﻿76 
  Prof. 
  H. 
  A. 
  Rowland 
  on 
  Electrical 
  

  

  Taking 
  two 
  observations 
  we 
  can 
  eliminate 
  Z> 
  2 
  L/M, 
  and 
  we 
  

   have 
  

  

  M 
  

  

  37 
  =R,{f- 
  (*)'}■ 
  

  

  Knowing 
  L/M 
  we 
  can 
  find 
  C 
  Throwing 
  out 
  C 
  (i. 
  e. 
  

   making 
  it 
  oo 
  ) 
  we 
  can 
  find 
  6 
  2 
  L/M 
  in 
  absolute 
  measure 
  : 
  then 
  

   put 
  in 
  C 
  and 
  find 
  its 
  value 
  as 
  above. 
  

  

  To 
  correct 
  for 
  self-induction 
  in 
  R 
  ; 
  , 
  we 
  have 
  for 
  case 
  

   R 
  x/ 
  = 
  co 
  the 
  exact 
  equation 
  

  

  ^I/M-^ 
  / 
  =E 
  / 
  (r+B 
  y 
  )+5»[L'+L 
  / 
  -M]L 
  / 
  -^. 
  

  

  The 
  correction, 
  therefore, 
  nearly 
  vanishes 
  for 
  two 
  twisted 
  

   wires 
  in 
  a 
  coil 
  where 
  I/ 
  — 
  M 
  = 
  and 
  C 
  is 
  taken 
  out. 
  

  

  Method 
  10. 
  

  

  M 
  M 
  

  

  _#7M+- 
  or 
  62/M-- 
  = 
  

  

  c 
  c 
  

  

  rK^-K^l^rER' 
  + 
  R^ 
  + 
  ^ 
  + 
  R^ 
  + 
  CW 
  + 
  R^C^ 
  + 
  RJ} 
  

  

  [R'+tt' 
  + 
  Rj+RJ* 
  

  

  This 
  can 
  be 
  used 
  in 
  the 
  same 
  manner 
  as 
  9, 
  to 
  which 
  it 
  

   readily 
  reduces. 
  But 
  it 
  is 
  more 
  general 
  and 
  always 
  gives 
  

   zero 
  deflexion 
  when 
  adjusted, 
  however 
  M 
  is 
  connected. 
  To 
  

   throw 
  out 
  makes 
  it 
  oo 
  . 
  

  

  Method 
  11. 
  

   L-M 
  

  

  c 
  

   L 
  + 
  M 
  

  

  = 
  rR 
  + 
  6 
  2 
  (J-M)(L-M), 
  

  

  = 
  rR 
  + 
  6 
  2 
  (Z 
  + 
  M)(L 
  + 
  M). 
  

  

  For 
  the 
  upper 
  equation 
  the 
  last 
  term 
  may 
  be 
  made 
  small 
  

   and 
  the 
  method 
  may 
  be 
  useful 
  for 
  determining 
  L— 
  M 
  when 
  

   c 
  is 
  known. 
  Method 
  8, 
  however, 
  is 
  better 
  for 
  this. 
  

  

  Method 
  12. 
  

  

  V 
  R 
  + 
  R' 
  

  

  / 
  " 
  r 
  

  

  