﻿Audibility 
  Factor 
  of 
  a 
  Shunted 
  Telephone. 
  489- 
  

  

  Prof. 
  Love 
  found 
  between 
  the 
  received 
  current 
  and 
  the 
  

   audibility 
  factor 
  was 
  due 
  entirely 
  to 
  this 
  oversight; 
  his 
  

   results 
  involve 
  the 
  relationship 
  between 
  the 
  impedance 
  and 
  

   the 
  resistance 
  of 
  the 
  telephone 
  and 
  would 
  vary 
  with 
  different 
  

   receivers. 
  There 
  can 
  obviously 
  be 
  no 
  simple 
  relation 
  between 
  

   the 
  antenna 
  current 
  and 
  the 
  audibility 
  factor, 
  unless 
  the 
  latter 
  

   be 
  calculated 
  in 
  such 
  aivay 
  as 
  to 
  give 
  correctly 
  the 
  ratio 
  between 
  

   the 
  total 
  sound-producing 
  current 
  and 
  that 
  fraction 
  of 
  it 
  which 
  

   passes 
  through 
  the 
  telephone 
  receiver. 
  It 
  is 
  obvious, 
  moreover, 
  

   that 
  for 
  large 
  values 
  of 
  (R 
  + 
  S)/S, 
  the 
  wrongly 
  calculated 
  

   audibility 
  factor 
  will 
  also 
  vary 
  as 
  the 
  square 
  of 
  the 
  antenna 
  

   current, 
  but 
  that 
  for 
  small 
  values 
  of 
  (R-fS)/S, 
  that 
  is, 
  for 
  

   weak 
  signals, 
  the 
  wrongly 
  calculated 
  audibility 
  factor 
  will 
  

   vary 
  less 
  rapidly, 
  as 
  is 
  clearly 
  shown 
  in 
  the 
  table 
  given 
  in 
  

   my 
  paper 
  (Phil. 
  Mag. 
  Jan. 
  p. 
  133). 
  

  

  This 
  then 
  is 
  the 
  simple 
  explanation 
  of 
  Prof. 
  Love's 
  sug- 
  

   gestions 
  which 
  the 
  experiments 
  of 
  Mr. 
  van 
  der 
  Pol 
  were 
  

   intended 
  to 
  test. 
  

  

  Mr. 
  van 
  der 
  Pol's 
  experiments 
  have 
  simply 
  confirmed 
  the 
  

   fact 
  that 
  if, 
  when 
  using 
  such 
  detectors, 
  one 
  miscalculates 
  the 
  

   audibility 
  factor 
  by 
  taking 
  the 
  resistance 
  instead 
  of 
  the 
  im- 
  

   pedance 
  of 
  the 
  telephone 
  receiver, 
  the 
  result 
  will 
  have 
  the 
  

   peculiarity 
  found 
  by 
  Prof. 
  Love. 
  This 
  was 
  obvious, 
  however, 
  

   without 
  any 
  experimental 
  confirmation. 
  

  

  Mr. 
  van 
  der 
  Pol's 
  remark 
  that 
  "it 
  is 
  by 
  no 
  means 
  clear 
  

   whether 
  Austin 
  or 
  Hogan 
  employed 
  the 
  true 
  impedance 
  of 
  

   their 
  telephones, 
  as 
  in 
  their 
  papers 
  no 
  references 
  at 
  all 
  are 
  

   given 
  how 
  they 
  determined 
  these 
  impedances 
  " 
  is 
  obviously 
  

   unjust 
  in 
  view 
  of 
  the 
  work 
  of 
  these 
  two 
  experimenters. 
  

   The 
  table 
  given 
  above 
  indicates, 
  if 
  it 
  does 
  not 
  prove, 
  that 
  

   the 
  impedance 
  of 
  the 
  receiver 
  has 
  been 
  fairly 
  accurately 
  

   determined. 
  

  

  In 
  reply 
  to 
  Mr. 
  van 
  der 
  Pol's 
  statement 
  that 
  " 
  no 
  assump- 
  

   tions 
  as 
  that 
  made 
  by 
  Prof 
  . 
  Howe 
  that 
  the 
  true 
  impedance 
  of 
  

   the 
  telephone 
  under 
  actual 
  working 
  conditions 
  is 
  equal 
  to 
  four 
  

   times 
  [I 
  gave 
  3 
  and 
  4 
  as 
  alternatives] 
  the 
  steady 
  resistance 
  

   has 
  been 
  justified 
  by 
  any 
  experiments," 
  I 
  wish 
  to 
  say 
  that 
  the 
  

   figures 
  given 
  were 
  not 
  assumptions 
  but 
  measured 
  values 
  at 
  

   the 
  frequencies 
  quoted. 
  It 
  will 
  be 
  noticed 
  that 
  Austin's 
  

   receiver 
  had 
  an 
  inductive 
  resistance 
  3^ 
  times 
  the 
  steady 
  

   current 
  resistance. 
  

  

  With 
  respect 
  to 
  the 
  closing 
  paragraph 
  of 
  the 
  note 
  I 
  think 
  

   that 
  " 
  the 
  uncertainty 
  attending 
  the 
  constants 
  employed 
  by 
  

   Austin 
  and 
  Hogan 
  and 
  the 
  difficulty 
  of 
  determining 
  exact 
  

   values 
  " 
  are 
  by 
  no 
  means 
  so 
  great 
  as 
  Mr. 
  van 
  der 
  Pol 
  

   imagines; 
  but 
  even 
  were 
  it 
  otherwise, 
  I 
  cannot 
  agree 
  that 
  it 
  

  

  