﻿llotation 
  of 
  Electric 
  Discharge. 
  511 
  

  

  Experiment 
  V. 
  — 
  In 
  the 
  next 
  place 
  a 
  small 
  coil 
  (J 
  inch 
  

   thick) 
  containing 
  36 
  turns 
  of 
  wire, 
  in 
  circuit 
  with 
  a 
  ballistic 
  

   galvanometer 
  and 
  an 
  earth 
  inductor 
  (in 
  series) 
  was 
  placed 
  

   in 
  the 
  same 
  relative 
  position 
  to 
  the 
  soft 
  iron 
  rod, 
  as 
  the 
  ring 
  

   of 
  the 
  discharge-tube 
  (which 
  was 
  removed 
  for 
  the 
  purpose) 
  

   and 
  the 
  throws 
  (d) 
  o£ 
  the 
  galvanometer 
  corresponding 
  to 
  

   different 
  currents 
  were 
  noted. 
  Then, 
  if 
  /jl 
  = 
  strength 
  of 
  pole 
  

   of 
  an 
  elementary 
  magnet 
  of 
  length 
  dx, 
  fjbd.v 
  = 
  ldv, 
  where 
  I 
  is 
  

   the 
  intensity 
  of 
  magnetization 
  ; 
  

  

  or 
  

  

  or 
  

  

  m 
  

  

  = 
  lds 
  

  

  = 
  — 
  x 
  total 
  magnetic 
  induction. 
  

  

  Hence, 
  p 
  - 
  ~~ 
  = 
  T7/> 
  where 
  P 
  is 
  the 
  magnetic 
  induction 
  

  

  Jl 
  a 
  

  

  through 
  the 
  earth 
  inductor, 
  and 
  d' 
  the 
  corresponding 
  throw, 
  

   when 
  the 
  earth 
  inductor 
  is 
  rotated 
  through 
  180°, 
  about 
  a 
  

   horizontal 
  axis. 
  Therefore 
  m 
  evidently 
  varies 
  as 
  d. 
  Now 
  

   when 
  these 
  throws 
  were 
  plotted, 
  as 
  abscissas 
  on 
  a 
  suitable 
  

   scale, 
  currents 
  in 
  amperes 
  being 
  ordinates 
  as 
  in 
  Experi- 
  

   ment 
  IV., 
  it 
  is 
  seen 
  the 
  curve 
  so 
  obtained 
  virtually 
  coincides 
  

   with 
  the 
  curve 
  obtained 
  in 
  Experiment 
  IV. 
  This 
  proves 
  that 
  

   a> 
  <x 
  m. 
  

  

  In 
  particular, 
  when 
  the 
  current 
  in 
  the 
  magnetizing 
  coil 
  is 
  

   2*2 
  amperes, 
  m 
  is 
  given 
  by 
  

  

  -±7n?ix3G 
  17*2 
  . 
  -r, 
  , 
  , 
  n 
  1A 
  , 
  

  

  — 
  - 
  — 
  j- 
  = 
  •=— 
  -, 
  since 
  jt 
  was 
  known 
  to 
  be 
  b'o 
  x 
  10* 
  : 
  

   8*b 
  x 
  10 
  I'D 
  

  

  and 
  we 
  have 
  ultimately 
  

  

  

  where 
  

  

  2 
  m 
  

  

  \Y 
  = 
  2ttx9-1 
  when 
  V 
  = 
  3E, 
  

  

  17*2 
  

   and 
  m 
  = 
  -— 
  - 
  x 
  8*6 
  x 
  10 
  4 
  

  

  7*5 
  

  

  In 
  order 
  to 
  determine 
  jV 
  2 
  ds 
  and 
  frfs, 
  the 
  band 
  discharge 
  

  

  