

THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OP SCIENCE. 



[SIXTH SERIES.] 



JUL Y 1911. 



I. The Mode of Conduction in Gases illustrated by the 

 Behaviour of Electric Vacuum Valves. By Sir Oliver 

 Lodge *. 



ASSISTED by Mr. E. E. Robinson, I have during the 

 past few years made many experiments in connexion 

 with electric vacuum valves, and have arrived at a view or 

 theory concerning their action which may be worth setting 

 down with as much brevity as is consistent with clearness. 

 The main points to bear in mind are three : — 



(1) One is that the current in vacuum-tubes is mostly con- 

 veyed unobtrusively by positively charged carriers or 

 atoms, which travel from anode to cathode as best they 

 can, — readily taking a roundabout path if necessary, 

 i. e. if any serious obstruction exists in a more direct 

 path. 



(2) The second point is quite familiar, and is that from the 

 surface of the cathode a bombardment of: negative cor- 

 puscles or electrons occurs from every place at adequate 

 tension, and issues everywhere perpendicular to the sur- 

 face without regard to destination. 



At high vacua these projectiles travel with prodigious 

 speed for a considerable distance, and they have the 

 effect of blocking the -path by driving back any small 

 bodies such as atoms advancing in an opposite direction. 



* Communicated by the Author. 

 Phil. Mag. S. 6. Vol. 22. No. 127. July 1911. B 



