IMPROVEMents in Pneumatic SignALO FOR RAILWAVO ”
Year: 1875

page_text: LETTERS PATENT to Austin Chambers, of No. 258, Marylebone Road,
in the County of Middlesex, Signal Engineer, for the Invention of
"IMPROVEMents in Pneumatic SignALO FOR RAILWAVO ”
PROVISIONAL SPECIFICATION left by the said Austin Chambers at
the Office of the Commissioners of Patents, with his Petition, on
the 30th June 1875.
I, AUSTIN CHAMBERS, of No. 258, Marylebone Road, in the County
of Middlesex, Signal Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN PREUMATIC SIGNALS FOR RAILWAys," to be
as follows: —
This Invention has reference to signalling apparatus in which the
signalling objects or bodies are moved pneumatically, and has for its
object to combine simplicity of construction with ease and rapidity of
working, and to preclude the assumption of the "safety or "pass on "
positions by the signalling object or body in the event of breakage or
failure of intermediate parts of the apparatus.
"

page_text: To expedite the operation of moving over the lever or handle to the
necessary extent for changing the position of the signalling object or
body I employ a compressor so constructed and connected with the
actuating lever or handle as that by the compression of the elastic fluid
effected by moving over the lever or handle the resistance shall be over-
come of a portion of the compressor, the capacity of the compressor
being thereby temporarily augmented beyond that which obtains when
the operation of compression has been completed, the latter capacity
being attained by the automatic return to the original position, or nearly
so, of the part or parts of the compressor whose resistance to outward
or extensible movement shall have been temporally overcome by the
movement of the lever.
Instead of actuating the signalling objects or bodies by compression of
elastic fluid it may be done by rarefaction, for which purpose apparatus
as above described may obviously be arranged to operate inversely.
The compressors, rarefiers, and collapsible vessels I by preference
construct mainly of flexible material, such as sheet india-rubber, and in
order to guard against failure through leakage, whilst at the same time
securing a maximum amount of flexibility, I use thin sheets of such
flexible material, which I fasten together in two or more layers by the
interposition of suitable adhesive substance, the layers of flexible
material being so arranged as that the joint or junction of the inner
thickness or layer shall be amply covered, strengthened, and protected
by one or more superposed layers of the same material.
One sheet of flexible material may be so wound around a block or
cylindrical object as to cause one part of such sheet to overlap another,
and so to form the several layers without breakage of the continuity of
the material.
و,
"E
I so arrange and dispose the weight of the signalling objects or bodies
that they shall have to be drawn down when required to assume the
"safety or pass on" position, and that when the normal pressure of
the external atmosphere prevails in the pipes, tubes, and vessels of tho
apparatus the signalling objects shall automatically resume the
"danger" position.
I provide the following arrangement where necessary for indicating
at any required place when the signalling object has resumed or occupies
the "danger" position :-A. U shaped liquid gauge or other pressure

page_text: gauge placed in the situation at which the indications are required is:
connected by a pipe, tube, or passage with a valve chamber fixed to the
collapsible or expanding and contracting vessel constituting the means;
of actuating by changes of fluid pressure the signalling object or body.
A passage is formed between the valve chamber and the interior of the
collapsible vessel, the orifice of which passage is provided with a valve
pressed against its seat by a spring or weight.
When the collapsible vessel is expanded, the signalling object being
in the safety position, the valve will be closed, but when the collapsible
vessel is collapsed the valve will be moved from its seat, thus establishing
communication between the interior of the collapsible vessel and the
gauge, and by the change of pressure effecting the required indication.
In juxtaposition to the above-named gauge I arrange a second gauge,
which I place in communication with the interior of the compressor or
air pump, whereby the changes of pressure are effected, so that the
shewing of different pressures by the two gauges shall indicate that the
collapsible vessel has not returned to the "danger" position.
The two gauges must shew the same pressure when the collapsible
vessel has opened the valve by returning to the "danger" position, and
has thus established free communication between the two gauges.
In cases where it is desired that the concurrence of two or more
persons stationed at different places shall be an essential preliminary to
the moving of the signalling object or body into the safety or pass
on position I provide in some convenient elastic fluid containing
portion of the apparatus an escape opening furnished with a balanced
valve lid or closure arranged to be fastened in its closed position by
means of a locking or holding arrangement operated by electricity from
the place whence it is required to govern the moving of the signalling
object into the "safety or pass on " position.
دو
66
The locking arrangement may be in the form of a catch, or the
armature of an electro-magnet may be connected to the valve lid or
closure, and so be made to serve for holding it in the closed position
when required. By this arrangement, assuming the lever whereby the
compressing or rarefying apparatus (as the case may be) is worked, or
by which communication is when required established between the
collapsible vessel and a reservoir of compressed elastic fluid, or a vessel'
n which a partial vacuum is maintained, to be moved into the position
A 2

