﻿MECHANICAL 
  ACTION 
  OF 
  HEAT. 
  185 
  

  

  The 
  data 
  in 
  this 
  case 
  for 
  calculating 
  the 
  power, 
  are, 
  

  

  P 
  1 
  = 
  8468 
  lb. 
  per 
  square 
  foot. 
  

   Vj 
  = 
  7 
  - 
  584 
  cubic 
  feet 
  for 
  one 
  lb. 
  of 
  steam. 
  

   P 
  x 
  V 
  1 
  = 
  64221 
  lb. 
  raised 
  one 
  foot. 
  

  

  5^ 
  = 
  I, 
  whence 
  * 
  = 
  8 
  f 
  =5-944. 
  

  

  Maximum 
  possible 
  effect 
  of 
  one 
  pound 
  of 
  water, 
  

  

  = 
  P 
  t 
  Vj 
  x 
  7 
  (l 
  - 
  f^\ 
  F) 
  =115600 
  lb. 
  raised 
  one 
  foot. 
  

  

  Being 
  the 
  mechanical 
  equivalent 
  of 
  92°-3 
  centigrade 
  degrees 
  applied 
  to 
  one 
  

  

  pound 
  of 
  liquid 
  water 
  at 
  0° 
  C. 
  ; 
  or, 
  

  

  92°-3 
  K 
  w 
  

  

  Maximum 
  possible 
  effect 
  of 
  one 
  cubic 
  foot 
  of 
  water, 
  7,225,000 
  lb. 
  raised 
  one 
  foot. 
  

  

  In 
  order 
  to 
  calculate 
  directly 
  the 
  heat 
  converted 
  into 
  power, 
  we 
  have, 
  

   Tj=0 
  + 
  144°-1 
  cent. 
  t 
  2 
  = 
  C 
  + 
  81°-7 
  

   L 
  2 
  = 
  549°-7K 
  W 
  

   H 
  2 
  , 
  1 
  = 
  568°-7 
  K 
  w 
  = 
  heat 
  expended 
  in 
  the 
  boiler. 
  

   I 
  — 
  »? 
  = 
  '14 
  nearly 
  = 
  proportion 
  of 
  steam 
  liquefied 
  during 
  the 
  expansion. 
  

  

  The 
  heat 
  converted 
  into 
  mechanical 
  power, 
  as 
  calculated 
  from 
  these 
  data, 
  is 
  

  

  found 
  to 
  be, 
  

  

  91°-6 
  K 
  w 
  

  

  differing 
  by 
  only 
  o, 
  7 
  from 
  the 
  amount 
  as 
  calculated 
  from 
  the 
  power 
  produced. 
  

  

  The 
  direct 
  method, 
  however, 
  is 
  much 
  less 
  precise 
  than 
  the 
  other, 
  and 
  is 
  to 
  

   be 
  regarded 
  as 
  only 
  a 
  verification 
  of 
  the 
  general 
  principle 
  of 
  calculation. 
  

  

  92-3 
  

   The 
  heat 
  rendered 
  effective, 
  in 
  the 
  above 
  example, 
  is 
  ggg«, 
  or 
  less 
  than 
  one- 
  

   sixth 
  of 
  that 
  expended 
  in 
  the 
  boiler. 
  

  

  As 
  a 
  second 
  example, 
  I 
  shall 
  suppose 
  the 
  steam 
  to 
  be 
  produced 
  at 
  a 
  pressure 
  

   of 
  eight 
  atmospheres, 
  and 
  to 
  expand 
  to 
  that 
  of 
  one 
  atmosphere. 
  In 
  this 
  case, 
  

  

  P 
  x 
  = 
  16936 
  lbs. 
  per 
  square 
  foot. 
  

   V 
  1 
  = 
  403 
  cubic 
  feet 
  per 
  lb. 
  of 
  steam. 
  

   P 
  x 
  V 
  x 
  = 
  68252 
  lbs. 
  raised 
  one 
  foot. 
  

  

  PI 
  ft 
  

  

  "La 
  => 
  ... 
  *=5-657 
  = 
  8 
  6 
  

  

  Maximum 
  possible 
  effect 
  of 
  one 
  pound 
  of 
  water, 
  

  

  = 
  P 
  X 
  V 
  x 
  x 
  6 
  (l- 
  Q) 
  i\ 
  =119,942 
  lb. 
  raised 
  one 
  foot. 
  

  

  Being 
  the 
  equivalent 
  of 
  95 
  0, 
  8 
  K 
  w 
  (Centigrade). 
  

  

  Maximum 
  possible 
  effect 
  of 
  one 
  cubic 
  foot 
  of 
  water 
  = 
  7,496,375 
  lb. 
  raised 
  one 
  foot. 
  

  

  The 
  data 
  for 
  calculating 
  directly 
  the 
  heat 
  rendered 
  effective 
  are, 
  

  

  t 
  x 
  = 
  C 
  + 
  170°-9 
  cent. 
  t 
  2 
  = 
  C 
  + 
  100° 
  

   L 
  2 
  = 
  537°K 
  W 
  

   H 
  2 
  , 
  1 
  = 
  558 
  0, 
  6 
  K 
  w 
  = 
  heat 
  expended 
  in 
  the 
  boiler. 
  

   1 
  — 
  m 
  = 
  *148 
  nearly 
  = 
  steam 
  liquefied 
  during 
  the 
  expansion. 
  

  

  