[AIR- 7.]

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  1.  Any chamber or cavity filled with air in an animal or plant, esp. those in a ‘chambered-shell.’

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1847.  Ansted, Anc. World, iii. 43. In the Nautilus … we find a large, powerful, and complicated shell, composed of a number of separate compartments or air-chambers.

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1855.  Owen, Vertebr., I. ii. (L.). These air-chambers between the outer table and the immediate covering of the brain.

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  2.  In a pump or other hydraulic machine, a receptacle containing air, the elasticity of which, when condensed, maintains a constant pressure upon the water; an air-vessel.

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1873.  Atkinson, trans. Ganot’s Physics, § 206. The fire engine is a force pump in which a steady jet is obtained by the aid of an air-chamber.

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