US1819282A - Manometer - Google Patents

Description

Aug. 18, 1931. F. s. DICKINSON MANOME'IER 3 Sheets-Sheet 2 Filed Sept. 15, 1925 ATTORNEYS Patented Aug. 18, 1931 UNIT-ED STATES FAIRLEIGH S. DICKINSON, OF RUTHERFORD, NEW JERSEY MANOMETER Application filed September 15, 1925. Serial No. 56,428.

My invention relates to manometersand more particular to that type thereof commonly known as sphygmomanometers and p which are utilized for ascertaining the blood 5 pressure of an individual and in which a mercury column or an equivalent fluid column is the indicating element. The invention has for its object the provision of a manometer of simple construction and efficient operation capable of being professionally utilized with a minimum of manual effort. The invention contemplates further the provision of an instrument of the indicated class constructed in a manner to'enable it to be readily carried about in the pocket or in a bag by the physician or other user thereof. Othermore specific objects will appear from the description hereinafter and the features of novelty will be pointed out in the claims.

' In the accompanying drawings, which illustrate an example of the invention without defining its limits; Fig. 1 is a side view of the instrument in condition ready to be placed in the pocket or in a suitable bag; Fi 2 is a rear elevation thereof; Fig. 3 is a front elevation of the instrument as it appears in its operative condition; Fig. 4 is a sectional view on the line 44 of Fig.

section of the instrument on an enlarged scale showing the upper end portion of Fig. 1; Fig. 6 is a section on the line 6-6 of Fig. 4; Fig. '7 is a detail section illustrating a trap which forms part of the invention; Fig. 8 is a sectional view on the line 88 of Fig. 7; Fig. 9 is a front elevation showing another form of the invention; Fig. 10 is a sectional view on the line 1010 of Fig. 9; Fig. 11 is a front view of still another form of the invention; Fig. 12 is l a section on the line 12-12 of Fig. 11-

and Fig. 13 is an inverted plan view illustrating an example of the bottom construction of all of the illustrated forms.

In'the-illustrated example, the instrument comprises a fluid reservoir 15 which generally speaking is constructed of metal or equivalent material preferably in the form of a cylinder having its outer end closed and its 3; Fig. 5 is a fragmentary longitudinal.

inner end fitted over and secured upon the collar 16 of a bottom plug 17 as shown in 'Fig. 4. The plug 17 is provided with an aperture for the reception of the reduced neck 18 of a fitting 19 which in turn is provided with an aperture for the accommodation of the reduced neck 20 of a socket member 21. The latter includes a sleeve 22 into which one end of the mercury tube 23 or its equivalent, extends, and in which said tube end is secured in any convenient anner; a suitable scale 2311 may be provided either directly on the mercur tube 23 or in operative relation thereto. T e socket member 21 is further provided with a channel 24 which communicates with a passage 25 formed in the fitting 19, the passage 25 in turn communicating with'a channel 26-located in the bottom plug 17 and communicatin with the interior of the fiuidreservoir 15. T e upper end of the tube 23 may be rovided with a suitable closure 27 arrange to prevent the escape of any of the mercury or fluid which constitutes the column but to permit the ready escape and entrance of tom plug 17, preferably so as to be detach- 1 able therefrom for instance by being threaded in said bottom plug, and communicates with a passage 29 formed in said bottom plug 17 to permit the admission of a pressure creating medium such as air under pressure into the interior of the reservoir 15. In the illustrated example the inlet nozzle 28 is adapted for connection, by means of a suitable tube, with the customary inflation instrumentalities. In the preferred arrangement, the passage 29 of the bottom plug 17 leads to and terminates in an inlet tube 30 which is screwthreaded into said plu with a ow restricting device which freely permits the passage of air under pressure or its equivalent into the reservoir 15 and prevents the mercury therein or its equivalent from passin out through said mlet nozzle 28 when t e instrument is in other than its operative position. In the form shown in the drawings, aforesaid flow restrictin device comprises a circular flange 31 pre erably comprising an integral part of the inlet tube 30 at its free end, and a disc 32 located in close proximity to the flange 31 and forming therewith a reduced exit or flow restricting passage 33 extendmg transversely to the axis of the tube 30. The illustrated example, shows the disc 32 carried by a stem 34 of rectangular or other polygonal or equivalent form in cross-section, which stem 34 is driven into the inlet tube 30 and because of its cross-sectional form, forms a lurality of minute channels 35 as shown in igs. 7 and 8.

