﻿70 
  Messrs. 
  M. 
  Greenwood, 
  C. 
  Hodson, 
  and 
  A. 
  E. 
  Tebb. 
  

  

  Table 
  I. 
  

  

  

  

  Paired 
  analv 
  

  

  ses 
  (C. 
  H.)- 
  

  

  

  

  

  

  values. 
  

  

  2 
  values. 
  

  

  4 
  

  

  •32 
  

  

  4 
  -23 
  

  

  16-22 
  

  

  16 
  

  

  •47 
  

  

  4 
  

  

  •40 
  

  

  4 
  - 
  28 
  

  

  16 
  -03 
  

  

  16 
  

  

  •18 
  

  

  3 
  

  

  •78 
  

  

  3 
  -29 
  

  

  16 
  -68 
  

  

  16 
  

  

  ■65 
  

  

  3 
  

  

  •78 
  

  

  3-28 
  

  

  16 
  -68 
  

  

  16 
  

  

  •75 
  

  

  3 
  

  

  '29 
  

  

  3 
  "28 
  

  

  16-65 
  

  

  16 
  

  

  ■75 
  

  

  4 
  

  

  •13 
  

  

  4-12 
  

  

  16 
  -51 
  

  

  16 
  

  

  ■62 
  

  

  4 
  

  

  13 
  

  

  4-08 
  

  

  16 
  -51 
  

  

  16 
  

  

  •58 
  

  

  4 
  

  

  •12 
  

  

  4-08 
  

  

  16-62 
  

  

  16 
  

  

  •58 
  

  

  3 
  

  

  •96 
  

  

  3-91 
  

  

  16 
  -30 
  

  

  16 
  

  

  •37 
  

  

  2 
  

  

  •87 
  

  

  2-78 
  

  

  17 
  "68 
  

  

  17 
  

  

  •65 
  

  

  3 
  

  

  •31 
  

  

  3 
  -23 
  

  

  17-46 
  

  

  17 
  

  

  ■51 
  

  

  3 
  

  

  13 
  

  

  3-07 
  

  

  17 
  -98 
  

  

  18 
  

  

  •00 
  

  

  4 
  

  

  •48 
  

  

  4-45 
  

  

  16-38 
  

  

  16 
  

  

  •44 
  

  

  3 
  

  

  •09 
  

  

  2-96 
  

  

  17 
  -21 
  

  

  17 
  

  

  •27 
  

  

  3 
  

  

  •67 
  

  

  3 
  67 
  

  

  17-02 
  

  

  17 
  

  

  •07 
  

  

  expired 
  air 
  were 
  analysed 
  by 
  C. 
  H. 
  using 
  a 
  small 
  analyser, 
  and 
  by 
  M. 
  S. 
  P., 
  a 
  

   much 
  more 
  experienced 
  gas 
  analyst, 
  using 
  the 
  larger 
  model. 
  In 
  one 
  

   experiment, 
  0. 
  H.'s 
  reading 
  was 
  987 
  per 
  cent, 
  of 
  M. 
  S. 
  Ps'., 
  in 
  the 
  other 
  

   100-2 
  per 
  cent, 
  of 
  his 
  value 
  (expressed 
  as 
  calories 
  per 
  unit). 
  It 
  would 
  

   therefore 
  seem 
  that 
  differences 
  between 
  two 
  results 
  reached 
  by 
  C. 
  H. 
  exceeding, 
  

   say, 
  6 
  per 
  cent, 
  are 
  unlikely 
  to 
  be 
  attributable 
  to 
  errors 
  of 
  technic. 
  It 
  must, 
  

   however, 
  clearly 
  be 
  understood 
  that 
  we 
  do 
  not 
  regard 
  this 
  estimate 
  as 
  more 
  

   than 
  a 
  rude 
  approximation. 
  Quite 
  apart 
  from 
  the 
  doubtful 
  truth 
  of 
  the 
  

   theoretical 
  assumptions, 
  it 
  is 
  plain 
  that 
  the 
  deduction 
  of 
  constants 
  from 
  so 
  

   short 
  and 
  irregular 
  a 
  series 
  as 
  the 
  one 
  quoted 
  here 
  is 
  hazardous 
  (the 
  deduced 
  

   values 
  are 
  of 
  course 
  themselves 
  subject 
  to 
  large 
  errors 
  of 
  sampling), 
  and, 
  for 
  

   that 
  reason, 
  we 
  shall 
  not 
  reproduce 
  the 
  necessarily 
  intricate 
  arithmetical 
  

   calculations 
  requisite 
  to 
  determine 
  the 
  errors 
  of 
  the 
  various 
  constants. 
  When 
  

   two 
  or 
  three 
  hundred 
  paired 
  analyses 
  are 
  available 
  for 
  statistical 
  treatment 
  

   it 
  will 
  be 
  possible 
  to 
  import 
  some 
  degree 
  of 
  precision 
  into 
  this 
  branch 
  of 
  the 
  

   research. 
  Had 
  our 
  enquiry 
  been 
  continued 
  (as 
  would 
  have 
  been 
  the 
  case 
  if 
  

   the 
  war 
  had 
  not, 
  fortunately, 
  come 
  to 
  an 
  end) 
  we 
  should 
  have 
  discussed 
  the 
  

   subject 
  at 
  length. 
  We 
  now 
  pass 
  to 
  a 
  still 
  more 
  difficult 
  topic, 
  viz., 
  the 
  

   interpretation 
  of 
  differences 
  between 
  experimental 
  findings 
  which 
  lie 
  outside 
  

   the 
  range 
  which 
  we 
  have 
  provisionally 
  adopted 
  as 
  a 
  margin 
  of 
  purely 
  

   experimental 
  error. 
  

  

  It 
  is 
  recognised 
  that 
  the 
  likelihood 
  that 
  the 
  difference 
  between 
  the 
  mean 
  

   values 
  of 
  two 
  series 
  of 
  variable 
  quantities 
  has 
  been 
  produced 
  by 
  the 
  operation 
  

  

  