1. The relativistic t ransformation properties of thermodynamical quantities have been discussed even before the advent of the special theory of relativity. In 1904 HASENOEHRL (1) derived a formula for the spectral intensi ty of the radiation emit ted from a moving black body. By 1919 the problem seemed to be solved and clearly understood: a chapter in Pauli 's (2) Relativltdtstheorie is dedicated to this question. The classical opinion can be memorized by stating tha t according to it the ideal gas equation (in which the pressure is considered to be a scalar) is form-invariant , so tha t the temperature has to transform like a volume: it is smaller in the moving frame than in the rest frame of the system. This opinion was challenged in 1963 by OTT (3), who held tha t the temperature should increase in the transition from the' rest system to a moving frame. There followed an extensive discussion which is admirably documented in Moller's (4) article with the significant title: Relat iwst ic Thermodynamics .