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.
FROM SCIAGRAPH OF FOOT DEFORMED BY POINTED SHOES. § 204. By Prof. Miller. ]
FROM HAMMER’S MOLECULAR SCIAGRAPH. § 117., p. 114. ]
46. THOMSON’S EXPERIMENT. VELOCITY OF STRIAE CHECKED AT THE CATHODE. _Nature_, Lon. Jan. 31, ’96, p. 330.—A tube 50 ft. long was exhausted, § 8_a_., as to striking distance. In this particular experiment, he caused a single interruption in the primary of the induction coil, and observed the motion of the striae from the anode to the cathode by means of a rotating mirror. § 43. The luminosity began at the anode and travelled toward the negative with a high velocity, but upon its arrival at the negative pole its velocity was checked. He said that the striae did not disappear at the cathode like a rabbit would in entering a hole, but they lingered around the electrode for some time. As a consequence of this delay, he found as expected, an accumulation of positive electricity, § 4, in the neighborhood of the cathode. It is a general principle, therefore, that when a discharge passes between a gas and metal, there is an accumulation, illustrating that the discharge experiences a difficulty or resistance. § 32 and 33. The experimenter, Prof. J. J. Thomson, acknowledged that Profs. Liveing and Davy had noticed similar effects.
