barometer Meaning, Definition & Usage

Ba*rom"e*ter noun

Etymology

Gr. weight + -meter: cf. F. baromètre.

Definitions

1. An instrument for determining the weight or pressure of the atmosphere, and hence for judging of the probable changes of weather, or for ascertaining the height of any ascent. ✍ The barometer was invented by Torricelli at Florence about 1643. It is made in its simplest form by filling a graduated glass tube about 34 inches long with mercury and inverting it in a cup containing mercury. The column of mercury in the tube descends until balanced by the weight of the atmosphere, and its rise or fall under varying conditions is a measure of the change in the atmospheric pressure. At the sea level its ordinary height is about 30 inches (760 millimeters). See Sympiesometer. Nichol.