﻿192 
  MR 
  W. 
  J. 
  M. 
  RANKINE 
  ON 
  THE 
  

  

  Specific 
  Heat 
  of 
  Atmospheric 
  Air 
  as 
  Compared 
  with 
  Liquid 
  Water.— 
  (Section 
  II 
  

  

  Article 
  14.) 
  

  

  The 
  dynamical 
  values 
  of 
  the 
  specific 
  heat 
  of 
  atmospheric 
  air 
  are 
  calculated 
  

   independently 
  from 
  the 
  velocity 
  of 
  sound, 
  without 
  reference 
  to 
  the 
  specific 
  heat 
  

   of 
  liquid 
  water 
  ; 
  and 
  from 
  the 
  closeness 
  of 
  the 
  agreement 
  of 
  the 
  experiments 
  of 
  

   M.M. 
  Bravais 
  and 
  Martins, 
  Moll 
  and 
  Van 
  Beek, 
  Stampfer 
  and 
  Myrbach, 
  

   Wertheim 
  and 
  others, 
  it 
  is 
  clear 
  that 
  the 
  limits 
  of 
  error 
  are 
  about 
  ^q 
  for 
  the 
  

   velocity 
  of 
  sound, 
  ^ 
  for 
  the 
  ratio, 
  and 
  from 
  jg 
  to 
  jq 
  for 
  the 
  dynamical 
  values 
  of 
  

   the 
  specific 
  heat 
  of 
  air, 
  at 
  constant 
  volume 
  and 
  constant 
  pressure. 
  Those 
  values, 
  

   as 
  given 
  by 
  Equation 
  27, 
  are 
  — 
  

  

  Real 
  specific 
  heat, 
  — 
  

  

  ft 
  — 
  238-66 
  feet 
  = 
  72*74 
  metres 
  per 
  centigrade 
  degree. 
  

   = 
  132-6 
  feet 
  per 
  degree 
  of 
  Fahrenheit. 
  

  

  Apparent 
  specific 
  heat 
  under 
  constant 
  pressure, 
  — 
  

  

  K 
  P 
  =334 
  feet 
  =101-8 
  metres 
  per 
  centigrade 
  degree. 
  

   = 
  185-6 
  feet 
  per 
  degree 
  of 
  Fahrenheit. 
  

  

  The 
  ratio 
  of 
  these 
  two 
  quantities 
  being 
  taken 
  as 
  

  

  5?=l 
  + 
  N=l-4 
  

  

  K 
  

  

  The 
  dynamical 
  equivalent 
  of 
  the 
  specific 
  heat 
  of 
  liquid 
  water, 
  as 
  determined 
  

   by 
  Mr 
  Joule, 
  is 
  

  

  K 
  w 
  = 
  1389*6 
  feet 
  =423-54 
  metres 
  per 
  centigrade 
  degree. 
  

   = 
  772 
  feet 
  per 
  degree 
  of 
  Fahrenheit. 
  

  

  The 
  specific 
  heat 
  of 
  air, 
  that 
  of 
  liquid 
  water 
  being 
  taken 
  as 
  unity, 
  has 
  there- 
  

   fore 
  the 
  following 
  values 
  : 
  — 
  

   Real 
  specific 
  heat, 
  — 
  

  

  132J6 
  

   K 
  w 
  772 
  ' 
  ' 
  

  

  Apparent 
  specific 
  heat 
  under 
  constant 
  pressure, 
  — 
  

  

  =0-2404 
  

  

  K 
  P 
  185-6 
  

  

  K 
  w 
  ~ 
  772 
  

  

  This 
  last 
  quantity, 
  according 
  to 
  De 
  la 
  Roche 
  and 
  Berard, 
  is 
  

  

  0-2669 
  

  

  The 
  discrepancy 
  being, 
  . 
  . 
  00265 
  

  

  or 
  one-ninth 
  of 
  the 
  value 
  according 
  to 
  Mr 
  Joule's 
  equivalent. 
  

  

  Specific 
  Heat 
  of 
  Steam. 
  (Section 
  III. 
  Art. 
  20.) 
  

   The 
  apparent 
  specific 
  heat 
  of 
  steam 
  (Eq. 
  34 
  and 
  36) 
  as 
  a 
  gas 
  under 
  constant 
  

  

  