used for the up line and the other set for the
down line. Or the posts may be erected between the two lines of rails
and having double arms, one arm projected towards the up line and to
be used for that line, the other arm projecting towards the down line
and to be used for that line, in which case there would be a saving of
one-half of the number of semaphore posts.
The following description and Drawings refer to the first-mentioned
system, but the same apparatus and mechanism would apply to the
second system if that were adopted.
The signal posts may be placed at any required distance apart, and if
wished the existing semaphore posts may be utilized and my improved
apparatus adapted to them; or part of my apparatus, viz., the levers
and detonating powder may be added to the existing permissive block
system worked by signal men.
I construct and work my improved apparatus in the following
manner I crect signal posts along the line of railway at any desired
invervals, say one, two, or three miles; to cach signal post is attached

page_text: a sliding vertical bar, furnished at its lower extremity with a metal rack
of from two to three feet in length; at the upper extremity of the
sliding bar is attached a chain or wire rope running over pulleys fixed
to the signal posts for the purpose of raising or lowering the semaphore
arm as the sliding bar is raised or lowered, or if preferred a bell
crank may be substituted for raising the semaphore arm.
In the signal
post is a small metal slot or hole, and the sliding bar is furnihsed
with a spring bolt which shoots into the slot when the bar is raised; in
this way the bar is kept stationary and the semaphore arm at danger
position. Attached to the signal post is a metal clamp projecting beyond
the sliding bar and supporting a strong electro-magnet, connected by
insulated wires to a galvanic battery at the foot of the post. The clamp
and magnet are placed exactly opposite the metal slot, and the spring
bolt is furnished with a cross head of soft iron, forming a keeper for the
magnet by which to withdraw the bolt from the slot when the electrical
circuit is completed.
Working into the rack at the bottom of the sliding bar is a small spur
wheel keyed to a horizontal shaft working in two uprights. On the
outer end of this shaft is keyed a wooden or metal drum covered with
leather or other tough and yielding material. This drum is placed in
such a position as to be covered by the footboard of a passing train.
Attached below the footboard of the last carriage of the train is a pro-
jecting bar, which comes in contact with the drum as the train passes
over, by which means the spur wheel is turned and the rack and sliding
bar raised so as to move the semaphore arm to the danger position, where
it is held by the sliding bolt. The striking bar is fixed to the footboard
by bolts and springs so as to prevent any sudden jar to the apparatus.
The projecting bar or striker may if preferred be placed in the centre
and below the framework of the carriage, the drum being situate
between the rails, but in such a position as to be out of the way of. all-
parts of the engine and carriages except the striker; or instead of
working the danger signal in the above manner a circular vertical bar
may be used with a lever projecting so as to be caught by the advancing.
train, the bar having a spiral groove cut in it, which on being turned
traverses upwards through a rifled bearing, turning at the same time a
disc which would indicate danger, or the sliding bar may be raised by
means of a jointed lever and cam, the first and last of these methods.
being illustrated by the accompanying Drawings..

page_text: To complete the circuit of electricity through the galvanic battery and
electro-magnet a galvanic needle instrument is supplied. The needle of
this instrument is placed horizontally and moves on an ivory pivot. This
pivot protrudes above the carriage of the needle and has a copper wire
fixed at right angles to the needle. This copper wire is bent at the
extremities, and two small cups of mercury are placed so that the diver-
gence of the needle causes the ends of the copper wire to come in contact
with the mercury. The wires of the electro-magnet are fixed in constant
contact with the mercury, and when the motion of the needle brings
the copper wire into the cups of mercury the circuit between the battery
and the magnet is completed and the magnet becomes excited. One
wire of the needle instrument and its galvanic battery is carried from
the first signal post to the next distant signal post, while the other wire
is buried in the earth for the earth circuit. At the second post the line
wire coming from the needle instrument of the first signal is attached to
the sliding bar of the second signal, and on the post of this signal is a
copper band in connection with the earth. The raising of the sliding
bar at the second signal brings the line wire into connection with the
earth circuit for a moment as the studs or bands connected with them
come into contact by the raising of the sliding bar.
As the batteries both of the magnet and of the needle instrument are
only brought into activity for a moment on each occasion the loss of the
clements of each is very small.
The apparatus by which the detonating powder or fog signal is worked
is as follows:-A metal arm or lever is placed upon a wooden board
on the sleepers of the railway at the outer side of the rail. This arm or
lever works horizontally on a pivot, a spring being set against this lever
in such a manner as to force it back from the rail when the lever is
released. To the other arm of the lever is attached a small chain or
wire rope carried over a pulley or pulleys and fixed to the lower end of
the sliding bar of the danger signal. When the sliding bar is raised the
lever and a piece of sheet metal fixed to it are moved forward to the
rail and take such a position that the detonating powders or fog signals
carried by the sheet metal are placed over the rail, and if while in that
position a train passes the signals are exploded. But if the sliding bar
is allowed to fall, as it would be when the last train had passed the next
signal post, then the detonating signal would be removed by the spring

