IMPROVEMENTS IN PNEUMATIC SIGNALLING APPARATUS
Year: 1874

page_text: LETTERS PATENT to Sir Samuel Canning, William Henry Homfray,
and Henry Francis Joel, all of Great Winchester St. Buildings,
in the City of London, Engineers, for the Invention of "IMPROVE-
"
Scaled the 20th November 1874, and dated the 15th September 1874.
PROVISIONAL SPECIFICATION left by the said Sir Samuel Canning,
William Henry Homfray; and-Henry Francis Joel at the-Office of
the Commissioners of Patents, with their Petition, on the 15th
September 1874.
We, Sir SAMUEL CANNING, WILLIAM HENRY HOMPRAY, and HENRY
FRANCIS JOEL, all of Great Winchester St. Buildings, in the City of
London, Engineers, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN PNEUMATIC SIGNALLING APPARATUS," to be as
follows:-

page_text: plicity and economy of construction, combined with efficiency of action,
are obtained.
According to one arrangement of our improved signalling apparatus
the order shutters are held in any required position mechanically and
independently of the means of action which brings them into view,
thereby entirely dispensing with the use of valves, stop-cocks, and other
like appliances used in other forms of pneumatic signalling and indicating
apparatus. The order shutter is moreover so held up as not to be
interfered with by expansion or contraction of the atmosphere in the
tubes, or caused to fall by vibration or concussion.
The peculiar arrangement of mechanism for carrying out this part of
our Invention consists of an arm supported and pivotted at one end on
an axle, which also carries any other number of arms carrying shutters,
each with two faces at their free ends, one face of the shutter being
blank, and the other an open frame, in which the order or printed signal
is inserted. Attached to this arm, by means of a screw or otherwise, is
a connecting rod with a flat circular plate, which plate rests upon a
receiving air bag.
Further away from the supporting axle and nearer the shutter there
is fitted a small curved catch piece on one side of each arm fixed in
position by a screw at one end, upon which the said catch piece is free
to turn. This catch piece carries a roller at its other extremity similarly
fixed and free to turn, the roller projecting beyond the end of the catch
piece. This catch piece is supported by means of a pin fixed into the
side of the shutter arm and under the said catch piece; it is also
prevented from turning backwards by means of another pin fixed on
the shutter arm and immediately behind the catch piece. Between the
connecting rod and the catch piece an upright crank arm is fixed upon
an independent axle, which axle is supported and free to turn in separate
bearings. Each crank arm is inclined or made of such shape that when
the shutter arm is lifted up the corresponding roller of the catch piece
presses against the crank arm and forces it back, the rollers on the
catch piece running along the face of this crank arm and thus reducing
friction.

page_text: of the receiving bags is inflated, the corresponding plate, connecting rod,
and shutter arm are lifted, causing the roller on the catch piece to roll
against the inclined face of the crank arm, forcing it back until the
roller arrives at the extreme point of the crank arm, when a spring or
weight attached to the bell hammer (herein-after described) now brings
the crank arm forward again to its original position, its upper surface
being brought under the roller and fixed pin, while the force inflating
the bag being removed the arm and shutter are left resting upon or
propped up by the top of the crank arm. This action is so adjusted
that when the crank arm is restored to its original position the open
frame with the order becomes visible and is retained and prevented from
falling by the crank arm.
When a fresh signal is sent a similar arm to that last referred to is
lifted up, and as it rises it forces all the other crank arms back, and
when they have been forced back about one-third of their travel the
order that was last sent, and which was supported as before described,
is now free to fall, and does so, the small catch piece being tilted back
on passing the point of the crank arm and then falling into its original
position again, so as to be free for further action; whilst this is going
on the last order received is in its turn retained until another order is
given, and so on.
We shall now proceed to describe the bell action in connection with
the before-mentioned signalling apparatus. One of the crank arms
herein-before referred to is prolonged so as to form a long arm with a
hammer head fixed at its extremity, and this hammer may be connected
to a spring secured to a bracket, which also serves as one of the bearings
of the axle which carries the several orank arms. When the crank arms"
are pushed back the hammer alone, or the spring and hammer, are
forced away from the bell, and upon the crank arm being freed, us
previously explained, the hammer is carried or falls forward and strikes
the bell. As all the crank arms are fixed on the same axle with the-bell
action it follows that when any one of them is pushed back the whole
of them will be simultaneously pushed back and the bell struck once,
consequently upon change from one order to another the bell is always
sounded once.
We also construct a peculiar bell action, specially applicable to the
bells of pneumatic signalling apparatus, it being capable of being rung

