IMPROVED APPARATUS FOR EXHAUSTING AND COMPRESSING AIR, APPLICABLE TO THE TRANSMISSION OF DESPATCHES AND OTHER OBJECTS THROUGH TUBES, TO RAISING WATER
Year: 1866

page_text: LETTERS PATENT to George Davies, of No. 1, Serle Street, Lincoln's Inn,
in the County of Middlesex, and No. 87, St. Vincent Street, in the City
of Glasgow, Civil Engineer and Patent Agent, for the Invention of
"IMPROVED APPARATUS FOR EXHAUSTING AND COMPRESSING AIR, APPLICABLE
TO THE TRANSMISSION OF DESPATCHES AND OTHER OBJECTS THROUGH TUBES,
TO RAISING WATER."-A communication from abroad by Jean
Baptiste Java Mignon and Stanislas Henri Rouart, of Paris, France.
Sealed the 30th October 1866, and dated the 5th May 1866.
PROVISIONAL SPECIFICATION left by the said George Davies at the
Office of the Commissioners of Patents, with his Petition, on the
5th May 1866.
I, GEORGE DAVIES, of No. 1, Serle Street, Lincoln's Inn, in the County of
Middlesex, and No. 87, St. Vincent Street, in the City of Glasgow, Civil
Engineer and Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVED APPARATUS FOR EXHAUSTING AND COMPRESSING AIR, APPLICABLE TO
THE TRANSMISSION OF DESPATCHES AND OTHER OBJECTS THROUGH TUBES, AND TO
RAISING WATER," (a communication to me from abroad by Jean Baptiste Java.
Mignon and Stanislas Henri Rouart, of Paris, France,) to be as follows:-
This Invention relates principally to an arrangement of apparatus for
rapidly transmitting despatches and other objects of similar dimensions or

page_text: weight for short distances. To accomplish this it is proposed to employ the
well-known principle of pneumatic pressure,
The Invention consists in certain novel mechanical arrangements, ordinary
tubes are made available for this purpose. The tube (in which is placed a
carriage of suitable construction, bereafter described) is connected at one end
by two tubes with two closed vessels or reservoirs, one at a slightly lower
level than the other. The upper closed vessel (which is twice the capacity of
the other) is provided with a pipe leading from an open tank or cistern of
much larger dimensions filled with water and placed about thirty-three feet
above its own level, and the smaller closed vessel is also in communication by
means of a pipe with an open cistern placed about thirty-three feet below its own
level. The two closed vessels are also connected together by means of a pipe,
These several .pipes, are all furnished with stop-cocks. Both ends of the
atmospheric tube are closed by means of air-tight traps or covers kept closed
by weighted levers.
:
The action of the apparatus is as follows:-Supposing the cock on the pipe
between the lower closed vessel and the lower tank to be closed, and that
between the two closed vessels open, the air is permitted to escape from the
upper closed vessel by opening an air valve or cock, and water is allowed to
flow from the upper tank or cistern until the lower closed vessel is full; the
cock on the pipe between the two closed vessels is then closed and the air
valve shut; the cock on the tube leading to the lower open cistern is then
opened; the water will now descend the pipe to the lower cistern, causing a
vacuum in the upper closed vessel. Supposing now the further end of the
atmospheric tube to be opened, and a carriage containing despatches or other
objects and fitting close into the interior to be placed therein, if the cock
between the upper closed vessel (where the vacuum exists) and the near end
of the atmospheric tube to be quickly opened the carriage will be rapidly
transmitted towards the operator; if now on the contrary the communication
between the two closed vessels be shut off, and that between the larger closed
vessel and the open tank above be opened, the weight of the thirty-three feet
column of water will compress the air in the upper closed vessel, and if the
cock between the latter and the atmospheric tube be quickly opened the
carriage will be driven back to the other end of the tube. Where there is a
constant supply of water, and waste is no object, the water may be allowed to
run away by an overflow pipe from the lower cistern, but in other cases the
water must be returned (by means of a pump or otherwise) into the upper
cistern or tank.
