﻿138 
  

  

  Mr. 
  a. 
  W. 
  Todd 
  071 
  the 
  

  

  that 
  the 
  temperature 
  in 
  the 
  balance 
  was 
  slowly 
  rising 
  and 
  

   that 
  the 
  covered 
  junctions 
  were 
  " 
  lagging." 
  

  

  After 
  this 
  the 
  temperature 
  of 
  the 
  air 
  inside 
  the 
  balance 
  

   was 
  measured 
  by 
  thermojunctions 
  to 
  avoid 
  errors 
  due 
  to 
  

   lagging. 
  One 
  set 
  of 
  junctions 
  was 
  kept 
  at 
  a 
  fairly 
  constant 
  

   temperature 
  in 
  a 
  Dewar 
  tube 
  containing 
  water, 
  the 
  tem- 
  

   perature 
  being 
  indicated 
  on 
  a 
  Beckmann 
  thermometer. 
  

  

  An 
  idea 
  of 
  the 
  sensitiveness 
  of 
  such 
  a 
  balance-barometer 
  

   may 
  be 
  obtained 
  from 
  the 
  table 
  given 
  below 
  and 
  the 
  corre- 
  

   sponding 
  micro-barograph. 
  The 
  observations 
  given 
  extended 
  

   over 
  half 
  an 
  hour. 
  The 
  Beckmann 
  thermometer 
  in 
  the 
  

   Dewar 
  vessel 
  indicated 
  the 
  same 
  temperature 
  throughout. 
  

  

  Table. 
  

  

  1° 
  C. 
  difference 
  between 
  the 
  junctions 
  in 
  the 
  balance 
  and 
  

   those 
  in 
  the 
  Dewar 
  vessel 
  corresponded 
  to 
  28*8 
  divisions 
  

   on 
  the 
  galvanometer-scale. 
  

  

  Galv. 
  zero 
  = 
  272-2. 
  Eoom 
  temp. 
  = 
  13°-8 
  0. 
  Eider 
  at 
  13-152. 
  

  

  Time. 
  

  

  Telescope. 
  

  

  Galv. 
  

  

  Time. 
  

  

  Telescope. 
  

  

  Galv. 
  

  

  P.M. 
  

  

  

  

  P.M. 
  

  

  

  

  4-0 
  

   1 
  

   2 
  

  

  3 
  

  

  243-7 
  

   243-3 
  

   242-6 
  

   243-6 
  

  

  239-1 
  

  

  238-9 
  

  

  4—16 
  

   17 
  

   18 
  

   19 
  

  

  229-2 
  

   226-3 
  

   225-6 
  

   223-1 
  

  

  237-3 
  

  

  4 
  

  

  243-7 
  

  

  

  20 
  

  

  224-7 
  

  

  237-0 
  

  

  5 
  

  

  243-9 
  

  

  238-6 
  

  

  21 
  

  

  227 
  

  

  6 
  

  

  242-8 
  

  

  22 
  

  

  227-0 
  

  

  

  7 
  

   8 
  

   9 
  

  

  242-2 
  

   244-9 
  

   246-7 
  

  

  238-3 
  

  

  23 
  

   24 
  

   25 
  

  

  226-1 
  

   225-8 
  

   226-1 
  

  

  236-7 
  

  

  10 
  

   11 
  

   12 
  

  

  245-0 
  

  

  246-2 
  

   246-3 
  

  

  238 
  

  

  26 
  

   27 
  

   28 
  

  

  227-7 
  

   228-5 
  

   230-9 
  

  

  236-3 
  

  

  1 
  

  

  13 
  

  

  244-0 
  

  

  

  29 
  

  

  232-0 
  

  

  236-0 
  

  

  14 
  

  

  240-1 
  

  

  237-7 
  

  

  30 
  

  

  232-6 
  

  

  15 
  

  

  234-6 
  

  

  31 
  

  

  2321 
  

  

  

  rea 
  

  

  The 
  second 
  column 
  in 
  the 
  table 
  gives 
  the 
  telescope- 
  

   dings 
  of 
  the 
  balance-pointer, 
  and 
  the 
  third 
  gives 
  the 
  

  

  