air engine, caloric engine

Any engine which has for its moving power heated air, that is, which employs air, like steam in a steam-engine, as a medium for transforming heat into mechanical energy. The best krown air-engines have been those of the Rev. Dr. Stirling in 1816, Capt. Eric on in 1833, and Mr. Philander Shaw in 1867. yet they have been very partially succe ful. Were they so they would have this advantage among others over steam-engines, that air can with safety be raised to a higher temperature than steam, and therefore can generate a higher amount of mechanical energy. As air-escape, s . A contrivance for permitting the escape of the air which tends to accumulate till it obstructs the progre of the water in pipes led over a rising ground. It consists of a hollow ve el, having in its top a ball-cock, so adjusted that when air collects in the pipes it ascends into the ve el, and, displacing the water, causes the ball to descend till it opens the cock and allows the air to escape.