﻿204 
  MR 
  W. 
  J. 
  M. 
  RANKINE 
  ON 
  EXPANSIVE 
  STEAM-ENGINES. 
  

  

  The 
  expenditure 
  of 
  steam 
  per 
  annum 
  is 
  

  

  2038 
  x 
  6000 
  = 
  12,228,000 
  lb. 
  

   Hence 
  we 
  have 
  the 
  following 
  estimate 
  : 
  — 
  

  

  Cost 
  of 
  engine, 
  24-072 
  square 
  feet 
  of 
  piston 
  at 
  £250, 
  . 
  £6018000 
  

   Cost 
  of 
  boilers, 
  32-608 
  tons 
  at 
  £27, 
  . 
  . 
  . 
  880416 
  

  

  Total 
  capital 
  expended, 
  £6898-416 
  

  

  Interest 
  at 
  five 
  per 
  cent, 
  per 
  annum, 
  . 
  . 
  . 
  £344-921 
  

  

  Cost 
  of 
  fuel 
  per 
  annum, 
  12,228,000 
  lb. 
  of 
  steam 
  at 
  0-01d., 
  509-500 
  

  

  Annual 
  cost 
  for 
  interest 
  and 
  fuel, 
  £854-421 
  

  

  I 
  wish 
  it 
  to 
  be 
  understood 
  that 
  the 
  rates 
  I 
  have 
  adopted 
  in 
  the 
  foregoing 
  

   calculations, 
  for 
  interest, 
  cost 
  of 
  fuel, 
  and 
  cost 
  of 
  construction, 
  are 
  not 
  intended 
  

   as 
  estimates 
  of 
  their 
  average 
  amount, 
  nor 
  of 
  their 
  amount 
  in 
  any 
  particular 
  case, 
  

   but 
  are 
  merely 
  assumed 
  in 
  order 
  to 
  illustrate, 
  by 
  a 
  numerical 
  example, 
  the 
  rules 
  

   laid 
  down 
  in 
  the 
  preceding 
  article. 
  It 
  is 
  of 
  course 
  the 
  business 
  of 
  the 
  engineer 
  

   to 
  ascertain 
  those 
  data 
  with 
  reference 
  to 
  the 
  special 
  situation 
  and 
  circumstances 
  

   of 
  the 
  proposed 
  work 
  ; 
  and 
  having 
  done 
  so, 
  the 
  method 
  explained 
  in 
  this 
  paper 
  

   will 
  enable 
  him 
  to 
  determine 
  the 
  dimensions 
  and 
  ratio 
  of 
  expansion 
  which 
  ought 
  

   to 
  be 
  adopted 
  for 
  the 
  engine, 
  in 
  order 
  that 
  it 
  may 
  effect 
  its 
  duty 
  with 
  the 
  greatest 
  

   possible 
  economy. 
  

  

  