elatrometer
El`a*trom"e*ter, n. Etym: [Gr. -meter.] (Physics) Defn: An instrument for measuring the degree of rarefaction of air contained in the receiver of an air pump. [Spelt also elaterometer.]
El`a*trom"e*ter, n. Etym: [Gr. -meter.] (Physics) Defn: An instrument for measuring the degree of rarefaction of air contained in the receiver of an air pump. [Spelt also elaterometer.]