IMPROVEMENTS IN APPARATUS FOR CONVEYING LETTERS OR PARCELS BETWEEN PLACES BY THE PRESSURE OF AIR AND VACUUM
Year: 1857

page_text: LETTERS PATENT to Josiah Latimer Clark, of 35, Adelaide Road,
Haverstock Hill, in the County of Middlesex, for the Invention of
IMPROVEMENTS IN APPARATUS FOR CONVEYING LETTERS OR PARCELS BETWEEN
PLACES BY THE PRESSURE OF AIR AND VACUUM,"
Sealed the 11th December 1857, and dated the 11th June 1857.
PROVISIONAL SPECIFICATION left by the said Josiah Latimer Clark
at the Office of the Commissioners of Patents,. with his Petition, on
the 11th June 1857.
I, JOSIAH LATIMER CLARK, of 35, Adelaide Road, Haverstock Hill, in the
County of Middlesex; do hereby declare the nature of the Invention of
"IMPROVEMENTS IN APPARATUS POR CONVEYING LETTERS OR PARCELS BETWEEN
PLACES BY THE PRESSURE OF AIR AND VACUUM," to be as follows:-
This Invention has for its object improvements in telegraphs, in which
letters or other articles are conveyed through pipes by pneumatic pressure.
In laying the pneumatic pipes between the stations considerable difficulty has
been experienced in making the joints in the line of pipes in such a way as
not to interfere with the passage of the package. In order to obviate 'this I
make the joints by causing the ends of the pipes to butt together, and slipping
a ring or short piece of tube of vulcanized india-rubber or of other air-tight
ונם.מ

page_text: material over the joint, and the ends of the metal pipes are held accurately
in their positions by a socket made in two halves connected together with
screws, which socket covers the vulcanized india-rubber ring, and clips firmly
the ends of the pipes. Or I connect the pipes by butting their ends together
before, and slipping a short metal tube over the junction, which is made
r-tight by an exterior tube of vulcanized india-rubber bound at its two
eds to the main tubes by wire or twine. Or the short metal connecting tube
ay be placed in sockets at the ends of the pipes to be joined, and then the
junction be made tight by an exterior india-rubber tube, as before. If I wish
to make one main line of telegraph to diverge into two or more branch lines,
I arrange the main line so that it can be brought in connection with either
of the branch lines, as may be required, by means of a switch. For this pur-
pose the two branch lines terminate side by side in holes in a face plate, on
the surface of which another plate slides, being governed in its course by
guides. In a hole in this second plate the main line of pipe terminates, and
this is left unsupported laterally for such a distance that it can be moved back-
wards and forwards freely with its plate, 'so as to bring its end in communi-
cation with the end of either of the branch lines as may be required. This
switch may either be worked by hand according to the direction of electric
signals, or it may be worked from a distance bya cylinder and piston, or similar
apparatus, into which air is admitted or withdrawn by a pipe communicating
with it from a distance. In work ng telegraphs of this description. I have
found that a saving of cost may be effected by so arranging the apparatus
that the packages are propelled in one direction by exhausting the air from
the pipe in front of the package, and in the other direction by admitting
behind it air under a pressure exceeding that of the atmosphere. When the
apparatus is arranged in this way one pumping engine only will be nece-sary,
and this engine works to produce 2L partial vacuum in one vessel, and a
pressure in another vessel. These vessels may resemble ordinary gasometer,
as they are described in a Specification of a former Patent granted to me; or
large cylinders containing weighted pistons, or vessels with flexible sides like
the wind chests of organs, may be employed. In order to obviate as much as
possible the retarding effect of the friction of the air within the pipe, I
employ valves at convenient distances along the pipe, which valves when work-
ing by vacuum open, and when working by pressure close immediately after
the passage of the package; and in order to work the valves I employ cylinders
containing pistons, and each of these cylinders is in communication at each
end with the main pipe; but the two communications are made at places at

