US28626A - Babometeb - Google Patents

Description

UNITED STATES PATENT OFFICE.

L. WOODRUFF, OF ANN ARBOR, MICHIGAN.

BAROIVIETER.

Specification of Letters Patent No. 28,626, dated June 5, 1860.

To all 'whom it may concern:

Be it known that I, LUM WOODRUFF, of Ann Arbor, in the county of Washtenaw and State of Michigan, have invented certain new and useful Improvements in Mercurial Barometers; and I do hereby declare that the following is a full, clear, and eX- act description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a central vertical section o f a barometer with my improvements. Fig. 2 isa vertical section of the cisterns on a larger Scale than Fig. l. Fig. 3 is a horizontal section of the same.

Similar letters of reference indicate corresponding parts in the several figures.

To enable others skilled in the art to make and use my invention I will proceed to describe its construction and operation.

A, is the cistern, and B, the reservoir made of cast iron in one piece, the cistern having an opening at the top, and a closed bottom and the reservoir being made open throughout, and closed at topfand bottom by Stoppers a, a, made air tight with cement. C, is the tube cemented into the cistern, and dipping to within a short distance of the bottom thereof.

D, is the valve for closing the lower end of the tube, attached loosely to the upper end of an upright screw E, which screws through a tapped opening in the bottom of the cistern. This valve is faced with a piece of stout india-rubber or other fieXible and elastic substance Z), to prevent its injuring the tube, and to enable it to make a tight joint with the bottom thereof, and at the back of this rubber a cavity c, is formed in the valve to allow the rubber to yield to any expansion of the mercury that may take place when the tube is filled and the valve closed, and thereby to prevent the bursting of the tube. I will here remark, however, that before letting the mercury fill the tube and shutting it in, the instrument should be placed where the temperature is from 80 to 90o F., and in that case there will be little danger of subsequent expansion.

F, is the screw plug for closing the orifice of communication (Z, between the cistern and t-he reservoir, said plug screwing through a tapped hole e, in the back of the reservoir opposite to the orifice ci, which is tapped with a taper tap so that 'the plug may screw into it very tightly. VWhen the plug is screwed up into the lorifice d, it also fits closely into the hole e, but when it is unscrewed from (Z, a flat place or recess f, which is filed or out in one side of it is brought into the Ahole e, forming a passage for the admission of air to the reservoir from which it passes through the orifice d, into the cistern A. The lower edge of the orifice cl, is at the required level of the mercury in the cistern, and all the surplus mercury runs through the said orifice into the reservoir. The cistern A, and the whole of the tube C, except the indicating` portion, are inclosed within a tubular casing Gr, of wood or other material, the inclosed portion of the tube being wound around with paper, cloth, or other soft material g, (Fig. l) to form a packing filling the space between it and the casing, and thereby being protected from breakage.

To bring this barometer from the operative condition, shown in Fig. l, to the portable' condition, illustrated in Fig. 2, 'it is first placed horizontally with the reservoir B, upward and then shaken or jarred to make enough of the mercury from the cistern A, run into the tube C, to fill it, and the spare mercury from the reservoir B, run into the cistern to fill that completely. The screw plug F, is then screwed in tightly and the screw E, afterward screwed in to close the bottom of the tube C, by the valve D, and this being done it may be carried -in any posit-ion, and will bear any amount of jarring or throwing about that it is likely to receive in transportation, Without injury.

To bring it from the portable to the op-I erative condition, it is first placed lupside down, and while in this position the screw E, is unscrewed to open the valve D, and the barometer is jarred and shaken for a time to expel from the tube into the cistern any small quantity of air that may have accidentally entered the tube in packing for transportation. It is then hung up, and the plug F, unscrewed to let the surplus mercury out of the cistern into the reservoir.

I do not claim the reservoir for containing mercury t0 fill up the eistern; ner yet to tbe reservoir and eistern, substantially as, the use of a valve or cock to close the comherein described, and operating as herein set munication between the reservoir and cisforth.

tern. But LUM WOODRUFF. 5 What I claim as my invention, and de- Witnesses:

sire to secure by Letters Patent, is GEORGE C. MAYNARD,

The screw plug constructed and applied FRASER.

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