﻿654 
  Mr. 
  J. 
  Patterson 
  on 
  the 
  Change 
  of 
  the 
  Electrical 
  

  

  Prof. 
  Thomson 
  * 
  has 
  shown 
  that 
  if 
  

  

  n 
  be 
  the 
  number 
  of 
  corpuscles 
  in 
  unit 
  volume, 
  

   e 
  the 
  charge 
  on 
  a 
  corpuscle 
  and 
  m 
  its 
  mass, 
  

   u 
  Q 
  the 
  velocity 
  acquired 
  under 
  a 
  unit 
  field, 
  

   A, 
  the 
  mean 
  free 
  path 
  of 
  the 
  corpuscle, 
  

   c 
  the 
  initial 
  velocity, 
  which 
  is 
  about 
  7*6 
  x 
  10 
  6 
  at 
  27 
  ° 
  C, 
  

   t 
  the 
  time 
  a 
  corpuscle 
  takes 
  to 
  complete 
  its 
  mean 
  free 
  path, 
  

   q 
  the 
  number 
  of 
  corpuscles 
  produced 
  per 
  sec. 
  in 
  the 
  steady 
  

  

  state, 
  

   H 
  the 
  transverse 
  magnetic 
  field 
  ; 
  

  

  then 
  the 
  conductivity 
  is 
  — 
  = 
  neu 
  Q 
  . 
  Also 
  if 
  do- 
  is 
  the 
  change 
  of 
  

  

  resistance 
  due 
  to 
  the 
  magnetic 
  field, 
  

  

  Using 
  the 
  values 
  for^ 
  the 
  change 
  in 
  the 
  resistance 
  of 
  

   platinum 
  given 
  in 
  Table 
  V. 
  and 
  substituting 
  in 
  above 
  equation, 
  

  

  then 
  ^ 
  

  

  •44xlO- 
  4 
  = 
  -(29200)V 
  2 
  

  

  or 
  « 
  =r?-9xl0- 
  7 
  , 
  

  

  ai 
  I 
  e 
  X 
  

  

  Also 
  u 
  = 
  --v 
  , 
  

  

  I 
  m 
  c 
  

  

  or 
  \ 
  = 
  2u 
  — 
  

  

  e 
  

  

  = 
  2 
  x 
  3-9 
  x 
  10- 
  7 
  x 
  10 
  ~ 
  7 
  x 
  7-6 
  x 
  10 
  6 
  ", 
  

  

  = 
  5*9 
  X 
  10~ 
  7 
  for 
  platinum. 
  

  

  Since 
  

  

  ] 
  

   neu 
  n 
  = 
  - 
  , 
  

   a 
  

  

  1 
  

  

  ne 
  = 
  , 
  

  

  cru 
  

  

  = 
  9iOO^T3-9xlO- 
  7 
  in 
  the 
  Case 
  o£ 
  P 
  latinum 
  » 
  

  

  = 
  280 
  about. 
  

  

  If 
  N 
  is 
  the 
  number 
  of 
  molecules 
  of 
  hydrogen 
  in 
  1 
  c.c. 
  

  

  * 
  J. 
  J. 
  Thomson, 
  Rapports 
  presentes 
  au 
  Congres 
  International 
  de 
  

   Physique, 
  iii. 
  p. 
  138, 
  Paris, 
  1900. 
  

  

  