the number of watts that can be radiated from the cable in one duct. In order that the temperature of the cable may be constant, the losses in the cable must equal the amount of heat radiated. Was a curve showing the variation of dielectric loss with temperature to start with, we can for any temperature subtract the dielectric losses from the total radiation and secure the copper losses. From the latter figure, the current in the cable can be readily calculated. The results of such calculations for the old and the new cable are shown by curves in Fig.8.