The construction of the carriage which it is proposed to employ. and which

page_text: is adapted to run in tubes which are not mathematically regular, is as follows:
-A light box closed at its forward end with a lid in any suitable manner, its
exterior being of smaller diameter than the interior of the atmospheric tube,
the rear end of the box (or that which has to bear the atmospheric pressure)
has attached to it a cup-shaped piece of leather forming part of a sphere of
larger diameter than the inside of the atmospheric tube and working air-tight
against the interior of the same. The forward end of the box is provided
with small springs, which keep it steady in the tube. It will be evident that
instead of causing the water to flow from one vessel to another, as above
described, the same effect may be produced by causing the reservoirs to move
up or down in the water, like the bell of a gasometer, as follows:-A closed
vessel (from the bottom of which projects a tube about forty feet long) is
placed in a well, being filled with counterbalance weights and raising and
lowering apparatus, an air cock is opened and the vessel is allowed to fill with
water; the cock in the above-named tube being open and the air cock
closed, the vessel is now raised to a height of about thirty-three feet above
the level of the water in the well, the lower end of the tube being of course
still below the level of the water; this will cause a vacuum in the vessel,
and if the cock of the forty-feet pipe is now closed, and a cock in communi-
cation with a lateral pipe leading to the atmospheric tube is opened the air in
the latter will be exhausted and the carriage and its contents will travel along
the tube. The compression of the air to return the carriage is produced by
lowering the reservoir into the well. This arrangement is also applicable to.
raising water for irrigation and other purposes.
A pneumatic apparatus for the laboratory may also be made upon this
principle by having a small open vessel with a long tube projecting downwards
from its bottom like a well, being filled with mercury; into this the lower
open end of a small glass tube is plunged, the upper end of the tube being:
closed and in communication with two flexible tubes fitted with valves. The
tube is supported in vertical guides, and by moving the tube up or down in the:
mercury exhaustion or compression is produced in the flexible tubes..
A stop-cock suitable for any of the above arrangements and also for other
purposes where an air-tight cock is required. The cock is similar to an
ordinary stop-cock, with the exception that there is a circular recess in the top.
of the body round the stem of the plug, the bottom of the recess being level.
with the top of the plug and of rather larger diameter. Rings of india-
ubber, leather, or other material are placed in this recess, covering the joint
between the top of the plug and the bottom of the recess, and are pressedi
herein by means of a cap which is bolted down on to the body of the cock,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Davies in the Great Seal Patent Office on the 5th
November 1866.
TO ALL TO WHOM THESE PREȘENTS SHALL COME, I, GEORGE
DAVIES, of No. 1, Serle Street, Lincoln's Inn, in the County of Middlesex,
and No. 87, St. Vincent Street, in the City of Glasgow, Civil Engineer and
Patent Agent, send greeting,
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of May, in the year of our Lord One
thousand eight hundred and sixty-six, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said George Davies, Her special licence that I, the said George Davies, my
executors, administrators, and assigns, or such others as I, the said George
Davies, 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
yend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVED APPARATUS FOR
EXHAUSTING AND COMPRESSING AIR, APPLICABLE TO THE TRANSMISSION OF DESPATCHES
AND OTHER OBJECTS THROUGH TUBES, AND TO RAISING WATER," (a communication
to me from abroad by Jean Baptiste Java Mignon, and Stanislas Henri
Rouart, of Paris, France,) upon the condition (amongst others) that I, the
said George Davies, 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 George Davies, do hereby declare the
nature of the said Invention, and in what mauner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, and on reference to the accompanying Sheets of Drawings,
that is to say:
This Invention relates principally to an arrangement of apparatus for rapidly.

