Contributions to the theory of specific heat IV—On the calculation of the specific heat of crystals from elastic data

This paper contains a development of a method of calculating θD values from elastic data (at low temperatures) originally given in Part II. 1—The general problem is that one is given the equation of motion of a continuum, and hence the velocity of the elastic waves as a function of the direction of the waves in a crystal and of the elastic constants; for specific heat purposes it is necessary to obtain from this equation the mean value of the velocity, and this is correlated fairly easily with the Debye θD value.