page_text: "
for "taking off" a signal, or in other words, into the proper position for
moving the signalling object or body into the "safety" or "pass on
position, such movement of the said lever will exercise no influence upon
the signalling object or body unless the valve or closure has been pre-
viously locked or fastened in its closed position, because, by reason of
the arrangement of the apparatus, so long as the valve or closure
remains unlocked the pressure within the clastic fluid containing appa-
ratus cannot be made to differ sensibly from the normal pressure of the
external atmosphere, and whilst that pressure prevails within the
apparatus the signalling object or body must of necessity be in the
danger position.
It will be evident that this part of my Invention may be so applied
as to make the concurrence of any desired number of persons stationed
at different places an essential preliminary to the moving of a signal
into the safety position.
The valve lid or closure and locking or holding arrangement may be
enclosed in a suitable casing arranged to admit of the circulation of
elastic fluid, but so as to preclude tampering with the apparatus.
Where I have in this Specification used the words "signalling object
or body" I desire it to be understood that I mean those words to include
also any single set of signalling objects or bodies, as for example, a
semaphore arm with its lenses operating in conjunction with a lamp or
other well-known appliances for signalling on railways.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Austin Chambers in the Great Seal Patent 28
Office on the 29th December 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, AUSTIN
CHAMBERS, of No. 258, Marylebone Road, in the County of Middlesex,
Signal Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 30
Letters Patent, bearing date the Thirtieth day of June, in the year
of our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors, give

page_text: and grant unto me, the said Austin Chambers, Her special license that I,
the said Austin Chambers, my executors, administrators, and assigns,
or such others as I, the said Austin Chambers, my exccutors, admini-
strators, 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 PNEUMATIC
SIGNALS FOR RAILWAYS," upon the condition (amongst others) that I, the
said Austin Chambers, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, 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 Austin Chambers, 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, and the three Sheets of Drawings
therein referred to (that is to say) :-
This Invention bas reference to signalling apparatus, in which the
signalling objects or bodies are moved pneumatically, and has for its
object to combine simplicity of construction with ease and rapidity of
working, and to preclude the assumption of the "safety" or "pass on"
position by the signalling object or body in the event of breakage or
failure of intermediate parts of the apparatus.
To expedite the operation of moving over the lever or handle to the
necessary extent for changing the position of the signalling object or
body I employ a compressor, so constructed and connected with the
actuating lever or handle as that by the compression of the air or other
elastic fluid in the compressor effected by moving over the lever or
handle the resistance shall be overcome of a portion of the compressor,
the capacity of the compressor being thereby temporarily augmented
beyond that which obtains when the operation of compression has been
completed, the latter capacity being attained by the automatic return
towards the original position of the part or parts of the compressor
whose resistance to outward or extensible movement shall have been