When the instrument is in use, the reservoir 15 and the mercury tube 23 occupy upright positions, as shown in Figs. 3 and 4. In order to maintain the parts of the instrument in this position, a supporting means is provided which constitutes a base whereby the instrumentis held in its operative position; for the purpose of enabling the instrument when not 1n use to be dismant'led and easily carried about, in the pocket or in a suitable bag, the base is preerably detachably combined with the instrument and in addition is constructed so as to be foldable into a small compass. In the illustrated example, the supporting means or base consists of members 36 and 37 ivotally connected at 38 so that when un olded to an operative'position, said members extend transversely to each other to provide a cruciform sup orting stand. At its opposite free ends, t e member 37 is preferably provided with lugs 39 adapted to rest upon the supporting surface on which the instrument is standing and to compensate for the thickness of the member 36; in other words, the lugs 39 prevent the supporting means from rocking on the member 36. In addition, one or both of the members 36 and 37 may be provided with a projection 40 which, by en agement with the other member arrests t e unfolding or opening movements of said members with respect to each other and also the folding movements thereof; to facilitate the manipulation of the members 36 and 37 they are'preferably provided with upstanding finger pieces 36a and 37a respectlvely. The base consisting of the members 36 and 37 is detachably connected with the instrument by continuing the pivot 38 in the form of a stem 38a arranged to fit into a co-operating' recess 17 and at its free end is formed formed in the bottom plug 17 as shown in Fig. 1. The stem 38a and the recess of the-bottom plug 17 are preferably tapered slightly in a corresponding manner and the connection between these elements may be accomplished simply by friction; it is preferred however to provide the recess of the bottom plug 17 with an internal spring 17 a located in an interior annular groove 17b and adapted to snap into an external annular groove 38b-of the stem 38a when the latter is in position in said recess. The cooperation of the spring 17a and the groove 38?) prevent. unintentional disconnection of the stem 38a and the plug 17 without interfering with the connection of these parts and the intentional separation thereof. The

stem 38m and the plug 17 may be connected with and disconnected from each other by simply exerting a pushing and pulling force upon the base sufficient to overcome the tension of the spring 17a. With the arrangement described, the instrument is firmly supported in an upright,

position on the cruciform base and when not in use may be dismantled by detaching the base and adjusting the members 36 and 37 to their folded positions as illustrated in Fig. 2. "In its folded condition,

the base may be carried in a receptacle 41 located in fixed position between the mercury tube 23 and the reservoir 15 and extending lengthwise of the latter as shown in Figs. 1 and 4; the receptacle 41 is constructed and dimensioned to receive the folded members 36 and 37 and to frictionally engage the same to an extent sufficient to hold said folded members in place therein and to permit their easy removal when the instrument is to be set up for use. The base is thus always available for use when revide the desired arrangement, the cover 42 may be screwthreaded upon the sleeve 22 of the socket member 21, which sleeve in such case is externally screwthreaded as shown in Fig. 11 to accommodate said cover 42 an annular shoulder21a. being formed on said socket member at the base of the screwthreaded sleeve 22, against which shoulder the protecting cover 42 is arranged to abut. As illustrated in Figs. 9 and 10 the protecting means may consist of a cover 42a similar to the cover 42, and likewise fitted over the mercury tube 23, the cover 42a however being fenestrated as indicated at 43; this fenestrated tube or cover 42a may be permanently fixed upon the instrument in such a manner that the scale 23a will be visible through the fenestration 43 or it may be removably attached in place for instance by being screwthreaded upon the sleeve 22 of the socket member 21 as in the previous form.

