Indian Institute of Science, Bangalore.
A brief history of air-testing with particular reference to hydraulic structures and machines is traced. The advantages that result by employing air as a working medium in the place of water are given and the increasing predominance and importance of air-testing, as also its limitations are set out. The analogy between the supercritical flow of water and the supersonic flow of gases is mentioned and a collected bibliography is added at the end.
