Torques on a nearly rigid body in a relativistic gravitational field

The effect of post-Newtonian potentials on the rotation of a perfect fluid, nearly rigid body is shown to consist of a precession and a torque. The frequency of the precession can be exactly represented by means of suitable differential operators. The relativistic torques, in the quadrupole approximation, depend on the instantaneous orientation of the principal axes of one body with respect to the position-like the classical torque-and velocity of the other. For a relatively low-mass body, such as a gyroscope, these velocity-dependent torques have no observable consequences.National Research Council Resident Research Associate.