page_text: transmitting despatches and other orjects of similar dimensions or weight for
short distances. To accomplish this it is proposed to employ the well-known
principle of pneumatic pressure.
The Invention consists in certain novel mechanical arrangements whereby
ortlinary tubes are made available for this purpose. The tube (in which is
placed a carriage of suitable construction hereafter described) is connected at
one end by two tubes with two closed vessels or reservoirs, ono at a slightly
lower level than the other. The upper closed vessel (which is twice the capacity
of the other), is provided with a pipe leading from an open tank or cistern of
much larger dimensions filled with water and placed about 33 feet above its
own level, and the smaller closed vessel is also in communication by means of a
pipe with an open cistern placed about 33 feet below its own level. The two
closed vessels are also connected together by means of a pipe; these several pipes
are all furnished with stop-cocks. Both ends of the atmospheric tube are
closed by means of air-tight traps or covers kept closed by weighted levers.
The action of the apparatus is as follows:-Supposing the cock on the pipe
between the lower closed vessel and the lower tank to be closed, and that
between the two closed vessels open, the air is permitted to escape from the
upper closed vessel by opening an air valve or cock, and water is allowed to
flow from the upper tank or cistern until the lower closed vessel is full. The
cock on the pipe between the two closed vessels is then closed and the air
valve shut; the cock on the tube leading to the lower open cistern is then
opened; the water will now descend the pipe to the lower cistern, causing a
vacuum in the upper closed vessel. Supposing now the further end of the
atmospheric tube to be opened, and a carriage containing despatches or other
objects and fitting close into the interior to be placed therein; if the cock
between the upper closed vessel (where the vacuum exists) and the near end
of the atmospheric tube be quickly opened the carriage will be rapidly trans-
mitted towards the operator; if now on the contrary the communication
between the two closed vessels be shut off, and that between the larger closed
vessel and the open tank above be opened, the weight of the 33 feet column of
water will compress the air in the upper closed vessel, and if the cock between
the latter and the atmospheric tube be quickly opened the carriage will be
driven back to the other end of the tube. Where there is a constant supply
of water, and waste is no object, the water may be allowed to run away by an
overflow pipe from the lower cistern, but in other cases the water must be
returned (by means of a pump or otherwise) into the upper cistern or
tank.
The construction of the carriage which it is proposed to employ, and which

page_text: is adapted to run in tubes which are not mathematically regular, is as follows:-
A light box closed at its forward end with a lid in any suitable manner, its
exterior being of smaller diameter than the interior of the atmospheric tube,
the rear end of the box (or that which has to bear the atmospheric pressure),
has attached to it a cup-shaped piece of leather forming part of a sphere of
larger diameter than the inside of the atmospheric tube and working air-tight
against the interior of the same. The forward end of the box is provided
with small springs which keep it steady in the tube. It will be evident that
instead of causing the water to flow from one vessel to another, as above
described the same effect may be produced by causing the reservoirs to move
up or down in the water, like the bell of a gasometer, as follows:-A closed
vessel (from the bottom of which projects a tube about forty feet long) is placed
in a well, being fitted with counterbalance weights and raising and lowering,
apparatus; an air-cock is opened and the vessel is allowed to fill with water.
The cock in the above-named tube being opened and the air-cock closed, the
vessel is now raised to a height of about thirty-three feet above the level of the
water in the well, the lower end of the tube being of course still below the level of
the water; this will cause a vacuum in the vessel, and if the cock of the forty
feet pipe is now closed, and a cock in communication with a lateral pipe
leading to the atmospheric tube is opened, the air in the latter will be
exhausted, and the carriage and its contents will travel along the tube. The
compression of the air to return the carriage is produced by lowering the
reservoir into the well; modifications of this principle will be herein-after
described. This arrangement is also applicable to raising water for irrigation
and other purposes.
