Abstract: The static coefficient of friction between contacting surfaces of a plurality of bodies is determined by applying a load to the bodies in a direction normal to the contacting surfaces. Opposite ends of a flexible filament are fixedly connected to a load cell and a first of the bodies. A motor continuously moves a second of the bodies away from the load cell at constant velocity to pull the first body at right angles to the force of the normal load so that the first body moves intermittently relative to the second body across a contact surface between them. The load on the surfaces, the nature of the surfaces, and the speed of the first body relative to the load cell are such that the filament is alternately and cyclically tensioned and relaxed as the movement occurs. The maximum tension occurs at the incipient stages of movement of the first body relative to the second body.