In the preferred construction, the mercury tube is protected by means of adevice which in one position completely encloses and covers the mercury tube and which is capable of being adjusted to another position in which the scale 23a, and the mercury column are exposed to view. In the illustrated example as shown in Figs. 1 to 6 inclusive the device referred to comprises an inner covering tube 42?) which is fenestrated as indicated at 43a and is secured in position on the instrument and over the mercury tube 23 for instance by being permanently or otherwise fastened upon the sleeve 22 of the socket member 21. An outer covering tube 44, fenestrated as indicated at 44a, is fitted upon the inner tube 421) so as to be capable of being rotated thereon, to bring its fenester 44a into and out of registry with the fenester 43a of the inner tube 42?) to thereby expose the mercury tube, its scale and mercury column to view or to completely enclose said mercury tube 23 to protect it against injury. In the preferred arrangement, the inner tube 426 is provided with a plurality of annular raised beads 45 projecting outwardly from its surface and constituting bearings on which the outer tube 44 may be freely rotated relatively to the inner tube 42?); the beads 45, in addition to theirother functions, maintain the outer tube 44 out of surface contact with the inner tube 42?; and thereby not only reduce fric- 1 tion to a minimum but also prevent the outer tube 44 from rubbing upon the tube 42?) and marring the outer surface thereof. The outer tube 44 finds a bearing with its one .end upon an annular shoulder 46 formed on the inner tube 42?) in any convenient manner as for instance by enlarging one end thereof, the enlarged end in such case constituting the means whereby the tube 42b is fixed in place upon the instrument; at its other end, the outer tube 44 may be provided with means for facilitating its rotation, said means comprising for instance a knurled collar 48 which preferably is an integral part of said tube. In order to lock the outer tube 44 in its two positions, projections 49 may be provided, at diametrically opposite points, upon the annular shoulder 46 for cooperation with recesses 50 correspondingly located upon the one end of the outer tube 44, the arrangement being such that the projections 49 and recesses 50 will be interengaged when the tube 44 is in a position to close the fenester 43a of the tube 42?) and also when said tube is in a position .to expose the same and the mercury tube 23. The projections 49 and recesses 50 or their equivalents preferably are maintained yieldingly in engagement with each other by suitable means; in the illustrated example the aforesaid means comprises aspring 51 which surrounds the inner tube 426 and bears with one end against an annular shoulder 52 formed interiorly of the outer tube 44 and with its other end engages a collar 53 screwthreaded upon said end of the tube 42b. The arrangement is such that the spring is completely enclosed, in the assembled condition of the parts and exerts a tension whereby the outer tube 44 is pressed toward the annular shoulder 46.

action of the spring 51; the latter permitsthe tube 44 to yield in a lengthwise direction sufficient to permit the recesses 50 to pass out of engagement with the projections 49. It will be understood that the location of the projections 49 and recesses 50 with respect to the annular shoulder 46 and the tube 44 may be'reversed without interfering with the intended operation of these elements and further that said projections and recesses may be replaced by other devices whereby equivalent results a are obtained.

If the instrument is constructed as shown in Figs. 11 and 12, the cover 42.is removed prior to theuse of the instrument in order to render the scale 23a and the mercury column visible to the operator, the same result being obtained if the instrument is made as shown in Figs. 1 to 6 inclusive by rotating the outer tube 44 on the inner tube 42?) until the two fenesters 43a and 44a are in registry with each other; if the'instrument is of the type shown in Figs. 9 and 10 no adjustment of the cover 420; is required as the fenester 43 thereof occupies a fixed position with respect to the scale 23a of the mercury tube 23. In any case, when the use of the instrument in its operative condition is desired, the inlet nozzle 28 is connected with the customary inflation instrumentalities generally consisting of the usual air-reservoir and the conventional air bulb, the aforesaid air-reservoir being contained in the well known bandage and being connected by means of a rubber tube with the inflating bulb in the conventional manner.