A pneumatic apparatus for the laboratory may also be made upon this
principle by having a small open vessel with a long tube projecting downwards
from its bottom like a well, being filled with mercury; into this the lower
open end of a small glass tube is plunged, the upper end of the tube being
closed and in communication with two flexible tubes fitted with valves. The
tube is supported in vertical guides, and by moving the tube up or down in
the mercury exhaustion or compression is produced in the flexible tubes.
A stop-cock suitable for any of the above arrangements, and also for other
purposes where an air-tight cock is required, is constructed as follows:-The
cock is similar to an ordinary stop-cock, with the exception that there is a
circular recess in the top of the body round the stem of the plug, the bottom
of the recess being level with the top of the plug and of rather larger diameter.
Rings of india-rubber, leather, or other material are placed in this recess
covering the joint between the top of the plug and the bottom of the recess,

page_text: and are pressed therein by means of a cap which is bolted down on to the'
body of the cock, having a projection beneath fitting into the recess, and
being bored through the middle to allow the stem of the plug. to pass.
through.
Such being the nature and object of the said Invention for "Improved.
Apparatus for Exhausting and Compressing Air, applicable to the Transmission
of Despatches and other Objects through Tubes, and to raising Water,"
(a communication to me from abroad by Jean Baptiste Java Mignon and
Stanislas Henri Rouart, of Paris, France,) I will now proceed to describe more
in detail the manner in which the same is to be or may be performed or
carried into practical effect, and in order that the same may be distinctly
understood I have annexed hereunto two Sheets of Drawings illustrative.
thereof, and have marked the same with figures and letters of reference
corresponding with those in the following explanation thereof, that is.
to say:
In Sheet 1 of the annexed Drawings (Figures 1 and 2) A is a tube or
conduit of a suitable length and diameter, according to the distanco and the
size of the carriage which it is to contain; this tube or conduit is connected.
by the tube p with the reservoir B, and by the tube m with the reservoir C.
This reservoir C is connected to another reservoir or cistern D by the tube g;
the reservoir B communicates with the reservoir E (open at the top) by the
tuber. The distance which separates the lower part of the reservoir B from.
the upper level of the vessel E is about thirty-three feet, and the distance
which separates the bottom of the cistern D from the water levels of the
reservoir C is also about thirty-three feet. The cistern D is fitted with water
which can flow from D into C by the tube 2, on which is placed a cock h;'
this water can run from the reservoir C into B by the tube v, on which is a
cock t; lastly, it can flow from the reservoir B into the cistern E. The capacity,
of the reservoir B is greater than that of the tubo or conduit A, and the
reservoir C is double the capacity of the reservoir B; the cistern D is of a-
capacity considerably larger than that of the reservoir B, and it is filled with
water. The whole of this arrangement is such as to permit of the creation.at
will of a vacuum or of compression, which may be readily used for the trans-,
mission of a carriage along the conduit pipe A in either direction. For
example, supposing that the cock f is closed, and the cock t open (and the
reservoir B furnished with an air valve or cock), the water is allowed to flow.
from D into C by opening the cork h until it completely fills the space B; the
cock t is then to be closed as well as the air cock, and the cock ƒ opened;
the water from the reservoir B will now run away until its level stops at the

page_text: lower part of the reservoir B, that is, about thirty-three feet above the uper
level of the cistern E. It will run over the top of the cistern E or be carried
away by an overflow pipe into a drain or well made for that purpose. When
the column of water has thus descended a vacuum will be established in the
reservoir B, and will be indicated by a vacuum gauge attached thereto. A
water gauge will also indicate when the level of the water has descended
sufficiently in the reservoir B; the cock f is now closed, and if a carriage,
fitting sufficiently air-tight, is placed at the further extremity of the con-
duit A, and the nearer end of the conduit closed, on suddenly opening the
cock of the tube p, the air contained in the conduit A will rush into the
reservoir B and the carriage will be driven quickly towards the operator. If
now the cock t be closed, and the cock h be opened, the water from the
cistern D will flow into the reservoir C (supposed to be originally full of air),
and this flow will not stop until the level is such, that the air in the reservoir-
C will be compressed to such an extent as to equalibrize the atmospheric
pressure plus the column of water contained between the level of D and the
level of C. Under the conditions indicated the air will attain a pressure of
rather more than two atmospheres, and by the aid of this pressure the
carriage may easily be returned to the original sender by opening the cock k
on the tube m.
