44. SOLOMONS’ EXPERIMENT. DARK BANDS BY SMALL DISCHARGES. _Nature_, Lon., Sept. 13, ’94. _Proc. R. So._, June 21, ’94.—Solomons found that in a very dark room, striae (alternate light and darkness) appeared with very _minute_ discharges, and as the current was increased, they vanished, appearing again when the discharge was strong. He could not obtain them until the luminous column extended to the glass forming the large glass tube. § 40. 45. SPOTTISWOODE’S EXPERIMENT. GOVERNING THE MOTION OF STRIAE. EFFECT UPON MOTION BY DIAMETER OF DISCHARGE TUBE. MOTION STOPPED BY MAGNET. _Proc. R. So._, vol. 33, p. 455.—Spottiswoode found that he could obtain motion when he desired. He introduced some constant resistances and also a rheostat of fine adjustment. The least change of resistance caused some effect upon the striae. The general principle that he established was that letting it be assumed that the striae are stationary then; “An increase of resistance produces a forward flow, and a decrease of the resistance a backward flow,” differences of as little as 1 ohm in the primary current caused the effect. Sometimes the velocity of the flow is fast and sometimes slow, being so rapid in certain instances that the unaided eye cannot distinguish them, but they are known to exist by the use of the revolving mirror. § 46. With tubes of small diameter, compared with their length, he noticed the fact that the striae in one portion of the tube moved faster than those in another portion. § 46. Sometimes one group moved while the other one was stationary. Sometimes they moved in opposite directions. This last named phenomenon occurred also in very wide tubes. The points at which the charge took place he called nodes. He discovered external means for stopping this action. He did it by means of a magnet located opposite one end of the tube. § 31. When the magnet was energized, all motion ceased. § 31. [Illustration: FROM SCIAGRAPH OF FOOT DEFORMED BY POINTED SHOES. § 204. By Prof. Miller. ] [Illustration: FROM HAMMER’S MOLECULAR SCIAGRAPH. § 117., p. 114. ]