IMPROVEMENTS IN MERCURIAL AIR PUMPS
Year: 1881

page_text: LETTERS PATENT to Charles Henry Stearn, of Number 51, Osborne Road,
in the Borough and County of Newcastle upon Tyne, Electrician, for an
"
Invention of IMPROVEMENTS IN MERCURIAL AIR PUMPS."
PROVISIONAL SPECIFICATION left by the said Charles Henry Stearn at the
Office of the Commissioners of Patents on the 15th November 1881.
CHARLES HENRY STEARN, of Number 51, Osborne Road, in the Borough and
County of Newcastle upon Tyne, Electrician. "IMPROVEMENTS IN MERCURIAL
AIR PUMPS."
My Invention relates to mercurial air pumps of the type known as Sprengel's,
and has reference to the employment of an automatic feed, by which the mercury
is frequently returned from a lower to a higher level, whereby a large reservoir is
dispensed with, and the quantity of mercury necessary to keep the pump in
continuous action is greatly reduced. The fall tubes of the pump are enclosed in
or connected at their lower ends with a partially exhausted vessel, and are made
of less length than the barometric column, the vessel in which they are enclosed
being exhausted by a mechanical air pump or other exhausting mechanism. The
atmospheric pressure is used to effect the raising of the mercury by allowing it to
act intermittently, either directly on the surface of the mercury, or on a flexible
diaphragm or india rubber vessel containing the mercury. In mercurial pumps
constructed according to my Invention great uniformity and celerity of action are
obtained by reason of the reduction in the length of the exhausting portion of the
pump, and by keeping the mercury in closed and exhausted vessels during the
period of its circulation. An immunity from danger to the operators from mercurial
vapors is also ensured by completely secluding the mercury from contact with the
external atmosphere, and when a number of the pumps are combined together in a
general system the inercurial portion of each pump is rendered completely inde-
pendent of that of the others.
In carrying out my Invention I construct the pump in the following manner,
viz.
The compound fall tube passes through a closely fitting india rubber or other
air tight-stopper, which fits into the outer or enclosing vessel. This tube com-
municates by another tube with an upper mercurial receiver, and also is capable of
[Price 6d.1

page_text: being placed by means of a flexible tube and stop cock in communication with a
mechanical air pump or aspirator or exhausted chamber, so that the vessel before
referred to may be exhausted, after which the stop cock is closed. The lower
mercurial receiver (which is constructed of iron or other material not acted on by
mercury) consists of two hemispheres separated by a flexible diaphragm, by
preference of india rubber. This receiver is mounted so as to be capable of
turning upon a centre, and is supported by a spring, the tension of which is
adjusted so as exactly to counterbalance the weight of the receiver when empty or
nearly so, and keep it in close contact with a valve or stopper, which is carried by
a support and adapted to an orifice in the receiver. The receiver is provided on
one side of its diaphragm with a tube in communication with another air pump or
aspirator, and on the opposite side of the diaphragın it communicates on the one
hand by means of tubes and a valve with the lower end of the enclosing vessel
before referred to, and on the other hand through the intervention of a narrow
tube and a valve with the upper mercurial receiver. The latter receiver com-
municates by an outer tube surrounding the said narrow tube, and by a supply
pipe with the compound fall tube, a trap being provided of ordinary construction.
The apparatus operates in the following manner :—
The lower receiver being full of mercury, so soon as the air pump communi-
cating with the enclosing vessel before referred to and the upper receiver is put in
action, the air is partially exhausted from the said vessel and receiver, and from a
vessel attached to the said enclosing vessel. On opening the stop cock (the valve
or stopper of the lower receiver being also open) the atmospheric pressure on the
india rubber diaphragm forces the mercury into the upper receiver, whence it
passes through the compound fall tube of the apparatus in the usual way, the valve
interposed between the lower receiver and the vessel which encloses the compound
fall tube closing and preventing the mercury from_passing_direct-into-the said
vessel. -So-soon as the lower receiver is empty the spring draws it against the
valve or stopper, and the air pump or aspirator connected with it exhausts the air
from one side of the flexible diaphragm, and the mercury passes from the vessel
enclosing the compound fall tube through the interposed valve into the lower
receiver.
