Interpretation of the longitudinal forces detected in a recent experiment of electrodynamics G. Cavalleri, E. Cesaroni, E. Tonni and G. Spavieri Eur. Phys. J. D, 26 2 (2003) 221-226 Published online: 22 July 2003 DOI: 10.1140/epjd/e2003-00220-8