MOTIVE POWER OF HEAT. 171 



EXPLANATION OF TABLE II. 



38. The calculation of the mechanical effect, in 

 any case, which might always be effected in the 

 manner described in 37 (with the proper modifi- 

 cation for fractions of degrees, when necessary), is 

 much simplified by the use of Table II., where the 

 first number of Table I., the sum of the first and 

 second, the sum of the first three, the sum of the 

 first four, and so on, are successively exhibited. 

 The sums thus tabulated are the values of the in- 

 tegrals 



/I />2 />3 /*2 



pdt, I pdt, I dt,.... I 

 e/0 I/O t/0 



and, if we denote / pdt by the letter M, Table II. 



may be regarded as a table of the value of M. 



To find the amount of mechanical effect due to a 

 unit of heat descending from a body at a tempera- 

 ture 8 to a body at T, if these numbers be integers, 

 we have merely to subtract the value of M, for the 

 number T, from the value for the number S, given 

 in Table II 



