On a method of finding the conductivity for heat

Abstract

This paper contains an account of a method for finding the conductivity for heat, especially in bad conductors. The substance is supposed given in the form of a cylinder, or rather of two half-cylinders pressed together and heated by a current passing through a wire along the axis. When the steady state has been reached, the conductivity is given in terms of the difference of temperatures at known distances from the axis, and the heat supplied by the wire. The latter can be found when we know the current passing through it and the difference of potential at its ends. The first part of the paper contains a detailed account of the methods employed for finding the difference of temperature, and a description of the apparatus used. The results of some experiments made with it are also given, and compared with those found by other observers.