It will be evident that the relative arrangement of the vessels D, B, C, E,
may be varied in such a manner as to suit the apparatus best to the necessities.
of the locality in which it is placed, thus the cistern D may be brought
down to a little above the reservoir B, provided that the reservoir C be taken
to the level of the cistern E. This is a question of arrangement which should
be studied in each particular case. In large establishments, and in certain
houses, we might have at our disposal reservoirs of water placed in the roof,
which would allow us to obtain a very active circulation of despatches of any
nature without any appreciable expence, and in some cases the ordinary water
supply may be used which is always kept at a pressure sufficient to act
directly in the reservoir where the air is to be compressed. In other instances
it will be necessary to have machines more or less powerful to raise the water
again from the level of the cistern E to that of the cistern D. By these means
the displacement of a carriage of considerable weight may be effected.
Particular attention is here called to the construction and arrangement of
the carriage or conveyance (Figure 3), which is such as to allow of its
travelling in the conduit without requiring mathematical accuracy in the
latter. This carriage is simply a box a, b, c, d, extremely light (it can be
made of aluminium if necessary), and is of a diameter considerably less than

page_text: that of the conduit pipe A. The part c, d, (which is the end of the carriage
intended to bear the effect of the differential pressure created either by
vacuum or compression,) is provided with a leather suitably cupped, so as to
represent a segment of the sphere c, d, e, f, the diameter of which is greater
than the inner diameter of the conduit pipe. The anterior portion a, b, of the
carriage is provided with small springs m, which prevent the jumping of the
carriage in the tube, and at the same time give way in passing any deforma-
tions or irregularities in the tube. The part a, b, operis in such a manner as.
to allow of the introduction of despatches (or of other articles to be conveyed)
into the interior of the carriage. The stop-valves or doors placed at the
extremities of the tube A may also be arranged in different ways, according to
the necessities of the service; in most cases, however, the arrangement shown
at Figure 4, which is simple in its construction and action, may be employed.
A bent lever a, b, c, carries fixed to its arm b, c, a metallic disc of rather a
larger diameter than the tube A; this disc is provided with a piece of india-
rubber, which is pressed against the end of the conduit pipe by the effect of
the weight D placed at the extremity of the lever a, b. The weight D must
be so arranged as to overcome the pressure produced. by the passage of the
compressed air in the tube A. In certain particular cases this problem may
be treated in another manner which presents some advantages. Instead of
making the water move, the reservoirs may be caused to move in the water
like the bell of a gasometer. For instance, suppose a reservoir A (Figure 5)
to be provided with a tube a; the reservoir A is originally placed at the
bottom of a well of such dimensions, that the reservoir A can descend a little
below the level of the water in the well, and the tube a plunges into a pipe of
sufficient length. The reservoir A is provided with a suitable counterpoise,
and its upper part carries a hook at c, fast to a chain moved by a capstan ; it
has friction rollers at the sides which direct its movement between suitable
guides. The vessel A which is furnished with an air cock can be allowed to
fill with water, and will be easy then to raise it till its bottom part is about
thirty-three feet above the level of the water in the well. A vacuum will
thus be formed in the reservoir A, and if now the cock g, placed near the top
of the tube a, be closed, the vacuum thus obtained can be used to produce
the suction of the carriage along the conduit pipe as above mentioned. The
compression is obtained by lowering the reservoir (supposed to be originally
full of air as well as the tube a) until the volume of air is reduced to a
proportion determined by the relative capacities of the reservoir A, and the
conduit to be operated on.
