1. 1853. “On Transient Electric Currents”, June This term I first introduced in a communicationto designate what for any electric current through a given conductor isidenticalin meaning with the “simple-mass equivalent” in the motion of Attwood's machine as ordinarily treated. A rule for calculating the electrodynamic capacity is given in that communication; also the rule, with an example, in Nichol's Cyclopædia, article “Magnetism—Dynamical Relations of.”