The area of the valve or stopper of the lower receiver is such that the weight
of the receiver when full of mercury is sufficient to overcome the atmospheric
pressure and open the valve.
By this arrangement, if connected with a constantly acting mechanical air pump
or other exhausting apparatus, the mercury is periodically returned to the upper
receiver, and a very small quantity of mercury is sufficient to maintain the
instrument in constant action. All contamination of the mercury and all loss by
waste or danger to the operators is completely avoided, whilst at the same time
the space occupied by the apparatus is extremely small, and there is little risk of
breakage.
The intermittent admission of the air may be effected by the use of an electro-
magnet, the circuit of which is completed by the mercury on reaching a fixed
point, the electro-magnet attracting a valve attached to its armature; or the
closing of the valve may be effected by a counterpoise instead of a spring; or the
air inay be admitted by means of a stop cock, the lever of which may be turned
at the right moment by any of the above mentioned devices.
The automatic feed described above may also be applied to a Giessler or other
mercurial pump in which mercury is carried from a lower to a higher level.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Henry Stearn in the Great Seal Patent Office on the
15th May 1882.
CHARLES HENRY STEARN, of No. 51, Osborne Road, in the Borough and County
of Newcastle upon Tyne, Electrician. "IMPROVEMENTS IN MERCURIAL AIR
PUMPS."
By this
My said Invention relates to improvements in inercurial air pumps, such as those
known as the Sprengel pump, the Geissler pumps, and the like pumps which
require the periodical return of mercury from one level to another and has reference
to the arrangement of an automatic fred by which the mercury employed therein
is periodically returned to the higher level of its original source, whereby a con-
tinuous action of the pump is obtained in a most economical manner.
means the reservoir of large dimensions ordinarily employed is dispensed with and
only a very small vessel substituted therefor, which is intermittently replenished
by an automatic device hereinafter described. Greater uniformity and celerity of
action are also attained owing to the reduction of the length of the exhausting
portion of the pump and the keeping of the mercury in sealed exhausted vessels
during the periods of its circulation. In this manner the mercurial portion of each
pump may be rendered entirely independent of others when combined in a general
system, there being one or more air pumps in connection with each mercurial
pump or system of mercurial pumps, while the complete seclusion of the injurious
mercurial vapors evolved prevents the contamination of the atmosphere in the
neighbourhood of the pump, which is so dangerous to the operators.
The automatic supply or return of the mercury to its elevated reservoir or
receiver, as before mentioned, is effected by utilizing the pressure of a fluid, such
as that of the external atmosphere, by causing or allowing it to intermittently act
upon the fallen mercury, to return it to the said elevated reservoir or receiver, as
hereinafter described.
And in order that my said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 is a vertical section of a mercurial air pump to which my said Invention
is applied; the pump to which it is shewn as being applied being of the Sprengel
type. A is the compound mercurial fall tube, which in consequence of the
combination therewith of my improvements, may be of less height than the
barometric column, the said tube passing through a closely fitting india rubber or
other air tight stopper into the outer tube B, which latter communicates with the
upper receiver C by the tube c, and is in communication at its lower end with
the lower receiver D through the tubes b and d. The upper receiver C communi-
cates by means of a cock c' and flexible or other suitable tube c² with a mechanical
or other air pump aspirator or exhausting apparatus, and as soon as a sufficient or
a partial vacuum is obtained within the apparatus, the stop cock c¹ is closed, so
as to sever the communication of the receiver C with such exhausting device.
Instead of the stop cock c¹ a valve may be employed.
The lower receiver D, which may be constructed either of glass, iron, or other
material not injuriously acted upon by the mercury, is of any convenient shape
and construction; as illustrated it is formed as a spherical chamber of two separate
united hemispheres, supported by a spring e adjustably attached to one arm of the
lever turning on the centre c', supported by a standard or standards, the said
receiver having an india rubber or other flexible diaphragm E extending between

page_text: and subdividing the receiver into two compartiments d', d³. F is a valve or stopper,
of conical or of other convenient form, ground to fit air tightly the seating on the
opening provided at the side of the said receiver in any convenient position,
for instance, in the position shewn in the Drawing. This valve F is maintained
closed so long as the lower receiver D is empty or sufficiently light to permit of its
being held in its raised position by the spring e, but when a certain amount of the
fallen mercury has accumulated in the said receiver, then it descends slightly,
turning upon the rocking joint G, so as to open the valve F and establish
communication with the external atmosphere.