page_text: temporarily overcome by the movement of the lever. By this arrange-
ment when the lever has been moved over and the signal thereby
lowered the signal will be retained in its lowered position by the
constant pressure of the air or other fluid in the pipe, tube, or passage
and collapsible vessel, as the upper portion of the compressor will in its
effort to resume its normal position have the important effect of
maintaining an uniform pressure in the pipe, tube, or passage and
collapsible vessel.
Instead of actuating the signalling object or body by compression of
air or other elastic fluid the same result may be produced by rarefaction,
for which purpose apparatus as above described may obviously be
arranged to operate inversely.
The compressors, rarefiers, and collapsible vessels I by preference
construct mainly of flexible material, such as sheet india-rubber, and in
order to guard against failure through leakage, whilst at the same time
securing a maximum amount of flexibility, I use thin sheets of such
flexible material, which I fasten together in two or more layers by the
interposition of suitable adhesive substance, the layers of flexible
material being so arranged as that the joint or junction of the inner
thickness or layer shall be amply covered, strengthened, and protected
by one or more superposed layers of the same material.
One sheet of flexible material may be so wound around a block or
cylindrical object as to cause one part of such sheet to overlap another,
and so to form the several layers without breakage of the continuity of
the material.
66
"
I so arrange and dispose the weight of the signalling objects or bodies
that they shall have to be drawn down when required to assume the
'safety" or pass on" position, and that when the normal pressure of
the external atmosphere prevails in the pipes, tubes, and vessels of the
apparatus the signalling objects shall automatically resume the "danger"
position.
I provide the following arrangement where necessary for indicating
at any required place when the signalling object has resumed or occupies
the "danger" position. A. U shaped liquid gauge or other pressuro
gauge placed in the situation at which the indications are required is
connected by a pipe, tube, or passage with a valvo chamber fixed to the

page_text: collapsible or expanding and contracting vessel constituting the means
of actuating by changes of fluid pressure the signalling object or body.
A passage is formed between the valve chamber and the interior of the
collapsible vessel, the orifice of which passage is provided with a valve
pressed against its seat by a spring or weight.
When the collapsible vessel is expanded the signalling object being
in the " safety" position the valve will be closed, but when the
collapsible vessel is collapsed the valve will be moved from its seat, thus
establishing communication between the interior of the collapsible vessel
and the gauge, and by the change of pressure effecting the required
indication. In juxtaposition to the above-named gauge I arrange a
second gauge, which I place in communication with the interior of the
compressor or air pump, whereby the changes of pressure are effected,
so that a comparison of the two gauges shall indicate whether the
signalling object has returned to the "danger" position or not.
The two gauges must shew the same pressure by reason of the opening
of the valve, which will occur as soon as the base of the collapsibl
vessel has returned sufficiently to replace the signalling object in the
danger" position.
"
In cases where it is desired that the concurrence of two or more
persons stationed at different places shall be an essential preliminary to
the moving of the signalling object or body into the "safety" or "pass
on" position, I provide in some convenient portion of the apparatus
containing air or other elastic fluid an escape opening, furnished with a
balanced valve lid or closure arranged to be fastened in its closed
position by means of a locking or holding arrangement operated by
electricity from the place whence it is required to govern the moving of
the signalling object into the "safety" or "pass on " position.
The locking arrangement may be in the form of a catch, or the
armature of an electro-magnet may be connected to the valve lid or
closure, and so be made to serve for holding it in the closed position
when required. By this arrangement, assuming the lever whereby the
compressing or rarefying apparatus (as the case may be) is worked, or
by which communication is when required established between the
collapsible vessel and a reservoir of compressed elastic fluid, or a vessel
in which a partial vacuum is maintained, to be moved into the position,
for "taking off" a signal, or, in other words, into the proper position

