Highly Rarefied Elastic Fluids Applicable to a Variety of Useful Purposes.
Year: 1885

page_text: Highly Rarefied Elastic Fluids Applicable to a Variety of
Useful Purposes.
We, ANTHONY GAPPER SOUTHBY of the Condensed Beer Works, Jersey, Engineer
and FREDERICK DELACOURT BLYTH, of N° 79 Mark Lane, in the city of London,
Manufacturer do hereby declare the nature of the said invention for "IMPROVE-
MENTS IN THE MODE OF AND APPARATUS FOR PUMPING HIGHLY RAREFIED ELASTIC
FLUIDS APPLICABLE TO A VARIETY OF USEFUL PURPOSES to be as follows:-
"
Our improvements in the mode of and apparatus for pumping highly rarefied
elastic fluids such as air gases and vapours and applicable to a variety of purposes
such as ice making, refrigerating, evaporating, desiccating and producing almost
perfect vacuum apply to apparatus where two or more pumps of different capacities
are used in a combined series and have to do with the largest of them or the one
which is used to draw off the elastic fluids from whatever vessel it is desired to
exhaust them and after more or less compressing them deliver them, if non-
condensable, to be further compressed by the other one or more smaller pumps and
forced into the atmosphere or otherwise or if condensable vapours to be either
condensed in a condenser either before or after further compression by the other
pump or pumps or forced into the atmosphere as described in the specification of
Letters Patent N° 3017 of 1877 granted to the said Anthony Gapper Southby.
The present improvements consist firstly, in a new mode of making pumps
especially adapted for pumping bigbly rarefied elastic fluids and apparatus for
carrying it into effect; secondly, in a new mode of making the joints of valves
applicable to all kinds of pumps intended for drawing off and more or less com-
pressing highly rarefied elastic fluids; thirdly, in a new mode of and apparatus for
starting all kinds of pumps intended for drawing off and more or less compressing
highly rarefied elastic fluids.
In our new pump we apply the principle of the well known bell pump to the
pumping of highly rarefied elastic Huids by enclosing the bell in a close vessel
capable of sustaining the pressure of the atmosphere which vessel we exhaust of
the greater portion of the pressure of the atmosphere by one or more supple-
mentary pumps and we seal the lower edge of the bell by making it dip into a
non-volatile mobile liquid, such as animal, vegetable, and fish oil so that by forcing
11.71

page_text: the bell up and down inside the partially exhausted vessel the elastic fluid is drawn
off and more or less compressed by the different levels of the non-volatile mobile
liquid inside and outside the bell the vessel and bell being provided with inlet and
outlet valves.
We provide a chamber to catch any of the non-volatile mobile liquid that may
be forced through the exit valve with a regulated passage for the return of the
liquid.
Our new description of valve applicable to all kinds of pumps intended for
drawing off and more or less compressing highly rarefied elastic fluids has the joint
between the valve and the valve seat made with a narrow shallow bead closing on
a more or less yielding substance the bead being either formed on the valve and
the more or less yielding substance fixed to the valve seat or vice versa.
Our new mode of and apparatus for starting pumps used for drawing off and
more or less compressing highly rarefied elastic fluids consists in providing means
for practically shortening the effective stroke of the piston of the pump by either
preventing the closing of the inlet valve during the first portion of the stroke of
the piston or by opening a passage from some portion of the cylinder on one side
of the piston and communicating with the receiver or with the cylinder on the
other side of the piston otherwise than through the exit valve which passage is
closed at some portion of the end of the stroke by making it open into the side of
the cylinder so that it will be closed by the passing of the piston beyond it or by
means of a valve or valves worked by one or more cams or excentrics or other
suitable means the opening being either in the cylinder, cylinder cover or covers or
the piston, with the exception of through the exit valve or valves.
G. F. REDFERN,
4, South Street, Finsbury, London,
Agent for the Applicants.

page_text: Useful Purposes.