page_text: continuous rotatory motion of the hammer in one direction is obtained,
rendering it a perfect mechanical movement as applied to pneumatic
signalling apparatus, and extremely sensitive to small power, whilst at
the same time facility is afforded for ringing again and again without
adjusting or resetting any of the parts, and without the use of springs
for that purpose. This peculiar bell action consists of an arrangement
of segment or quadrant of a large tooth wheel gearing into and driving
a small pinion, the quadrant being worked by the inflation of an air bag
acting upon a flat plate connected by a rod and screw to the quadrant.
On the axle of the pinion there is fixed a ratchet wheel with fine
segmental teeth, and by the side of this wheel and on the same axle is a
double centrifugal hammer, which is quite free to turn loosely upon the
axle. Upon one of the arms of the hammer a light steel spring is fixed,
which acts the part of a pall, and gears in with the teeth of the ratchet
wheel, the whole of the parts being secured in and supported by a
convenient frame with a guide bracket fixed thereto to prevent the plate
and connecting rod from falling out of their place. The gong is fixed
on the outside or inside of a small wood case in a suitable position in
regard to the hammer. The action is such that the bag being inflated
by means of an air pump or other means lifts the flat plate, and this, by
means of the connecting rod, causes the quadrant to turn, and the
pinion and hammer to revolve and ring the bell. Upon the completion
of the signal or the contraction of the air bag the quadrant plate and
rod being all on one side of the axle will cause it to fall, the spring pall,
which is a special feature in this movement, allowing the ratchet wheel
to revolve backwards without interfering with the hammer.
·
We also combine a number of indicators or tell-tales with a single
bell, worked by air in such a manner that a very small force is required
to work the instrument, whilst at the same time the readjustment is
readily accomplished.
This arrangement consists as follows:-On a common axle supported
in bearings at each end a number of bell-crank arms are arranged, tho
arms on one side being nearly horizontal and having flat plates attached
to their ends resting upon flat air bags, the other and vertical arms being
made with an under lip or catch projecting from the top and bevelled off
above. These crank arms are supported upon the axle and are kept in
position by means of a pin fixed into the axle, and through a slot in the
collar of the crank arms. By the side of these crank arms and supported

page_text: .
by suitable bearings are the tell-tale or indicating tablets, which are free
to be turned by means of milled headed buttons. On the side of the
spindle next the crank arm a small catch piece projects, and is so
adjusted that when the tablet is out of sight in a horizontal position, the
catch piece slides down the inclined top of the vertical crank arm,
pushing it back, lifting the arm and plates, and then locking under the
lip which returns by the weight of the plate into its original position.
A single quadrant bell similar to that already described is combined with
the several tablets, and is worked by an arm fixed to the axle (upon
which the crank arms work) and a connecting rod as before, the action
being supported by a suitable bracket which also supports the bell at its
extremity. The whole of these works are fixed upon a plate of metal
and enclosed in a wood case, and in the front of the case small openings
are made for the tablets. Above the openings are milled headed buttons
for the purpose of readjustment. The action is such that the order
tablets being all set out of sight upon the inflation of any one of the
bags, the plate rises, moves the axle partly round, and the vertical crank
arm travels back, releasing the order tablet which falls down in front of
the opening, and at the same time the arm attached to the quadrant
moves upwards, causing the bell to ring. The other crank arms do not
move because the pins with which they gear only travel round, and the
arms remain stationery, thus preventing the work of shifting the other
arms, and also allowing only one tablet to show for the one signal. The
other tablets may be caused to shew at the same time if they are also
worked, and when a tablet is once down it must be attended to and
replaced by hand, thus forming a check upon the attendant, but the
bell can always be rung.
In single stroke bells for pneumatic signalling apparatus we combine
a peculiar catch piece with the hammer head, such catch piece being
pivotted slightly below the point of contact with the actuating arm and
on the side of the hammer farthest from the spring; the catch being
immediately behind the arm is kept from falling too low by a pin; the
slightest inflation of the bag instantly presses the actuating arm against
the catch on the side of the hammer, forcing the spring back until it is
released and strikes the bell, thus rendering the action exceedingly
sensitive for long distances.
The general arrangement of our improved single stroke bell is as
follows: Pivotted to a small bracket is a bell-crank arm. the horizontal

