  The problem of point particle in the 1/r gravitational field was studied in
SR-based Mechanics. Equations of motion under assumption of field dependent
proper mass were obtained in the relativistic Lagrangean framework. The
dependence of proper mass on field strength was derived from the equations of
particle motion. The result was the elimination of 1/r divergence. It was shown
that a photon in a gravitational field may be described in terms of a
refracting massless medium. This makes the gravity phenomenon compatible with
SR. New results concerning gravitational properties of particle and photon are
discussed. The conclusion is made that the approach of field-dependent proper
mass is perspective for further studies on divergence-free gravitational field
development.
  Key words: Relativity, gravity, particle, photon, speed of light, proper mass
variation.
  {\small\it PACS 03.30.+p, 04.20.-g}