In actual practice, the base is removed from the rece tacle 41 and after the mem- A bers 36 and 37 ave been unfolded, to provide the pivot 38 into the recess of the bottom plug 17 After this has been done, the in strument may be set upon a supporting surface in its operative position in which the reservoir 15, mercury tube 23, and its scale 23a occupy upright positions in which the relation of the mercury or other column to the scale is easily perceptible. In this position of the parts, the inlet nozzle 28, in the preferred construction as illustrated in the drawings, is located at the lower end of the reservoir and the mercury tube 23 is in connection therewith also at its lower end; in

other words, the connection between the instrument and the inflation system is located in close proximity to the supporting means or base on which the instrument is mounted. To complete the setting up of the instrument for use, the bandage is applied, for instance, to the arm of a person whose blood pressure is to be tested and the air reservoir is then connected with the inlet nozzle 28 by means of the usual tubing in the well known way; the air-reservoir is then inflated by the action of the customary bulb in the usual manner. As this inflation of the air-reservoir takes place, air will pass through the inlet nozzle 28 and passage 29 into the tube 30 and will flow from the latter through the restricted exit passage 33 between the flange 31 and the disc 32 into the interior of the reservoir 15 and there become effective upon the mercury or other fluid a to force the same up into the mercury tube 23 in the form of a fluid column which in cooperation with the scale 23a provides the desired indication.

Because of. the fact that in the preferred construction the inlet nozzle 28 is located at a low point in the apparatus, that is at a point in proximity to the supporting base on which the instrument is supported, any forces which may be developed at said inlet nozzle during the introduction of the air or other pressure creating medium intoi the reservoir 15 or during the use of the instrument and which would otherwise exert a tendenc to tilt over the latter are neutralized an have no effect to overturn said instrument. This is an important feature of the invention as it permits the manipulation of all parts thereof including the creation of the pressure in the reservoir 15 to be efficiently accomplished with the use of only one hand and thus leaves the other hand free for any purpose for which it may be reuired. By providing a flow restricting device at the free end of the inlet tube 30, or in other words by providing the disc 32 and the flange 31 to form the restricted air exit passage 33 within the reservoir 15, the

danger of having the mercury or other fluid a pass into the tube 30 and out through the inlet nozzle 28 into the other arts of the apparatus is entirely avoided, it being understood that the passage 33 is of such small dimensions as to prevent the exit of the mercury or its equivalent from the reservoir 15 without, however, interfering with the free admission of air or-other pressure creating medium into said reservoir.

The manometer is extremely simple in construction and is easily adjusted to an operative position and to a folded inoperative position and in its operative position maintains the fluid column tube with its associated scale in an upright position, in which the parts are fixed against unintentional tilting, without requiring the assistance of the operator to maintain them in such'position. The manometer is adapted for any use for which such an instrument is generally intended and obviates disadvantages and objections which up to the present time have been inherent in existing apparatus of the indicated class.

In addition to its other advanta es, the manometer is capable of being rea ily dismantled and brought to a condition in which it may be easily carried about in the pocket or in a suitable case or bag in which the elements of the inflation system may also be contained. The instrument is so constructed that handling or transporting thereof may be freely undertaken without danger of spilling the mercury or of injuring the mercury tube or any other part of the instrument. The novel construction thus makes it possible for a physician or other person to carry about with him amanometer in which a-mercury column or its equivalent is the mdlcatln medium and thus renders available .at al times an ex- .tremely desirable type of such instrument ported by said reservoir in an upright position, an indicating fluid in said-reservoir normally acting as ballast therein to assist in retaining the reservoir and tube against tilting from said upright position, and 'an inlet nozzle for admitting a pressure-creating medium into said reservoir to force the fluid therein up into the tube in the form of an indicating column.

2. In a manometer, the combination of a fluid reservoir provided with a gravity-supporting base to hold said reservoir in an upright operative position, a tube connected with said reservoir and supported thereby in an upright operative position and an inlet nozzle for admitting a pressure creating medium into said reservoir to force the fluid therein up into the tube in the form of an indicating column, said inlet being located at the lower end of said reservoir in radical relation thereto and at close proximity to the upper plane of the gravity-supporting base whereby forces developed at said inlet nozzle in the use of the instrument and tending to impart tilting efiects to the gravity-supporting base are neutralized.