page_text: arm having a flat plate upon its extremity, which rests upon an air bag,
the other and vertical arm which acts upon the hammer being bevelled
off at its top into a point. On the same bracket and behind the vertical
arm a vertical blade spring is fixed, at the top of which and coming by
the side of the vertical arm there is secured a hammer head. On the
side of this head the peculiar catch piece herein-before described is
pivotted at the end farthest away from the spring. This catch piece is
undercut so as to form a lip or projection with which the bevelled point
of the vertical actuating arm engages; the catch is supported by a
pin fixed below it in the hammer head, and is prevented from turning
backwards by a pin fixed above it on the hammer head. The action
is such that the air bag on being inflated lifts the plate and arm; this
throws back the vertical or actuating arm, and the point immediately
engages with the lip in the catch piece, and presses the hammer head
and spring back until it is released by reason of the difference of radius
between the arm and the spring; the spring hammer then flies back and
strikes the bell. On the force inflating the air bag being removed the
plate falls back again, and by its weight brings the vertical arm under
the catch piece, thereby tilting the catch piece up, which immediately
falls after the passage of the arm, and is again ready for further action.
Another part of our Invention relates to what is known as the
"communicator" in pneumatic signalling apparatus, and consists
essentially in the construction, application, and use of a single air pump
in combination with any desired number of transmitting tubes, the said
pump being adjustable from one tube to another, as required, by a lateral
movement of the lever handle which actuates the air compressing piston.
This handle is jointed to a vertical swivelling spindle which also carries
a radial bracket arm for supporting in a suitable socket at its outer or
free end the cylinder of the air pump, which is free to move up and
down in such socket, the cylinder and its actuating lever always moving
together in the same arc.
In order to ensure an air-tight junction between the outlet orifice of
the air pump and the orifice of any one of the transmitting tubes, we
propose according to one arrangement to employ a tube attached to the
under side of the piston of the air pump, such tube working air-tight
within a second tube attached to the bottom of the cylinder of the pump,
there being openings left near the top of the first-mentioned tube for the
passage of the air into and down such tube when the air is compressed

page_text: in the cylinder by the descent of the piston. The accurate fitting of the
cylinder over any of the mouths of the transmitting tubes is effected by
a fixed perforated guide plate in which the tubes are fixed; which guide
plate the tube attached to the cylinder is first caused to enter by a slight
depression of the cylinder; such depression being produced by the
descent of the piston, which is locked for the time being by means of a
bolt and spring with the cylinder, the said piston being trunk-shaped.
The throw of the connecting rod, during the continued descent of the
piston, unlocks the piston and cylinder again, and the piston alone
descends, forcing the tube attached thereto into the orifice of the trans--
mitting tube immediately beneath it, the compressed air in the lower
part of the cylinder of the pump escaping through the piston tube as
before explained into the transmitting tube. Or the air-tight junction
may be effected by simply having a leather or other washer on the
bottom of the cylinder, fitting so as to form a flush joint when depressed
upon a smooth metal plate, in which the openings to the several trans-
mitting tubes are made. The descent of the piston brings as before
described the cylinder down with it, pressing the washer firmly upon the
perforated plate, and the continued descent of the piston alone and the
pressure of the air in the cylinder tend to maintain the said joint air-
tight, whilst the air is being forced into the transmitting tube.
In lieu of locking the piston with the cylinder as before described a
helical spring may be placed round the upper part of the trunk piston
so as to bear against a flange on the top of the cylinder, consequently
the descent of the piston will necessarily bring down with it the
cylinder, and thus produce sufficiently tight contact to keep the joint
air-tight when in the act of signalling.
In some cases the friction of the piston against the cylinder, along
with the pressure of the air within the cylinder, will be sufficient to
establish and maintain an air-tight junction.
In all these arrangements the casing of the communicator is provided
with a circumferential slot, from which descend as many vertical slots as
there are transmitting tubes, so that the lever can be readily moved from
one slot to another as required.
We also construct a simple form of "reply "instrument which consists
of an inflated bag which acts upon one arm of a bell-crank lever, the
other arm of which carries a disc which moves to and fro or up and

