BAROMETER

n. Ba?r-o2m‘e*t-u5r. Lat., barometrum (from Bépos, weight, and wérpov, a measure). Fr,, baromètre. Ger., Barometer, Wetterglas. It., barometro. Sp., barémetro. A term (first used By Boyle, in 1664 or 1665) applied to’any instrument for ascertaining the pre ure of the atmosphere, 7. e., the weight with which it pre es upon the earth's surface at any given point. There are two chief sorts of b’s. [B.] See Aneroid b. and Cistern b.—Air b. See Sympresomerur.—Aneroid b. Fr., baromètre anéroide. Ger., ‘Aneroid barometer. A form of b. devised by Bigi in 1847; a small round metallic box, nearly exhausted of air, with a thin corrugated lid which the weight of the atmosphere tends to pre in more or le . A system of levers causes an index, sweeping over a dial. to mark the slightest movements of the thin lid. [B, 2.|—B’natur (Ger.). A morbid susceptibility to atmospheric impre ions. [R. ‘Arndt (A, 319).|—Boiling-point b. Syn.: thermo-b., hypsometer [Regnault]. An instrument for estimating the atmospheric pre ure from the temperature at which water boils when subjected this pre ure. - It consists e entially of a delicate thermometer immersed in the steam rising from boiling water. The result is reached by reference to a table of vapor-pre ures, [A, 376; B.J— Bourdon’s metallic b. A variety of the aneroid b. consisting of a vacuous metallic box in the form of a flat tube bent almost into a circle. Its two ends approach or recede from each other as the atmospheric pre ure increases or diminishes. [B, 2.]—Cistern b. [B, 270.) See illustra- O. no; 02, not: 03, whole: Th, thin; Th, the; U?, like 00 in too; U2, blue: U%, lull; U4, full; US, urn; US, like ü (German), Fr., baromètre à cuvette. Ger., Gefä b*, Kapselb’. The simple form of b., invented by Torr i cell i. It consists of a tube, closed at one end, filled with liquid (usually mercury), and inverted into a ve el containing the same liquid. The liquid in the tube falls, leaving above it a closed vacuous space (the Torr i cell i an vacuum),