﻿224 
  Dr. 
  C. 
  Chree's 
  Notes 
  on 
  Thermometry. 
  

  

  by 
  9° 
  or 
  10° 
  C, 
  from 
  a 
  gas 
  thermometer 
  near 
  the 
  top 
  of 
  its 
  

   scale 
  is 
  mentioned 
  in 
  several 
  English 
  books 
  *, 
  but 
  has 
  hardly 
  

   met 
  with 
  the 
  recognition 
  it 
  merits. 
  

  

  Loio-Temperature 
  Results. 
  

  

  § 
  17. 
  At 
  temperatures 
  below 
  0° 
  C. 
  the 
  natural 
  scales 
  of 
  

   mercury 
  thermometers 
  show 
  much 
  larger 
  departures 
  from 
  

   the 
  hydrogen 
  scale 
  than 
  are 
  met 
  with 
  between 
  0° 
  and 
  100° 
  C. 
  

   Thus, 
  according 
  to 
  the 
  determinations 
  of 
  the 
  Bureau 
  Inter- 
  

   national, 
  u 
  verve 
  dur 
  reading 
  less 
  hydrogen 
  reading 
  5 
  ' 
  

  

  = 
  _0°-170at 
  -20° 
  C, 
  

  

  = 
  — 
  O- 
  426 
  at 
  the 
  freezing-point 
  of 
  mercury. 
  

  

  For 
  this 
  latter 
  point 
  the 
  Bureau 
  has 
  found, 
  " 
  avec 
  une 
  ap- 
  

   proximation 
  de 
  2 
  centiemes 
  de 
  degre 
  " 
  f> 
  

  

  — 
  38 
  o, 
  80 
  C. 
  on 
  the 
  hydrogen 
  scale, 
  

  

  — 
  39°'22 
  C. 
  on 
  the 
  scale 
  of 
  verve 
  dur. 
  

  

  As 
  to 
  the 
  scale 
  of 
  English 
  glass 
  at 
  temperatures 
  below 
  0° 
  C, 
  

   the 
  only 
  published 
  result 
  I 
  know 
  of 
  is 
  a 
  determination 
  of 
  the 
  

   freezing-point 
  of 
  mercury 
  on 
  the 
  natural 
  (fixed 
  zero) 
  scale 
  

   of 
  a 
  Kew 
  Standard, 
  No. 
  45, 
  by 
  Balfour 
  Stewart 
  J. 
  The 
  mean 
  

   of 
  three 
  separate 
  experiments 
  — 
  giving 
  an 
  extreme 
  difference 
  

   of 
  0°' 
  IF.— 
  was 
  

  

  -38°-2F. 
  (-39°-0C). 
  

  

  This 
  comes 
  much 
  nearer 
  the 
  hydrogen 
  scale 
  than 
  does 
  the 
  

   verve 
  dur 
  reading. 
  

  

  Results 
  from 
  a 
  single 
  thermometer 
  are, 
  however, 
  at 
  best 
  

   somewhat 
  inconclusive, 
  and 
  some 
  doubt 
  might 
  reasonably 
  be 
  

   entertained 
  as 
  to 
  the 
  closeness 
  of 
  the 
  temperature 
  produced 
  

   by 
  freezing 
  mercury 
  in 
  Balfour 
  Stewart's 
  apparatus 
  to 
  that 
  

   produced 
  in 
  the 
  Bureau 
  International's 
  experiments. 
  

  

  As 
  to 
  the 
  latter 
  point 
  some 
  collateral 
  evidence 
  exists. 
  The 
  

   experiments 
  on 
  the 
  Kew 
  Standard, 
  No. 
  45, 
  are 
  mentioned 
  in 
  

   Balfour 
  Stewart's 
  paper 
  on 
  the 
  determination 
  of 
  the 
  freezing- 
  

   point 
  of 
  mercury 
  on 
  the 
  scale 
  of 
  the 
  air-thermometer, 
  and 
  

   seem 
  to 
  have 
  been 
  carried 
  out 
  under 
  fairly 
  similar 
  conditions 
  

   to 
  those 
  of 
  the 
  main 
  object 
  of 
  the 
  research. 
  

  

  The 
  hydrogen 
  and 
  air 
  scales 
  are 
  unlikely 
  to 
  differ 
  much 
  

  

  * 
  E.g. 
  Lord 
  Kelvin's 
  'Mathematical 
  and 
  Physical 
  Papers,' 
  vol. 
  iii. 
  p. 
  147, 
  

   and 
  Glazebrook 
  and 
  Shaw's 
  'Practical 
  Physics/ 
  p. 
  189 
  of 
  first 
  edition. 
  

  

  t 
  Comptes 
  rendus 
  . 
  . 
  . 
  de 
  la 
  deuxieme 
  Conference 
  General. 
  . 
  . 
  . 
  Paris, 
  

   1896, 
  p. 
  '29. 
  

  

  \ 
  Phil. 
  Trans, 
  for 
  1863, 
  p. 
  428. 
  

  

  