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  CORRECTION 
  TO 
  BAROMETER 
  FOR 
  FORCE 
  OF 
  WIND. 
  

  

  best 
  suited 
  for 
  the 
  purpose.* 
  The 
  wind-gauge 
  was 
  of 
  a 
  very 
  simple 
  construction, 
  

   and 
  on 
  the 
  same 
  principle 
  as 
  the 
  instrument 
  used 
  for 
  weighing 
  letters, 
  the 
  weight 
  

   or 
  pressure 
  being 
  indicated 
  by 
  the 
  compression 
  of 
  a 
  spiral 
  spring 
  in 
  a 
  tube. 
  

  

  Fig. 
  1. 
  

  

  Lufra 
  Cottage, 
  Granton. 
  

  

  The 
  wood-cut, 
  fig. 
  1, 
  represents 
  my 
  cottage 
  ( 
  -----) 
  and 
  an 
  open 
  summer-house 
  (^") 
  

   near 
  it. 
  The 
  table 
  in 
  my 
  room 
  in 
  the 
  cottage, 
  the 
  seat 
  of 
  the 
  summer-house, 
  and 
  

   the 
  surface 
  of 
  the 
  ground 
  (""") 
  close 
  to 
  the 
  summer-house, 
  are 
  all 
  on 
  the 
  same 
  level 
  ; 
  

   I 
  could 
  thus 
  very 
  readily 
  compare 
  the 
  indications 
  of 
  the 
  barometer 
  in 
  these 
  three 
  

   different 
  situations 
  — 
  that 
  is, 
  as 
  sheltered 
  by 
  the 
  cottage, 
  as 
  sheltered 
  by 
  the 
  back 
  

   only 
  of 
  the 
  open 
  summer-house, 
  and 
  as 
  laid 
  on 
  the 
  ground 
  without 
  any 
  shelter 
  

   whatever. 
  

  

  During 
  calm 
  weather 
  I 
  found 
  that 
  the 
  indications 
  of 
  the 
  barometer 
  were 
  iden- 
  

   tically 
  the 
  same 
  in 
  all 
  three 
  positions 
  ; 
  but 
  that 
  when 
  the 
  wind 
  blew 
  with 
  any 
  

   considerable 
  force, 
  the 
  barometer 
  in 
  the 
  two 
  sheltered 
  positions, 
  that 
  is, 
  in 
  the 
  

   cottage 
  and 
  in 
  the 
  summer-house, 
  were 
  depressed 
  as 
  compared 
  with 
  the 
  indica- 
  

   tions 
  of 
  the 
  instrument 
  on 
  the 
  open 
  ground, 
  and 
  that 
  in 
  the 
  two 
  sheltered 
  posi- 
  

   tions 
  the 
  depressions 
  were 
  in 
  proportion 
  to 
  the 
  force 
  of 
  the 
  wind 
  ; 
  and 
  further, 
  

  

  * 
  The 
  correction 
  for 
  temperature 
  to 
  my 
  aneroid 
  between 
  56° 
  and 
  92°, 
  is 
  -0025 
  for 
  every 
  degree 
  

   of 
  increase 
  or 
  decrease 
  of 
  temperature, 
  but 
  the 
  barometer 
  is 
  more 
  immediately 
  affected 
  by 
  a 
  change 
  

   of 
  temperature 
  than 
  the 
  enclosed 
  thermometer. 
  

  

  