page_text: for moving the signalling object or body into the "safety" or "pass
on" position, such movement of the said lever will exercise no influence
upon the signalling object or body unless the valve or closure has been
previously locked or fastened in its closed position, because, by reason of
the arrangement of the apparatus, so long as the valve or closure
remains unlocked the pressure within the apparatus containing air or
other elastic fluid cannot be made to differ sensibly from the normal
pressure of the external atmosphere, and whilst that pressure prevails
within the apparatus the signalling object or body must of necessity be
in the "danger" position.
The valve lid or closure and locking or holding arrangement may be
enclosed in a suitable casing arranged to admit of the circulation
of air or other elastic fluid, but so as to preclude tampering with the
apparatus.
Where I have in this Specification used the words "signalling object
or body," I mean those words to include also any single set of signalling
objects or bodies, as, for example, a semaphore arm with its lenses
operating in conjunction with a lamp or other well-known appliances for
signalling on railways.
Fig. 1 (Sheet 1) of the Drawings is an elevation, partly in section, of
apparatus according to my Invention.
Fig. 2 is a vertical section of the compressor.
Fig. 3 is a horizontal section shewing the mode of constructing the
flexible portion of the compressor.
Fig. 4 is an elevation shewing the signal post with its lamp, the 1
semaphore arm, spectacles, or lenses, and the arrangements for drawing
the same down when the pressure of the air in the pipe leading from the
compressor exceeds the pressure of the external atmosphere.
Fig. 5 (Sheet 2) is an elevation, partly in section (to an enlarged
scale), of the air escape opening with its valve or closure and apparatus, &
for holding the valve in its closed position, as seen from the contrary
side to that shewn in Fig. 1.
This apparatus is suitable for use at a junction or crossing, being so
contrived that the signal cannot be drawn down by moving the lever a,
shewn in Fig. 1, until the electrical apparatus has been concurrently a
operated upon.

page_text: '
a is the lever for actuating the signals. The arm a', to which a
guided rod with a bracket or arm b' is suspended, carries a rod `bº;
which enters a tube c (see Fig. 2). This tube is open at its lower end;
which is fastened to the base of the compressor into which the tube
projects, the upper end of the tube being closed, as shewn, with the
exception of a small hole to admit air for the purpose herein-after
mentioned. The upper end of the rod 6³ serves as a valve to close the
small hole. The central portion of the compressor consists of a fixed
flanged metal ring d, having an opening through it, and communicating
by a pipe e with the collapsible vesself, by whose motions the semaphore
arm is actuated (see Fig. 4). The lateral portions of the upper part d
and lower part d² of the compressor are formed of flexible material, such
as sheet india-rubber, fastened by the ordinary cement, but wrapped
round in the manner shewn in Fig. 3, rigid rings d³ being introduced at
suitable intervals, as well understood, to ensure the collapsing of the
compressor as required. To prevent too sharp a fold of and consequent
injury to the flexible material when the compressor is collapsed I inter-
pose distance pieces do between the rings d³, as shewn, so that the rings
cannot approach each other beyond a predetermined limit.
It will be evident that flanges formed with the rings may be
substituted for the distance pieces d. The ends or covers d', d³, are
made heavy; the upper cover d' carries a couple of rods d* working in
guide tubes de carried by a plate or cross piece di resting upon an
internal ledge of the central portion or ring d; the plate or cross piece d'
also carries a central tube & for guiding the tube c. The collapsible
vesself is made similarly to the compressor of flexible material attached
to rings, and is suspended from a bracket attached to the signal post, a
part of which bracket forms the upper end of the collapsible vessel,
whose lower end may consist of a metal plate, as shewn. To the lower
end of the collapsible vessel is secured a frame 9 connected by a rod h
to the longer arm i of the semaphore whose fulcrum is at (Fig. 4);
the shorter arm of the semaphore carries a "danger glass and a
'safety" glass **; the Drawing shews the positions of the parts when
the signal is at "danger." If the lever a be now moved over in the
direction indicated by the arrow (Fig. 1) the lower portion of the
compressor will be collapsed, the air within it being compressed will
cause the upper portion d' to suddenly expand, but the weight of the
end or cover d' and its attachments will cause the upper portion d¹ to
"