page_text: down behind an opening in the casing of the apparatus, and is acted on,
when the air bag is not inflated, by a spring which tends to keep the
disc out of sight. On the slightest inflation of the bag the disc is
instantly brought into view, showing that the order has been received,
and the spring then returns the disc to its normal position again.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Sir Samuel Canning, William Henry Homfray,
and Henry Francis Joel in the Great Seal Patent Office on the 15th
March 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, Sir SAMUEL
CANNING, WILLIAM HENRY HOMFRAY, and HENRY FRANCIS JOEL, all
of Great Winchester St. Buildings, in the City of London, Engineers,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of September, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Sir Samuel Canning, William Henry
Homfray, and Henry Francis Joel, Her special license that we, the said
Sir Samuel Canning, William Henry Homfray, and Henry Francis Joel,
our executors, administrators, and assigns, or such others as we, the
said Sir Samuel Canning, William Henry Homfray, and Henry Francis
Joel, our executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after 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 SIGNALLING APPARATUS," upon the condition
(amongst others) that we, the said Sir Samuel Canning, William Henry
Homfray, and Henry Francis Joel, our executors or administrators, by
an instrument in writing under our, 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

page_text: Figures 1, 2, and 3 (Sheet 1), of our Drawings have reference to the
first part of our Invention; Figure 1 represents a sectional elevation;
Figure 2, a corresponding plan or horizontal section; and Figure 3, a front
clevation (drawn to a smaller scale) of our improved indicator or receiving
instrument. In this instrument the order shutters are held in any
required position mechanically and independently of the means of
action which brings them into view, thereby entirely dispensing with
the use of valves, stop-cocks, and other like appliances employed in other
forms of pneumatic signalling and indicating apparatus. The order
shutter in use for the time being is moreover so held up as not to be
interfered with by expansion or contraction of the atmosphere in the
tubes, or caused to fall by vibration or concussion. A is a lever arm
supported and pivotted at one end on an axle B, which also carries any
other number of similar lever arms (two being shown in Figure 2 as an
example) carrying shutters, each with two faces a and b at their free
ends, one face a of the shutter being blank, and the other b an open
frame in which the order or printed signal is inserted (see Figure 3).
Attached to each of these lever arms by means of a screw or otherwise
is a connecting rod C with a flat circular plate D, which plate rests
upon a receiving air bag E.
•
Further away from the supporting axle B and nearer the shutter
there is fitted a small curved catch piece c on one side of each arm fixed
in position by a screw at one end, upon which the said catch piece is
free to turn. This catch piece carries a roller d at its other extremity,
similarly fixed and free to turn, the roller projecting beyond the end of
the catch piece. This catch piece is supported by means of a pin e fixed
into the side of the shutter arm A and under the said catch piece; it is
also prevented from turning backwards by means of another pin f
(Figure 1), fixed on the shutter arm and immediately behind the catch
piece. Between the connecting rod C and the catch piece c there is
interposed an upright crank arm F, which arm is fixed upon an
independent axle or rocking shaft G supported and free to turn in
separate bearings at H. Each crank arm F is inclined or made of such
shape that when the shutter arm is lifted up the roller d of the corre-
sponding catch piece presses against the said crank arm and forces it
back, the roller on the catch piece running along the face of this
crank arm and thus reducing friction.
The action of this apparatus is such that when by means of an air

page_text: pump or other air forcing apparatus, or by the "communicator" any
one of the receiving bags E is inflated the corresponding plate D, con-
necting rod C, and shutter arm A are lifted, causing the roller d on
the catch piece to roll against the inclined face of the crank arm F,
forcing it back until the roller arrives at the extreme point of the crank
arm, when a spring I or weight attached to or pressing upon the arm of
the bell hammer K (herein-after described) now brings the crank arm
forward again to its original position, its upper surface being brought
under the rollerd and fixed pin e, while the force inflating the bag being
removed the arm and shutter are left resting upon or propped up by
the top of the crank arm, as shown in dotted lines in Figure 1, thereby
causing the open frame with the order to become visible through
the corresponding aperture in the casing, in which position it is retained
and prevented from falling by the supporting action of the crank
arm F.
When a fresh- signal is sent, another one of the series of arms similar
to that last referred to is lifted up, and as it rises it forces back all the
other crank arms F which are fast on the rocking shaft G, and when
they have been forced back about one-third of their travel, the order that
was last sent and which was maintained in an elevated position or
supported as before described is now free to fall and does so, the small
catch piece o being tilted back on passing the point of the crank arm,
and then falling into its original position again so as to be free for
further action. Whilst this is going on the last order received is in its
turn retained until another order is given, and so on. In Figure 3 wo
have represented one of the order tablets exposed to view whilst the
other apertures in the casing are backed by the blank shutters.
We shall now-proceed--to describe the bell action in connection with
this our improved signalling apparatus. One of the crank arms F,
Irerein-before referred to, is prolonged so as to form a long arm K with a
hammer head Ļ fixed at its extremity, and this hammer may be con-
nected to a spring I secured to a bracket H, which also serves as one of
the bearings of the rocking shaft G which carries the several crank arms.
When the crank arms are pushed back the hammer alone or the spring
and hammer are forced away from the bell M, and upon the crank
arm F being freed, as previously explained, the hammer is carried or
falls forward and strikes the bell. As all the crank arms are fixed on
the same rocking shaft & with the ball action, it follows that when any

