Barometer

(bar-om' '-et-er). An instrument for determining the weight and tension of the atmosphere. It consists e entially of a gla tube about 36 inches long, closed at one end, filled with mercury, and inverted in a basin of mercury. The mercury will sink in the tube until it rests at a height of about 30 inches at the sea-level, the height varying as the atmospheric pre ure increases or diminishes. B., Aneroid, a metallic box from which the air has been exhausted, the tension being indicated by the collapsing or bulging of the thin corrugated cover, which is connected with a movable index. B. -maker's Disease, a form of chronic mercurial poisoning among the workmen who make barometers. It is due to the inhalation of the fumes of mercury.