'It will be evident that this arrangement is also applicable to pumps for.

page_text: raising water. Suppose, for example, that the reservoir A (Figure 5) is
so placed that its upper level or top is only about thirty-three feet above the:
level of the water in the well, the reservoir would tlien be completely full of
water; if now the cock g be shut, and the cock h in the side of the reservoir:
be opened, at the same time that air is admitted by a valve at the top there
will be a continuous flow of water from the reservoir, and consequently a con-
siderable quantity of water would have been raised. This kind of pump would
render great service in draining and irrigation, and the system which is
applicable to such great displacements of water is also equally adapted for
pneumatic apparatus, the dimensions of which may be small enough to be
used in. the laboratory. Place a tube a, b, Figure 6 (like a mercury baro-
meter) in a vessel c, d, prolonged by a tube e, f, in which the tube a, b, is:
plunged. The tube a, b, carries at a a metallic disc on which are placed two.
valves &, s³, opening in opposite directions; these valves communicate with
tubes r, r¹, t, t¹, which are connected to the enclosure to be operated on. The
tubes r, r¹, t, t¹, are sufficiently flexible and resisting to allow of the alternating
movement of the tube a, b, and to resist internal and external pressure ;
they may be made of india-rubber covered with cloth or with coiled wire
inside; the rod 1, P, serves to alternately raise and depress the tube a, b, which
will cause an alternate vacuum and compression.
In making the different apparatus just described, all the ordinary organs
employed in trade may be made use of, such as valves, cocks, and so forth,.
but I will bere describe a special construction of stop-cock, which may be
applied with advantage, not only to the apparatus above mentioned, but also.
to any other apparatus where an air-tight stop-cock is required. This stop-
cock represented in section at Figure 7 is similar to ordinary stop-cocks,
excepting that there is a circular recess a in its upper part; the bottom of this
recess is turned flush (as exactly as possible) with the upper part of the plug b,
so that the junction of these two pieces is simply represented by a circular line c,
(Figure 8). The recess a is filled with rings of india-rubber, leather, or
metal, held down by the plate or cap d, d, which is fixed by bolts e, e¹. The
upper part of the plug passes through the plate d, d, and terminates in the:
handle f. This very simple arrangement makes a perfectly air-tight stop-
cock.
In Sheet 2 of the Drawings, Figures 9 and 10 represent a modification of
the organ of reception and departure of the carriages, which is particularly
applicable to a despatch carriage driven by compression, which will be the
most general case. A is a hollow pedestal, which carries at its upper end a
hollow column B. The extremity of the conduit pipe is fixed in the pedestal,

page_text: whilst the upper part of the column B is connected to the reservoir of com-.
pressed air by means of the cock R. The front or anterior face of the square.
part C of the column B is provided with a small door closed by means of a.
screw clamp. The lateral faces carry two tubes t and t, which lead to the
cock R' communicating with the open air; the cocks R and R' are moved by.
the same screw in such a manner that their movements are contrary; one is
open during the closing of the other, and vice versa. If it be desired to send
off the carriage the door is to be opened and the carriage placed in the hollow
column B head downwards; the door is then shut and the cock R opened,
which closes the cock R', the compressed air immediately acts on the carriage
and despatches it along the conduit pipe. If a carriage is to be received the
cock R is to be shut, which opens the cock R¹, and the air expelled from the
tube escapes by the two lateral tubes t and t, and the carriage despatched
from the other end continuing its movement in a right line is received by the
cushion of air contained in the upper part of the column B.
The action of the apparatus previously described is simple and single-acting,
but it might happen in certain cases (especially where large capacities are
required) that a practical difficulty would arise from the dimensions of the
reservoirs. To remedy this defect it is proposed to employ a machine which
the Inventors call "double-acting," which consists of two reservoirs A, A'.
