The calculation of the development of the temperature in and around a heated contact is reduced to the use of some simple formulas for certain fundamental variables and to making readings from a diagram. Applications are made to a contact that is heated by the current and to circular or oval heat sources (for example, friction-heated sliding contact-surfaces) stationary or moving on the face of a semi-infinite body. The practicability of the method is due primarily to the fact that the numerical calculations, which are made before using the standard curves, are so simple that the chance of a numerical error is very small.