The degree of tensile elasticity of the spring e may be adjusted or varied by
means of the screw nut e', so as to counterbalance any desired variable degree of
weight in the receiver D. It will be understood that according to my arrangement
the valve F and its support c³ are free to turn on the centre c* (which centre may
be carried by the framing of the pump), and derive their motion from the move-
ment of the receiver D, while the seating of the valve formed in the aperture in
the receiver D rises or falls bodily to or from the valve, so as to automatically
open or close the passage into the receiver as required.
The rocking joint G may be of any description that will constitute a centre for
the receiver D to slightly fall and rise upon, without interfering with its permanent
communication with the main portion of the apparatus.
The passage and tube H, controlled by a cock h and arranged at the bottom of
the lower receiver, is for establishing communication with another mechanical air
pump or exhauster of any convenient kind, while the cock I on the tube d is for
cutting off the connection between the main part of the apparatus and the said
lower receiver D, if desired.
The lower receiver D is in communication with the upper receiver or reservoir C
through the curved tube K and_the_narrow vertical-tube J, which passes up the
centre-of-the-outer tube L, on or to the top of which the said receiver C is formed
or attached.
The lower end of this outer tube L communicates with the upper part of the
interior of the compound fall tube A by means of the tube l, through which the
mercury is fed to the pump, an air trap or air traps of the usual construction being
a is the
provided in any convenient position, for example, as indicated at 1.
ordinary exhaust tube connected to the top of the fall tube A, and attached at its
opposite extremity to the chamber globe or the like a', which it is required to
exhaust.
The valve b' at the end of the tube b opens towards the receiver D, so as to
allow the fallen mercury to flow at the proper time into the said receiver, but not
return therefrom. The valve k provided at the top of the curved tube K opens
away from the receiver D, so as to allow the mercury thus collected to ascend the
tube J communicating with the upper receiver C, but prevent the return of the
said mercury.
Assuming that a sufficient quantity of mercury has been introduced into the
lower receiver D, the said receiver is thereby caused to overcome the tension of the
spring e and slightly descends, turning about the joint G, and turning the support c³
about the centre c* so as to open the valve F. The air pump in connection with
the pipe c, which is kept continually acting by an engine, then partially exhausts
the air from the upper receiver or reservoir C, the tubular casing B, the receptacle a¹
to be exhausted, and their intermediate connections.
Upon opening the stop cock I the external atmospheric pressure enters the lower
receiver by the valve F, and by impinging upon the elastic diaphragm E and
causing it to distend in the direction indicated by the dotted line E', forces the
mercury through the pipes & and K up the small tube J into the upper receiver C,
whence it descends by the tubular connection L, and then passes by the tube 1 to
the compound fall tube A, acting therein in the manner in which it ordinarily acts
in mercurial pumps of this kind.
An the mercury is thus automatically caused to ascend to a higher level, so the

page_text: lower receiver D obviously becomes gradually lighter until it is brought up by the
spring e, and the valve F is again closed against the entrance of the atmospheric
air in the manner already described.
When the lower receiver D is thus emptied of mercury and the valve F closed,
the pump or aspirator in connection with the tube H is brought into operation and
the air is exhausted from the one side of the elastic diaphragm, which is thereupon
caused to recede to the position indicated by the dotted line a E2, and the mercury
then flows from the bottom of the tube B, through the tube b, through the valve b¹
and tube back to the lower receiver D. Upon the return of the mercury the
valve F is again opened by the descent of the receiver D owing to its increased
weight, as before described, and thus this recurrent cycle of operations is
continuously and automatically maintained as long as the pump or pumps are
put in connection with the upper and lower receivers C and D at the proper
intervals.
It will be understood that the area of the valve F should be proportionate to
and governed by the weight of the lower moveable receiver D when it contains its
maximum amount of mercury, and the extreme height of the apparatus or elevation
of the upper receiver C should be within the limits of a barometric column, while
the bottom of the tube B should be at a level above that of the lower receiver D.