3. In a manometer, the combination of a gravity support, a mercury reservoir occupying an upright operative position and having its one end resting on said support, a tube having its lower end connected with the lower end of said reservoir and supported thereby in an upright position, and an inlet nozzle for admitting a pressure creating medium into said reservoir to force the mercury up into the tube in the form of an indicating column, said inlet nozzle being located at the lower end of said reservoir in radical relation thereto and at close proximity to the upper plane of the gravitysuppo rting base whereby forces developed at the inlet in the use of the instrument and tending to impart tilting effects to the gravity-supporting base are neutralized.

4. In a manometer, the combination of a fluid reservoir provided with a gravity-supporting base to hold said reservoir in an upright operative position during use of the instrument but otherwise manipulatable to 4 permit the transportation of the instrument as in the pocket of the user, a tube connected with said reservoir and supported thereby in an upright operative position, an inlet nozzle for admitting a pressure creating medium into said reservoir to force the fluid therein up'into the tube in the form of an indicating column, said inlet nozzle being located at the lower end of said reservoir whereby forces developed at said inlet nozzle in the use of the instrument and tending to tilt the same are neutralized, and means within said reservoir whereby said pressure creating medium is conducted above the fluid therein and whereby said fluid notwithstanding such agitation as it may receive during transportation in the pocket of the user is prevented from passing out of said reservoir through said inlet nozzle when the instrument is in its non-operative position.

5. In a manometer, the combination of a gravity support, a mercury reservoir having the bottom thereof mounted upon said gravity support and standing in an upright operative position on said support, a tube supported by said reservoir in an upright operative position and having its lower end connected with the lower end of said reservoir, an inlet nozzle for admitting a pressure creating medium into said reservoir to force the mercury up into the tube in the form of an indicating column, said inlet nozzle being located at the lower end of said reservoir in radical relation thereto whereby forces developed at the inlet in the use of the instrument and tending to tilt the same are neutralized, an inlet tube within said reservoir connected with said inlet nozzle and extend ing above the mercury in said reservoir and a flow restricting device at the free end of said inlet tube whereby the pressure creating medium is freely admitted to said reservoir and the mercury notwithstanding such agitation as it may receive during transportation in the pocket of the user is prevented from flowing out through said inlet nozzle when the instrument is in its non-operative position.

6. In a manometer, the combination of a support, a mercury reservoir occupying an upright operativeposition on said support, a tube likewise occupying an upright operative position and having its lower end connected with the lower end of said reservoir, an inlet nozzle for admitting a pressure creating medium into said reservoir to force the mercury up into the tube in the form of an indicating column, said inlet nozzle being located at the lower end of said reservoir whereby forces developed at the inlet nozzle in the use of the instrument and tending to tilt the same are neutralized, an inlet tube within said reservoir connected with said inlet nozzle and extending above the mercury in said reservoir, a flange at the free end of said inlet tube and a disk fixed in spaced relation to said flange and forming therewith a .flow restricting passage whereby the pressure creating medium is freely admitted to said reservoir and the mercury is prevented from flowing out through said inlet nozzle when the instrument is in other than its operative position.

7. In a manometer, the combination of a support, a mercury reservoir occupying an upright operative position on said support, a tube likewise occupying an upright operative position and having its lower end connected with the lower end of said reservoir. an inlet nozzle for admitting a pressure creating medium into said reservoir to force the mercury up into the tube in the form of an indicating column, said inlet nozzle being located at the lower end of said reservoir whereby forces developed at the inlet nozzle in the use of the instrument and tending to tilt the same are neutralized, an inlet tube within said reservoir connected with said inlet nozzle and extending above the mercury in said reservoir, a flange at the free end of said inlet tube, a stem of polygonal cross-section fitted into said inlet tube and forming exit passages at its free end,

and a disk carried by said stem and fixed thereby in spaced relation to said flange to form a flow restricting passage through which the pressure creating medium is freely admitted to said reservoir and the mercury is prevented from flowing out through the inlet nozzle when the instrument is innozzle extending radically outward from said reservoir at the bottom thereof, an inlet tube connected with said nozzle and extending lengthwise of the reservoir beyond the fluid level therein and a flow restricting device connected with said inlet tube at the free inner end thereof whereby a pressure creating medium is freely admitted to said reservoir and the fluid therein'i's prevented from flowing out through the inlet nozzle when the reservoir is tilted.

