Weber's electrodynamics based on a velocity-dependent potential with instantaneous action-at-a-distance reproduced the observational agreements of Ampere's force law. Critics such as Helmholtz pointed out that Weber's law implied nonphysical negative mass effects. A modernization of Weber's formulation is suggested that overcomes Helmholtz's objection. The consequences offer possibilities of experimental testing and revival of the action-at-a-distance mode of description. A method of clock synchronization based on proper time, which confirms the feasibility of such a development, is reviewed in an appendix. Another appendix examines the possibility of higher-order modifications of the force law.