The intermittent actuation of the valve F for the admission of atmospheric air
upon the flexible diaphragm may be effected by the use of an electro magnet, the
circuit of which is completed upon the mercury reaching a determined level in the
lower receiver D, and thus attracting the valve as its armature; or other equivalent
devices may be substituted for those herein before described, as, for example, a
counterweight may be used in lieu of the spring e; or the lever of a stop cock may
be actuated by such or equivalent means for effecting substantially the same end.
Figure 2 of the accompanying Drawings represents in side elevation, and Figure 3
in front elevation a modification of the herein before described arrangement, wherein
the valve for the admission of the air to the receiver D is upon a pipe opening into
the said receiver, and is operated by a rod separate from the spring e. In this
arrangement here shewn, a bag E3 is substituted for the diaphragm E described
in the first arrangement, but a diaphragm may be used in place of the bag if
preferred. The modification may be employed with each inercurial pump, but it is
especially adapted for use with a system of pumps communicating by pipes or
passages with the air inlet and the air exhaust pump, aspirator, or the like; froin
Figure 2 it will be understood how it may be applied to any convenient number
of such pumps combined in a system. Where the one receiver D is used to actuate
the valves for admitting air to and exhausting air from a number of receivers D of
mercurial pumps combined in a system, the column of the mercury in communica-
tion with the receiver D which actuates the said valves may be an independent
column with an upper receiver C in communication with the air exhaust pipe
common to the upper receivers of all the mercurial pumps or the said column of
mercury may be that of one o the pumps in the system. I will now describe the
mechanism for opening the valves according to this modification.
The receiver D is hinged to the standards M by the joint at m, so as to be
capable of turning thereon without destroying the communication of its bag with
the pipe L, which pipe is in communication with the said flexible bag Es contained
in the said receiver D. The pipe to the air pump is marked p, and from it are
branches as at p², p², leading into each of the receivers D of the system; q is the
valve closing and opening the passage of the said pipe, the said valve being opened
and closed by the lever q¹ turning on the centre at q2, the other end of the said
lever being connected to the rod q³, sliding in the standard R, and furnished with
an adjustable projection q. A tube at fis in communication at one end with the
outer air and at the other with the pipe p² communicating with the interior of the
receiver. A valve F carried by a rod f rests upon a seating in this pipe f, the
said rod sliding in the standard R and carrying adjustable projection f³. A rocker
lever S turns upon a centre pin 8 on the standard R, the said lever 8 carrying at

page_text: each end a tappet 8, 81, the one of which is in the path of the projection q*, and the
other of which is in the path of the projection f³ Connected to the receiver D is
a rod t, with a slotted upper end engaging with a pin r on one arm of the rocker
lever S, which lever carries a counter weight at s³. When air by the action of the
pump is exhausted from the receiver D, the mercury descending into the bag E³ so
weights the receiver D as before described with regard to the first described
arrangement, that the said receiver descends, and through the rod t pulls the rocker
lever S over until the counterweight s² passes the vertical line, when it carries over
the said lever S, and by causing one of the tappets s¹ to come into contact with the
under side of the projection f³ lifts the rod f and raises the valve F from its
seat. when atmospheric air passes into the receiver D, and drives the mercury out
from the bag and up to its original source, as described with regard to the first
arrangement. The tappet s' at the other end of the said rocker lever S at the same
time by coming out of contact with the projection q* allows the lever q' to descend
to close the valve 7 and cut off communication with the air pump. When the
receiver D ascends, the rocker lever S is pushed by the rod t over in the other
direction, and when the counterweight passes the vertical line it brings over the
said rocker lever, so that the tappet s¹ on the one end allows the air valve F to
close, and at the same time the valve of the air pump is opened by the other
tappet coming against the projection q*, when air is again drawn from the
receiver D through the pipe p, as before described.
As before stated this mechanism for opening the air inlet and exhaust valves
may be applied to each individual mercurial pump, or where a number of mercurial
pumps are combined in a system, there may be only one receiver provided with the
said mechanism actuating the valves of main air inlet and exhaust pipes, which are
common to all the mercurial pumps in the system, each pump being provided with
a stationary lower receiver D) for receiving the mercury and returning it to its
original elevation, as herein before described, there being a branch pipe from the
main air inlet and exhaust pipe to each such receiver for causing air to pass into
the receivers to press up the mercury, and for enabling the air to be withdrawn to
allow the mercury to enter the said receptacle or the chamber or bag contained in
the same.