9. In a manometer, the combination of a fluid reservoir, an inlet nozzle extending radically outward from said reservoir at the bottom thereof, an inlet tube connected wlth said nozzle and extending lengthwise of the reservoir beyond the fluid level there in and provided with a protected and restricted air passage located at the upper, free terminal of said inlet tube whereby a pressure creating medium is freely admitted to said reservoir and the fluid therein is prevented from flowing out through said inlet nozzle when the reservoir is tilted.

I 10. In a manometer, the combination of a mercury reservoir, an inlet nozzle for admitting air to said reservoir, an inlet tube.

connected with said nozzle and located within said reservoir, a flange at the free end of said inlet tube, a stem of polygonal crosssection fitted into said tube and forming interior passages at its free end and a disk carried by said stem and fixed thereby in spaced relation to said flange to form a flow restrlctmg passage through which the air is freely admitted into said reservoir and the mercury is prevented from flowing out through said nozzle when the reservoir is tilted.

lL In a collapsible manometer, the combination of demountable supporting means constituting a base, an upright mercury reservoir occupying a standing position on said base, a mercury tube connected with said res ervoir and supported thereby in an upright posltlon and an inlet nozzle detachably cona foldable base, an upright mercury reservoir mounted upon said base in detachable connection therewith whereby said base is capable of easy separation from said reservoir, a mercury tube connected with the lower end of said reservoir and supported thereby in an upright position and an inlet nozzle located at the lower end of said'reservoir for admitting air under pressure thereto.

13. In a manometer, the combination of a foldable base, an upright mercury reservoir mounted upon said base in detachable connection therewith whereby said base is capable of easy separation from said reservoir, a mercury tube connected with the lower end of said reservoir and supported thereby 1n an upright position, an inlet nozzle located at the lower end of said reservoir for admitting air under pressure thereto, and holding means aifording a support lengthwise of and adjacent to said mercury tube and said reservoir for the said base when detached fromthe reservoir and in a folded condition.

14. In a collapsible manometer, the combination of demountable, gravity supporting means constituting a base, an upright mercury reservoir occupying .a standing pos1- projecting tube fitted over said mercury tube individually.

16. In a manometer, the combination of a mercury reservoir, an upright mercury tube connected therewith and supported thereby in an upright position, at protecting cover extending over said mercury tube and comprising two sections provided with opention on said base, a mercury tube connected 'ings, one of said sections being rotatable relatively to the other to completely enclose said mercury tube and to expose a portion thereof to view through said openings, and means for fixing said'rotatable section in either of its positions.

17. In a collapsible manometer, the combination of a demountable, gravity support, a mercury reservoir arranged to stand upon a support, an upright mercury tube connected therewith and supported thereby in an upright position, a fenestrated inner cover extendingover said mercury tube individually in fixed relation thereto and a fenestrated outer cover extending over said inner cover individually and rotatable thereon to shift the fenesters into and out of registry with each other to expose the mercury tube to view and to completely enclose the same.

18. In a manometer, the combination of a mercury reservoir, an upright mercury tube connected therewith, a fenestrated in ner cover fitted over said mercury tube in fixed relation thereto, a fenestrated outer cover tube extending over said inner tube and rotatable thereon to shift the fenesters into and out of registry with each other to expose the mercury tube to view when they are in registration and to completely enclose the same when they are out of registration, said cover tube having locking projections and cooperating recesses for fixing said outer tube in either of its positions and a spring for pressing said outer tube in a direction to maintain said projections and recesses in engagement with each other and for permitting the outer tube to yield in a lengthwise direction to permit disengagement of said projections and recesses.

