In the following communication an account is given of some experiments made in the Physical Laboratory of the Glasgow University, whose object was the measurement of the change of conductivity produced by strain in a metal conductor.

Two constants are required in order to determine this alteration in the most general case of a homogeneous isotropic conductor, strained in any way, as may be easily inferred from the analogy with elastic strains and stresses, constants expressing the change produced by uniform cubical compression and by simple distortion. The determination of the latter for brass is the object of the present paper.