barom'eter

[G. baros, weight, + metron, measure.] An instrument for measuring the pre ure of the atmosphere, either the variations of pre ure in one locality determined by cyclonic and anticyclonic disturbances, or the diminution of pre ure at elevations, thereby determining the height above sea-level. The older form is a. column of mercury in a tube sealed at its upper end, the pre ure of the air being measured by the height of the column of mercury, an'eroid b., see aneroid, plague b., animals, such as guinea-pigs, are kept in a house during the prevalence of plague in the city; if one dies it is immediately examined, and if found to be plague infected, the nece ary antiplague measures are at once instituted, self-reg'istering b., barograph.