IMPROVEMENTS IN PNEUMATIC SIGNALLING OR COMMUNICATING APPARATUS
Year: 1879

page_text: LETTERS PATENT to Arthur Clarke, of Featherstone Street, City Road, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN PNEUMATIC
SIGNALLING OR COMMUNICATING APPARATUS."
Sealed the 30th September 1879, and dated the 23rd April 1879.
PROVISIONAL SPECIFICATION left by the said Arthur Clarke at the Office
of the Commissioners of Patents on the 23rd April 1879.
ARTHUR CLARKE, of Featherstone Street, City Road, in the County of Middlesex.
IMPROVEMENTS IN PNEUMATIC SIGNALLING OR COMMUNICATING APPARATUS."
My Invention relates, first, to the collapsible indiarubber air vessel or holder
forming part of the transmitting portion of pneumatic signalling or communicating
apparatus. This air vessel is usually made in a hemispherical or oval form, and
entirely closed with the exception of a small hole, generally fitted with a short neck
or tube for connection to the air tube leading to the bell or indicator, and contains
a spring to expand it after it is compressed.
Its chief disadvantages are that it usually retains within it some acid deposit
resulting from its process of manufacture, and which is ultimately injurious, both to
the indiarubber and to the spring, corroding the latter, and rendering it liable to
break and pierce the indiarubber vessel, or allow it to collapse; the spring inside
the holder expands it again immediately the finger is taken from the pusher, causing
it to draw the air back again into it before it has given the desired signal in the
case of a long distance. Lastly, the connection made by binding with wire, or
securing it with a metal connecting screw to the air tube, bardens, and in time
destroys the indiarubber at that part.
My Invention has for its object, first, to obviate these disadvantages by making
the holder of a cup form, i.e., entirely open on the flat side, so that it can be readily
and thoroughly cleaned out before being fixed for use. I also dispense with the spring
inside the airholder for long distances. When the latter is compressed by a pusher
the spring is applied outside the finger piece. Where a pull handle is used to
compress the holder, the spring is applied inside it, but does not touch it in any part.
According to my Invention the cup shaped air vessel or holder is closed on the
Prime G37

page_text: flat side by a plate of metal or wood, against which the edges of the cup shaped
vessel abut closely without being clamped or fastened thereto. This plate may be
the top or bottom of the box in which the air holder is contained. For short
distances the air tube communicates with the interior of the holder through this
plate, so that no binding or other form of connection with the indiarubber is neces-
Bary. The indiarubber air vessel may be compressed either by means of a pusher
connected to a disc bearing against the convex bottom of the air vessel, the said
pusher being provided with a spring in the case of long distances, or by means of
a pull handle passing through the indiarubber air vessel, and attached to a cup
shaped disc bearing against the convex bottom of the said indiarubber vessel. In
this case there would be a spiral spring on the pull handle rod within the indiarubber
holder, and confined between the top of the box containing said holder and a metal
disc bearing against the inside of the bottom of said holder.
For long distances the indiarubber air vessel of the pull handle arrangement is
open to the atmosphere through holes in the covering plate, and the air tube
communicates with the metal box or case in which the indiarubber vessel is
contained, and not with the interior of the indiarubber vessel, as before.
A pin
hole is pierced in said tube, close to the bell or indicator for the inlet and egress of
air, which obviates the use of a valve to prevent the return of air. In this case
the compression of the air vessel by the pull handle creates a partial vacuum in the
tube, thereby drawing in air at the pin hole. When the pull handle is released the
expansion of the indiarubber vessel compresses the air behind it, thereby causing it
to act on the bell or indicator whilst the surplus is escaping at the pin hole. Thus,
however quickly the pull handle may be released, the bell or indicator cannot fail to
be actuated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur Clarke in the Great Seal Patent Office on the 22nd October
1879.
ARTHUR CLARKE, of Featherstone Street, City Road, in the County of Middlesex.
"IMPROVEMENTS IN PNEUMATIC SIGNALLING OR COMMUNICATING APPARATUS."
My Invention relates, 1st, to the collapsible indiarubber air vessel or holder
forming part of the transmitting portion of pneumatic signalling or communicating
apparatus. This air vessel is usually made of hemispherical or oval form, and
entirely of indiarubber in two or more pieces cemented together, so that the vessel
is entirely closed with the exception of a small hole generally fitted with a short
tubular neck for connection to the air tabe leading to the bell or indicator, and the
said vessel usually contains a spring to expand it after it is compressed.