page_text: some distance from each other, so that when the package is in the part of the
pipe between the two points of communication, the pressures on the two sides
of the piston will be different, and the piston will move, and will open or close
the valve. Or the cylinder may be caused to act by means of a trigger,
which is displaced by the passage of the package, and which then opens a
communication between the cylinder (on one side of the piston) and the
vacuum or pressure.
In the use of pneumatic telegraphs great difficulty is experienced in
regulating the velocity at which the package issues from the end of pipe.
For this purpose, when working by vacuum, 1 cause the package when
it comes near the end of its course to strike a trigger, and by displacing
this trigger to allow a valve in the exhausting pipe to close by the pressure
of the air. When the vacuum is cut off the valve again opens by its
own weight or otherwise, and the trigger resumes its first position, and the
same trigger may also act to allow a valve to open immediately behind the
package, so as to admit the external air to destroy the vacuum behind the
package, and prevent it sticking in the pipe, as sometimes occurs when this
precaution is not taken. The valves consist of plates of metal which close
loosely against a seat in the box which contains them, and in order to make
the valves tight I employ a ring of vulcanized india-rubber, leather, or other
similar material attached round its exterior edge to the seat of the valve; I
also place at the end of the main pipe a tube or chamber of larger diameter
than the main pipe, against the end of which and within this chamber is a
padded valve, against which the package strikes. The valve is thus displaced
and the external air rushes into the pipe by a small hole at the end of
chamber, and against and past the package, which is thus quickly stopped,
and brought back by the valve into the end of the main pipe, where there is a
door or opening for its removal. Sometimes I dispense with the hole at the
end of the chamber, and in chat case I make the chamber of a size to hold
just sufficient vacuum to draw the package quietly up to the end of the pipe
after the exhaust is cut off by the displacement of the trigger, as before
described, and I employ a grating to stop the package opposite the door or
opening for its removal. Or in place of using the enlarged chamber at the
end of the main pipe, this pipe may be simply prolonged so as to act as a
buffing chamber; and to draw the package quietly up to a door, at the end of
this buffing chamber, I use a pipe of very small diameter to connect the
exhaust with the extremity of the buffing chamber. In order still further to
check the velocity with which the package is delivered, the main pipe may be

page_text: so arranged towards its end before arriving at the exhaust pipe that the air
pressing behind the package may be able to pass it, and for this purpose a
branch pipe may be used, communicating at its two ends with the main pipe,
or the main pipe itself may be made of such a section that the package shall
not fit it, so as to prevent the air passing it. It will be seen that this method
of checking the velocity of the package is as applicable when using pressure
behind the package as when using vacuum before it. The quiet delivery of
the package may also be ensured by cutting off the vacuum or pressure after
it has been on a regulated time, and this may either be done by clock work,
or by electric apparatus brought into action by the package coming in contact
with a trigger in the tube at some distance from its end; or there may be a
valve in the pipe itself at some distance from its end, which, after the passage
of the package, falls and partially closes the pipe.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Josiah Latimer Clark in the Great Seal Patent Office
on the 11th December 1857.
JOSIAHI
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
LATIMER CLARK, of 35, Adelaide Road, Haverstock Hiil, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of June, in the year of our Lord
One thousand eight hundred and fifty-seven, in the twentieth year of Her
reigu, did, for Herself, Her heirs and successors, give and graut unto me,
the said Josiah Latimer Clark, Her special licence that 1, the said Josiah
Latimer Clark, my executors, administrators, and assigns, or such others as
I, the said Josiah Latimer Clark, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE
MENTS IN APPARATUS FOR CONVEYING LETTERS OR PARCELS BETWEEN PLACES BY
THE PRESSURE OF AIR AND VACUUM," upon the condition (amongst others) that
I, the said Josiah Latimer Clark, 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,

