dasymeter

from The Century Dictionary.

• noun An instrument designed for testing the density of gases. See manometer.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physics) An instrument for testing the density of gases, consisting of a thin glass globe, which is weighed in the gas or gases, and then in an atmosphere of known density.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An instrument for testing the density of gases, consisting of a thin glass globe, which is weighed in the gas or gases, and then in an atmosphere of known density.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun densimeter consisting of a thin glass globe that is weighed in a gas to determine its density