74 



Professors Ayrton and Perry on the 



We have made the calculations for various points on curve 

 A B C D (fig. 1), knowing that pl-i-T is constant (see § 3). 



Table VIII. 



1. 



p. 



Absolute 

 tempera- 

 ture. 

 T. 



Tempera- 

 ture of 

 fluid. 



t°0. 



t° -60° C. 



Ordinate of 

 semicircle. 



Ratio. 



•889 



44-5 



476 



203 



143 







QO 



•949 



86 



982 



709 



649 



28 



23-18 



•989 



105 



1244 



974 



914 



35-5 



25-74 



1-089 



126 



1644 



1371 



1311 



48 



27-33 



1-389 



90 



1496 



1223 



1163 



65 



17-89 



1-689 



66 



1344 



1071 



1011 



66 



15-32 



2-089 



49 



1231 



958 



898 



40 



22-45 



From some diagrams examined by us we find that the fluid 

 may have as high a temperature as 1900° C. 



The temperature of the water leaving the water-jacket was 

 about 60° C. ; and we may for our purposes assume that the 

 rate at which the fluid loses heat to the cylinder is proportional 

 to the excess of its temperature above 60° C, so that t— 60° 

 represents, to some scale, the fluid's loss of heat to the 

 cylinder per second. This rate of loss is shown on the curve 

 AB(fig.6>_ 



Now if H is the quantity of heat which has been given by 



JTT 



the fluid to the cylinder-jacket at the time t, then -7— is 

 represented by the ordinate of the curve A B. But 

 dR_dRdr dK^dX^ 



dX ~~ dr d\ dr ' dr' 



and as the piston-motion is very nearly 



X=r(l— cosar), 

 dX 

 dr 



that is, -j- is proportional to the ordinate of a semicircle CE F. 



Describing the semicircle C E F with a diameter equal to the 

 length of the stroke, and dividing the ordinates of A B by 

 those of C E F, we obtain the curve G H I, whose ordinate at 

 any point represents the rate of the fluid's loss of heat to the 

 cylinder per foot of piston-motion ; so that the whole area 



ra sin ar 