page_text: and in what manner the satne 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 Josiah Latimer Clark, 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, that is to say:
This Invention has for its object improvements in telegraphs, in which
letters or other articles are conveyed through pipes by pneumatic pressure.
In laying the pneumatic pipes between the stations, considerable difficulty has
been experienced in making the joints in the line of pipes in such a way as
not to interfere with the passage of the package. In order to obviate this, I
make thejoints by causing the ends of the pipes to butt together, and slipping
a ring or short piece of tube of vulcanized india-rubber or of other air-tight
material over the joint, and the ends of the metal pipes are held accurately in
their positions by a socket made in two halves, connected together with screws,
which socket covers the vulcanized india-rubber ring, and clips firmly the
ends of the pipes.
The Figures 1 show a joint made in this way: a, a, are the ends of the main
pipe; is a piece of vulcanized india-rubber tube slipped o'er them where
they butt together, and bound to them at ', '; c, c, are the two parts of the
metal socket which fits over the vulcanized tube, and prevents the ends a, a,
from shifting out of their proper position.
The Figures 2 shows another way in which I sometimes form the joints in
the pipe, as shewn in these Figures; they are connected by butting their ends
a, a, together as before, and slipping a short metal tube over the junction,
which is made air-tight by an exterior tube of vulcanized india-rubber c bound
at its two ends c³, c, to the main tubes by wire or twine. This method of cou-
necting the pipes may be varied, as shown at Figures 3 and 4, by placing the
short metal connecting tube in sockets at the ends of the pipes a, a, and
making the junction tight by an exterior india-rubber tube c, c, as before.
If I wish to make one main line of telegraph to diverge into two or more
branch lines, I arrange the main line so that it can be brought in connection
with either of the branch lines, as may be required, by means of a switch. For
this purpose the two branch lines terminate side by side in holes in a face plate,
as is shown at a in Figure 4; and on the surface of this plate another plate b
slides, being governed in its course by guides. In a hole in this second plate
the main line of pipe cte: minates, and this is left unsupported laterally for such

page_text: a distance that it can be moved backwards and forwards freely with its plate
so as to bring its end in communication with the end of either of the branch
lines, as may be required. This switch may either be worked by hand
according to the direction of electric signals, or it may be worked from a
distance by a cylinder and piston or similar apparatus, into which air is
admitted or withdrawn by a pipe communicating with it from a distance.
Figure 5 is a section of a cylinder which may be used to work the switch;
its piston rod is connected directly to the switch, and there are two pipes
connected with the cylinder which proceed to the place from whence it is
desired to work the switch, and the motion of the switch is produced by
connecting one or other of the two pipes to the source of accuin or pressure.
In working telegraphs of this description I have found that a saving of cost
may be effected by so arranging the apparatus that the packages are propelled
in one direction by exhausting the air from the pipe in front of the package,
and in the other direction by admitting behind it air under a pressure
exceeding that of the atmosphere. When the apparatus is arranged in this
way one pumping engine only will be necessary, and this engine works to
produce a partial vacuum in one vessel and a pressure in another vessel.
These vessels act as reservoirs, and may resemble ordinary gasometers, as they
are described in the Specification of a former Patent granted to me, with
this difference, when the apparatus is used for pressure, that the weights are
so applied as to give the gasometer a tendency to descend in place of to rise;
or large cylinders containing weighted pistons, such as are shewn in section
at Figures 6 and 7, or vessels with flexible sides like the wind chests of
organs, as is shown at Figure 8, may be employed.
The vessel shewn at Figure 6 is intended for a vacuum, and that shown at
Figure 7 for pressure. The vessel shewn at Figure S may be used either for
pressure or vacuum, according as it is used in the position shown in the
Drawing or inverted In order to obviate as much as possible the retarding
effect of the friction of the air within the pipe, I employ valves at convenient
distances along the pipe. which valves when working by vacuum open, and
when working by pressure close immediately after the passage of the package.
And in order to work the valves I employ cylinders containing pistons, and
each of these cylinders is in communication at each end with the main pipe;
but the two communications are made at places at some distance from each
other, so that when the package is in the part of the pipe between the two
points of communication, the pressures on the two sides of the piston will
be different, and the piston will move and will open or close the valve.

