﻿396 
  

  

  ON 
  THE 
  CAUSE 
  OF 
  THE 
  

  

  A 
  is 
  apipe 
  with 
  a 
  stop 
  cock 
  to 
  allow 
  the 
  air 
  to 
  escape 
  

   on 
  first 
  filling 
  the 
  reservoir. 
  B, 
  a 
  pipe 
  by 
  which 
  a 
  

   communication 
  with 
  the 
  mains 
  of 
  the 
  public 
  water- 
  

   works 
  was 
  established. 
  C, 
  a 
  pipe 
  for 
  delivering 
  the 
  

   water. 
  

  

  The 
  height 
  of 
  the 
  vessel 
  was 
  three 
  feet 
  ; 
  greatest 
  

   diameter 
  eighteen 
  inches, 
  least 
  diameter 
  twelve 
  

   inches. 
  

  

  Some 
  days 
  had 
  elapsed, 
  during 
  which 
  I 
  was 
  unable 
  

   to 
  offer 
  any 
  explanation 
  of 
  the 
  phenomenon; 
  but 
  

   having 
  mentioned 
  the 
  occurrence 
  to 
  another 
  highly 
  

   respectable 
  and 
  intelligent 
  plumber, 
  Mr 
  Ewing, 
  he 
  

   alleged 
  that 
  facts 
  no 
  less 
  surprising 
  had 
  fallen 
  within 
  the 
  range 
  of 
  his 
  

   experience. 
  He 
  had 
  known 
  an 
  opening 
  made 
  in 
  a 
  leaden 
  pipe 
  at 
  one 
  

   time, 
  to 
  be 
  closed 
  at 
  another, 
  by 
  some 
  unaccountable 
  inward 
  pressure 
  ; 
  

   and, 
  upon 
  one 
  occasion, 
  a 
  small 
  fish 
  to 
  be 
  caught 
  in 
  the 
  fissure. 
  

  

  It 
  then 
  occurred 
  to 
  me 
  that 
  the 
  phenomenon 
  of 
  the 
  collapse 
  had 
  been 
  

   the 
  consequence 
  of 
  circumstances 
  the 
  inverse 
  of 
  those 
  which 
  are 
  known 
  

   to 
  take 
  place 
  in 
  the 
  water 
  ram 
  of 
  Montgolfier, 
  in 
  which 
  water, 
  while 
  

   flowing 
  rapidly 
  in 
  a 
  trunk, 
  being 
  stopped 
  suddenly 
  in 
  front, 
  is 
  made 
  to 
  

   produce 
  a 
  jet 
  rising 
  above 
  the 
  level 
  of 
  the 
  head 
  to 
  which 
  the 
  current 
  

   arrested 
  is 
  indebted 
  for 
  existence. 
  

  

  The 
  momentum 
  of 
  the 
  water 
  which 
  is 
  in 
  that 
  case 
  expended 
  in 
  a 
  

   jet, 
  must, 
  in 
  the 
  case 
  in 
  which 
  an 
  arrestation 
  takes 
  place 
  in 
  the 
  rear 
  of 
  

   a 
  given 
  portion 
  of 
  the 
  stream, 
  continue 
  to 
  propel 
  that 
  portion 
  directly 
  

   forwards, 
  causing 
  an 
  hiatus 
  or 
  vacuum 
  between 
  it 
  and 
  the 
  valve 
  or 
  

   cock 
  by 
  which 
  the 
  stoppage 
  has 
  been 
  effected. 
  

  

  The 
  inward 
  pressure, 
  or 
  suction, 
  arising 
  from 
  such 
  a 
  momentum, 
  was 
  

   demonstrated 
  by 
  Venturi 
  ;* 
  and 
  has 
  latterly 
  been 
  ingeniously 
  applied 
  

   to 
  the 
  filling 
  of 
  syphons, 
  and 
  removal 
  of 
  back 
  water 
  from 
  water 
  wheels. 
  

  

  In 
  this 
  view 
  of 
  the 
  subject 
  then, 
  we 
  find 
  the 
  rationale 
  of 
  the 
  collapse 
  

   of 
  the 
  reservoir. 
  

  

  The 
  current 
  through 
  the 
  main 
  being 
  arrested 
  at 
  a 
  point 
  nearer 
  the 
  

   head 
  than 
  that 
  from 
  which 
  the 
  pipe 
  supplying 
  the 
  reservoir 
  proceeded, 
  

  

  Nicholson's 
  Journal, 
  4to 
  series, 
  vol. 
  2, 
  page 
  172. 
  

  

  