Page:Collected Physical Papers.djvu/146

126 of wood, of ebonite and of pitch were interposed without checking the action. I then used polarised electric radiation, and interposed a book analyser, 6 cm. in thickness; when the analyser was held parallel, there was a vigorous action, but when it was held in a crossed position all action was stopped. No visible or heat radiation could have been transmitted through such a structure, and there can be no doubt that the action was entirely due to electric radiation. (Proc. Roy. Soc., Apr. 1899.)