air built

Built in the air or of air; constructed of basele hopes by a wayward fancy; chimerical. "Hence the fool's paradise, the statesman's scheme, The air-built castle, and the golden dream.' Pope: Dunciad. air-cells, air-sacs, s. Animal Physiol. Certain cells existing in ma es in the lungs, where they surround and terminate each lobular pa age. In man they are but th of an inch in diameter; in the other mammals they are also very small. In birds they are not merely distributed over the chest and the abdomen, but they penetrate the quills, and in birds of powerful flight even the bones. They communicate with the lungs, afford a great extension to the surface with which the air inhaled comes in contact, and in consequence increase the heat and muscular energy of the bird, while at the same time diminishing its specific gravity. In insects some branches of the tracheæ dilate into air-receptacles, the number and size of which, like the air-cells in birds, are in direct relation with the powers of flight. (See Owen's Invertebrata , Lect. xvii.) "On the exterior of a lobule [of the lungs) we observe bubbles of air of various sizes in its ti ue; and if the bronchial tubes be injected the lobule is distended, and its exterior presents a number of bulgings known as the air - cells , about which much controversy has existed."-Todd & Bowman: Physiol. Anat . , ii. 388, 389. IMG:content-0313.png:[blocks in formation] Mech. One of the chambers in a suction and force-pump. [PUMP.] (At kins on: Ganot's Physics, 3rd ed., § 185.) In the plural . Veg. Physiol. The same as AIR-CELLS (q.v.). air-condenser, s . Any machine for rendering air more dense by subjecting it to pre ure. The principle is that of a syringe driving air into a close ve el till the required degree of condensation is produced.