﻿382 
  CORRECTION 
  TO 
  BAROMETER 
  FOR 
  FORCE 
  OF 
  WIND. 
  

  

  in 
  them, 
  as 
  in 
  the 
  above 
  experiments 
  ; 
  and 
  this 
  view 
  is 
  further 
  confirmed 
  by 
  the 
  

   fact, 
  that 
  if 
  a 
  window 
  or 
  door 
  exposed 
  to 
  the 
  wind 
  is 
  opened 
  in 
  any 
  room 
  in 
  which 
  

   there 
  is 
  a 
  barometer, 
  the 
  mercury 
  is 
  raised, 
  shewing 
  that 
  the 
  air 
  is 
  compressed 
  in 
  

   the 
  room, 
  as 
  it 
  is 
  in 
  Leslie's 
  cylinder, 
  when 
  we 
  blow 
  through 
  the 
  larger 
  tube. 
  

   So 
  also 
  the 
  barometer 
  is 
  elevated 
  by 
  the 
  compression 
  of 
  the 
  air 
  on 
  the 
  windward 
  

   side 
  of 
  the 
  summer-house, 
  whilst 
  it 
  is 
  depressed 
  on 
  the 
  leeward 
  in 
  proportion 
  to 
  the 
  

   force 
  of 
  the 
  wind 
  and 
  the 
  intermittent 
  gusts 
  ; 
  but 
  the 
  effect 
  in 
  a 
  room, 
  the 
  doors 
  

   and 
  windows 
  of 
  which 
  are 
  usually 
  closed 
  on 
  the 
  windward 
  side, 
  is 
  to 
  produce 
  a 
  

   depression. 
  We 
  may 
  also 
  infer, 
  but 
  I 
  know 
  of 
  no 
  experiments 
  to 
  support 
  the 
  

   opinion, 
  that 
  during 
  gales 
  of 
  wind 
  the 
  barometer 
  would 
  stand 
  at 
  a 
  higher 
  level 
  on 
  

   the 
  windward 
  side 
  of 
  a 
  hill 
  than 
  on 
  the 
  leeward, 
  the 
  points 
  of 
  observation 
  being 
  

   at 
  the 
  same 
  altitude. 
  The 
  known 
  discrepancies 
  between 
  the 
  heights 
  deduced 
  from 
  

   the 
  indications 
  of 
  the 
  barometer 
  during 
  high 
  winds 
  and 
  calms, 
  are, 
  however, 
  most 
  

   probably 
  due 
  to 
  this 
  cause. 
  

  

  Professor 
  Daniell, 
  indeed, 
  suggests 
  this 
  very 
  question, 
  " 
  Whether 
  local 
  cur- 
  

   rents 
  of 
  air, 
  and 
  those 
  deflections 
  of 
  the 
  wind 
  which 
  are 
  caused 
  by 
  the 
  different 
  

   directions 
  of 
  different 
  valleys, 
  may 
  not 
  produce 
  various 
  partial 
  adjustments 
  of 
  

   density 
  which 
  may 
  have 
  an 
  influence 
  upon 
  barometrical 
  measurements 
  ;" 
  and 
  

   in 
  the 
  experiments 
  which 
  he 
  made 
  for 
  determining 
  the 
  altitude 
  of 
  Hedley 
  Heath, 
  

   by 
  observation 
  at 
  different 
  stages 
  of 
  the 
  height, 
  he 
  found 
  an 
  error 
  of 
  75 
  feet 
  in 
  

   157 
  in 
  the 
  height 
  of 
  the 
  station 
  in 
  a 
  ravine 
  ; 
  he 
  says, 
  " 
  omitting 
  the 
  second 
  result 
  

   (the 
  one 
  in 
  the 
  ravine) 
  all 
  the 
  rest 
  are 
  correct, 
  and 
  the 
  third 
  is 
  deficient 
  ex- 
  

   actly 
  the 
  quantity 
  which 
  is 
  in 
  excess 
  in 
  the 
  second 
  ;" 
  it 
  is, 
  therefore, 
  obvious 
  

   that 
  the 
  configuration 
  of 
  the 
  ground 
  was 
  the 
  cause 
  of 
  this 
  anomaly. 
  It 
  is 
  much 
  

   to 
  be 
  regretted 
  that 
  Professor 
  Daniell 
  had 
  not 
  followed 
  up 
  the 
  inquiry 
  ; 
  but 
  he 
  

   concludes 
  his 
  remarks 
  by 
  putting 
  the 
  following 
  question 
  : 
  — 
  " 
  What 
  is 
  the 
  effect 
  of 
  

   wind 
  upon 
  barometrical 
  mensurations 
  ? 
  If 
  I 
  had 
  the 
  means 
  of 
  prosecuting 
  these 
  

   inquiries 
  in 
  the 
  complete 
  manner 
  which 
  the 
  nicety 
  of 
  the 
  subject 
  requires, 
  I 
  would 
  

   not 
  have 
  suffered 
  them 
  to 
  retain 
  the 
  form 
  of 
  crude 
  speculation." 
  

  

  By 
  a 
  repeated 
  series 
  of 
  comparisons 
  at 
  Granton, 
  I 
  obtained 
  the 
  following 
  

   results 
  ; 
  but 
  I 
  wish 
  them 
  to 
  be 
  considered 
  as 
  merely 
  approximate 
  results, 
  to 
  which 
  

   I 
  desire 
  to 
  draw 
  the 
  attention 
  of 
  meteorologists, 
  that 
  those 
  who 
  are 
  stationed 
  in 
  

   countries 
  subject 
  to 
  violent 
  storms 
  and 
  hurricanes, 
  may 
  supply 
  us 
  with 
  the 
  amount 
  

   of 
  the 
  depressions, 
  corresponding 
  to 
  higher 
  velocities 
  of 
  the 
  wind 
  than 
  I 
  have 
  been 
  

   able 
  to 
  supply, 
  and 
  that 
  thus 
  the 
  law 
  connecting 
  the 
  amount 
  of 
  depression 
  with 
  

   the 
  velocity 
  or 
  pressures 
  at 
  different 
  stations 
  may 
  be 
  established. 
  The 
  effect 
  of 
  

   the 
  wind 
  when 
  blowing 
  from 
  different 
  quarters 
  will 
  also 
  have 
  to 
  be 
  studied, 
  that 
  

   the 
  amount 
  of 
  the 
  corrections 
  necessary 
  to 
  be 
  applied 
  to 
  the 
  observed 
  height 
  of 
  

   the 
  barometer 
  at 
  any 
  particular 
  station, 
  when 
  the 
  wind 
  blows 
  from 
  any 
  quarter, 
  

   may 
  be 
  known. 
  

  

  