page_text: Figure 9 is a longitudinal section showing the way of applying a valve to
admit air to the pipe behind the package when it is propelled by means of
vacuum. a is the main pipe, and b is a valve box in connection with it; c is a
valve centred at 1, and having a slight spiral spring d connected to it to
give it a tendency to close over the hole in the valve box. The valve is kept
tight by a disc of vulcanized india rubber or other suitable material, e, as is
shown; f is a catch which, until it is withdrawn, as will be presently
described, keeps the valve closed notwithstanding the pressure of the external
air; is a cylinder containing a piston, which has a slotted rod, and
through the opening in which a pin on the catch f passes. Thus it will be
seen that when the vacuum in the valve box is rendered less perfect by the
passage of the package, the catch will be withdrawn by the motion of the
piston, and the valve will open so as to admit air freely behind the package.
When the vacuum is completely destroyed the valve closes again of itself.
The distance between the two openings into the main pipe should be about
80 feet apart. When the package is propelled through the pipe by pressure,
it is necessary to modify the arrangement of this apparatus so that the valve
shall remain open till the package comes up to it, and that it shall then close.
For this purpose the valve is furnished with a spring which has a tendency to
keep it open, and at such a distance from its seat as not to be closed by the
rush of air; then, when the package passes the end of the small connecting
pipe, the piston moves as before, and this raises up the valve to its seat, the
pressure then keeps it tight.
.
Figure 10 shows the way in which the cylinder may be cansed to act by
means of a trigger displaced by the passage of the package, which then opens
a communication between the cylinder (on one side of the piston) and the
vacuum or pressure. a is the main pipe; b, a trigger which, when pressed
down, opens the cock G₁ which (when vacuum is used) raises the piston d and
opens a communication with the atmosphere by turning the the cock e. When
pressure is used in place of vacuum the action of the apparatus is reversed.
In the use of pneumatic telegraphs great difficulty is experienced in regu-
lating the velocity at which the package issues from the end of pipes. For this
purpose, when working by vacuum, I cause the package when it comes near
the end of its course to strike a trigger, and by displacing this trigger to allow
a valve in the exhausting pipe to close by the pressure of the air. When the
vacuum is cut off the valve again opeus by its own weight or otherwise, and
the trigger resumes its first position. This arrangement is shewn at Figure 11.
a is the main pipe; b, the pipe leading to the vacuum supply; c, a spindle

page_text: valve in this pipe, which has a light tendency to rise given it (as shewn in the
Drawing) by a spring; d is a catch, which holds the valve up till the trigger
e is depressed by the package, and then the valve falls and the vacuum is shut
off. The trigger e should be placed at a distance of about 10 feet from the
end of the pipe a; it is preferred that the valve c should not fit with perfect
accuracy, as a slight leakage will facilitate the delivery of the package. The
trigger e or another similar trigger mayalso act to allow a valve to open imme-
diately behind the package, so as to admit the external air to destroy the
vacuum behind the package and prevent its sticking in the pipe, as sometimes
occurs when this precaution is not taken. An arrangement of this sort is
shown at Figure 12, which will be readily understood without any detailed
description. The valves which I employ for these purposes consist each of a
plate of metal a, Figure 13, which closes loosely against a seat in the box b,
which contains it. And in order to make the valve air-tight I employ a ring of
vulcanized india-rubber, leather, or other similar material c,attached round its
exterior edge to the seat of the valve. The following is a convenient arrange-
ment of the delivery of the package:-I place at the end of the main pipe a
(see Figure 1.4) a tube or chamber 6, of larger diameter than the main pipe,
against the end of which and within the chamber is a pad c, against which the
passage strikes. The valve is thus displaced, and the external air rushes
into the pipe by a small hole at the end of chamber, and against and past the
package, which is thus quickly stopped and brought back by the pad to a point
in the pipe where there is a door or opening e, for its removal. Sometimes I
dispense with the hole at the end of the chamber, and in that case I make the
chamber of a size to hold just sufficient vacuum to draw the package quietly
up to the end of the pipe after the exhaust is cut off by the displacement of
the trigger, as before described, and I employ a grating to stop the package
opposite the door or opening for its removal. The size of the vacuum chamber,
in proportion to the area of section of the main pipe, will vary according to the
distance from the end at which the vacuum is cut off, and the strength of the
vacuum used; but this may easily be adjusted in each particular case by
making the vacuum chamber in sections which screw or fit together, so that a
greater or less number of these sections can be put on as may be found desir-
able, or the vacuum chamber may be made at first larger than is necessary,
and the adjustment may afterwards be effected by filling a part of the chamber
with water.
In place of using an enlarged chamber at the end of the main pipe, as just
described, this pipe may be simply prolonged, so as to act as a buffing chamber:

