Prof. Thomson acknowledged that independently of himself, Dr. M. I. Pupin, of Columbia College, had reported in _Science_, Apr. 10, ’96, see also _Electricity_, Apr. 15, ’96, p. 208, upon investigations on the same general subject, namely diffusion, and also referred to experiments of Lenard, § 69, and Roentgen on diffusion. Agrees also with experiments of A. Imbert and H. Bertin-Sans in _Comptes Rendus_, Mar. 2, ’96. He suggested that this property of diffusion acted as an explanation why sciagraphs can never have absolutely clearly cut shadows of the bones or other objects imbedded in a considerable depth of flesh. 103_a_. A. IMBERT AND H. BERTIN-SANS’ DIFFUSION AND REFLECTION IN RELATION TO POLISH. X-RAYS. _Comptes Rendus_, Mar. 2, ’96. Translated by Louis M. Pignolet.—They concluded, under the conditions of their experiments, that if X-rays were capable of reflection it was only in a very small proportion; on the other hand, the rays can be diffused _en assez grande quantité_, the intensity of the diffusion appearing to depend much more upon the nature of the diffusing body than upon its degree of polish. From this they attributed to the rays a very small wave length, such that it would be impossible to get in the degree of polish necessary to obtain their regular deflection. Perrin attempted unsuccessfully to reflect the rays from a polished steel mirror and a plate of “flint,” but with exposures of one hour and seven hours respectively, nothing was obtained. From trans. by L. M. Pignolet, _Comptes Rendus_, Jan., 96. By exposing a metal plate to the rays and suitably inclining it in front of the opening, Lafay also proved reflection, for it was possible to discharge the electrified screen; hence, as he called it, diffused reflection. _Comptes Rendus_, Apr. 27, ’96; from trans. by L. M. Pignolet. 104. FLUOROMETER.—He constructed an instrument for comparing the merits of different discharge tubes, and for indicating the comparative luminosity of different screens subjected to the action of the same discharge tube. The instrument served also to act as an indicator of the diffusing power of different materials. “By placing two exactly similar fluorescent screens at opposite ends of a dark tube, and employing a Bunsen photometer screen, movable as usual between the screens, a comparison of the diffusing power of different materials might be made by subjecting the pieces placed near the ends of the photometer tube outside, to equal radiation from the Crookes’ tube.” From Prof. Thomson’s description.