IMPROVED APPARATUS FOR SIGNALLING UPON RAILWAYS
Year: 1862

page_text: LETTERS PATENT to William Henry Preece, of the Town and County of
Southampton, Civil Engineer, for the Invention of "IMPROVED APPARATUS
FOR SIGNALLING UPON RAILWAYS."
Sealed the 24th June 1862, and dated the 10th January 1862.
PROVISIONAL SPECIFICATION left by the said William Henry Preece, at
the Office of the Commissioners of Patents, with his Petition, on the
10th January 1862.
I, WILLIAM HENRY PREECE, of the Town and County of Southampton,
Civil Engineer, do hereby declare the nature of the said Invention for "IMPROVED
APPARATUS FOR SIGNALLING UPON RAILWAYS," to be as follows:-
The object of this Invention is to simplify the system of telegraphing signals
to pointsmen and others engaged upon or in the working of railways, that the
risk of mistakes in the reading of the signals may be wholly avoided. To this
end I propose in place of relying upon the deflections of needles or other
arbitrary signals, dissimilar from those used on the line of railway to which
my Invention is to be applied, to assimilate the signals of telegraphic instru-
ments to the visible signals used upon the line, and familiar to all persons
engaged in the working of the railway. This I effect by adapting to tele-
graphic instruments a şemaphore arm or a disc, as the case may be, which I
operate by magnetic power, the electric current employed acting either directly
upon wheelwork, or by an electro-magnet, releasing and then locking an
arrangement of clockwork.

page_text: One convenient arrangement which I employ may be described as a
semaphore arm mounted on a pillar, and connected by a rod to a weighted bell
crank lever. The short arm of this lever bears upon and is kept in an elevated
position by means of one of a series of studs projecting from a wheel which
is made to rotate by means of clockwork. On the other side of this wheel is
a second series of studs carrying bowls, which are in succession engaged by one
or other of a pair of pallets carried by a pallet lever. The tail of this lever
carries an armature, which is acted upon by an electro-magnet, and the lever
is thereby caused to rock the pallets, and alternately to release and to lock the
wheel. At each partial revolution of the wheel, the stud that for the time
being supports the bell crank lever moves forward, and the lever, deprived of
its support, falls by its own weight, thereby bringing down the semaphore arm.
When the armature is no longer attracted by the magnet, a spring bearing
upon the pallet lever will operate it in the reverse direction; the wheel will
then continue its revolution, until a stud thereon lifts the weighted bell crank
lever and with it the semaphore, which will then again show the danger signal.
When this is effected the pallet lever will again lock the wheel and prevent
the further action of the instrument until a current of electricity is again sent
through the coils of the electro-magnet.
Instead of the arm standing at "danger" when the instrument is at rest,
the arm may by the action of the magnet be used to raise it by simply altering.
the connection between the arm and the bell crank lever.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Henry Preece in the Great Seal Patent Office
on the 10th July 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HENRY PREECE, of the Town and County of Southampton, Civil Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of January, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said William Henry Preece, Her special license that I, the said William
Henry Preece, my executors, administrators, and assigns, or such others
as I, the said William Henry Preece, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to time'
-

page_text: 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 "IMPROVED APPARATUS FOR SIGNALLING UPON RAILWAYS," upon the
condition (amongst others) that I, the said William Henry Preece, by an
instrument in writing under my hand and seal, 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 William Henry Preece, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
-
The object of this Invention is so to simplify the system of telegraphing
signals to pointsmen, and others, engaged upon or in the working of railways,
that the risk of mistakes in the reading of the signals may be wholly avoided.
To this end I propose in place of relying upon the deflections of needles or
other arbitrary signals, dissimilar from those used for the regulation of trains,
upon the line of railway to which my Invention is to be applied, to assimilate
the signals of telegraphic instruments to the visible line signals used upon
and familiar to all persons in the working of the railway. This I effect by
adapting to telegraphic instruments a semaphore arm or disc or other indicator,
as the case may be, which I operate by electro-magnetic power.
In
my Provisional Specification I described an arrangement of apparatus in
which a clock movement was required in addition to an electro-magnet for
operating the semaphore arm; I have however found in practice that it is better
to rely upon the weight of the semaphore arm and its connections (without
the intervention of an escapement operated by clockwork), to effect its
depression or maintain its elevation, as the case may be, and to apply the electro-
magnet directly to the lever connected to the rod of the semaphore, for the
purpose of raising or depressing that arm to indicate the danger signal.
In the accompanying Drawing, Fig. 1 shews in side elevation, and Fig. 2 in
front view, the instrument thus modified for telegraphing to pointsmen signals,
which are a counterpart of those used upon the line for indicating whether it
is blocked or open. A, A, is a wooden stand, on which the signalling instrument
is fixed; B is a pair of metal standards screwed down to a metal bed plate C,
and coupled together at top by a cross bar. These standards B serve to

