150 BELL SYSTEM TECHNICAL JOURNAL 



spread over the metal surface (Fig. 12)." Mathematically the simplest 

 case (at least before the space-charjje l)egins to afTect the field) is 

 realized by a slender cylindrical wire stretched along the axis of a 



Fig. 13 — Mjyiiiln .itiDii ■il one (it ilic pliitircs in l-'i^. H. (The lowest bright spot 

 is a rcllotlioii in the cathode surface) 



much wider hollow cylinder, the wall of which may be imagined 

 to recede to infinity in the limiting case. In this case the glow bears 

 the euphonious nxime of corona, and has been intensively studied 

 l)ccause it wastes the power transmitted over high-tension lines. 



"I am indelileil to I'rofessor J. Zcleny (or plates from which these figures were 

 made. 



