THE theory generally adopted in treatises on Physics and Electricity to explain the fundamental fact of electrical induction in an insulated cylinder A B, acted on by an electrified body c, is as follows:—It is admitted that on the extremity B of the induced cylinder, that Is, the extremity next to the inductor G, is found only the electricity opposite to that of the inductor; while on the rest of the same cylinder is found only electricity similar to that of the inductor. But these two opposite electricities are both supposed to be endowed with tension, consequently they ought to be divided by a neutral line. When it is wished to represent in a graphic manner the electrical distribution indicated, obtained by induction upon the cylinder A B, this is done by means of Fig. 1. In this figure A B represents the induced and insulated cylinder, C the positive inductor, a b the neutral line, a p b the negative induced electricity, which may also be called induced electricity of the first kind, and a q b the positive electricity, or induced electricity of the second kind.