page_text: carry the fulcrum pin of a compound rock lever D, D', to which is attached an
armature E soft iron. This armature E stands over the poles of the electro-
magnet F, through the coils of which a current of electricity is transmitted
when it is desired to set the magnet in action and cause it to attract the
armature E. The rear end D' of the rock lever is connected to a vertical
rod G, which slides in guides in a hollow standard II, and is furnished at its
upper end with rack teeth H. These teeth gear into a pinion I attached to
the axle of the semaphore arm K, which axle has its bearings in the hollow
standard H. The end D of the rock lever carries a pair of flat springs 1, 1,
which have a tendency to stand out from the lever, and serve to ease the
action of the instrument as the rock lever plays between two adjustable stops,
2, 3, the former of which is carried by a metallic standard L secured to the
wooden stand, and the latter by a metallic pillar M also attached to the wooden
stand. Both of these supports are therefore insulated. The rock lever is
furnished with a bracket arm N for carrying an adjustable weight O, the
object of which is to regulate the poise of the semaphore arm and its connec
tions. The instrument when not in action will stand in the position shewn
at Fig. 1, that is, the weight of the semaphore arm, together with the rod G,
which is connected therewith through the gearing by depressing the end D¹ of
the rock lever that carries the armature, will hold that armature suspended
above the magnet. When, however, a current of electricity is thrown into the
coils of the magnet, the armature will be attracted by the magnet and held in
contact therewith so long as the current is maintained. This downward
movement of the armature will raise the end D¹ of the rock lever, and with it
the rack rod G, which through the pinion I will turn the axle of the semaphore
arm in its bearings, and elevate the semaphore to the position shewn at Fig. 3,
As soon, however, as the current is broken the attraction of the magnet will
cease and the armature E, being free, the semaphore arm will fall and all the
parts will return to the position shewn at Fig. 1.
The manner in which I propose to adapt the Invention to the requirements
of railways will be best explained by reference to the Diagram, Fig. 4, which
represents two similar instruments with their batteries set at two distant
points A and B, say, at opposite ends of a long tunnel, and connected with
two bell or audible signal instruments fitted with a visible signal, which signal
indicates the state of the semaphore at the distant station. I would, however,
remark that this arrangement for producing secondary signals is not essential
to the proper working of my improved instruments. Let it now be supposed
that it is the duty of the pointsman at the station A to operate the instru
ment at the station B, and that the pointsman at B has the operation of the

