  We give an explicit method for calculating the equations of state of a
thermodynamical substance from the following information: in the calibrated
case, the system of isotherms and a single adiabat, in the uncalibrated one,
the same but with two adiabats. For simple examples the entropy function can be
computed explicitly from this material but it involves steps (solution of
non-linear equations and an integration) which will usually require numerical
methods for their implementation.