The chief disadvantages of the air vessel or holder as now made are, 1st, that it
usually retains within some acid deposit resulting from its process of manufacture,
which is ultimately injurious to the indiarubber, and which corrodes the spring
when one is used, rendering the spring liable to break, and thus allowing the india-
rubber vessel to collapse, the broken spring sometimes piercing the indiarubber and
rendering it totally useless; 2nd, the spring inside the holder expands it again
immediately the finger is taken from the pusher, causing the air vessel (in the case
of long distances) to draw the air back again into it before the desired signal has
been given; 3rd, when the air vessel is used without a spring it soon collapses by
reason of its form and holds but little air, and in a short time becomes useless; and
lastly, the connection made by binding with wire or securing it with a metal
connecting screw to the air tube, hardens and in time destroys the indiarubber at
that part.
My Invention consists in obviating these disadvantages by making the air vessel
(so far as it is composed of indiarubber) of a cup form, i.e., entirely open on the
flat side, so that it can be readily and thoroughly cleaned out before being fixed for
use, and in closing such vessel by a metal or other plate or surface, the indiarubber
vessel being moreover made of such a shape and thickness that it will not collapse
with usage. I also dispense in some cases with the spring inside the air vessel.
For long distances a spring is applied to the pusher, when the air vessel is com-
pressed by a push handle, and when a pull handle is used to compress it, a spring
is applied inside the air vessel, but does not touch it in any part.
My Invention also comprises improvements, whereby the valves generally used
to prevent the return of air in long tubes may be dispensed with. According to
my Invention, the cup shaped air vessel or holder is closed on the flat side by a
plate of metal or wood, against which the edges of the cup shaped vessel abut
closely without being clamped thereto. This plate may be the top or bottom of the
box in which the air vessel is contained. For short distances the air tube commu-
nicates with the interior of the air vessel through this plate, so that no binding or
other form of connection with the indiarubber is necessary. The air vessel may be
compressed either by means of a pusher connected to a disc bearing against tho
convex bottom of the air vessel, the said pusher being provided with a spring in the
case of long distances, or by means of a pull handle passing through the air vessel,
and attached to a cup shaped disc bearing against the convex bottom of the air
vessel. In this case there would be a spiral spring on the pull handle rod within
the air vessel, said spring being confined between the top of the box containing
the air vessel and a metal disc bearing against the inside of the bottom of said
vessel.
For long distances the air vessel of the pull handle arrangement is open to the
atmosphere through holes in the covering plate, and the air tube communicates with
the metal box or case in which the indiarubber vessel is contained, and not with the

page_text: interior of the air vessel, as above mentioned. A pin hole for the inlet and egress
of air is pierced in said tube close to or in the air vessel of the bell or indicator,
which obviates the use of valves to prevent the air returning before it has acted on
the signalling apparatus at the receiving end of the tube, should the transmitting
apparatus be quickly released. By using a pinhole as above mentioned, the com-
pression of the air vessel by the pull handle creates a partial vacuum in the tube,
thereby drawing in air at the pin hole. When the pull handle is released the
expansion of the indiarubber vessel compresses the air behind it, thereby causing it
to act on the bell or indicator whilst the surplus is escaping at the pin hole. Thus,
however quickly the pull handle may be released, the bell or indicator cannot fail
to be actuated.
Figures 1, 2, 3, 4, represent horizontal central sections of various arrangements of
transmitters for actuating pneumatic signalling or communicating apparatus;
Figure 1 shows one for short distances, and also shows how it is fitted without
cutting away the wall to receive the holder; Figure 2 shows another one for short
distances let into the wall. When intended for longer distances, the pusher is
provided with a spring, as seen in this Figure. In both these arrangements a push
handle is used to compress the air vessel; Figure 3 shows another arrangement
for short distances; and Figure 4, an arrangement for long distances, in both of
which a pull handle is employed. The same letters of reference indicate similar
parts in all the Figures. A is the indiarubber air vessel of hemispherical or cup
form, made quite open on the flat side, instead of being closed as usual by a disc of
indiarubber cemented to the sides. It is however closed when fitted up for use by
a plate b, forming either the top or the bottom of the zinc box in which the vessel
A is contained. In Figure 1, this box consists only of the bottom plate b, and the
sides B within which the open mouth of the air vessel is confined, its edges fitting
accurately against the plate b and sides B to prevent the escape of air without
being clamped thereto. The edges of the india rubber may however be cemented
with india-rubber solution to plate b and sides B if necessary to make a tight joint.