The lower receiver D which actuates the mechanism for opening and
closing the valves may have a separate column of mercury, or it may be actuated
by the column of mercury of one of the pumps of the system. In Figure 2
I have shewn the lower receiver D which actuates the valves, as being
provided with an independent column of mercury in the tube L2, having at
top the upper receiver C' in communication by the branch pipe C with the
main pipe C leading to the air pump or aspirator, similar branch pipes C*
leading from all the upper receivers of the mercurial pumps of the system into the
said pipe C. I have also shewn a lower receptacle D of one of the pumps of the
system, the said lower receptacle communicating by the branch pipe på with the
main air inlet and exhaust pipe F, common to the lower receivers of all the
mercurial pumps of the system, each lower receiver communicating by a similar
branch pipe p with the said main pipe F. I have not shown a complete pump in
Figures 2 and 3, as it is not necessary for the understanding of this description. It
will readily be understood that they will have a position in relation to their
receivers, like that described with reference to Figure 1. It is desirable that
whilst the passage of the mercury from the lower receiver to the upper receiver of
the pumps is slow, its return to the lower receiver is as rapid as possible. In order
to effect this there is placed between the lower receiver and the pump proper n
small tube or annular piece u, with a passage between its outer side and the inside
of the tube d leading to the bag Es of lower receiver. A small hole w² is made
through this annular piece u. The mercury passing from the lower receiver presses
the said piece u forward to bear against a seat at v, and consequently the mercury
can only pass slowly through the small opening therein.
When the mercury
returns however the said annular piece u is moved back, and the mercury can pass
rapidly through the space around the outer side of the said annular piece.

page_text: The tube L is provided with a cock or valve to regulate the rise and fall of
the mercury, to synchronize with the rise and fall of the mercury in the pumps of
the system. A similar cock may be used on the corresponding tubes of the
mercurial pumps of the system.
The flexible diaphragm or bag in the receptacle D may be dispensed with, and
atmospheric air be caused to act directly upon the mercury in the lower receiver D,
in which case the orifice of the tube d opening into the receiver should be so
situate as to be always sealed by the mercury.
Although I have described the pressure upon the diaphragm or mercury in the
receiver as being obtained from the ordinary pressure of atmospheric air, yet it
will be understood that it may be obtained in an analogous manner from other fluid
or fluids.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the saine is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,
First. The combination with mercurial air pumps of an automatic feeding
apparatus, whereby the fallen mercury utilized is repeatedly restored to its
original elevated source, substantially as herein before described and illustrated in
the accompanying Drawings under various modifications.
Second. In mercurial air pumps, the combination of a fall tube or fall tubes of
less length than the barometric column, with the automatic feeding apparatus
claimed by the preceding clause, the said fall tube or fall tubes being placed in
communication with or enclosed in a tube or receptacle partially exhausted of its
air by a mercurial air pump or other equivalent appliance, substantially as and for
the purposes herein before described with reference to the accompanying Drawings.
Third. In mercurial air pumps, the employment of the automatic self regulating
feeding apparatus in which the mercury after use in the pump proper is caused to
be elevated from a low to a higher level upon exhausting the air above it by the
intermittent influence of air or other fluid pressure acting directly on the mercury,
or through the intervention of an elastic diaphragın, bag, or chamber contained in
the lower receiver, the admission thereto being controlled by a valve actuated by
the fluctuating weight of the said receiver itself, or of a separate receiver provided
for the purpose, or by electricity or other equivalent means, whilst the return of
the mercury to the said lower receiver after use in the pump proper is effected
upon exhausting the receiver of such fluid, whether the same be used in immediate
connection with each pump separately, or with a system of pumps, substantially as
and for the purposes bereinbefore described and illustrated in the accompanying
Drawings.
In witness whereof, I, the said Charles Henry Stearn, have to this my
Specification set my hand and seal. this Sixth day of April. Oue thousand
C. H. STEARN. (L.S.)