  The propagation of photon in a dielectric may be described with the help of
the scalar and vector potentials of the medium. The main novelty of the paper
is that the concept of the vector potential (which is connected with the
velocity of the medium) can be extended to relativistic velocities of the
medium. The position-dependent photon wave function was used to describe the
propagation of the photon. The new concepts of the velocity of photon as
particle and the photon mass in the dielectric medium were proposed.
