A typical experiment, consists of a glass tube of volume V, and of cross-section A, which is open on one of its end. A ball (or sometimes a piston) of mass m with the same cross-section, creating an air-tight seal, is allowed to fall under gravity g. The entrapped gas is first compressed by the weight of the piston, which leads to an increase in temperature. In the course of the piston falling, a gas cushion is created, and the piston bounces. Harmonic oscillation occurs, which slowly damps. The result is a rapid sequence of expansion and compression of the gas. The picture shows a revised version of the original Rüchardt setup: the sphere oscillating inside the tube is here replaced by a "breast-pump" which acts as an oscillating glass-piston; in this new setup three sensors allow to measure in real-time the piston oscillations as well as the pressure and temperature oscillations of the air inside the bottle (more details may be found in )