page_text: move back towards its original position. The air within the compressor
and tube e being compressed by the downward movement of the end or
cover dwill (if the valve / be closed) expand the collapsible vessel f,
thereby drawing down the longer arm i of the semaphore into the
position indicating that a train may proceed. On then moving the i
lever a back into the position shewn in the Drawing the rod b² will be
caused to move partly out of the tube c, the movement of the lever being
more rapid than that of the lower end of the compressor, which however
will gradually follow (expedited by air entering through the small hole
in the end of the tube c) until it has resumed the position shewn, and
by restoring the pressure within the compressor and pipe e to the
normal or external atmospheric pressure will have caused the partial
collapse of the vesself into the position shewn in the Drawing, thus
restoring the signal to the "danger" position.
It will be evident that instead of the small hole in the end of the 1
tube c a suitable valve may be arranged either on the top or bottom of
the compressor. upon the air pipe leading to the collapsible vessel f,
which valve shall act automatically by the partial vacuum formed in
the compressor, or may be so arranged as to open and close as required
by the action of the compressor itself. e' is an escape opening furnished
with a valve & carried by a lever having its fulcrum at. and carrying
an adjustable weight at which is to be so adjusted that when the
pressure in the pipe e does not exceed that of the external atmosphere
it will keep the valve k against its seat (see Fig. 1). m is the armature
of an electro-magnet m¹ arranged in the same circuit m³ as the ordinary
telegraphic indicator m³, so that the same operation which changes the
position of the indicator pointer will also positively control-the-valve-k,-
and consequently the moving of the signal into the "safety" or "pass
on" position.
The telegraph indicator will shew the man in charge of the lever a
when he may move over that lever to draw the signal down into that
position. n is a case enclosing the valve, electro-magnet, and other
parts to preclude tampering; aro air holes; n is a guard over them,
it is open at its sides to the case to allow free passage of air; o is a
water gauge (see Fig. 1).

page_text: be made the electric current will lower the indicator arm and cause the
electro-magnet to attract the armature, thus holding the valve in its
closed position, so that should the lever a be moved over the air in the
compressor pipe e and vessel f will be compressed so as to bring down
the signal. Assuming that the lever a be moved over before the valve /
has been locked in its closed position, or that after the signal has been
drawn down and whilst it is in the "safety" or "pass on" position, the
commutator or apparatus at the controlling station be operated so as to
break the circuit the pressure of air in the pipe e will in either case
move the valve k and permit the escape of fluid from the pipe e, thus
returning the signal to the horizontal or "danger" position. Thus
until and unless this valve is locked in its closed position it is impossible
either to draw down the signal by moving over the lever a or to retain
it in the "safety or "pass on" position. The valve adjusting screw (*
forms a stop to prevent the lever being tilted too far.
"
Fig. 6 shews in central vertical section a modified arrangement of
compressor, in which the rod b and the small hole in the tube c described
with reference to the preceding arrangement are dispensed with. In
this case the arm a¹ of the lever is connected by chains p¹ and a cross
head p to the lower end of the compressor.
Fig. 7. shews in side elevation another modification of the compressor,
in which d¹ and d³, instead of being arranged one above the other, are
placed at a distance from each other, and connected by a tube or
passage d".
When the apparatus is to actuate the signal by rarefaction I connect
the arm a¹ of the lever a to the upper end d, and for the tube c (Fig. 2)
in the lower part d³ I substitute a simple guide rod. I invert the col-
lapsible vesself, and connect what then becomes the upper end of the
vesself to the arm i. By this arrangement, assuming the lever a to be
moved over so as to expand or move up the upper portion of the rarefier,
the lower portion will by the pressure of the external air be temporarily
collapsed, but will automatically resume its normal position or one
approximating thereto, thereby completing the rarefaction of the air or
'other elastic fluid, and drawing down the signal arm i by causing the
collapse or partial collapse of the vessel f.
'
As respects the electrically controlled valve arrangement when the
signal is to be drawn down by rarefying the air in the pipe e, I make the

