Also -piez-. [irreg. (for *sympiesiometer) f. Gr. συμπίεσις compression (f. συμπιέζειν to compress, f. σύν SYM- + πιέζειν to press) + -OMETER. In Fr. sympiézomètre.]

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  1.  A form of barometer in which the column of liquid in the tube has above it a body of confined air or other gas (instead of a vacuum as in the mercurial barometer), so that the pressure of the atmosphere acts against the weight of the liquid and the elastic pressure of the gas; a thermometer is attached for correction of the readings according to the expansion or contraction of the gas with changes of temperature.

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1817.  Blackw. Mag., I. 418. Mr. Adie has given it the name of sympiesometer (or measure of compression).

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1843.  Mech. Mag., XXXVIII. 117. The sympiesometer, from its delicacy and susceptibility to changes in the atmospheric pressure … seems peculiarly fitted for the purpose of an indicator of danger in the mine.

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1851.  H. Stephens, Bk. Farm (ed. 2), II. 301/2. One mercurial barometer, two sympiesometers with oil in the tube, and two more with a mineral solution in the tube.

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1869.  A. R. Wallace, Malay Archip., I. 49. The height, as measured by a sympiesometer, was about 2,800 feet.

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  2.  An instrument for measuring the pressure or velocity of a current of water or other liquid, by the difference of level of the liquid in two bent tubes with open submerged ends pointing in opposite directions, against and with the current.

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In recent Dicts.

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