SECT. ii. IN VACUUM TUBES. 79 



A glow surrounded the negative pole, and in close 

 approximation to the glow, a well defined black space 

 appeared, while from the positive pole there issued in 

 rapid succession a series of alternate dark and brilliantly 

 luminous curved strata, which formed a column of 

 stratified light, the concavities of the strata being turned 

 to the positive pole. The stratifications do not extend 

 to the black band round the negative wire or ball, 

 which is quite different to the dark intervening space 

 between the stratified discharge and the luminous nega- 

 tive glow. On making and breaking the electric circuit, 

 the stratified discharge emanates from each pole alter- 

 nately, the concavities of the strata turning alternately 

 in different directions ; in fact the whole phenomena are 

 reversed, but not changed. ' The stratified discharge 

 arises from the impulses of a force acting on highly 

 attenuated but resisting media,' a new proof of the 

 wonderful power inherent in highly attenuated gases ; 

 the number of stratifications given out at each discharge, 

 depending upon the intensity of the electricity and rarity 

 of the gas. 



.Fig. 1. 



Fig. 1 represents the form which the stratified dis- 

 charge assumes in a vacuum tube one inch diameter 

 and 38 inches in length, 4- and representing platinum 

 wires attached to the terminals of a Ruhmkorff's in- 

 duction coil. 



When the tube, with its stratifications just described, 

 was laid horizontally on the pole of a magnet, the 



