It has been shown by numerous experiments (see Proc. Roy. Soc. Edin., 1911) that the equation yn(x + a) = b holds very accurately for wires of different materials, where y = range of oscillation, x = number of oscillations, n, a, and b, constants depending on the metal under the given conditions. In the following experiments a magnesium wire was subjected to various conditions, e.g. extensional strain, torsion, change of temperature, etc., and in each case the above law was tested. The method of procedure was as follows :— A magnesium wire of known dimensions and under ordinary physical conditions was fixed at its upper end to a clamp, and to its lower end was attached centrally a long horizontal heavy cylinder. To the cylinder a circular scale divided into millimetres was attached concentrically with the wire. When the upper end of the wire was turned round the cylinder was made to rotate round the wire as an axis, and the reading on the scale, when the maximum angular deflection was reached, was taken by means of a telescope. Similarly, consecutive maxima were read until the oscillations became small, when the zero was taken, and thus successive values of y were found.