The deflection was in the same direction when the silver leaf was connected to the negative pole of a static electric machine, but was in the opposite direction when the leaf was connected to the positive pole of the machine. The test was criticised in the scientific press, and, therefore, in order to be certain that the deflections observed were not due to the combined effects of the electro-magnet which produced the magnetic field and the electric field of the charged silver leaf, the experiments were modified. To remove this uncertainty, the electrified rays were caused to enter a grounded Faraday cylinder (see figure at E. F. G. H., p. 47), through a small opening, before passing between the poles of the electro-magnet. The deviations which were recorded on a photographic plate in the box were the same as before. Additional experiments showed that the deflections by the magnetic field took place as well when the rays were electrified, after their passage through another magnetic field, as before. Lafay continued the experiments in great detail and by many control tests, and he took accurate measurements and followed the suggestions of others. It would be well for those who have facilities to repeat these most interesting and important researches, to determine for themselves some satisfaction. It is of interest to note that an American, Paul A. N. Winand, (_Mem. Amer. Inst. Elect. Engs._), in the absence of facilities for experimenting, proposed (_Elect. World_, N.Y., June 6, ’96) to interpose a hollow sphere, which had high potential, in the path of X-rays, and to learn in what manner, if any, the rays are influenced. He argued that it would seem natural that, inasmuch as the rays produce a discharge, there should be a reaction of the charged surface upon the rays. It is evident that if any one repeats these experiments, expert manipulation is required. 139_b_. GOUY’S EXPERIMENTS. THE PENETRATION OF GASES INTO THE GLASS WALLS OF DISCHARGE TUBES. _Comptes Rendus_, March 30, ’96. From trans. by Louis M. Pignolet. From observations with slightly different glass from four tubes, it seemed that the cathode rays cause the gases in the tubes to penetrate the glass where they remain occluded until the glass is nearly softened (after cutting off the current), by heat, whereby they are set at liberty as minute bubbles visible by the microscope, which finally partly combine and become visible to the naked eye. [Illustration: HALOS 1 FT. DIAM., IN CLEAR AIR, AROUND INCANDESCENT ELECTRIC LAMPS OF USUAL SIZE. CROSS AT CENTER OF EACH HALO. § 140, p. 143. Observed by means of a photograph, in 1882, by William J. Hammer. ] [Illustration: MORTIFICATION OF THE ULNA. § 204. From sciagraph by Prof Miller. ] Under the same conditions, tubes which have been used for a long time exhibit numerous wrinkles, indicating a superficial modification of the glass. These may exist with or without the bubbles.