I9I1.J OF ELECTRICITY THROUGH FLAMES. 399 



ging effect observable around it. The air-film which carried the dis- 

 charge was in close contact with the film, as is shown by the char- 

 acter of the shadow. The lowest part of the rounded pin-head only 

 was effective in this shielding of the film, as is shown in Fig. i. 



The interior of the disruptive channel is also a drainage or con- 

 duction channel. It is in a highly rarified condition, approaching 

 that of a vacuum tube. The discharge w'hich passes through it is 

 in the nature of a cathode discharge. The air molecules which form 

 the stepping stones for this conduction discharge are urged in the 

 opposite direction from that in which the corpuscular discharge is 



Fig. I. 



passing. This is incidental to the fact that the conductor is in gaseous 

 form. These air molecules have in some cases produced effects at 

 the negative terminal, similar to those shown in Fig. i. They are, 

 however, less marked in character. They are in the nature of 

 " canal rays," as observed in a vacuum tube. A photographic plate 

 showing such effects was reproduced in a former paper.- In a 

 copper wire the transfer from atom to atom likewise occurs. There 

 the atoms cannot yield, they are nearer together, and the phenomena 

 of conduction are much more simple. 



' Trans. Acad, of Sci. of St. Louis, Vol. XIX., No. 4, plate XXII., Fig. A. 



