﻿Itoioland 
  and 
  Penniman 
  — 
  Electrical 
  Measurements. 
  41 
  

  

  From 
  this 
  A 
  is 
  found 
  for 
  the 
  period 
  used. 
  By 
  doing 
  this 
  for 
  

   a 
  number 
  of 
  different 
  values 
  of 
  R, 
  the 
  true 
  value 
  of 
  A 
  is 
  

   approximated. 
  A 
  was 
  thus 
  found 
  for 
  the 
  condensers 
  2 
  and 
  3 
  

   microfarads 
  with 
  different 
  values 
  of 
  n. 
  The 
  calculations 
  were 
  

   again 
  performed 
  adding 
  to 
  the 
  different 
  values 
  of 
  R 
  a 
  constant 
  

   resistance 
  A. 
  The 
  capacity 
  that 
  was 
  found 
  when 
  A 
  is 
  added 
  

   to 
  R 
  is 
  called 
  the 
  corrected 
  capacity. 
  In 
  the 
  table 
  below 
  are 
  

   collected 
  the 
  corrected 
  values 
  of 
  the 
  capacities 
  together 
  with 
  n 
  

   and 
  the 
  resistance 
  A. 
  

  

  Capacity 
  

  

  4-94 
  

  

  4-96 
  

  

  4-96 
  

  

  4-64 
  

  

  microfarads. 
  

  

  n 
  

  

  131-1 
  

  

  53-3 
  

  

  31-98 
  

  

  14- 
  

  

  complete 
  alternations. 
  

  

  A 
  5-19 
  20-5 
  34-09 
  139-62 
  absorption 
  resistance 
  in 
  ohms 
  

  

  The 
  last 
  value 
  of 
  the 
  capacity 
  seems 
  to 
  be 
  an 
  error, 
  possibly 
  

   one 
  of 
  calculation. 
  However, 
  the 
  results 
  seem 
  to 
  show 
  a 
  

   nearly 
  constant 
  capacity, 
  but 
  a 
  resistance 
  increasing 
  rapidly 
  

   with 
  decrease 
  of 
  period, 
  as 
  Maxwell's 
  formula 
  shows. 
  The 
  

   constant 
  value 
  of 
  the 
  capacity 
  remains 
  to 
  be 
  explained. 
  

  

  But 
  in 
  the 
  above, 
  determinations 
  of 
  absorption 
  resistance 
  are 
  

   by 
  approximation. 
  Professor 
  Rowland 
  has, 
  therefore, 
  devised 
  

   a 
  method 
  by 
  which 
  it 
  can 
  be 
  measured 
  directly. 
  This 
  method, 
  

   with 
  the 
  results 
  that 
  have 
  been 
  derived 
  by 
  it, 
  will 
  now 
  be 
  given. 
  

  

  Method 
  for 
  the 
  Direct 
  Measurement 
  of 
  Absorption 
  Resistance. 
  

  

  In 
  a 
  Wheatstone 
  bridge 
  (fig. 
  3) 
  let 
  the 
  resistance 
  of 
  the 
  dif- 
  

   ferent 
  arms 
  be 
  denoted 
  by 
  R^, 
  R', 
  R^^, 
  R'^ 
  and 
  r. 
  Let 
  R^ 
  

   have 
  in 
  circuit 
  a 
  self-inductance 
  L^ 
  and 
  let 
  r 
  have 
  in 
  circuit 
  

   with 
  it 
  a 
  self-inductance. 
  

  

  Let 
  Ce'^^^ 
  be 
  the 
  current 
  through 
  R^ 
  and 
  CeK^t+'P) 
  be 
  the 
  cur- 
  

   rent 
  through 
  r 
  when 
  a 
  periodic 
  electromotive 
  force 
  is 
  applied 
  

   to 
  a 
  and 
  cl 
  in 
  the 
  figure. 
  

  

  Let 
  C/ 
  be 
  the 
  current 
  through 
  R^, 
  and 
  C^ 
  be 
  the 
  current 
  

   through 
  r 
  when 
  there 
  is 
  a 
  constant 
  difference 
  of 
  potential 
  

   between 
  a 
  and 
  cl. 
  The 
  ratio 
  of 
  the 
  current 
  in 
  this 
  case 
  is 
  

  

  