PROFESSOR FORBES ON THE TEMPERATURE OF THE EARTH. 217 



Subtracting (5) from (4), 



4:1)1 x=a (A — B) 



and substituting the value of a just found 



_m A-B 



*~2 ■ A + B 



which determines the position of the greatest ordinate, whence that ordinate may 

 be deduced. 



The results are contained in the following table. 



Table XVIII. 



These results, obtained in a different manner, may be compared with those 

 in Tables VIII. and XIII. The inspection of the deviations of the annual curve 

 in Plate VII., from the average results in Plate VIII., illustrates well the remark- 

 able variations in the character of the seasons in these five years, and renders it 

 probable that the mean effects of ordinary atmospheric temperatures throughout 

 the year may be most conveniently and accurately studied, and the annual curve 

 ascertained, by observations at a moderate depth in the soil. 



F. 071 the Influence of" Specific Heaf on the Results. 

 The quantity which we have, in page 208, called B (after M. Quetelet*) is 

 equal to 



- — log e 



Where tr = 3-1416, e is the base of natural logarithms, and a the symbol used by 



* Annales, &c., vol. iv. p. 112. 



VOL XVI. PART II. 



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