1. AN INTEGRATING CIRCUIT COMPRISING A VOLTAGE SUPPLY, MEANS PROVIDING COMPLEMENTARY RESISTANCE PORTIONS REPRESENTATIVE OF A FUNCTION TO BE INTEGRATED, A CAPACITOR, MEANS RESPONSIVE TO A PREDETERMINED STATE OF CHARGE OF SAID CAPACITOR FOR ALTERNATELY CONNECTING SAID CAPACITOR TO SAID VOLTAGE SUPPLY THROUGH ONE OF SAID RESISTANCE PORTIONS AND THEN THE OTHER FOR SUCCESSIVE TIME INTERVALS, A REVERSIBLE MOTOR, MEANS FOR CAUSING OPERATION OF SAID MOTOR IN ONE DIRECTION WHILE SAID CAPACITOR IS IN CIRCUIT WITH SAID ONE RESISTANCE PORTION AND IN AN OPPOSITE DIRECTION WHILE SAID CAPACITOR IS IN CIRCUIT WITH THE OTHER RESISTANCE PORTION, AND MEANS FOR INDICATING THE NET AMOUNT OF MOVEMENT OF SAID MOTOR AND THUS DENOTE THE TIME INTEGRAL OF SAID FUNCTION FOR THE PERIOD OF ALTERNATE OPERATION OF SAID MOTOR.