page_text: one of them is pushed back the whole of them will be simultaneously
pushed back, and the bell M struck once, consequently upon change
from one order to another the bell is always sounded. N is the casing
of the apparatus composed of wood, metal, or other suitable material,
and O, O, are the apertures through which the orders are read.
We shall now proceed to describe, with reference to Figures 4, 5, 6,
and 7, the second part of our Invention, which consists of a peculiar
bell action specially applicable to the bells of pneumatic signalling
apparatus, it being capable of being rung through a long distance with
very slight force. By this action a continuous rotatory motion of the
hammer in one direction is obtained, rendering it a perfect mechanical
movement as applied to pneumatic signalling apparatus, and extremely
sensitive to small power, whilst at the same time facility is afforded for
ringing again and again without adjusting or resetting any of the parts,
and without the use of springs for that purpose. Figure 4 is a sectional
elevation, and Figure 5, a corresponding plan or horizontal section of
one mode of carrying out this part of our Invention. A is an outer
casing of wood, metal, or other suitable material which contains within
it a segment or quadrant B of a large tooth wheel gearing into and
driving a small pinion C, the quadrant being worked by the inflation of
an air bag D acting upon a plate E connected by a brass rod F and
screw to the said quadrant. On the axle of the pinion there is fixed a
ratchet wheel G with fine segmental teeth, and by the side of this wheel and
on the same axle is a double centrifugal hammer H, having loose strikers
hinged thereto, which is quite free to turn loosely upon the axle of the
pinion and ratchet wheel. Upon one of the arms of the hammer a light
steel spring I is fixed which acts upon a pall, which pall gears in with the
teeth of the ratchet wheel G, the whole of the parts being secured in
and supported by a convenient frame K with a guide bracket fixed
thereto if required to prevent the plate E and connecting rod F from
falling out of their place. The gong L is fixed on the outside of the
case A in a suitable position in regard to the hammer. The action is
such that the bag being inflated by means of an air pump or other means
lifts the flat plate, and thus by means of the connecting rod causes the
quadrant B to turn, and the pinion and hammer to revolve and ring the
bell. Upon the completion of the signal or the.contraction of the air
bag, the quadrant, plate, and rod, being all on one side of the axle will
cause it to fall, the spring pall which is a special feature in this move-

page_text: ment allowing the ratchet wheel to revolve backwards without interfering
with the hammer.
We also combine a number of indicators or tell-tales with a single
bell worked by air, in such a manner that a very small force is required
to work the instrument, whilst at the same time the readjustment is
readily accomplished.
This arrangement is illustrated in sectional elevation and partial plan
at Figures 6 and 7. On a common axle M supported in bearings N at
each end a number of bell crank arms E, E', are arranged, the arms E on
one side being nearly horizontal, and having their ends resting upon flat
air bags D, whilst the other and vertical arms E¹ are made with an
under lip or catch a projecting from the top and bevelled off above (see
Figure 6). These crank arms are supported upon the axle M, and are
kept in position by means of a pin fixed into the axle, and through a
slot 6 in the collar of the crank arms, as shown clearly in Figure 7.
O represents one of a series of tell-tale or indicating tablets which are
suspended from spindles o, supported in suitable bearings, and free to be
turned by means of milled headed buttons & fast on the outer ends of
the spindles c. A small arm or catch piece e projects from the side of
each spindle c, and is so adjusted that when the tablet O is out of sight
in a horizontal position the catch piece slides down the inclined top a of
the vertical crank arm E¹, pushing it back and lifting the arm slightly
and locking under the lip (as shown in dotted lines in Figure 7), which
returns by the weight of the arm E into its original position again.
A single quadrant bell action, similar to that already described, and
illustrated at Figures 4 and 5, is combined with the several tablets. O,
and is worked as before explained. The corresponding parts are
indicated by similar letters of reference to those in Figs. 4 and 5, and
need not therefore be further alluded to………. The bräcket-K-may-be-mada
to support the bell L, which is here shown as contained within the
case-A, and above-the-mechanism, but it may be otherwise placed if
preferred. The whole of these works may be fixed upon a plate of metal
and enclosed in the wood case A, small openings being made in the front
of the case for the purpose of showing the order tablets O. Above these
openings are situate the milled headed buttons d, before referred to, for
the purpose of readjustment. The action is such that the tablets being
all adjusted back or in a horizontal position, upon the inflation of any one
of the air bags D, the corresponding lever arm É rises, moves the axle M

