An instrument used for measuring the change in atmospheric pressure. It uses a long glass tube, open at one end and closed at the other. After first filling the open end with mercury, it is then temporarily sealed and placed into a cistern of mercury.
mercurial barometer—A barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.
Mercurial barometer Same as mercury barometer. Mercury A metallic element of atomic weight 200.61, unique (for metals) in that it remains liquid under all but very extreme temperatures.
The name comes from the use of mercurial barometers which equate the height of a column of mercury with air pressure. One inch of mercury is equivalent to 33.86 millibars or 25.40 millimeters. See barometric pressure.
With centuries of research and improvement, barometers have evolved into a variety of types, such as mercurial barometers, aneroid or elastic barometers, resistance barometers, capacitor barometers, and micro barographs.
An instrument used to measure atmospheric pressure. Two examples are the aneroid barometer and the ~.
See also: What is the meaning of Temperature, Atmosphere, Pressure, Water, Earth?