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of the mercury exhibited intense light, hut the remainder of the sur- 

 face appeared unaffected by the discharge. In order to test whether 

 any signs of interference could be detected, he had a tube prepared 

 with four wires, by which discharges could be observed when taken 

 from separate coils, as shown in fig. 2, where a b and a 1 V are 



platinum wires hermetically sealed, as in the previously described 

 apparatus. Care was taken to manipulate with induction-coils giving 

 discharges of equal intensity ; but in no case did any sign of inter- 

 ference appear. The discharges, whether in the same or in opposite 

 directions, mingled ; the stratifications, having a tendency to rotate 

 round the poles of a magnet and obeying the well-known law of 

 magnetic rotations, could be separated by either pole. 



If, instead of sealed wires, tin-foil coatings, a b (fig. 3), are placed 



on the vacuum tube, and the coatings are attached to the terminals 

 of the induction-apparatus, brilliant stratifications immediately ap- 

 pear in the portion of the vacuum between the coatings, but without 

 any dark discharge. On approaching a powerful magnet, the stra- 

 tifications divide into two equal series, in which the bands or strata 

 are concave in opposite directions. 



If a vacuum tube, with or without wires or coatings, is placed on 

 the induction-coil, or on the prime conductor of an electrical machine, 

 stratifications appear which are divided by the magnet. Having 

 thus ascertained that there are two distinct forms of the stratified 

 electrical discharge, the author, for the sake of clearness of expres- 

 sion, terms them the direct and the induced discharge. The direct 

 discharge is that which is visible in a vacuum when taken from two 

 wires hermetically .sealed therein; this discharge has a tendency to 

 rotate, as a whole, round the poles of a magnet. The induced dis- 

 charge is that which is visible in the same vacuum when taken from 

 two metallic coatings attached to the outside of the tube, or from 

 one coating and one wire ; this discharge is divided by the magnet, 