page_text: partly round, and the vertical crank arm E¹ travels back so as to release
the catch e, thereby allowing the tablet to fall down opposite to the
opening, and at the same time the hammer in connection with the
quadrant B is rotated and rings the bell as herein-before described.
The other crank arms of the series do not move, because the pins with
which they gear only travel round leaving the arms stationary, thus
preventing the work of shifting the other arms, and also allowing only
one tablet to show for the one signal. The other tablets may be caused
to show at the same time if they are also worked, and when a tablet is
once down it must be attended to and replaced by hand, thus forming a
check upon the attendant.
Figures 8 and 9 (Sheet 2) illustrate the fourth part of our Invention,
Figure 8 being a vertical section, and Figure 9 a corresponding sectional
plan of a single stroke pneumatic bell or gong fitted with our improved
striking action. According to this part of our Invention we combine a
peculiar catch piece with the hammer head, such catch piece being
pivotted slightly below the point of contact of the actuating arm, and
on the side farthest from the spring; it falls directly behind the arm
and is then ready for action, the slightest inflation of the bag instantly
pressing the hammer back for striking the bell, thus rendering the action
exceedingly sensitive for long distances.
at a.
The general arrangement of our improved single stroke bell is as
follows: Pivotted to a small bracket A is a bell-crank lever, the hori-
zontal arm B of which rests at its extremity upon an air bag or
bellows C, the other and vertical arm D of the bell-crank lever which
acts upon the hammer being bevelled off at its top into a point, as shown
On the same bracket A and behind the vertical arm D, a vertical
blade spring E is fixed, at the top of which and coming by the side of
the vertical arm there is secured a hammer head F. On the side of this
head the peculiar catch piece b, herein-before described, is pivotted at
the end farthest away from the spring by means of a screw c. This
catch piece is undercut so as to form a lip or projection d, with which
the bevelled point a of the vertical actuating arm engages the catch is
supported by a pin e, fixed into the hammer head, and is prevented from
turning backwards by another pin falso fixed on the hammer head.
The action is such that the air bag C on being inflated lifts the arm B;
this throws back the vertical or actuating arm D, and its point a

page_text: engages with the lip d in the catch piece, and presses the hammer
head F back against the spring E until it releases by reason of the
arm and the spring working on separate centres; the spring hammer
then flies back and strikes the bell G. On the force inflating the
air bag being removed the horizontal arm B falls back again, and by its
weight brings the vertical.arm D once more under the catch piece b,
thereby tilting the catch piece up, and the arm still travelling onwards
the catch piece falls again at the back of the arm so, as to be ready for
further action, as shown clearly in Figure 8. H is the wooden or other
casing enclosing the striking action of the apparatus, and I the tubing
by means of which the bag or bellows O is inflated.
مدال
Figures 10 and 11 illustrate the fifth part of our Invention, Figure 10
being a vertical section of our improved communicator, and Figurre 11
a corresponding horizontal section and partial plan of the same taken
along the broken line 1-2, in Figure 10. In this form of communicator
a single air pump is employed in combination with any desired number
of transmitting tubes, the said pump being adjustable from one tube to
another, as required, by a lateral movement of the lever handle which
actuates the air compressing piston. A is the casing of the commu-
nicator which is here shown composed of metal; B is the air pump or air
compressing cylinder; D is the piston of trunk form, working therein;
and C, C, are the mouths of the several transmitting tubes leading to
different air bags or bellows in the receiving instrument already
described; E is the lever handle by which the piston and cylinder are
actuated, as will be herein-after fully explained. This handle is con-
nected with the vertical swivelling spindle F through the intervention
of the forked bent lever G, to the end of which it is jointed by a
fulorum pin-H. The said forked lever G works on a fulcrum pin
at I in the vertical spindle F, and is connected at its free end by
trunnions K, K, to the lower end of the cylinder B. The vertical
spindle Falso carries, a radial bracket-arm L for supporting in a suitable
socket at its outer or free end the cylinder of the air pump which is free
to be moved up and down in such socket by the combined action of the
levers E and G (as herein-after fully explained), the cylinder and its
actuating levers always moving together in the same arc. The short
arm E of the lever E is made open so as to work freely along the
vertical swivelling spindle F, and is connected by a pin joint M to the
connecting rod N of the trunk shaped compressing piston D, so that on
.

