The amplified action potential of the heart actuates an electrostatic integrator connected to a resistive-capacitive network and thermionic tubes which operate a pointer-type meter. The surges due to individual heart beats are suppressed. leaving a steady deflection which is linearly proportional to the average heart rate over a period of several sec. A second instrument, briefly described, is the electrical analogue of the "Zeitschreiber" of Fleisch.