Page:Collected Physical Papers.djvu/61

Rh In the next series of observations, the rays were refracted from air into glass. The electric beam was rendered parallel with the help of a glass lens (f = 4 cm.). The beam was incident on the plane face of the semi-cylinder. As the cylinder itself focussed the refracted beam, the objective hitherto used in conjunction with the receiver was dispensed with.

The different values of μ obtained are given below:—

The frequency of vibration was of the order 1010.

The value of the index of the glass for sodium light by the total reflection method was found to be

(Proc. Roy. Soc., Nov. 1897.)