﻿Dr. 
  C. 
  Chree's 
  Notes 
  on 
  Thermometry. 
  

  

  219 
  

  

  where 
  fi 
  6 
  is 
  temperature 
  on 
  the 
  scale 
  of 
  16 
  m 
  , 
  and 
  t 
  is 
  the 
  

   mean 
  for 
  the 
  scales 
  of 
  16 
  111 
  and 
  verre 
  dur. 
  From 
  these 
  

   formulae 
  are 
  deduced 
  differences 
  between 
  the 
  several 
  scales, 
  

   proceeding 
  apparently 
  to 
  o, 
  0001 
  C. 
  Particulars 
  of 
  a 
  com- 
  

   parison 
  of 
  the 
  natural 
  scales 
  of 
  verre 
  dur 
  and 
  English 
  crystal 
  

   by 
  Wiebe* 
  — 
  proceeding 
  to 
  0°*01 
  C. 
  only 
  — 
  are 
  quoted 
  in 
  

   Gruillaume's 
  ' 
  Thermometries 
  p. 
  214. 
  

  

  Combining 
  these 
  data 
  I 
  have 
  compiled 
  the 
  table 
  on 
  p. 
  218, 
  

   which 
  refers 
  all 
  the 
  scales 
  to 
  that 
  of 
  the 
  hydrogen 
  thermometer 
  

   at 
  the 
  Bureau 
  International. 
  

  

  § 
  12. 
  As 
  most 
  of 
  the 
  data 
  in 
  the 
  table 
  depend 
  on 
  the 
  com- 
  

   parison 
  of 
  the 
  verre 
  dur 
  and 
  hydrogen 
  scales, 
  it 
  is 
  only 
  proper 
  

   to 
  mention 
  that 
  a 
  more 
  recent 
  comparison 
  has 
  been 
  made 
  at 
  

   the 
  Bureau 
  International 
  over 
  part 
  of 
  the 
  fundamental 
  interval. 
  

   Full 
  particulars 
  do 
  not 
  appear 
  to 
  have 
  been 
  given 
  as 
  yet, 
  but 
  

   the 
  following 
  preliminary 
  details 
  are 
  contained 
  in 
  a 
  recent 
  

   publication 
  of 
  the 
  Bureau 
  f 
  :— 
  

  

  Table 
  V. 
  

   Excess 
  of 
  reading 
  of 
  verre 
  dur 
  over 
  hydrogen 
  thermometer. 
  

  

  

  10°. 
  

  

  20°. 
  

  

  30°. 
  

  

  40°. 
  

  

  Old 
  determination 
  ... 
  

   New 
  „ 
  

  

  •052 
  

   •046 
  

  

  •085 
  

  

  •078 
  

  

  •102 
  

   •098 
  

  

  ■107 
  

   •106 
  

  

  The 
  new 
  determination 
  was 
  made 
  by 
  M. 
  Chappuis, 
  using 
  a 
  

   hydrogen 
  thermometer 
  having 
  its 
  reservoir 
  of 
  glass 
  instead 
  

   of, 
  as 
  previously, 
  platinum-iridium. 
  

  

  The 
  close 
  agreement 
  of 
  the 
  tw 
  T 
  o 
  determinations 
  at 
  40° 
  

   where 
  the 
  difference 
  between 
  the 
  scales 
  is 
  greatest, 
  is 
  empha- 
  

   sized 
  in 
  the 
  text 
  ; 
  but 
  the 
  very 
  appreciable 
  discrepancies 
  at 
  

   10° 
  C. 
  and 
  20° 
  C. 
  seem 
  to 
  me 
  hardly 
  in 
  harmony 
  with 
  the 
  

   conclusion 
  " 
  Ainsi 
  les 
  anciennes 
  mesures 
  . 
  . 
  . 
  sont 
  complete- 
  

   ment 
  confirmees 
  par 
  les 
  nouvelles 
  . 
  . 
  ." 
  

  

  § 
  13. 
  At 
  the 
  Reichsanstalt 
  comparisons 
  have 
  been 
  made 
  of 
  

   thermometers 
  of 
  various 
  kinds 
  of 
  glass 
  and 
  the 
  air-thermo- 
  

   meter. 
  Formulae 
  have 
  then 
  been 
  calculated 
  to 
  fit 
  the 
  observed 
  

   differences 
  between 
  the 
  natural 
  scales 
  as 
  well 
  as 
  possible. 
  

   These 
  formulae, 
  though 
  really 
  of 
  the 
  type 
  (7), 
  are 
  arranged 
  

   somewhat 
  differently. 
  For 
  instance, 
  over 
  the 
  range 
  —20° 
  C. 
  

  

  * 
  Sitz. 
  der 
  k.preuss. 
  AJcad. 
  der 
  Wiss. 
  1885, 
  p. 
  633. 
  

  

  t 
  Proces-Verbaux 
  des 
  Seances 
  de 
  1895, 
  Paris, 
  1896, 
  p. 
  46, 
  

  

  