19. In a manometer, the combination of a mercury reservoir, an upright mercury tube connected therewith, a fenestrated inner cover tube fitted over said mercury tube in fixed relation thereto, a fenestrated outer cover tube extending over said inner tube and rotatable thereon to shift the fenesters into and out of registry with each other to expose the mercury tube to view when they are in registration and to completely enclose the same when they are out of registration, said inner tube having annular beads projecting outwardly from the surface thereof to provide bearings on which the outer tube rotates. i

20. In a manometer, the combination of supporting means constituting a base, a bottom plug mounted upon said base and provided with a channel and a passage, an upright mercury reservoir fitted upon said bottom plug, a fitting secured to said bottom plug and projecting outwardly therefrom, said fitting having a passage in communication with the passage of said bottom plug, a socket member having a reduced neck fitted into said fitting and provided with a channel leading to said passages, said socket member being externally screw-threaded and being provided with, an annular shoulder at the base of said screw-threaded poragainst said annular shoulder, an inlet noz-- zle extending outwardly from'said bottom plug and connected with the channel thereof and an inlet tube projecting upwardly from said bottom plug within said reservoir and connected with said channel 21. In a manometer, the combination of a mercury reservoir, an inlet nozzle at the lower end thereof, an inlet tube connected with said nozzle and extending interiorly of said reservoir above the mercury level therein, said inlet tube being provided with a flange at the free end thereof, supporting means connected with said tube, and a disk carried by said supporting means and fixed in spaced relation to said flange and forming therewith a restricted opening through which air under pressure is freely admitted to said reservoir and the mercury is prevented from flowing out through said inlet tube and nozzle when the reservoir is in other than its operative position.

22. In a manometer the combination of a reservoir for containing the indicating liquid, a tube extending into said reservoir for admitting a gaseous medium thereto, said tube terminating within said reservoir above the normal level of the indicating liquid therein, material presenting a face extending around and crosswise of the hollow tube, and a member covering the opening, of the tube and presenting a mating face in such close proximity to the aforesaid face as to form a narrow slit so restricted that it thwarts entry of the indicating liquid into the tube whileleaving the gaseous medium admissible into the reservoir under such pressure as is afforded by a manually operated bulb.

23. In a manometer the combination of a reservoir for containing the indicating liquid, a tube extending into said reservoir for admitting a gaseous medium thereto, said arranged to constitute means to thwart entry of the indicating liquid into the tube while leaving the gaseous medium admissible into the reservoir under such pressure as is afforded by a manually operated bulb.

24. In a manometer the combination of a reservoir for containing the indicating liquid, a tube extending into said reservoir for admitting a gaseous medium thereto, said tube terminating within said reservoir above the normal level of the indicating liquid therein, material presenting a face extending around and crosswise of the hollow tube, a stem fitted into the open end of said tube and having the exterior thereof 00- operate with the interior of the tube to form a restricted passage,,and a head associated with said stem in such spaced relation to the aforesaid face that it thwarts entry of the indicating liquid into the tube while leaving the gaseous medium admissible into the reservoir under such pressure as is afforded by a manually operated bulb.

25. In a manometer the combination of a reservoir for containing the indicating liquid, a tube extending into said reservoir for admitting a gaseous medium thereto, said tube terminating within said reservoir above the normal level of the indicating liquid therein, a flange positioned at the inner end of said tube, a stem seated within the open end of the tube and having an exterior surface whose outermost par'ts contact with the inner surface of the tube and whose innermost parts do not touch the said inner surface but are in such close proximity thereto as to form a relatively fine assage therewith, and a head associated with said stem in such intimate relation with said flange asto form a slit so restricted that it thwartsentry of the indicating liquid into the tube while leaving the gaseous medium admissible into the reservoir under such pressure as is afforded by a manually operated bulb.

26. In the combination set forth in claim 22 at least one of the two elements constituting respectively the outer surface of the material directlyexposed to 'the interior of the reservoir and the outer surface of the member is provided with an outer bevel, said bevel tapering toward the mouth of the narrow slit which communicates with the in-' terior of said reservoir.

27 In a manometer the combination of a reservoir for containing the indicating liquid, a tube extending into said reservoir for admitting agaseous medium thereto, said tube terminating within said reservoir above the normal level of the indicating liquid therein, amember including a stem seated within the open end of the tube and having a cross section in the form of an irre lar periphery, the outermost points of sai periphery are in frictional contact with the inner walls of the tube and thereby hold the stem firmly in position while the innermost points of said irregular periphery closely approach without touching the inner walls-

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