﻿MECHANICAL 
  ACTION 
  OF 
  HEAT. 
  193 
  

  

  pressure 
  is 
  equal 
  to 
  that 
  of 
  liquid 
  water 
  x 
  0305. 
  Its 
  dynamical 
  value 
  is 
  

   therefore 
  

  

  K 
  P 
  = 
  ft 
  + 
  ^-^ 
  = 
  1389*6 
  x 
  0-305 
  

  

  = 
  422*83 
  feet= 
  129-18 
  metres 
  per 
  centigr. 
  degree. 
  

   CnM' 
  

  

  But 
  p 
  — 
  =-==153-48 
  feet 
  = 
  46*78 
  metres 
  per 
  centigr. 
  degree. 
  

  

  Therefore 
  the 
  real 
  specific 
  heat 
  is 
  

  

  ft 
  =269*35 
  feet= 
  82-40 
  metres 
  per 
  centigr. 
  degree. 
  

  

  Or, 
  that 
  of 
  liquid 
  water 
  being 
  taken 
  as 
  unity, 
  

  

  Jfe__269 
  1 
  35_ 
  

   K 
  w 
  ~ 
  1389*6 
  

  

  The 
  ratio 
  of 
  these 
  two 
  values 
  of 
  the 
  specific 
  heat 
  of 
  steam 
  is 
  

  

  1 
  + 
  N 
  = 
  1*57. 
  

  

  Their 
  dynamical 
  equivalents 
  for 
  Fahrenheit's 
  scale 
  are 
  

   ft 
  = 
  149*64 
  feet 
  . 
  . 
  . 
  K 
  P 
  = 
  235*46 
  feet. 
  

  

  Neither 
  the 
  formulae 
  in 
  the 
  fourth 
  Section, 
  respecting 
  the 
  working 
  of 
  the 
  

   steam-engine, 
  nor 
  the 
  tables 
  at 
  the 
  end 
  of 
  the 
  paper, 
  require 
  any 
  alteration 
  ; 
  for 
  

   the 
  action 
  of 
  steam 
  at 
  full 
  pressure 
  being 
  calculated 
  from 
  data 
  independent 
  of 
  

   its 
  specific 
  heat, 
  is 
  not 
  at 
  all 
  affected 
  by 
  the 
  discrepancy 
  I 
  have 
  mentioned 
  ; 
  and 
  

   the 
  expansive 
  action 
  is 
  not 
  affected 
  to 
  an 
  extent 
  appreciable 
  in 
  practice. 
  

  

  