(Figure 11) for compression, each divided into two compartments B, B', and
C, C', by means of a diaphragm a, b, a, 6. At the bottom of the compart-
ments B and B open the water supply tubes c, d, c¹, d'; at e, f, e', f¹, are the,
water discharge pipes 9, h, g, h, are two plates acting as slide valves, and.
allowing of the opening or closing at will of the tubes c, d, c', d¹; e, f, e', f';
the movement of the plates g, h, g', h¹, is regulated in such a manner that the;
tube c, d, being closed the tubes c', d¹, and e, f, are opened and the tube e', f',,
closed. A displacement of the slides has the effect of closing the two tubes
which were open and opening those two which were closed; the diaphragms
a, b, a', ', are each furnished with a valve k, k¹, opening upwards. The
upper part of the reservoirs is provided with two air valves, the opening and
closing of which are regulated by a thin plate forming a slide valve, the move+:
ments of which are simultaneous with and connected to those of the plates
g, h, g, h, in such a manner that the orifice m is open, when the orifice e is
closed the orifice m' is closed and the orifice c' opened. At the height of the.
diaphragms on the side walls are two counterbalanced valves p, p', which are
moved by extremely slight differential pressure, and the movement of which,
may, however, be connected with that of the escape valves 1, 1', in such a
manner that
P is open at the same time as 2, and p² at the same time as 1.

page_text: All these conditions being fulfilled I will now point out bow the apparatus
above described operates, and indicate how these conditions may be carried
out. Suppose that the orifice c is open, then the orifice e, the orifice m, and
the valve p are closed; water under pressure is admitted into the compart-
ment B, compresses the air which is therein, raises the valve k, compresses
the air of the compartment C, and at the end of a certain time the air in C
is compressed to a certain definite pressure, the slide valves are then actuated,
m is opened, and at the same time p, c, and c', whilst on the contrary the
openings m', p', and e' are closed; then the water collected in B runs out,
and the air compressed in C escapes to be used according to the effect desired
to be produced; water is admitted into B' and compresses the air in C. If
a second movement of the slide valve takes place the reservoir A works as
mentioned in the first description, and the reservoir A¹ will fulfil the functions
which the reservoir A had performed during the second movement of the slide
valve. In this manner a certain number of exhaustions of the air can be
produced in a given time which are equivalent to a continuous flow.
It is now only necessary to indicate the arrangements to be made, in order
to realize practically the theoretical effects which have been analysed above.
These effects will be realized if there is a suitable concordance in the openings
and closings of the supply and escape orifices for the air and water. For this
purpose the two cylinders may be placed side by side, as in Figure 12. In
this arrangement the supply of water in the compartments B and B', the
exhaustion of air from the compartments C and C, the exhaustion of the
water from the compartments B and B', and the re-entry of air into these
latter compartments can be made (two and two) by one branch pipe having
two stop-cocks. Thus the supply of water is effected by the tube 1 by means
of the stop-cocks c', c', the exhaustion of air by the tube 2 by means of the
stop-cocks 1, 1, the exhaustion of water by the tube 3 by means of the stop-
cocks e, e¹; and, lastly, the re-entry of air by the tube 4 by means of the
stop-cocks p, p'. The four stop-cocks I, c, p, e, can be arranged in the same
plane, and the four stop-cocks l', c', pl, e', are also in one plane parallel to
that of the stop-cocks l, c, p, e.
Figure 18 represents the arrangement of the eight stop-cocks, the relative
movements of which should cause the working of the apparatus. To under-
stand this arrangement, suppose that it relates only to the four stop-cocks c,
p, c, l; when the stop-cock c is open the others must Le shut and vice versâ ;
and all that is necessary for this purpose is to connect the slides of the stop-
'cocks to the two levers r, s, s, t, which are jointed together, and have their
fulcra at u and v. The slides e', p', c', 1', can be moved by means of levers

page_text: 1, 8, s, t, which have their fulcra at u, and v¹, the line r, s, t, being parallel to
the line r, s, t, it is sufficient to give a suitable oscillating movement to the
line s, s', or to the central point of this line, which can be done by means of
water through the agency of the differential piston valve of a single-acting
water-pressure engine.
