Subtleties of the Thomas precession

The rarely mentioned fact that a pure boost in general distorts the axes of the boosted frame is shown to influence significantly the Thomas precession effect as observed in the laboratory frame. As a result the Thomas precession appears to be accompanied by a 'wobbling' motion of the axes of precessing rest frame connected with a moving particle. A simple method to get an exact solution for the development of the orientation of the frame axes in the case of uniform rotation of the particle is given. This is equivalent to finding the orientation of the spin vector used in the BMT theory. The discrepancy known from the literature in describing the spin, as performing a uniform rotation or as revealing in the same situation some additional oscillatory behaviour, is explained by pointing out two conceptually different approaches, 'hybrid' and fully consistent, in presenting the Thomas precession. (paper)