We ANTHONY GAPPER SOUTHBY, of the Condensed Beer Works, Jersey, Engineer,
and FREDERICK DELACOURT BLYTH, of N° 79, Mark Lane, in the city of London,
Manufacturer do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement :-
Our improvements in the mode of and apparatus for pumping highly rarefied
elastic fluids such as air, gases and vapours and applicable to a variety of useful
purposes such as ice making, refrigerating, evaporating, desiccating and producing
almost perfect vacuums apply to apparatus where two or more pumps of different
capacities are used in a combined series and have to do with the largest of them or
the one which is used to draw off the elastic fluids from whatever vessel it is desired
to exhaust them and after more or less compressing them deliver them if non-
condensable to be further compressed by the other one or more smaller pumps and
forced into the atmosphere or otherwise, or if condensable vapours to be condensed
in a condenser either before or after further compression by the other pump or
pumps or forced into the atmosphere as described in the specification of Letters
Patent N° 3017 of 1877 granted to the said Anthony Gapper Southby.
The present improvements consist firstly in an improved pump especially
adapted for pumping highly rarefied elastic vapours.
Secondly in a new mode of making the joints of valves applicable to all kinds of
pumps intended for drawing off and more or less compressly highly rarefied elastic
fluids.
Thirdly, in a new mode of and apparatus for starting all kinds of pumps
intended for pumping highly rarefied elastic fluids. .
In our new pump we use the principle of the well known pneumatic pump called
the bell pump, the vessel in which it is enclosed being made capable of sustaining
the pressure of the atmosphere, the greater portion of which pressure being
removed by one or more supplementary pumps, and non-volatile mobile liquids
such as animal, vegetable or fish oils being used to seal the lower edge of the bell
and compress the elastic fluids by the difference of the levels of the non-volatile
mobile liquid inside and outside the bell as it is moved up and dower in the outer
vessel, the bell being provided with inlet and outlet valves.
We do not claim the use of non-volatile liquids to seal elastic fluids in chambers
and by their difference of levels cause exhaustion and compression of the enclosed
elastic fluids as this has been before proposed in the specification of the said former
Letters Patent N° 3017 of 1877 which states that Archimedean and pneumatic
pumps working with mediums of very high boiling points may be used in con-
junction with supplementary pumps for drawing off and more or less compressing
vapours arising from water."
We are also aware that Harrison in Specification N° 3935 of 1878 describes the
use in combination with other apparatus of gasometer shaped vessels working in an
annular space filled with oil or mercury but describes no apparatus capable of
drawing off and compressing vapours of such extreme tenuity as those arising from

page_text: cold water when the pressure of the atmosphere is removed and to these purposes
which are the same as those of the before mentioned patent N° 3017 of 1877 we
confine this portion of our invention.
In the pumps for pumping the water vapours above mentioned one especial
property of the water vapour has to be considered namely its great compressibility
under very small differences of pressure; so compressible are they that in the case
of making ice a difference of pressure of only one half a pound on the square inch
will reduce the volume of the vapour to one fifth its original bulk; this com-
pressibility of the vapour necessitates that there shall be as little clearance as
possible at the ends of the stroke of the pump and this requires special provisions
to adapt this form of pump for the pumping of those vapours-on account of the
mobility of the non-volatile liquid.
These special provisions in pumps in which the upper part of the outer vessel is
in connection with the vessel from which the vapours are exhausted and in which
the bell fills itself from this outer vessel may be as follows;-
The diaphragm or top of the bell may be joined to the cylindrical portion of the
bell some distance below the top of the cylinder so that the non-volatile liquid may
rise a sufficient height above the place where the diaphragm joins the cylinder to
produce the compression of the vapour without the non-volatile liquid flowing over
the top of the cylinder. In this case we prefer to have a middle fixed chamber
standing centrally at the bottom of the outer vessel and to make the bell fit down
close on the top of this chamber which can be made in the form of a truncated
cone.