page_text: instrument at A under his command, and that the audible signals are operated
in the usual manner, and employed to attract the attention of the pointsman
and signify the approach of a train, the normal state of the semaphore instru-
ments being as shewn at Fig. 1, that is, indicating that the line is open. If
now the line is clear and a train is about to start from the station towards
the station B, the pointsman at A by means of the finger key P will sound
the bell at the station B signifying that the train has started. The pointsman
at B will then by means of a switch key Q return A signal, and raise the
semaphore of the instrument at A. By this action metallic contact will
be set up between the rock lever D and the pillar M of the semaphore
instrument at station A, and a current of electricity will pass thence to the
bell signal at station B, giving an audible signal intimating that the sema-
phore at A is raised, and indicate the same on the dial of the bell instrument.
The construction of this audible and visible signal instrument being well
known it will be unnecessary here to explain it. The semaphore at A will
continue elevated (thereby indicating danger) until the passing train has
arrived at B; the pointsman at B will then restore the key Q to its former
position, and thereby lower the semaphore of the instrument at station A, and
return the index on the bell instrument at station B to its former position.
When a train is passing along the line in the opposite direction, the reverse
of the above-described movements will take place, that is to say, the first
signal will be given by the pointsman at station B, who will by the depression
of the key P' set the audible signal apparatus at station A in action, and
the pointsman at A will by means of the key Q'set the semaphore of the
instrument B.
I will now explain the arrangement of the electrical connection for effecting
these operations. Referring first to the semaphore instrument A, an under side
view of which is shewn at Fig. 4, it will be seen that the metallic bed plate C
is connected by a wire 4 with a terminal 5, the electro-magnet is connected by
wires 6 to the terminals 7 and 8, the former of which is connected with the
earth, and the latter by means of the line wire 9 with the switch key Q at the
station B. The standard L, which carries the point 2, has metallic connection
through the wire 10 with the terminal 11, and the pillar M, which carries the
point 3, is similarly coupled by a wire 12 with the terminal 13. R. is a
battery at station A; connected by a wire 14 with the terminal 13, and this
terminal is further connected by a wire 15 with the key P. A second wire 13*
from the key P passes to the terminal 5, and a third wire from the key passes
to the line wire 16, which wire is connected with the corresponding key P¹ at
the station B. From the terminal 11 a wire 17 passes to the audible signal

page_text: apparatus of the station A, which apparatus is by means of a wire 18 con-
nected with the earth. I would here remark that the wires represented by
• blue lines convey the electricity for operating the semaphore instruments, and
the wires represented by the red lines convey the electricity for working the bell
instruments, the currents for the latter purpose being obtained from the batteries
R.and R', and the currents for the electro-magnets which work the semaphore
.instruments from the batteries S and S¹. The battery S at station A is connected
by a wire 19 with the switch key Q' of that station, and a line wire 20 con-
nects this key with the semaphore instrument at station B. The electric
connections at the station B are a counterpart of those already described.
It will now be understood that the pointsman at A, when signalling to B
that a train has started by the depression of the finger key P, causes a current
of electricity to flow from the battery R through the wires 14 and 15 to the
key P, thence by the line wire 16 to the key P¹ at station B, then to the
plate C of the semaphore instrument at the station, thence by the wire 4
leading from the terminal 5 up the standards B, and along the rock lever D
to the point 2, carried by the standard L, and from this standard by the wires
10. and 17 to the bell instrument at station B, when the current will find its
.way to earth by the wire 18. The pointsman at B having received this signal
will work the switch key Q, thereby connecting the line wire 9 with the
battery S¹. A current of electricity will consequently flow from the battery S¹
by the wires 9 and 6 to the electro-magnet of the semaphore instrument at A.
While this current is maintained the electro-magnet will hold down the rock
lever D and bring it through its lower spring 1 into contact with the point 3
of the pillar M, thereby raising the semaphore signal of the instrument at A.
But besides this the movement of the instrument completes the circuit for the
current from the battery R, and allows it to pass instead of through the
wire 15, as already explained, to the audible signal at the station B by the
wire 12 to the pillar M, thence through the rock lever D and standard B to
the bed plate C, and by the wires 4 and 13* to the key P, which is connected by
the line wire 16, as before described, with the bell instrument, and an audible
signal signifying that the semaphore at station A is set for "danger" is given.
As the course of the currents for giving the signals requisite for indicating the
passing of a train in the opposite direction is the inverse of that described, and
may readily be followed by means of the Diagram, Fig. 4, it will be unnecessary
further to refer to these counterpart operations.
Having now set forth the nature of my Invention of improved apparatus
for signalling upon railways, and explained the manner of carrying the same
into effect, I wish it to be understood that under the above in part recited

page_text: Letters Patent I claim, assimilating the signals of electrical railway signalling
instruments to the line signals of railways, in the manner and for the purpose
above described.
In witness whereof, I, the said William Henry Preece, have hereunto
set my hand and seal, the Ninth day of July, in the year of our
Lord One thousand eight hundred and sixty-two.
W. H. PREECE. (L.S.)