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  XXIII. 
  — 
  On 
  a 
  Necessary 
  Correction 
  to 
  the 
  Observed 
  Height 
  of 
  the 
  Barometer 
  de- 
  

   pending 
  upon 
  the 
  Force 
  of 
  the 
  Wind. 
  By 
  Captain 
  Henry 
  James, 
  R.E., 
  

   F.R.S., 
  M.R.I.A., 
  F.G.S., 
  &c. 
  

  

  (Read 
  15th 
  March 
  1852.) 
  

  

  The 
  oscillations 
  of 
  the 
  barometer 
  during 
  gales 
  of 
  wind 
  must 
  have 
  been 
  noticed 
  

   soon 
  after 
  the 
  invention 
  of 
  the 
  instrument 
  by 
  Torricelli 
  200 
  years 
  ago. 
  Every 
  

   observer 
  is 
  familiar 
  with 
  the 
  fact, 
  that 
  the 
  barometric 
  column 
  is 
  continually 
  

   rising 
  and 
  falling 
  during 
  gales 
  ; 
  and 
  we 
  frequently 
  meet 
  such 
  observations 
  as 
  

   " 
  Barometer 
  very 
  unsteady," 
  in 
  Meteorological 
  Registers. 
  

  

  In 
  Sir 
  William 
  Reid's 
  work 
  on 
  the 
  Law 
  of 
  Storms, 
  he 
  says, 
  " 
  during 
  the 
  

   hardest 
  part 
  of 
  the 
  gale 
  (the 
  Bermuda 
  hurricane 
  of 
  1839) 
  several 
  persons 
  ob- 
  

   served 
  remarkable 
  oscillations 
  of 
  the 
  mercury 
  in 
  the 
  tubes 
  of 
  the 
  barometers 
  ;" 
  

   and 
  in 
  a 
  letter 
  which 
  I 
  had 
  the 
  honour 
  to 
  receive 
  from 
  the 
  Astronomer-Royal, 
  

   Professor 
  Airy, 
  in 
  reply 
  to 
  one 
  from 
  myself 
  on 
  this 
  subject, 
  he 
  says, 
  " 
  I 
  think 
  (but 
  

   am 
  not 
  certain) 
  that 
  the 
  depression 
  of 
  the 
  barometer 
  at 
  every 
  gust 
  of 
  a 
  gale 
  of 
  wind 
  

   is 
  an 
  ordinary 
  phenomenon, 
  without 
  reference 
  to 
  the 
  position 
  of 
  the 
  barometer 
  with 
  

   regard 
  to 
  the 
  direction 
  of 
  the 
  w 
  r 
  ind. 
  Many 
  years 
  ago 
  I 
  was 
  in 
  the 
  observatory 
  of 
  

   Marseilles 
  during 
  the 
  blowing 
  of 
  the 
  Mistral 
  (a 
  wind 
  well 
  known 
  there), 
  and 
  there 
  

   I 
  saw 
  the 
  drop 
  of 
  the 
  barometer 
  at 
  every 
  gust 
  in 
  great 
  perfection. 
  I 
  do 
  not 
  

   remember 
  the 
  position 
  of 
  the 
  barometer." 
  

  

  I 
  am 
  not 
  aware 
  that 
  the 
  cause 
  of 
  this 
  unsteadiness 
  of 
  the 
  barometer 
  has 
  been 
  

   hitherto 
  investigated 
  by 
  any 
  one, 
  or 
  that 
  the 
  amount 
  of 
  the 
  depressions 
  has 
  been 
  

   shewn 
  to 
  depend 
  upon 
  the 
  force 
  of 
  the 
  wind. 
  

  

  My 
  attention 
  was 
  particularly 
  drawn 
  to 
  this 
  subject 
  last 
  December, 
  by 
  observ- 
  

   ing 
  that 
  during 
  the 
  heavy 
  gale 
  of 
  wind 
  which 
  we 
  had 
  on 
  the 
  7th 
  and 
  8th 
  of 
  that 
  

   month, 
  the 
  barometer 
  was 
  always 
  depressed 
  at 
  each 
  gust 
  of 
  wind, 
  and 
  that, 
  as 
  far 
  

   as 
  I 
  could 
  judge 
  by 
  the 
  ear, 
  by 
  listening 
  to 
  the 
  rush 
  of 
  the 
  wind 
  round 
  my 
  cottage 
  

   at 
  Granton, 
  the 
  amount 
  of 
  the 
  depression 
  was 
  in 
  some 
  proportion 
  to 
  the 
  force 
  or 
  

   velocity 
  of 
  the 
  wind. 
  

  

  My 
  cottage, 
  which 
  stands 
  alone 
  on 
  a 
  height 
  overlooking 
  the 
  Forth, 
  is 
  pecu- 
  

   liarly 
  well 
  situated 
  for 
  investigating 
  this 
  question 
  ; 
  and 
  the 
  succession 
  of 
  gales 
  

   from 
  the 
  south-west 
  which 
  we 
  had 
  during 
  the 
  months 
  of 
  January 
  and 
  February, 
  

   afforded 
  me 
  the 
  opportunity 
  for 
  following 
  up 
  this 
  inquiry, 
  to 
  confirm 
  my 
  previous 
  

   impressions, 
  and 
  to 
  give 
  approximately 
  the 
  depression 
  of 
  the 
  barometer 
  corre- 
  

   sponding 
  to 
  the 
  different 
  amounts 
  of 
  the 
  pressure 
  of 
  the 
  wind. 
  

  

  The 
  barometer 
  used 
  in 
  these 
  experiments 
  was 
  an 
  aneroid, 
  which 
  from 
  its 
  being 
  

   so 
  portable, 
  and 
  requiring 
  no 
  other 
  adjustment 
  than 
  to 
  be 
  laid 
  horizontal, 
  was 
  

  

  VOL. 
  XX. 
  PART 
  III. 
  5 
  K 
  

  

  