108. STINE’S EXPERIMENTS. SOURCE OF X-RAYS DETERMINED BY SCIAGRAPHS OF SHORT TUBES. _Elect. World_, N.Y., Apr. 11, ’96, pp. 392, 393.—Prof. Stine, of the _Armour. Inst. of Tech._, by means of the diagram shown in Fig. 1, p. 102, clearly proved that the X-rays have their source at the area struck by the cathode rays located directly opposite the disk marked “cathode.” If the reader will investigate the diagram and the sciagraphs, he will obtain a clearer knowledge of the evidence than by any verbal description, further than to explain how the elements are related to one another. In Fig. 1, therefore, will be noticed covered photographic plates, located as indicated with reference to the extreme left-hand end of the discharge tube, where the cathode rays strike. The surface of Plate 5 is parallel to that of the cathode, and the phosphorescent spot is in line between the two above named elements. The result is shown in Fig. 2, p. 102, the objects sciagraphed being several short sections of tubes with diameters varying from 1/2 to 3 inches. A, in Figs. 3, 4, p. 104 and in Figs. 5, 6, p. 112, identifies the ends lettered A in Fig. 1. The sciagraph in Fig. 3 was obtained on the plate shown at the top in Fig. 1; that in Fig. 4, on Plate 2; that in Fig. 5, on Plate 3; and that in Fig. 6, on Plate 4. Not only were direct shadows visible, but also secondary shadows, indicating, therefore, that, although the source of practically all the rays was at the phosphorescent spot, yet a portion of the rays came slightly from other directions, either by reflection or by actual production of rays, upon other portions of the tube. Look now especially at Fig. 3, p. 104. If the rays came from the anode, then would this appearance necessarily be the same as that in Fig. 2. Similarly, the other sciagraphs may be considered to show that the rays do not come from the anode. In the case of the sciagraphs in Figs. 4, 5 and 6, only a single tube acted as the body for casting a shadow. Prof. Stine stated that the experiments were repeated over and over again, thereby establishing the phenomena as uniform. 109. STINE’S ELECTRICAL APPARATUS EMPLOYED. § § 106, 112, 114, 131, 137.—Prof. Stine gave the following suggestive points: “Among the first points investigated was the influence of the interrupter. The coil was provided, first with the familiar mercury make and break, and then an ordinary vibrator. The mercurial device gave very good results. [Illustration: STINE’S EXPERIMENT. FIG. 3, § 108, p. 104. ] [Illustration: STINE’S EXPERIMENT. FIG. 4, § 108, p. 104. ]