page_text: and to draw the package quietly up to a door at the end of this buffing
chamber I use a pipe of very small diameter, or a pipe with an adjusting
stop-cock, to connect the exhaust with the extremity of the buffing chamber.
This arrangement is clearly shown at Figure 15, where a is the main pipe; b,
the pipe leading to the vacuum; c, the prolongation of the pipe a; d, the door
for removing the package; and e, a small pipe, furnished with a stop-cock,
and communicating with the exhaust for gradually sucking the package up to
the door d. The pipe 6 should be about 10 feet long. In order still further
to check the velocity with which the package is delivered, the main pipe may
be so arranged towards its end before arriving at the exhaust pipe that the air
pressing behind the package may be able to pass it, and for this purpose a
branch pipe may be used, communicating at its two ends with the main pipe,
or the main pipe itself may be made of such a section that the package shall
not fit it so as to prevent the air passing it. It will be seen that this method
of checking the velocity of the package is as applicable when using pressure
behind the package as when using vacuum before it. The quiet delivery of
the package may also be ensured by cutting off the vacuum or pressure after
it has been on a regulated time. For this purpose I sometimes employ clock-
work, so arranged that the movement of the handle by which the vacuum or
pressure is turned on winds up the spring or raises the weight of the clock-
work, which then in running down shuts off the vacuum, and the speed at
which the clockwork runs down is conveniently regulated by a fly. The
vacuum or pressure may also be shut off after it has been on the required
time by means of electric apparatus. When this is employed a trigger is
placed in the tube, and when this trigger is moved it completes the circuit of
a galvanic battery in which an electro-magnet is included; this then becomes
magnetised and attracts its keeper or armature which is connected with the
lever of the cock for shutting off the vacuum or pressure.
Figure 16 is another apparatus by which the vacuum may be cut off at any
desired point by the passage of the package itself, and this apparatus may,
with slight modifications, as will be readily understood, be adapted for use
with pressure.
a is the main pipe; b, a trigger; c, a valve which, when
the bolt d is withdrawn by the trigger, is caused to descend by the pressure
of the air on the piston e, but which is again lifted by the spring f, when
the pressures within and without the pipe become equalized. I prefer
that the vacuum or pressure should be shut off when the package arrives
within about 20 feet of the end of the tube.
I would remark, that wherever in this Specification I have given particular

page_text: dimensions for parts of the apparatus, those dimensions apply to a three-
inch pipe working with a vacuum of 12 inches, or with a pressure of 15
inches and a length of about 500 yards. I would also remark, with reference
to that part of my Iuvention which relates to the use of valves to open
behind the package when vacuum is employed, or to close behind it when
pressure is employed, so as to avoid the friction of the air through a long
length of pipe, that I do not claim the use of such valves generally, but
only the methods in which such valves are arranged and actuated.
In witness whereof, I, the said Josiah Latimer Clark, have hereunto
set my hand and seal, this Eleventh day of December, in the year
of our Lord One thousand eight hundred and fifty-seven.
Witness,
JNO. ALOOCK.
JOSIAH LATIMER CLARK. (L.S.)