Schwarzschild succeeded in integrating these equations for the particular case of the radially symmetrical field of gravitation produced by a mass-particle. The flatness of space-time at infinity, or, in other words, the degeneration of
to
at infinity, yielded a first condition; and the second condition was obtained by introducing into the solution the numerical value of the mass
exciting the gravitational field. In this way the solution became determinate. Schwarzschild then found that for a polar co-ordinate system the expression of
assumed the following form:
