﻿902 
  Dr. 
  F. 
  Horton 
  on 
  Low 
  Potential 
  

  

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  University 
  of 
  Pennsylvania, 
  

   Philadelphia, 
  U.S.A. 
  

  

  LXXVII. 
  jLow 
  Potential 
  Discharges 
  in 
  High 
  Vacua. 
  

   By 
  F. 
  Hobton, 
  D.Sc, 
  M.A* 
  

  

  IN 
  the 
  ' 
  Proceedings 
  ' 
  of 
  the 
  Royal 
  Society 
  (No. 
  A. 
  607, 
  

   1913) 
  Professor 
  Strutt 
  has 
  described 
  an 
  interesting 
  

   investigation 
  into 
  the 
  origin 
  of 
  a 
  peculiar 
  form 
  of 
  low 
  

   potential 
  discharge 
  produced 
  in 
  high 
  vacua 
  by 
  the 
  application 
  

   of 
  a 
  magnetic 
  field. 
  AVith 
  an 
  apparatus 
  in 
  which 
  the 
  

   electrodes 
  were 
  two 
  coaxial 
  cylinders, 
  and 
  the 
  gas 
  pressure 
  

   very 
  low, 
  Professor 
  Strutt 
  found 
  that 
  a 
  difference 
  of 
  

   potential 
  of 
  many 
  thousands 
  of 
  volts 
  can 
  be 
  applied 
  without 
  a 
  

   discharge 
  passing, 
  but 
  that 
  if 
  a 
  magnetic 
  field 
  parallel 
  to 
  the 
  

   axis 
  of 
  the 
  cylinders 
  is 
  created, 
  a 
  luminous 
  discharge 
  occurs 
  

   with 
  a 
  potential 
  difference 
  of 
  300 
  or 
  400 
  volts. 
  

  

  An 
  effect 
  of 
  a 
  similar 
  nature 
  to 
  that 
  observed 
  by 
  Professor 
  

   Strutt 
  is 
  obtained 
  when 
  the 
  negative 
  discharge 
  from 
  a 
  

  

  * 
  Communicated 
  by 
  the 
  Author. 
  

  

  