barometer

(Greek: baros, pressure; metron, measure)

An instrument to measure atmospheric pressure, invented by Evangelista Torricelli, consisting essentially of a hollow vertical glass tube, containing mercury; the upper end is sealed and the lower end is immersed in an open container of mercury. The varying weight of the atmosphere due to weather conditions acts upon the mercury in the container and is indicated by the variation of the height of the mercury in the tube. A special barometer known as the Faura barometer designed to foretell the approach of typhoons was invented by Father Frederic Faura, S.J., founder of the Manila Observatory.

New Catholic Dictionary

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