﻿644 
  Mr. 
  J. 
  Patterson 
  on 
  the 
  Change 
  of 
  the 
  Electrical 
  

  

  It' 
  the 
  corpuscles 
  be 
  acted 
  upon 
  by 
  a 
  magnetic 
  force 
  in 
  the 
  

   same 
  direction 
  as 
  the 
  electric 
  force, 
  they 
  describe 
  spirals 
  

   about 
  the 
  lines 
  of 
  magnetic 
  force, 
  and 
  consequently 
  the 
  

   resistance 
  is, 
  in 
  this 
  case, 
  also 
  changed. 
  

  

  It 
  was 
  suggested 
  by 
  Prof. 
  Thomson 
  that 
  I 
  should 
  make 
  a 
  

   series 
  of 
  experiments 
  on 
  some 
  of 
  the 
  non-magnetic 
  metals, 
  to 
  

   see 
  whether 
  they 
  also 
  showed 
  a 
  change 
  of 
  resistance 
  in 
  the 
  

   transverse 
  magnetic 
  field, 
  and, 
  if 
  so, 
  to 
  measure 
  its 
  magnitude, 
  

   and 
  from 
  these 
  measurements 
  to 
  obtain 
  the 
  mean 
  free 
  path, 
  

   mean 
  velocity, 
  and 
  pressure 
  of 
  the 
  corpuscles. 
  

  

  The 
  metals, 
  which 
  were 
  in 
  the 
  form 
  of 
  wires, 
  double 
  silk- 
  

   covered, 
  were 
  wound 
  non-inductively 
  in 
  flat 
  spirals. 
  These 
  

   spirals 
  were 
  about 
  15 
  mm. 
  diameter 
  and 
  1 
  mm. 
  thick 
  ; 
  they 
  

   were 
  wound 
  between 
  two 
  plates, 
  and 
  then 
  immersed 
  for 
  a 
  few 
  

   minutes 
  in 
  hot 
  paraffin-wax. 
  When 
  cold, 
  one 
  of 
  the 
  plates 
  

   was 
  carefully 
  removed 
  and 
  a 
  thin 
  strip 
  of 
  mica 
  put 
  over 
  the 
  

   spiral 
  and 
  fastened 
  with 
  paraffin- 
  wax. 
  The 
  other 
  side 
  was 
  

   then 
  treated 
  in 
  a 
  similar 
  manner. 
  The 
  ends 
  were 
  soldered 
  

   to 
  two 
  stout 
  pieces 
  of 
  copper 
  wire 
  twisted 
  together. 
  Fig. 
  1 
  

   shows 
  the 
  spiral 
  when 
  complete. 
  

  

  Fia-. 
  1. 
  

  

  Two 
  similar 
  spirals 
  were 
  made 
  of 
  the 
  same 
  metal, 
  each 
  

   having, 
  as 
  nearly 
  as 
  possible, 
  the 
  same 
  resistance, 
  so 
  that 
  

   the 
  second 
  would 
  act 
  as 
  a 
  compensating 
  resistance. 
  It 
  was 
  

   hoped 
  that 
  by 
  this 
  arrangement 
  greater 
  constancy 
  would 
  

   be 
  secured 
  than 
  if 
  another 
  resistance 
  was 
  used. 
  Two 
  other 
  

   non-inductive 
  resistances, 
  nearly 
  equal 
  to 
  the 
  others, 
  were 
  

  

  made 
  usually 
  of 
  german-silver. 
  These 
  four 
  resistances 
  

   joined 
  together 
  in 
  the 
  form 
  of 
  a 
  Wheatstone 
  bridge, 
  

   general 
  arrangement 
  is 
  shown 
  in 
  fig. 
  2. 
  

  

  were 
  

   The 
  

  

  