A torquemeter which operates on the principle of relating the torque to the angular deflection of the torque-transmitting shaft was developed for pot-er measurement In compressor testing. To convert the information into a signal convenient to human senses or control devices, a photoelectric unit war used to detect the displacement. Measurement was made by measuring the displacement required to null the photoelectric device. The torque would then be proportional to the final reading, which was the lateral deflection corresponding to the anghlar deflection. The proportionality constant was fixed for any apparatus set-ap, which was made possible by the linear nature of the to que-deflection relationship. The advantages sought by this torquemeter were simplicity in construction, accuracy, insensitivity to dirt, temperature variation and speed, and applicability for high speed operation. The torquemeter was statically calibrated. The performance of the torquemeter was verified.