Or, otherwise, if the diaphragm or top of the bell is on the top of the cylinder the
whole of the bell must fit as closely as possible over a middle chamber at the end of
the stroke and the middle chamber and bell must be sufficiently deep to produce the
necessary differences of level of the non-volatile liquid without the latter overflowing
the top of the bell, say a depth of not less than thirty inches of oil for making ice
where a very ample supply of cold condensing water is procurable, but a greater depth
would be generally advisable, as the former depth would only allow of the con-
densing water flowing away at about one hundred degrees Fahrenheit.
case the cylinder of the bell and sides of the middle chamber may be either parallel
or a little taper.
In this
In both the above arrangements we prefer to make a reservoir in the middle
chamber connected with the exit valve to catch any of the non-volatile liquids that
may be driven through the valve and we provide a pipe and cock for the return of
the liquid back to the outer vessel.
In pumps in which the bell delivers the more or less compressed vapour into the
upper part of the central vessel the inlet valve may be on the top of a large pipe or
chamber connected with the vessel from which the vapour is to be pumped, the pipe
or chamber standing as before in the centre of the outer vessel and being as well as
the cylinder of the bell not less than thirty inches longer than the stroke of the
pump in perpendicular height and the bell should fit closely over the upper
portion of the pipe or chamber and inlet valve at the end of the down stroke and
the cylinder of the bell should not leave much free play between it and the inside
of the outer cylinder so that the non-volatile liquid shall not rise much inside the
bell at the commencement of the upstroke.
We prefer to make a reservoir on the chamber communicating with the inlet
valve to catch any oil that may leak through the inlet valve, and we provide a
cock to draw off the oil from time to time when there is no vacuum in the reservoir
or return to the outer vessel as shewn in figure 3.
In pumps in which both inlet and outlet valves are inside the bell the inlet valve
may be on the top of a central chamber and the outlet valve on the top of a pipe
passing through the central chamber, and the upper part of the outer vessel may be
connected either with the inlet or outlet sides of the pump.
In the above description we have specified various types of pump but it will be
évident to engineers that they are susceptible of-variation; for instance we have

page_text: specified cylindrical vessels whereas rectangular vessels may be used, especially
where two bells are worked in a single outside vessel, in which case the bells may
be actuated from the ends of a beam either inside the outer vessel or working by
means of piston rods passing through stuffing boxes in the cover or they may be
actuated by cranks at opposite angles on a shaft.
Also the top or diaphragın of the bell and top of the inside chamber or pipe may
be varied in shape, though we prefer to use that of a truncated cone.
Also we have only mentioned the raising the top of the cylinder of the bell above
the junction therewith of the top or diaphragm in the cases where the bell is
supplied with vapour from the upper part of the outer vessel, but this raising will
be beneficial in all the forms though only necessary in the one named.
In specification N° 3017 of 1877 before referred to it is specified that all parts
of the pumps employed for pumping water vapours shall be heated. Since the date
of the present application we have found that the liquids employed in these pumps
must be further heated such further heating of the liquids forming the subject.
matter of an application by us for provisional protection No 12189 of 1885.
Having thus described the special provisions. required for success in applying
these pumps for the purpose of pumping water vapours of very low tension we will
now proceed to more fully describe our invention by the aid of the accompanying
drawings.
Figure 1, is a sectional elevation of a pump with the cylinder of the bell rising
above the diaphragm the section being taken in a line with the driving shaft.
Figure 2 is a sectional elevation at right angles to figure 1.
:
A, is a light metal cylinder which is here supposed to be made of galvanized
sheet iron moving freely inside a larger vertical fixed cylinder B; this outside.
fixed cylinder B may be made of galvanized plate iron with a cast iron curb b, on
top; the whole may be rivetted together but should be tolerably smooth inside;
the cast iron curb 6, has a flange on top turned with a face, say one and a half
inches wide between a bead on the outside and a straight projection on the inside
with an india rubber ring laid in the groove so formed between the bead and
projection C, is a raised cover resting with its rounded edge on the india rubber
ring and a little oil may be put in the groove if there is any suspicion of a leak but
if the edge and flange are true this will be scarcely necessary still it is a great
advantage to be able to cover all the joints with oil. The driving shaft is shewn
passing through a stuffing box in the side of the cast iron curb; this stuffing box is
made very long and is divided by a recess for oil with a perforated metal thimble
separating this packing to admit the oil to the shaft. The shaft is in two parts
connected by a one toothed clutch; the one half of this clutch fixed to the outer
portion of the shaft does not project over the inside of the fixed cylinder and the
crank portion of the shaft is carried by two cross bearers bolted to the curb 80
that when the bolts are removed and the single tooth of the clutch is perpendicular
all the moving parts inside the cylinder can be drawn out.
