﻿272 
  Mr. 
  (:!. 
  C. 
  Paterson 
  on 
  the 
  Proposed 
  

  

  by 
  Fleming 
  in 
  1905 
  may 
  be 
  attributed 
  to 
  the 
  fact 
  that 
  only 
  

   3 
  lamps 
  were 
  tested 
  *. 
  

  

  As 
  regards 
  the 
  flame-lamp 
  comparisons, 
  it 
  will 
  be 
  noticed 
  

   that 
  Perot 
  and 
  Laporte 
  (Column 
  12) 
  found 
  a 
  value 
  for 
  their 
  

   Pentane 
  lamp 
  which 
  was 
  appreciably 
  lower 
  than 
  that 
  

   obtained 
  by 
  other 
  observers. 
  Except 
  for 
  this 
  difference 
  the 
  

   agreement 
  between 
  the 
  ratios 
  is 
  fairly 
  close. 
  The 
  ex- 
  

   ceptionally 
  close 
  agreement 
  shown 
  in 
  columns 
  10, 
  11, 
  and 
  12 
  

   for 
  the 
  ratio 
  Bougie 
  Dec/Hefner 
  can 
  only 
  be 
  attributed 
  to 
  a 
  

   coincidence, 
  since 
  in 
  the 
  experiments 
  from 
  which 
  two 
  of 
  the 
  

   three 
  ratios 
  were 
  determined 
  the 
  observations 
  varied 
  between 
  

   3 
  and 
  4 
  per 
  cent, 
  from 
  the 
  mean. 
  

  

  The 
  chief 
  point 
  of 
  interest 
  in 
  these 
  comparisons 
  is 
  the 
  

   near 
  coincidence 
  of 
  the 
  value 
  of 
  the 
  Bougie 
  Decimale 
  with 
  

   that 
  of 
  the 
  Pentane 
  unit 
  as 
  indicated 
  by 
  lines 
  B 
  and 
  G. 
  An 
  

   inspection 
  of 
  these 
  values 
  indicates 
  that 
  the 
  Bougie 
  Decimale, 
  

   as 
  interpreted 
  by 
  the 
  Laboratoire 
  Central, 
  may 
  be 
  slightly 
  

   larger 
  than 
  the 
  Pentane 
  unit 
  — 
  but 
  the 
  amount 
  is 
  less 
  than 
  

   1 
  per 
  cent. 
  When 
  we 
  remember 
  that, 
  at 
  present, 
  the 
  value 
  

   of 
  the 
  Bougie 
  Decimale 
  depends 
  on 
  the 
  interpretation 
  of 
  the 
  

   Carcel 
  lamp 
  and 
  the 
  ratio 
  between 
  it 
  and 
  the 
  platinum 
  unit, 
  

   determined 
  by 
  Yiolle 
  in 
  1884, 
  it 
  must 
  be 
  admitted 
  that 
  this 
  

   small 
  apparent 
  difference 
  is 
  well 
  within 
  the 
  limits 
  of 
  the 
  

   errors 
  of 
  experiment. 
  

  

  The 
  second 
  point 
  to 
  notice 
  is 
  the 
  difference 
  of 
  1*6 
  per 
  cent, 
  

   between 
  the 
  units 
  of 
  the 
  Bureau 
  of 
  Standards 
  and 
  the 
  

   National 
  Physical 
  Laboratory. 
  It 
  is 
  generally 
  recognized 
  f 
  

   that 
  the 
  unit 
  at 
  present 
  adopted 
  by 
  the 
  Gas 
  interests 
  in 
  the 
  

   States 
  is 
  about 
  4 
  per 
  cent, 
  smaller 
  than 
  the 
  Bureau 
  of 
  

   Standards 
  unit. 
  It 
  will 
  then 
  be 
  seen 
  that 
  by 
  lowering 
  the 
  

   value 
  of 
  their 
  unit 
  by 
  1*6 
  per 
  cent, 
  the 
  Bureau 
  comes 
  into 
  

   exact 
  agreement 
  with 
  this 
  country 
  and 
  approximately 
  halves 
  

   the 
  difference 
  between 
  the 
  units 
  employed 
  by 
  the 
  Gas 
  and 
  

   Electrical 
  industries 
  in 
  the 
  States. 
  

  

  A 
  further 
  point 
  of 
  interest 
  and 
  importance 
  which 
  results 
  

   from 
  the 
  comparisons 
  (see 
  line 
  A 
  in 
  the 
  table) 
  is 
  that 
  the 
  

   Hefner 
  unit 
  is 
  in 
  the 
  ratio 
  9/10 
  to 
  the 
  new 
  candle. 
  The 
  

   French 
  authorities 
  have 
  for 
  some 
  time 
  taken 
  the 
  ratio 
  

   Hefner/Bougie 
  Dec. 
  as 
  0*895. 
  It 
  is 
  of 
  interest, 
  therefore, 
  

   to 
  see 
  from 
  lines 
  A 
  and 
  H 
  how 
  nearly 
  the 
  value 
  for 
  the 
  

   Hefner 
  unit 
  in 
  terms 
  of 
  both 
  Pentane 
  and 
  Bougie 
  Dec. 
  units 
  

  

  * 
  See 
  Journ. 
  Inst. 
  Elect. 
  Eng. 
  vol. 
  xxxviii, 
  p. 
  311 
  : 
  Discussion 
  by 
  

   Dr. 
  Fleming 
  of 
  the 
  Author's 
  paper 
  on 
  " 
  Investigation 
  of 
  Light 
  Standards 
  

   etc." 
  

  

  t 
  Report 
  of 
  Committee 
  on 
  Nomenclature 
  and 
  Standards, 
  Annual 
  

   Conv. 
  Ilium. 
  Eng. 
  Soc. 
  Oct. 
  5, 
  1908, 
  Dr. 
  A. 
  C. 
  Humphreys. 
  

  

  