page_text: forcing the lever away from the rail and into a covered recess provided
for the purpose.
When a train passing along the line arrives at the first signal post it.
causes the drum to revolve, which raises the sliding bar, and the sema-
phore arm is placed at danger, the detonating signals at the same time
being placed on the rail. As the train advances and arrives at the
second signal post it acts as before, but the act of throwing up the
sliding bar of the second post causes the bands or studs in connection
with the line wire and earth circuit to come into contact for a moment;
this moves the needle of the instrument at the first danger signal,
causing the completion of the galvanic current between the electro-
magnet and its battery; the electro-magnet is excited and draws back
the spring bolt allowing the sliding bar to fall, removing in its fall the
semaphore arm and the detonating signal.
A modification of the above described apparatus can be applied when
the railway consists of a single line only, to prevent any two trains
mecting through being started from opposite ends of the line without
the way being all clear, as was the case in the recent accident at Thorpe..
In situations as above described I would fix at each terminal station a
revolving disc actuated by clockwork, and having a loud sounding bell
attached, say at Norwich and Brundall. On the disc at Norwich would
be inscribed the names of Brundall and, say, three intermediate
stations, x, y, z; and on the disc at Brundall would be inscribed
Norwich and 2, y, x, the instruments being wound up and kept at rest
by a detent wheel which is connected with an electro-magnet this
magnet when excited withdraws the detent and allows the disc to move
one step and to sound the bell. Wires connecting batteries with the
electro-magnets are carried along the line from end to end, and at each
station a means is supplied which causes the completion of the galvanic
circuit between the battery and the electro-magnet. The action of this
system would be as follows:-Suppose a train to start from Norwich for
Brundall; as it leaves the Norwich station it passes over the first of tho
contact points, this completes the galvanic circuit with the magnet of
the disc instrument at Brundall," the detent is withdrawn, the bell
sounds, and the name Norwich is shewn on the Brundall instrument.
This remains exposed until the train arrives at station x, when contact
being again made the bell sounds and the name of the station x is
exhibited, and so on for each station. Again, a train starting from.
"

