﻿Dr. 
  C. 
  Chree's 
  Notes 
  on 
  Thermometry. 
  

  

  223 
  

  

  a 
  thermometer 
  of 
  German 
  soda-glass 
  with 
  a 
  hydrogen 
  ther- 
  

   mometer. 
  He 
  gives 
  a 
  table 
  * 
  comparing 
  his 
  results 
  with 
  

   Regnault's. 
  This 
  I 
  partly 
  reproduce 
  below. 
  It 
  should 
  be 
  

   noticed, 
  however, 
  that 
  the 
  gas-thermometer 
  was 
  air 
  in 
  the 
  

   case 
  of 
  Regnault, 
  hydrogen 
  in 
  the 
  case 
  of 
  Crafts, 
  and 
  that 
  

   the 
  latter 
  employed 
  a 
  movable 
  zero 
  method 
  — 
  differing, 
  how- 
  

   ever, 
  apparently 
  in 
  some 
  particulars 
  from 
  that 
  followed 
  at 
  

   the 
  Bureau 
  International. 
  The 
  figures 
  are 
  corrections 
  re- 
  

   quired 
  to 
  reduce 
  the 
  reading 
  of 
  the 
  mercury-thermometer 
  

   to 
  the 
  scale 
  of 
  the 
  gas-thermometer. 
  The 
  first 
  and 
  second 
  

   lines 
  A 
  and 
  B 
  supply 
  the 
  corrections 
  to 
  Regnault' 
  s 
  Choisy- 
  

   le-Roi 
  and 
  verre 
  ordinaire 
  thermometers, 
  respectively 
  ; 
  the 
  

   last 
  line 
  C 
  refers 
  to 
  the 
  modern 
  crystal 
  thermometers 
  used 
  

   by 
  Crafts. 
  

  

  The 
  centigrade 
  scale 
  is 
  that 
  employed 
  throughout. 
  

  

  Table 
  VII. 
  

  

  Temp 
  

  

  120°. 
  

   -12 
  

  

  140°. 
  

  

  160°. 
  

  

  180°. 
  

  

  200°. 
  

  

  220°. 
  

  

  Correction 
  A 
  ... 
  

  

  -•29 
  

  

  -•52 
  

  

  -•80 
  

  

  -1-25 
  

  

  -1-82 
  

  

  „ 
  B... 
  

  

  + 
  •05 
  

  

  + 
  •15 
  

  

  +•26 
  

  

  + 
  •37 
  

  

  + 
  -30 
  

  

  + 
  -20 
  

  

  o... 
  

  

  + 
  •04 
  

  

  +•16 
  

  

  + 
  •33 
  

  

  + 
  •34 
  

  

  + 
  -27 
  

  

  + 
  -08 
  

  

  Temp 
  

  

  240°. 
  

   -2-55 
  

  

  260°. 
  

  

  280°. 
  

  

  300°. 
  

  

  320°. 
  

  

  340°. 
  

  

  Correction 
  A 
  .. 
  

  

  -344 
  

  

  -4-48 
  

  

  -572 
  

  

  -7-25 
  

  

  -9-30 
  

  

  „ 
  B... 
  

  

  + 
  -10 
  

  

  - 
  -20 
  

  

  - 
  52 
  

  

  -108 
  

  

  -1-80 
  

  

  -3-00 
  

  

  „ 
  o... 
  

  

  + 
  -14 
  

  

  - 
  -39 
  

  

  - 
  63 
  

  

  -1-21 
  

  

  -2-03 
  

  

  

  Crafts's 
  table 
  really 
  gives 
  the 
  corrections 
  for 
  every 
  10°. 
  It 
  

   stops 
  at 
  330°, 
  but 
  I 
  have 
  obtained 
  the 
  data 
  under 
  340° 
  from 
  

   the 
  other 
  sources 
  mentioned. 
  In 
  Crafts's 
  opinion 
  the 
  ordinary 
  

   French, 
  German, 
  and 
  English 
  thermometers 
  of 
  fifteen 
  years 
  

   ago 
  possessed 
  fairly 
  similar 
  natural 
  scales. 
  It 
  is 
  important 
  

   to 
  notice 
  that 
  even 
  when, 
  as 
  in 
  line 
  C 
  of 
  the 
  table, 
  the 
  de- 
  

   parture 
  from 
  a 
  gas 
  scale 
  is 
  small 
  up 
  to 
  250° 
  C, 
  it 
  may 
  be 
  

   very 
  considerable 
  at 
  temperatures 
  over 
  300° 
  C. 
  

  

  The 
  fact 
  that 
  an 
  accurately 
  divided 
  glass-mercury 
  thermo- 
  

   meter, 
  with 
  its 
  zero- 
  and 
  boiling-points 
  correct, 
  may 
  differ 
  

  

  * 
  In 
  the 
  paper 
  last 
  quoted, 
  p. 
  838. 
  

  

  R2 
  

  

  