its former brightness. These actions do not appear instantaneous.
I have generalized the former experiments by employing, instead of a wire heated by an electric current, a sheet of platinum 0.1 mm. thick, inclined at 45° on the horizontal plane, partially heated to a dark red by a small gas flame placed underneath. A horizontal pencil of "N" rays, concentrated by a lens, was made to impinge on the under face of the sheet, so as to produce a focus at the heated spot; on the upper face the incandescent patch was observed without interposing ground glass. The variations in brightness are exactly analogous to those of the wire. When observing, through ground glass, the intensity of illumination of the bottom face of the sheet, due to the rays and the flame together, quite similar variations are found. Further, the same results are obtained if, instead of making the rays fall on the lower face, or the side on which the flame acts directly, they are directed upon the upper face.
The different effects produced by "N" rays, viz. their action on a spark or flame, and on phosphorescent or incandescent bodies, would