page_text: depressing the handle E the bent end of the lever G will also be
depressed, causing the cylinder B to be forced upwards in its guiding
bracket L, until the cylinder is stopped by the washer on the under side
of the perforated guide plate (to be after described). Then the com-
pressing piston D will also be forced upwards, thereby compressing the
air in the upper part of the cylinder. O is a tubular nozzle formed on
the end of the cylinder and caused to enter the mouth 0 of the par-
ticular transmitting tube to which it is adjusted when the cylinder is
elevated, as already explained.
The accurate adjustment of the cylinder under any one of the mouths
of the transmitting tubes is effected by the use of a fixed perforated guide
plate P placed under the several mouths of the transmitting tubes, into
which guide plate the nozzle O is first caused to enter by a slight eleva-
tion of the cylinder, such elevation being produced by the depression of
the handle E, as already explained. The nozzle having entered the
mouth of the tube, an air-tight junction is effected between the end
of the cylinder and the under surface of the guide plate by interposing
between the said surfaces a leather or other washer Q, and forming a series
of concentric knife edged projecting rings on the top of the cylinder, as
shown clearly in Figure 11, which rings by the upward motion of the
cylinder are caused to press firmly against and partly embed themselves
in the washer, the continued ascent of the piston inside the cylinder and
the downward pressure of the fulcrum of the actuating handle E upon
the end of the lever G tending by their combined action to main-
tain the said joint air-tight during the time the air is being forced into
the transmitting tube by the continued ascent of the piston, the greater
the resistance or compression of the air in the cylinder the greater being
the pressure of the cylinder against the washer Q. In some cases the
friction of the piston against the cylinder along with the pressure of
the air within the cylinder will establish a sufficiently air-tight junction
between the cylinder and washer. The casing of the communicator is
provided with a circumferential slot R (Figure 10), from which descend
as many vertical slots S, S, as there are transmitting tubes, so that
the lever handle E can be readily moved round from one slot to
another, as required, carrying the cylinder B round with it through the
same arc.
Figures 12 and 13 illustrate the sixth part of our Invention, which
imple Lanna of nonly" instrument wherein an infleting

page_text: b
bag a acts upon a flat plate 6 on the end of a rod or link connected to a
lever c, which lever carries at its free end a disc d, moving to and fro,
either horizontally or vertically behind an opening in the casing of the
apparatus (as shown in dotted lines in Figures 12 and 13), and is acted
on, when the air bag is not inflated, by a spring e, which tends to keep
the disc out of sight. On the slightest inflation of the bag a the disc d
is instantly brought into view, showing that the order has been received,
and the spring e then returns the disc to its normal position again. We
have shown this "reply" instrument applied to our improved commu-
nicator at Figures 10 and 11, f representing the small aperture in the
casing, behind which the disc d is caused to move to and fro hori-

page_text: substantially as and for the purpose herein-before described and illus-
trated by Figures 12 and 13 on Sheet 2 of our Drawings.
In witness whereof, I, the said Henry Francis Joel, for and on
behalf of myself, and the said Sir Samuel Canning and William
Henry Homfray, have hereunto set my hand and seal, this
Fifteenth day of March, in the year of our Lord One thousand
eight hundred and seventy-five.
Witness,.
EDWIN P. ALEXANDER,
HENRY FRANCIS JOEL. (L.S.)
Consulting Engineer and Patent Agent,
14, Southampton Buildings,
Chancery Lane, W.C.