﻿380 
  

  

  CORRECTION 
  TO 
  BAROMETER 
  FOR 
  FORCE 
  OF 
  WIND. 
  

  

  cock 
  which 
  confines 
  the 
  compressed 
  air 
  is 
  turned, 
  the 
  air 
  rushes 
  out 
  by 
  the 
  larger 
  

   tube, 
  drawing 
  with 
  it 
  part 
  of 
  the 
  air 
  which 
  was 
  in 
  the 
  two 
  boxes, 
  and 
  causing 
  a 
  

   partial 
  vacuum 
  — 
  as 
  is 
  demonstrated 
  by 
  the 
  fall 
  of 
  the 
  barometers 
  in 
  each 
  box. 
  

  

  Sir 
  John 
  Leslie's 
  experiment 
  is 
  of 
  a 
  more 
  simple 
  nature, 
  and 
  will 
  be 
  under- 
  

   stood 
  at 
  once 
  by 
  reference 
  to 
  the 
  wood-cut. 
  

  

  Fig. 
  3. 
  

  

  By 
  blowing 
  through 
  a 
  cylinder, 
  to 
  the 
  lower 
  sides 
  of 
  which 
  a 
  glass 
  syphon, 
  

   partially 
  filled 
  with 
  water, 
  is 
  attached, 
  he 
  found 
  that 
  if 
  the 
  eduction-pipe 
  was 
  

   larger 
  than 
  the 
  one 
  through 
  which 
  he 
  blew, 
  that 
  a 
  partial 
  vacuum 
  was 
  formed 
  in 
  

   the 
  cylinder, 
  as 
  indicated 
  by 
  the 
  rise 
  of 
  the 
  water 
  in 
  the 
  leg 
  of 
  the 
  syphon 
  

   attached 
  to 
  it 
  ; 
  but 
  by 
  reversing 
  the 
  instrument 
  and 
  blowing 
  through 
  the 
  larger 
  

   tube, 
  he 
  found 
  that 
  the 
  air 
  was 
  compressed 
  in 
  the 
  cylinder, 
  and 
  caused 
  a 
  depres- 
  

   sion 
  in 
  that 
  leg 
  of 
  the 
  syphon. 
  

  

  In 
  the 
  experiments 
  of 
  Bernouilli 
  and 
  Ventukt, 
  the 
  rush 
  of 
  a 
  stream 
  of 
  water 
  

   through 
  a 
  horizontal 
  tube 
  made 
  wide 
  at 
  the 
  end 
  by 
  which 
  the 
  water 
  escapes, 
  is 
  

   shewn 
  to 
  have 
  the 
  effect 
  of 
  drawing 
  up 
  water 
  through 
  a 
  smaller 
  pipe 
  leading 
  

   into 
  it. 
  

  

  In 
  fig. 
  4. 
  it 
  is 
  shewn 
  that 
  the 
  water 
  is 
  drawn 
  up 
  and 
  carried 
  away 
  by 
  the 
  rush 
  

  

  Fig. 
  4. 
  

  

  