The pipe connecting the pump with the vessel from which the elastic fluids are
to be exhausted may open through any part of the cast iron curb where most
convenient.
The lower end of the outside cylinder is closed by a vessel D shaped as a cone on
top of a short cylinder standing vertically and centrally inside it and attached to it
by a flange so as to form an annular space between the outside of the vessel D, and
the inside of the outside cylinder large enough for the inside working cylinder to
pass freely down into it.
The top of the cone is truncated and the exit valve seat is fixed in the opening
and the valve E, is supported in place by a conical spiral spring carried by
standards which also act as guides for the valve.
The inside cylinder A is divided into two parts by a conical diaphragm F, being
connected with it by the strengthening ring f, on which are fixed the pins for the
forked connection rod.

page_text: The inlet valve seat g, is fixed in the truncated top of the diaphragm and the
valve G is guided by four pins passing through guide holes on lugs on the valve
seat ring and supported by spiral springs on the pins.
The conical diaphragm, valve and valve seat aro shaped to fit closely over the
upper part of the fixed conical vessel so as to leave as little space as possible
between them at the end of the stroke and are so fixed to the inside cylinder that
the lower edge of the latter may clear the flange forming the bottom of the fixed
cylinder when the diaphragm is down on the cone and the inside cylinder,
diaphragm, etc. form the piston.
The annular space at the bottom of the fixed cylinder is filled for a little more
tlian the length of the stroke of the piston with the non-volatile mobile liquid.
In working the pump some of the liquid is liable to be driven through the exit
valve so we form a reservoir H in the top of the conical vessel to catch it and a pipe
with a cock h, to return it when required into the outer vessel.
The rarefied elastic fluids after they have been more or less compressed by the
action of the piston are forced through the exit valve into the reservoir H.
In the reservoir H is the exit pipe I which reaches some distance up in the
reservoir in order to prevent the liquid overflowing into it and it is either placed as
in the drawings directly under the exit valve or it is bent over or capped on top to
prevent the liquid spurting into it.
The pipe I conducts the clastic fluids from the reservoir H, to the condenser J,
which for this size of pump and for the manufacture of ice should have at least a
square yard of condensing surface and from thence the condensed and non-condensed
elastic fluids are drawn by the ordinary double action air pump K, to be expelled
into the atmosphere.
In all pumps for pumping highly rarefied elastic vapours it is very advisable to
actuate the inlet valves. The method shewn in the drawings figures and 2 is
very simple and convenient and is applicable to all pumps on the single-action
self-contained principle with the valves in the piston etc. closed by springs or
gravity.
In this method an arm L, is fulcrumed to a bracket on the bell and presses on the
valve G, by an adjustable pin 1, the springs supporting the valves being made
strong enough to carry the arm L, as well as the valve. This arm is so adjusted
that when the valve is closed it will just touch the fork of the connection rod at the
dead points and is so sloped or shaped that the connection rod may slide over and
depress it and open the valve on the up stroke while on the down stroke the arm
slopes away so as to allow the connection rod to go free and allow the valve to
close.
In pumps with piston rods and valve rods an arrangement similar to that shewn
as applied to an ordinary cylinder and illustrated in figure 6 will do, the valve
being opened by the friction of the valve rod through the stuffing box or by a tail
on the connection rod pressing on the arm L.
The bell or piston in the above method is shewn as driven on what is called the
self contained plan but it is evident it may be worked by a piston rod passing
through a stuffing box covered with oil in the cover of the outer vessel and by a
connecting rod or otherwise with a crank and shaft or with a beam outside the
cylinder.