page_text: terminal of the said pipe large enough to contain the valve (Fig. 5),
and around the opening e' I form an internal seat for the valve, which
when in its lowest position will be closed.
I invert the electro-magnet
and its armature so that when the circuit is made the valve shall be
drawn down against its seat.
It will be evident that in this arrangement when the armature is free,
if the pressure in the pipe e be reduced below that of the external
atmosphere, the valve will at once rise from its seat in the pipe
terminal, thus admitting air, and maintaining in the pipe e and vesself
the normal pressure at which the signal is arranged to be invariably in
the "danger" position.
Fig. 8 shews my improved arrangement for indicating at any required
place when the signalling object has resumed or occupies the "danger”
position. q is a liquid pressure gauge placed in the situation at which
the indications are required, and connected by a pipe q' with a valve
chamber containing a valve r¹, kept by its own weight (or it may be
by a spring) over and against a seat around an orifice leading into the
collapsible vesself, as shewn. 2 is a rod or stem fixed to the valve,
which rod when the vessel is in its collaped or partially collapsed position
raises the valve from its seat, thus establishing communication between
the interior of the collapsible vessel and the gauge q. A second gauge o
communicates with the interior of the compressor through the pipes o¹
and e.
Should the collapsible vessel not return sufficiently to place the
signal in the "danger" position at the proper time the fact will be indi-
cated by the difference of level of the liquid in the two gauges.
Fig. 9 shews a modification of the valve locking apparatus. In this
case the armature m of the electro-magnet m¹ is carried by a T shaped
catch lever 8, having its fulcrum at s*, and having at s' an adjustable
weight sufficient to cause the armature m to move away from the
magnet m¹ when the circuit is broken. 8² is an adjusting screw to control
the amount of movement of the armature m.
It will be understood that when the circuit is made, and so long as it so
remains, the catch s³ of the lever 8 will be under the part of the lever l,
which carries the valve k, and consequently that valve will be held
against its seat, but that whenever and so long as the circuit is broken
the catch will by the action of the weight & be kept clear of the lever
so that a very slight increase of pressure in the pipe e over the pressure

page_text: of the external atmosphere will force the valve from its seat, and thus
prevent the signal being drawn down.
Fig. 10 shews an arrangement of valve holding and releasing
apparatus, in which the terminal of the pipe e forms the pole of the
electro-magnet, and the valve itself constitutes the armature. In this
arrangement the part e* is made of brass; the parts l', e', 1, and k are
of iron.
The operation of this arrangement will be readily understood without
further description.
Fig. 11 shews an arrangement of valve holding and releasing apparatus,
in which the lever and weight 1 are dispensed with.
The electro-magnet and its armature are contained within an air-tight
chamber e', forming the terminal of the pipe e, and having in it the
escape orifice e', against which the valve k is arranged to close. The
armature m and valve k are suspended to a spring t, the valve and
armature being connected together by an adjusting screw k¹.
The screw is to be so adjusted that a very slight preponderence of
pressure in the pipe e over that in the case 12 (which of course will be
the same as that of the external atmosphere) will force the valve from
its seat.
Fig. 12 shews an arrangement of valve holding and releasing apparatus,
in which the axle of a magnetic needle u, arranged to be oscillated in
the ordinary way by changing the direction of the current of electricity
passing through coils ², is caused to lock or unlock the lever / carrying
the valve k. For this purpose the axle u³ of the magnetic needle carries
a cam piece or catch u³ arranged to move under the inclined end 1³ of
the lever when the electric current is passing in one direction, and
to be moved away or disengaged from the said lever so as to leave its
end free when the electric current is in the contrary direction.
Fig. 13 is a front elevation; and Fig. 14 is a sectional view at right
angles to Fig. 13, showing an arrangement in which the pipe e
terminates in an air-tight chamber eº, the air escape being at e¹, and the
orifice of the pipe e being opposite thereto. The valve is carried by
a flexible arm v fixed on the axle ² of a magnetic needle u, arranged to
be oscillated by the electric current passing through the coils ¹ in the
usual manner. It will be evident that when the electric current has

