The following paper contains a description of some experiments made with the object of detecting possible effects due to electric and magnetic fields and moving matter on the velocity of propagation of light in glass. The results obtained were negative, but it seems worth while to publish a short account of the experiments. The optical part of the apparatus is a simple form of interferometer which proved very easy and convenient to work with. It consists of a square glass frame made up of glass bars of square cross-section cemented together with canada balsam. Three of the corners are cut off at 45°, as shown in the figure, and the fourth corner contains a half silvered surface FF. Light entering in the direction of the arrow A is divided into two beams by the silver film, which pass round the frame in opposite directions, being totally reflected at the cut-off corners. Half of each beam emerges in the direction of the arrow B, and the two beams at B are in a condition to interfere with each other.
An attempt to detect some electro-optical effects
