﻿288 
  PROFESSOR 
  W. 
  THOMSON 
  ON 
  THE 
  DYNAMICAL 
  THEORY 
  OF 
  HEAT. 
  

  

  is, 
  that 
  the 
  steam 
  in 
  rushing 
  through 
  the 
  orifice 
  produces 
  mechanical 
  effect 
  which 
  

   is 
  immediately 
  wasted 
  in 
  fluid 
  friction, 
  and, 
  consequently 
  reconverted 
  into 
  heat, 
  

   so 
  that 
  the 
  issuing 
  steam 
  at 
  the 
  atmospheric 
  pressure 
  would 
  have 
  to 
  part 
  with 
  as 
  

   much 
  heat 
  to 
  convert 
  it 
  into 
  water 
  at 
  the 
  temperature 
  100° 
  as 
  it 
  would 
  have 
  had 
  

   to 
  part 
  with 
  to 
  have 
  been 
  condensed 
  at 
  the 
  high 
  pressure 
  and 
  then 
  cooled 
  down 
  

   to 
  100 
  , 
  which, 
  for 
  a 
  pound 
  of 
  steam, 
  initially 
  saturated 
  at 
  the 
  temperature 
  t, 
  is, 
  

   by 
  Regnault's 
  modification 
  of 
  Watt's 
  law, 
  -305 
  (t- 
  100) 
  more 
  heat 
  than 
  a 
  pound 
  

   of 
  saturated 
  steam 
  at 
  100° 
  would 
  have 
  to 
  part 
  with 
  to 
  reduce 
  it 
  to 
  the 
  same 
  state 
  ; 
  

   and 
  the 
  issuing 
  steam 
  must, 
  therefore, 
  be 
  above 
  100° 
  in 
  temperature, 
  and 
  dry. 
  

  

  