Classical-particle description of photons and phonons

An $\hslash$-free analogy-free synthesis of classical mechanics and geometrical optics (acoustics) is presented which embraces without distinction particles of both zero and finite rest energy. The point-particle Lagrangian and other classical-particle properties of a photon (corpuscle) in gallium phosphide are found explicitly. Further brief applications are given to Newtonian mechanics, relativistic particle dynamics, fluid-immersed-body dynamics, hole-electron recombination in semiconductors, electrostatic and magnetic lenses, standardization of particle-flux units, and the still-controversial question of optical and acoustical radiation pressure and momentum.