page_text: been so directed as to move the needle into the position shewn in Fig. 13,
the valve k will be opposite to the air escape opening e', around which
the valve seat is arranged and that any preponderence of pressure in the
pipe e and chamber e over the external atmospheric pressure will have
the effect of pressing the valve k against its seat; e' is a glass front
forming a guard to prevent tampering, openings for the passage of air
being provided at the sides e⁹.
bent as shewn,
in a position at
in Figs. 13 and
Fig. 15 shews an arrangement in which the arm (which may be
rigid) is fixed on the axle of the needle as before and is oscillated in the
same way as in the preceding plan, but is at its lower end
and carries the valve / so that the face of the latter is
right angles to that occupied by the face of the valve
14. In the present case the valve k is jointed at * to the end of the
lever, so that the valve may hang freely, and when in its closed position
with a pressure of air behind, it will adjust itself to its seat around the
opening e. The arm and lever are shown dotted in the positions they
occupy when the current is broken or when the current is reversed,
or in other words, is in the direction to preclude the drawing down of
the signal.
I prefer the valve arrangements shewn in and described with reference
to Figs. 1, 5, 9, 10, and 11, because they will enable the signal to be
moved to the "danger" position at any time by operating the com-
mutator in the circuit m³, so that should the man in charge of the
electrical apparatus have locked or fastened the valve by mistake, he
may remedy that mistake by unfastening the valve notwithstanding
any preponderence-of-pressure-in-the-pipe-c-above_that_of_the_external_
atmosphere.
Fig. 16 is a plan diagram of a junction, at which apparatus according
to my Invention, as for example the arrangement shewn in and described
with reference to Figs. 1 to 5 inclusive, may be advantageously applied. '
In apparatus so applied it will be evident that the valve % and its
electrically operated holding and releasing-apparatus will be dispensed..
with, when the signal to be operated does not require the concurrence of
a second person.
It will likewise be evident that for the valve onerating and releasing

page_text: in and described with reference respectively to Fig. 9, Fig. 10, Fig.
Fig. 12, Figs. 13 and 14, and Fig. 15.
In the diagram (Fig. 16) A' is the main down line; A², the main up
line; A, the branch down line; and A*, the branch up line.
Signal 1 is the down main juuction signal; it is to be operated
pneumatically from the junction signal box B, and controlled by elec-
tricity from the signal station A.
Signal 2 is the up main junction signal; it is to be operated pneu-
matically from the junction signal box B, and controlled by electricity
from the signal station D.
Signal 3 is the down branch junction signal; it is to be operated
pneumatically from the junction signal box B, and controlled by
electricity from the signal station A.
Signal 4 is the up branch junction signal; it is to be operated
pneumatically from the junction signal box B, and controlled by
electricity from the signal station C.
Signal 5 is the up branch distant signal; it is to be operated pneu-
matically from the junction signal box B.
Signal 6 is the up main line distant signal; it is to be operated
pneumatically from the junction signal box B.
Signal 7 is the up main line signal; it is to be operated pneumatically
from the signal station A, and controlled by electricity from the junction
signal box B.
Signal 8 is the down main line signal; it is to be operated pneu.
matically from the signal station A, and controlled by electricity from
the station in advance.
Signal 9 is the down main line distant signal; it is to be operated
pneumatically from the signal station A.
Signal 10 is the down main line distant signal; it is to be operated
pneumatically from the junction signal box B.
Signal 11 is the down main line signal; it is to be operated pneu-
matically from the signal station. D, and controlled by electricity from
the junction signal box B. By constructing the pneumatic apparatus'of'