In the case in which while the bell draws the vapour out of the upper part of
the outer vessel the cylinder of the bell does not rise above the top or diaphragm
of the bell little alteration is required from the above drawings and description
except the making the cylinder and top of the bell of the same size and shape as
that of the middle chamber but in this case to get a good result the chamber
should be turned true throughout and the bell should be bored and turned to fit,
in which case the galvanized sheet iron before specified would have to be replaced
by cast iron, brass, or copper and as before mentioned the middle chambers and bell
should have straight sides throughout either parallel or a little tapering inwards.

page_text: In figure 3 we have shewn a sectional elevation of a pump in which the bell
draws the vapour from the vessel to be exhausted through a pipe or chamber
passing up through the non-volatile liquid and delivers the vapour after more or
less compressing it, into the upper portion of the outer vessel. This machine is
shewn actuated by a piston rod passing through a stuffing box in the cover of the
outer vessel and a beam, the parts in this figure being referred to by the same
letters as those used in figures 1 and 2.
In this machine the inlet valve is shewn as actuated by an eccentric on the
driving shaft which pulls over the arm M, of the bent lever L, M, on the upstroke
by means of the hook n, at the end of the connection rod N, but which slips out
of clutch on the down stroke, the inlet valve G, being lifted by the rod 1, passing
through a stuffing box up the inlet pipe which conducts the vapour to the reser-
voir H, h, being the pipe for drawing off the oil from the reservoir H.
In the carrying out of the provisions necessary for success in pumps in which
the hell both fills and empties itself through passages passing through the non-
volatile liquid in the lower part of the outer vessel, the same directions apply as to
the before mentioned pumps as far as the bell is concerned except that there is no
inlet or outlet valve in the diaphragm or top.
If the machine is similar to that shewn in Figures 1 and 2 the upper portion of
the outer vessel must be connected by a pipe or passage with the inlet side of the
pump which pipe or passage should have a diameter of about one sixth that of
the bell and the same with machines similar to that next described, but if similar.
to that shewn in figure 3 the upper portion of the outer cylinder will be connected
in the same way with the exit side of the pump.
In each case the inlet and exit valves must be placed side by side in a chamber,
the top of which fits the top of the bell, one of the pipes passing through the
chamber which communicates with the other.
The inlet valves may be actuated as shewn in figure 3.
Our new description of valve applicable to all kinds of pumps intended for
drawing off and more or less compressing highly rarefied elastic fluids bas the joint
between the valve and the valve seat made with a narrow shallow bead closing on
a more or less yielding substance the bead being either formed on the valve and
the more or less yielding substance fixed to the valve seat or vice versâ ; in the
case of the valve the bead is placed on the face preferably close to its outer edge
and in the case of the valve seat on the face preferably close to its inner edge.
We adapt the width of the bead more or less to the area of the valve say one
eighth of an inch wide or less for small valves and one quarter of an inch or more
for large ones.
We adapt the rise of the bead more or less to the thickness and quality of the
more or less yielding substance. As a general rule the rise of the bead should not
be more than one fifth to one eighth the thickness of the substance and with the
more yielding ones it should be so proportioned that it may bury itself in
the substance without injuring it so that the flat face of the valve or valve seat
may sustain any extra pressure by coming in contact with the substance.
We use for this more or less yielding substance any one that will best withstand
the wear under the conditions in which it is placed; leather, india-rubber, felt,
compressed fibre and the end grain of wood we have found to answer well.
The yielding substance may be fixed to the valve or valve seat in any convenient
way for instance if in the form of a sheet it may be fixed to a valve by a disc of
metal a trifle smaller than the passage of the valve seat screwed on to the face
of the valve over the sheet of substance (see figure 4), or to a valve seat in the
same way by means of a ring of metal screwed on over the ring of substance;
or the substance may be laid in a dovetail groove as may be done with a ring of
square india rubber or with wood.
The inlet valve G, and the outlet valve E, Figures 1 and 2, in the drawings are
valves of this description with the beads on the valves and a ring of sheet of the
more or less yielding 'substance on the valve seat held in place by the rings g.and e;

page_text: respectively secured by bolts which in the case of e, are countersunk to make
a flush surface.