A machine for producing a vacuum may also be made by an analogous
arrangement, Figure 14, consisting of two reservoirs A and A' (without
compartments), into which water is admitted to run from the closed reservoir
into an open cistern placed about thirty-three feet below the reservoirs A and A¹;
they should have a common opening for drawing air with two stop-cocks, a
common opening for the supply of water with two stop-cocks, a common
branch pipe with two stop-cocks for the exbaustion of the water, and a
common branch pipe with two stop-cocks- for the exit of the air during the
filling of the reservoirs. It will be necessary then that the water supply cock
and the air exit cock should be opened together, that of the water exit and of
the air admission being closed, then that the water exit cock opens alone and
recloses; and, lastly, that the air admission cock opens and then closes again.
This series of operations represents the complete working and can be attained
by means in ordinary use in mechanism, for instance, by a compound eccentric
or cam.
It will often happen in practise (in the apparatus first above described)
that the water in the conduit or service pipes which might be used to produce
the compression would be at a greater pressure than that.required for driving
the carriage in the interior of the tubes; this over pressure can be made use of
in many cases to produce an economy of water. Suppose, for example, that the
water at disposal has forty-five feet pressure, and that a force of fifteen feet is
sufficient to produce the movement; three reservoirs A, A', A", (Figure 15) of
equal capacity should be placed vertically one above the other about fifteen feet
apart; the water should be allowed first to enter the reservoir A, where it
exerts its pressure, and the air thus compressed is made use of for the first
passage of the carriage; then passing on to A¹ and A" it will effect a second
and third transit, and thus the water performs the same office three times, and
thus three journeys of the carriage can be obtained from the same amount of
water,
It will be evident that the Figures above mentioned are only named for the
sake of illustration and will vary in each particular case. Generally it will
be advisable to collect all the working parts at one point, and for that purpose
the reservoirs A, A¹, A", should be made of smaller dimensions, and the
reservoir B (placed on the ground) of a size proportioned to the former, there

page_text: will be a communication with each of the other reservoirs, and it will be.in
this reservoir B that the pressure will accumulate successively when the others
are successively filled with water. It will be necessary to take precaution so
to arrange the working parts as to avoid confusion. .If only a small differential
pressure is needed the reservoirs may be brought nearer to each other, so as
to obtain an almost continuous action. In this case the working can be made
automatic in a very simple manner. Each reservoir 'should be divided into
two compartments, the upper one will receive the compressed air, and the
lower one the water intended to produce the compression. The upper reser
voir will be fitted with an air-exhausting equilibrium valve opening at a given
pressure, and an air supply valve closing of itself: The lower reservoir will
have a water exit valve opening of itself when the weight of water has acquired
a sufficient power, and an air admission valve placed laterally at the upper part
and opening under a slight differential pressure. The admission of water into
this reservoir should be regulated by means of a stop-cock or valve moved by
a portion of the water itself. If it is desired the opening of the valves above
mentioned may be effected mechanically, but there is no occasion to recur to
this complication if due regard is paid to the utilization of the force at
disposal.
Figure 16 represents a second arrangement of air-tight cock of a con-
struction nearly analogous to that above described. In this arrangement a is
the circle of separation between the body and the plug; b, a disc or ring of
india-rubber; and c, a metallic disc or ring pressing forcibly on the india-
rubber by means of bolts. When these cocks are of large dimensions motion'
may be given to them by means of a worm wheel actuated by a worm..
In witness whereof, I, the said George Davies, have hereunto set my
hand and seal, this Fifth day of November, in the year of-our Lord
One thousand eight hundred and sixty-six.