1. Psychological research has endeavoured for a long time to reach the best possible reliability and subtility in recording the pressure of hand-writing. 2. Various possibilities of electrical indication are considered. The principle of frequency modulation and the use of a capacity varying with the writing pressure is found to be the best method. 3. Tests show that the writing curves of the new apparatus prove to be more differentiated than the curves of the Kraepelin balance. Matching experiments prove the new curves to be very reliable.