Our new mode of and apparatus for starting pumps used for drawing off and
more or less compressing highly rarefied elastic fluids consists in providing means
for practically shortening the effective stroke of the piston of the pump by opening
a communication not through the exit valve from the exit end of the pump for
the escape of the elastic fluids either to the other side of the piston or back to the
receiver to be exhausted during a portion of the first part of the stroke of the
piston, the communication being of sufficient capacity to allow the elastic vapour
to pass freely and to be closed towards the end of the stroke in any convenient
manner.
It is well known that it takes much more power to drive a pump while getting
up a vacuum when a little more than one half a perfect vacuum has been obtained
than it does when the vacuum is either more or less and this has always
occasioned a difficulty in starting pumps especially when two or more pumps of
different capacities are worked in a combined series the larger pump delivering into
the less and so on.
In these combined pumps the difficulty of starting them has been more or less
overcome by getting up the vacuum by means of the smaller pumps alone and not
starting the larger pump till almost every trace of air has been pumped out of the
apparatus but this plan necessitates a very perfect pump.
Bye pass valves or regulated communications between the exit pipe and the
large cylinder have also been employed but those are not of much use in diminishing
the power required unless the communication is so free as to stop the action of the
pump altogether.
Our plan of allowing the pump to act for only a portion of the stroke entirely
gets over the difficulty.
We carry out this part of our invention in a variety of ways, for instance in
the case of a single action pump with the inlet valve in the piston we sometimes
keep this valve open for any desired portion of the stroke and in the case of what
are called self contained machines, this may be done by means of a bent lever ful-
crumed on to and carried by the piston. This lever is so bent and placed that while
one arm is pressing on and keeping open the valve the other arm is parallel with
the motion of the piston and is pressed on by an adjustable stop against which it
slides so as to keep the valve open. This latter arm is considerably longer than
the stroke of the piston and is bent away from the stop at the end of the stroke so
that by moving the stop along the line of the arm the stop may engage or release
the arm at the end of any desired position of the stroke or not engage it at all
when the vacuum is obtained.
This action is shewn in figures 1 and 2; M, L, being the bent lever, the arm L
of which acts on the valve by a pin as before described the other arm M, of the
bent lever being acted on by a stop n, at the end of the guided rod N, sliding
through a stuffing box on the lid of the machine.
Precisely the same arrangement will answer for a self contained single action
pump with an ordinary piston if the outlet valve is on the piston and is closed by
a spring.
A similar plan will answer for single action pumps with valves in the pistons
when driven by piston rods and cranks outside the cylinders as shewn in figure 6.
In these the bent levers L, M, are fastened to a bracket on the piston rod head
and the inlet valve is connected with the arm to work it by a valve rod passing
through a stuffing box on the cylinder cover, the other arm of the lever being
acted on by a stop n, adjustable on a standard fixed parallel with the cylinder.
It is also easy to adapt this plan to either single or double action pumps with
the inlet valves in valve boxes at the ends of the cylinder.
In these a similar bent lever L, M, (figure 7) for each valve may be fastened to
a bracket on the cylinder end and press on the valve by means of a pin passing
through a stuffing box on the valve box cover. And the stop n, to slide and press

page_text: on the arm M, of the bent lever parallel with the motion of the piston may be
moved backwards and forwards so as to engage and release the arm by attaching
it to a guided rod moving parallel to and carried by an arm and connecting rod O,
on the piston rod head the throw of the stop being regulated by a right and left
screw on the guided rod P or otherwise as is well understood.
In the above we have described simple apparatus for applying our invention to
all descriptions of pumps having inlet valves closed either by springs or gravity
but it will be obvious that other well known means can be employed for keeping
open the above and other inlet valves. For example the inlet valves may be held
open by cams or eccentrics, see figure 3 where two eccentrics are shewn one to
actuate the valve on the up stroke, the other to be brought into action to keep the
valve open at starting; this latter eccentric is nearly at opposite angles to the
other but with a slight lead to allow the valve to close for a short time at the end
of the stroke.
