Ba*rom"e*ter (&?;), n.
[Gr. baros weight + -meter: cf. F.
baromètre.]
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.
&fist;
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.
Aneroid barometer. See Aneroid barometer, under Aneroid. --
Marine barometer,
a barometer with tube contracted at bottom to prevent rapid oscillations of the mercury, and suspended in gimbals from an arm or support on shipboard. -- Mountain barometer,
a portable mercurial barometer with tripod support, and long scale, for measuring heights. --
Siphon barometer,
a barometer having a tube
bent like a
hook with the longer leg closed at the top. The height of the
mercury in the longer leg shows the pressure of the atmosphere. -- Wheel barometer, a barometer with recurved tube, and a float, from which a cord
passes over a pulley and moves an index.
Hear it pronounced