mercury barometer

noun

1. a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

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What does mercury barometer mean?

A mercury barometer is a barometer with a column of mercury whose height varies according to the atmospheric (barometric) pressure.A barometer is an instrument for measuring atmospheric pressure, which is used in forecasting the weather.Mercury barometers are no longer in wide use, having been replaced by other methods of measuring pressure, such as aneroid barometers, which use a small capsule with flexible walls that expand or contract in response to changes in atmospheric pressure.