The periodic motions of a rigid body in the Hess case

The conditions of the existence of periodic motions of the Hess gyroscope about a fixed point are studied. Depending on parameters the frequency vector of quasi-periodic motion of a rigid body under the Hess conditions are investigated. A parametric classification of the fixed hodographs of angular velocity is carried out. The precession of a rigid body about a vertical axis is considered. We propose the kinematic interpretation of precession, according to which the motion of the Hess gyroscope is represented by rolling motion of a cone on a fixed horizontal plane.