page_text: .
Brundall makes contact as it leaves that station, which causes the
instrument at Norwich to sound its bell and exhibit the name Brundall,
and as it proceeds on its journey and arrives at the stations 2, y, x, in
succession, the bell at the Norwich station is sounded for each, and the
names of the stations Z; Y, X, are successively exhibited on the Norwich
instrument. It must of course be understood that this system is
specially for single lines, and even then it does not in any way interfere
with the semaphore automatic danger signals which shew to following
trains moving in the same direction a "clear" or an "interrupted"
linc.
And in order that my Invention may be clearly understood and more
readily carried into practical effect, I will now proceed to describe the
two Sheets of Drawings hereunto annexed, similar letters of reference on
Figures 1 and 2 of Sheet 1, and also on all Figures of Sheet 2, referring
to similar parts.
Sheet I., Figure 1, shews two elevations of a semaphore signal post in
front of a train, and having the signal in the position to indicate "all
clear."
Figure 2 shews two elevations of a similar post in rear of the train
with the signal at the "danger" position. A, A, are signal posts erected
along the line of railway; B, the sliding vertical bar carrying rack C;
D is a small chain or wire rope attached at one end to the sliding bar,
then passing round pulleys E, E, and attached to arm F; G is a slot or
hole in the signal post to receive the spring bolt H; K is a metal clamp
to support the electro-magnet L; M is a soft iron cross head of the
bolt H to act as a keeper for the magnet when it is required to release
the bolt from the slot; N is a small spur wheel or rack pinion keyed on
to shaft O working in bearings P, P. At the outer end of the shaft O
is fixed the drum Q, this drum being actuated by the striking bar S
attached to the footboard of the last carriage. R, R, are the wires
from the clectro-magnet to the cups of mercury below.
Figure 3 is a plan view (drawn to a larger scale than Figures 1
and 2) of the detonating apparatus. A is a horizontal lever carrying
the metal plate B and working on a pivot at C; D is a spring for forcing
back the lever when the danger signal falls; E is a wood platform, on
which the lever moves; F is a cover to form a recess for the lever when
removed from its position on the line; G is a chain or wire for attaching

page_text: the lever to the sliding bar; H shews the position of the lever when
forced back by the spring; K, K, K, detonating powders or fog signals,
of which there may be any number fixed to the metal plate B.
Sheet 2 represents the method of raising the bar by means of a cam
motion, the other parts of the apparatus remaining the same as illus-
trated by Sheet I., this motion merely taking the place of the rack and
pinion, and consists of a jointed lever, one end of which is actuated by
the cam, and the other end acts upon the sliding bar.
Figure 1 shows the jointed arm of the lever passing the pin of the
sliding bar to get into the position shewn by Figure 2, where the lever
has hold of the bar, but is kept from moving by the cam.
.
Figure 3 shews the sliding bar raised to its proper height by the
jointed lever, the long arm of which has been allowed to fall owing to
the cam making half a revolution.
Figure 4 is an end view of the apparatus shewing the connection of
the striking bar to the footboard of the carriage. Similar letters of
reference are used to indicate similar parts in the four Figures. A is the
upright semaphore post, as in Sheet 1; B is the sliding bar; C is a slot
or recess in the bar for the reception of the spring bolt D working
through the post; E is the axle, on which is keyed the drum F and
cam G; F is the drum on the axle, which is actuated by the striking
plate of the last carriage of the train; G is a cam keyed to the same
axle as the drum; this cam is placed under and raises the lever N;
H, H, are the supports carrying the axle E; K is the striking plate
attached to the footboard L of the carriage. M, N is the jointed lever
for raising the sliding bar. This lever is weighted at M to cause it
readily to fall, and is jointed at N so as to pass the projecting pin O of
the sliding bar; O is a pin projecting from the bar B forming a lip for
the lever.
Having now particularly described and ascertained the nature of my
Invention and how the same may be put into practical operation, I
would have it understood that what I claim and desire to secure by the
herein-before in part recited Letters Patent is,―
Firstly. The mechanism and electrical apparatus attached to signal
posts for the purpose of indicating various railway signals, whether by

page_text: arms or discs, as herein-before described and illustrated by the accom-
panying Drawings, Sheet I., Figures 1 and 2.
÷
Secondly. The arrangement of mechanism for working such signals
automatically, whether by rack and pinion arrangement, as illustrated
by Sheet I., Figures 1 and 2, or by cam motion, as illustrated by Sheet 2,
as herein-before described.
Thirdly. The arrangement of mechanism for placing detonating
signals on the line, actuated by my before-mentioned apparatus, as
herein-before described and illustrated by the accompanying Drawing,
Sheet I., Figure 3.
And, Fourthly. The arrangement of mechanism for working signals
automatically to prevent trains running in opposite directions meeting
on a single line, as herein-before described.
In witness whereof, I, the said Henry James Barr, have hereunto
set my hand and seal, this Fourteenth day of November, in the
year of our Lord One thousand eight hundred and seventy-
four.