We do not confine ourselves to the use of the inlet valves as valves or cocks
distinct from the inlet valves placed on the covers or ends of the cylinders may be
employed which valves or cocks may be actuated in the same way as that herein-
before described for the inlet valves or by other well known means such as
eccentrics or cams, or cocks, or valves in ordinary cylinders may open passages
into the side of the cylinder near its exit end or ends. These passages may form
a connection between the two ends of the cylinders or between the exit ends of the
cylinders and the receivers to be exhausted (see figure 9 which shows such a pump
in part section); in double action pumps the valves or cocks at one end of the
cylinders may be connected with the valves or cocks at the other ends (see figure 8
which shews such a pump in part section) and as the valves or cocks open into
the side of the cylinder the passages will be closed to the ends of the cylinders
by the passing of the pistons beyond them, but in these cases it is most important
that there shall be as little clearance as possible between the valves or cocks
and the insides of the cylinders so as to avoid loss; these passages should not have
areas less than that of pipes one sixth the diameters of the cylinders.
This plan is very simple but has the disadvantage as compared with the others
of not being capable of regulation.
In combined pumps the portion of the cylinder beyond the opening may be
about one and one half times the capacity of the supplementary pump into which
it discharges.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is
1. In bell pumps for pumping highly rarefied water vapour (in which the bell is
supplied with vapour from the upper part of the vessel containing it) making the
cylindrical portion of the bell rise above its junction with the diaphragm or top of
the bell substantially as and for the purpose hereinbefore described and represented
in figures 1 and 2 of the accompanying drawings.
2. In bell pumps for pumping highly rarefied water vapour (in which the bell is
supplied with vapour from the upper part of the vessel containing it) making the
whole of the bell fit closely over a middle chamber at the end of its stroke substan-
tially as herein before described.
3. In bell pumps for pumping highly rarefied water vapour (in which the bell is
supplied with vapour by a passage passing through the liquid in the lower part of
the vessel) exhausting the vapour from the bell into the upper part of the vessel
containing it substantially as and for the purpose herein before described and
illustrated in figure 3 of the accompanying drawinga
4. In bell pumps in which the bell is both supplied with and exhausts the
vapour through passages passing through the liquid in the lower part of the vessel,
making a communication between the upper part of the vessel containing the bell

page_text: either with the inlet or outlet sides of the pump substantially as and for the purpose
bereinbefore described.
5. In bell pumps for pumping highly rarefied water vapour the use of reservoirs
for catching any liquid which may be driven through the outlet and inlet valves
and for, drawing off or returning the same to the vessel substantially as herein-
before described and represented in figures 1, 2, and 3 of the accompanying
drawings.
6. The improved apparatus for pumping highly rarefied water vapours berein-
before described and represented in figures 1 and 2 and in figure 3 of the
accompanying drawings.
7. In pumps for pumping highly rarefied elastic fluids, the use of the joint
between the valve and its seat formed by means of a narrow shallow bead closing
on a more or less yielding substance substantially as and for the purpose herein-
before described and illustrating in figures 4 and 5 of the accompanying drawings.
8. The described method of more or less equalizing the power required in getting
up the vacuum of air pumps and other pumps used for pumping highly rarefied
elastic fluids by practically shortening the effective stroke of the pump by opening
a communication during a portion of the first part of the stroke of the pump from
the exit end of the cylinder (but not through the exit valve) for the escape of the
elastic fluids either to the cylinder on the other side of the piston or back to the
receiver to be exhausted. The communication being of sufficient capacity to allow
the elastic vapours to escape freely and to be closed towards the end of the stroke
so as to allow the pump to act substantially as hereinbefore described and repre-
sented in the accompanying drawings.
.
9. The use in pumps for pumping highly rarefied elastic vapours of apparatus
employed for keeping open the valves substantially as hereinbefore described and
represented in figures 1, 2, 3, 6, 7, 8 and 9 of the accompanying drawings.