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The barometric height must, however, be corrected for temperature, as in the cistern barometer.

Common Upright Barometer; Marine Barometer The common or cistern barometer, which is a modification of the Torricellian tube, consists of a glass tube 33 inches in length and about one-third of an inch in diameter, hermetically sealed at the top, and having the lower end resting in a small vessel containing mercury, or bent upwards and terminating in a glass bulb partly occupied by the mercury and open to the atmosphere.

In the "cistern barometer" the tube is placed with its open end in a basin of mercury, and the atmospheric pressure is measured by the difference of the heights of the mercury in the tube and the cistern.

A siphon barometer takes less mercury than a cistern barometer.

As I have already said, this was a standard cistern barometer, of Troughton's construction.