page_text: this signal with an additional valve (like ), with corresponding holding
apparatus arranged to be operated electrically, and having in the circuit
a commutator situate at station C, it will be rendered impossible for the
man at station D to draw down the signal without the concurrence
of the man at station C, as well as that of the man in the junction
signal box B.
Signal 12 is the up main line signal; it is to be operated pneu-
matically from the signal station D, and controlled by electricity from
the signal station in advance of it.
Signal 13 is the up main line distant signal; it is to be operated
pneumatically from the signal station D.
Signal 14 is the down branch signal; it is to be operated pneu-
matically from the signal station C, and controlled by electricity from
the junction signal box B. By constructing the pneumatic apparatus
of this signal with an additional valve (like k), with holding apparatus
arranged to be operated as described, the commutator being situated at
station D, it will be rendered impossible for the man at station C to
draw down the signal without the concurrence of the man at station D,
as well as that of the man in the junction signal box B.
Signal 15 is the up branch signal; it is to be operated pneumatically :
from the signal station C, and controlled by electricity from the signal
station in advance.
Signal 16 is the up branch distant signal; it is to be operated pneu-
matically from the signal station C.
Signal 17 is the down branch distant signal; it is to be operated 2
pneumatically from the junction signal box B.
In conclusion, I would remark that it will be readily understood that
the amount of working pressure of the enclosed air or other elastic fluid
in apparatus constructed according to my Invention as herein-before
described is regulated and sustained by the weight of the moveable 8
upper end of the vessel called a compressor, and that when the same
vessel acts by rarefaction instead of by compression it must be inverted,
as already explained, and the amount of rarefaction will be regulated and
sustained by the weight of the descending lower end.
Having described the nature of my said Invention and the mode of 3
carrying the same into practical effect, I desire to have it understood

page_text: that I do not claim generally as of this Invention the operating railway
signals pneumatically in such wise as that the signalling objects shall be
in their danger positions whenever the pressure of the enclosed air or
other elastic fluid is the same, or nearly so, as that of the external
atmosphere. Various arrangements of signals designed to operate on
this principle are described in the Specifications of two former Patents
granted to me, viz., No. 2045, dated 12th June 1874, and No. 4293¹,
dated 12th December 1874; and my present Invention relates to
improvements in the apparatus comprised in the above-mentioned
Specifications; and save and except as herein-after mentioned I do not
intend to claim any of the mechanical or electrical parts of the apparatus
herein-before shewn and described when taken separately and apart
from the combination or application thereof, in manner and for the
purposes herein described; but what I consider to be novel and original
and therefore claim as secured to me by the herein-before in part
recited Letters Patent is,-
1. The use for the purpose of actuating railway signalling objects of
an improved pneumatic apparatus consisting of a hand or signal lever,
a nearly balanced signalling object, which returns automatically to the
danger position, a collapsible vessel or chamber operating the signalling
object, and which for greater security in the signalling I prefer to
construct with a valve and indicating gauges, as described, and which
vessel or chamber is in communication by means of a pipe or passage
with a compressor made in two parts or chambers, but having a free
opening from the one to the other, whereby the sudden pulling over of
the hand or signal lever acting to compress the air in one part or
chamber causes the other part or chamber to expand so as to relieve the
sudden pressure, but afterwards to act by inducing a sustained and
uniform pressure on the air or other elastic fluid enclosed in the appa-
ratus, and thereby to operate the signalling object, as herein-before
shewn and described.
2. The use for a like purpose of a similar pneumatic apparatus con-
structed of the same working parts, save as herein-before explained, but
inverted in arrangement as described, so as to actuate the signalling object
by rarefaction of the air or other elastic fluid enclosed in the apparatus
instead of by compression.
3. The adaptation and use as herein-before described of an electrically

page_text: containing air or other elastic fluid and communicating with the
collapsible vessel or chamber, which operates the signalling object for the
purpose of governing from a distance the movement of the latter.
4. The use for the purpose of operating railway signals of the improved
signalling apparatus for railways, constructed, arranged, and operating |
substantially as shewn and described in reference to Figs. 1, 2, 3, 4, 5,
and 8 of the accompanying Drawings,
In witness whereof, I, the said Austin Chambers, have hereunto
set my hand and seal, this Twenty-ninth day of December, in
the year of our Lord One thousand eight hundred and seventy-
five.
AUSTIN CHAMBERS. (L.S.)