﻿402 
  SUNDRY 
  IMPROVEMENTS 
  IN 
  

  

  HYDRO-PNEUMATIC 
  CISTERN. 
  

  

  Fig. 
  1. 
  In 
  Silli 
  man's 
  Journal 
  will 
  be 
  found 
  an 
  engraving 
  and 
  descrip- 
  

   tion 
  of 
  a 
  pneumatic 
  cistern, 
  which 
  I 
  employed 
  in 
  the 
  experimental 
  

   illustrations 
  of 
  my 
  lectures 
  for 
  more 
  than 
  ten 
  years 
  ; 
  and 
  which 
  I 
  should 
  

   probably 
  continue 
  to 
  use 
  now, 
  had 
  not 
  the 
  command 
  of 
  water 
  from 
  the 
  

   public 
  works, 
  put 
  it 
  into 
  my 
  power 
  to 
  dispense 
  with 
  the 
  mechanism 
  

   for 
  keeping 
  the 
  water 
  at 
  a 
  proper 
  level. 
  As 
  I 
  am 
  now 
  situated, 
  any 
  

   deficit 
  of 
  water 
  is 
  easily 
  supplied 
  from 
  the 
  pipes 
  known 
  here 
  as 
  the 
  

   hydrant 
  pipes, 
  by 
  which 
  the 
  city 
  is 
  supplied 
  with 
  water; 
  and 
  any 
  ex- 
  

   cess 
  is 
  carried 
  off 
  by 
  a 
  waste 
  pipe. 
  Many 
  chemists 
  designate 
  as 
  a 
  

   pneumatic 
  trough 
  or 
  tub, 
  apparatus 
  for 
  the 
  purposes 
  to 
  which 
  that 
  in 
  

   question 
  is 
  applied. 
  Neither 
  of 
  these 
  names 
  is, 
  in 
  my 
  opinion, 
  as 
  ap- 
  

   plicable 
  to 
  the 
  apparatus 
  which 
  I 
  have 
  hitherto 
  used, 
  as 
  that 
  of 
  cistern, 
  

   to 
  which 
  I 
  resorted 
  ; 
  and 
  although 
  the 
  last 
  term 
  be 
  less 
  suitable 
  to 
  the 
  

   apparatus 
  which 
  I 
  am 
  about 
  to 
  describe, 
  yet 
  I 
  beg 
  leave 
  to 
  adhere 
  to 
  it 
  for 
  

   want 
  of 
  a 
  better 
  appellation. 
  

  

  A 
  A, 
  a 
  water-tight 
  platform, 
  surrounded 
  by 
  a 
  wooden 
  rim, 
  RRRR, 
  

   rising 
  above 
  it 
  about 
  an 
  inch 
  and 
  a 
  half. 
  B, 
  C, 
  D, 
  three 
  wells 
  or 
  

   cavities, 
  each 
  in 
  the 
  form 
  of 
  a 
  hollow 
  parallelopiped, 
  with 
  all 
  of 
  which 
  

   the 
  cavity 
  bounded 
  by 
  the 
  rim 
  communicates, 
  so 
  that 
  when 
  supplied 
  

   with 
  water 
  to 
  the 
  level 
  of 
  the 
  waste 
  pipe, 
  this 
  liquid 
  fills 
  the 
  wells, 
  and 
  

   covers 
  the 
  platform 
  to 
  the 
  depth 
  of 
  about 
  three-fourths 
  of 
  an 
  inch. 
  

  

  E, 
  F, 
  G, 
  shelves, 
  which 
  severally 
  move 
  in 
  grooves 
  over 
  the 
  wells, 
  so 
  

   that 
  they 
  may 
  be 
  placed 
  in 
  the 
  most 
  convenient 
  position. 
  Under 
  H 
  

   is 
  a 
  waste 
  pipe. 
  At 
  I 
  is 
  a 
  hydrant 
  pipe. 
  K, 
  a 
  pipe 
  for 
  emptying 
  the 
  

   wells 
  and 
  casks, 
  with 
  all 
  of 
  which 
  it 
  maybe 
  made 
  to 
  communicate 
  by 
  

   cocks, 
  when 
  requisite. 
  N, 
  O, 
  casks 
  which 
  act 
  as 
  gas 
  holders, 
  each 
  

   having 
  a 
  communication 
  with 
  the 
  cistern 
  at 
  Q 
  or 
  q, 
  for 
  letting 
  in 
  

   water 
  from 
  that 
  source 
  ; 
  the 
  orifices 
  being 
  controlled 
  by 
  valves. 
  By 
  

   means 
  of 
  a 
  pipe 
  proceeding 
  from 
  its 
  vertex, 
  each 
  gas 
  holder 
  communi- 
  

   cates 
  with 
  a 
  pipe 
  or 
  cock, 
  at 
  S 
  or 
  s. 
  

  

  To 
  these 
  gallows 
  screws, 
  flexible 
  leaden 
  pipes 
  may 
  be 
  attached, 
  for 
  

   transferring 
  gas 
  either 
  from 
  one 
  of 
  the 
  holders 
  to 
  a 
  bell 
  glass, 
  or 
  from 
  

   a 
  bell 
  glass 
  to 
  one 
  of 
  the 
  holders. 
  When 
  a 
  communication 
  is 
  esta- 
  

  

  