C is the air tube connecting the air vessel with signalling or communicating
apparatus of the usual construction. This tube communicates with the interior of
vessel A through a hole in plate b to which it is soldered, thus avoiding any direct
connection with the india-rubber vessel itself. D is the ornamental casing of
vulcanite, wood, or metal, enclosing the air vessel, and provided with a pusher E
fitted to slide through a socket in casing D, and attached to a metal plate F inside
the casing D, which plate bears against the convex bottom of the vessel A, and also
serves to retain the pusher E in place. The plate b is screwed or otherwise fixed to
the wall, and the casing D is attached removably to said plate by studs b' on the
latter engaging in slots d in the former, or in any other suitable manner.
In Figure 2, B is a complete box sunk in a recess G in the wall. The cross bar
or plate c at top of the box is made removable to give access to the interior, and
the whole is enclosed by an ornamental cover or rose plate D in which the pusher E
is fitted. In this case, the socket in which the pusher slides, is a short tube e fixed
to the plate c of the box B. The pusher E is attached to a plate F bearing against
the air vessel as before, and is also provided with a spiral spring H, which is
confined between the head of the pusher and the collar in the rose plate D which
screws on the tube e.
In Figure 3, the position of the air vessel A is reversed in its box B, that is to
say, the open mouth is closed by the top instead of the bottom of said box, the air
tube C being connected to the top of the box. The air vessel A is compressed by a
pull handle E instead of a pusher, the pull handle rod passing through the vessel A,
and having attached to its inner end a cupped plate F, which bears against the
convex bottom of the air vessel. In this case, the spiral spring is placed upon the
pull handle rod within the air vessel, and is confined between the top of box B and

page_text: a metal disc I, which bears against the bottom of vessel A on the inside, so
that the spring cannot by any possibility come in contact with said vessel A. Tho
pull handle rod slides through a bearing on the top of the box B, and the recess in
the wall in which the apparatus is fitted is covered by a suitable rose plate.
Figure 4 represents a somewhat similar arrangement for long distances, but in
this case the air tube C does not communicate with the interior of the air vessel A
as before, but with the space between the latter and the box B as shown, the air
vessel A being open to the atmosphere through holes B' in the top of the box B. A
pin hole is pierced in the tube C near its other end, that is to say, just before it
enters the expanding air vessel which actuates the bell or indicator, or the pin hole
may be in the said expanding air vessel itself, so that when handle E is pulled,
vessel A is compressed, thus causing air to be drawn in at the pin hole, and when
handle E is released, the expansion of vessel A drives a portion of the air into the
expanding vessel which actuates the bell or indicator, the surplus escaping at the
pin hole. When the distance is very long indeed, the tube C is a two-way tube,
i.e., a tube with a mid-feather or longitudinal central division, and instead of the
pin-hole, I leave one half or thoroughfare of the said tube open near the air vessel
of the bell or indicator for the same purpose.
Having described the nature of my said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is,―
1st. The improved transmitter for pneumatic signalling or communicating
apparatus, consisting of an open mouthed or cup shaped indiarubber air vessel, the
open mouth of which is closed by a separate covering plate or surface, substantially
as and for the purpose shown and described.
2nd. In the transmitter of a pneumatic signalling or communicating apparatus,
the employment in combination with an open mouthed or cup shaped indiarubber
air vessel operated by a pull handle as herein described, of a spiral spring and
protecting plate applied within the air-vessel, substantially as and for the purpose
shown and described.
3rd. The employment in combination with transmitting apparatus as herein
described of a pin hole in the air tube or in the expanding air vessel which actuates
the bell or indicator, substantially as and for the purpose specified.
In witness whereof, I, the said Arthur Clarke, have hereunto set my hand
and seal, this Twenty first day of October, in the year of our Lord One
thousand eight hundred and seventy nine.
ARTHUR CLARKE, (L.S.)