Search the Dictionary

A kind of pump for exhausting air from a vessel or closed space; also, a pump to condense air of force in into a closed space.

andle at the top for lifting it. It is used for a great variety of purposes; as, with the air pump, and for holding gases, also for keeping the dust from articles exposed to view.

work under water, respiration being sustained by the compressed air at the top, by fresh air pumped in through a tube from above. -- Diving dress. See Submarine armor, under Submarine. -- Diving stone, a kind of jasper.

instrument for measuring the degree of rarefaction of air contained in the receiver of an air pump. [Spelt also elaterometer.]

at the lower end of a pipe; esp., such a valve in a steam-engine condenser opening to the air pump.

dicate pressure, as of steam, or the degree of rarefaction produced in the receiver of an air pump or other vacuum; a manometer. -- Sliding gauge. (Mach.) (a) A templet or pattern for gauging the commonly accepted dimensions or shape of certain parts in general use, as screws, railway-car axles, etc. (b) A gauge used…

al cups forming, when placed together, a cavity from which the air can be withdrawn by an air pump; -- used to illustrate the pressure of the air. So called because invented by Otto von Guericke at Magdeburg.

well (Condensing Engines), a receptacle for the hot water drawn from the condenser by the air pump. This water is returned to the boiler, being drawn from the hot well by the feed pump. -- In hot water (Fig.), in trouble; in difficulties. [Colloq.]

er spring so as to set in motion an index; a pressure gauge. See Pressure, and Illust. of Air pump.

ich the vacuum is produced, and the objects of experiment are put, in experiments with an air pump. Cf. Bell jar, and see Illust. of Air pump.

A form of air pump in which exhaustion is produced by a stream of mercury running down a narrow tube, in the manner of an aspirator; -- named from the inventor.

terior of a closed vessel, which has been exhausted to a high or the highest degree by an air pump or other artificial means; as, water boils at a reduced temperature in a vacuum.