In the following paper are included: the graphical synthesis which originally led to the belief that the tangential motion of a phonograph playback needle would cause distortion of the output signal; the mathematical analysis of the forces which would tend to cause such motion; and descriptions of equipment, tests, and conclusions reached.These conclusions are, in brief, as follows: In a common type of crystal pick‐up, equipped with the usual steel needle, tangential motion of the stylus tip does occur as postulated, ranging in amplitude up to 0.0012″, the amplitude of the motion being a function of the recorded frequency, the amplitude of recording, the radius of the groove in which the signal is recorded, recording speed, record and needle wear, and needle pressure. In addition to the tangential motion caused by the recorded signal, a vertical resonance occurring in the needle‐pick‐up arm system causes low frequency tangential motions of the needle tip (24 cps) with amplitudes of up to 0.0015″. Attempts to detect the distortion of the output signal caused by tangential motion were unsuccessful principally because of the presence of other distortions which masked the tangential motion distortion, and which could not be removed from the equipment used. However, since the existence of tangential motions and their amplitudes were established, it became possible to compute the cross‐modulation products caused by such motion.