
PROFESSOR FORBES ON THE TEMPERATURE OF THE EARTH. 217 
Subtracting (5) from (4), 
4mx=a(A—B) 
and substituting the value of a just found 
m A—B 
DP joN sR 
which determines the position of the greatest ordinate, whence that ordinate may 
be deduced. 
The results are contained in the following table. 
z= 
TABLE XVIII. 
Ne mee ae ee ee ee ae a aU aT Rac Ge Mee mR a ee pene re tte pret ee 








MAXIMA. MINIMA. 
Eprocu. Epoca. 
y q Fraction of | Month and g x Fraction of | Month and 
3 FEET. Year. Day. Year. Day. 
Observatory . . 53°20 | 224° 30! 624 Aug. 16:7|| 36:39 50° 29’ "140 Feb. 21:0 
Experimental Garden 55°73 | 214° 48’ “597 Aug. 7:0|| 37:46 50° 12’ 139 Feb. 20:5 
Craigleith . . .~ 54:29 | 220° 50’ 613 Aug. 12°7|| 37:96 44° 49/ 124 Feb. 15:3 
6 FEET. : 
Observatory . . 51:23 | 240° 19’ “668 Sept. 2:0]/ 41:02 om AW bala Mar. 19:0 
Experimental Garden| 5350 | 235° 29° 654 Aug. 27:7|| 40:12 67° 30/ 188 Mar. 10°7 
Craigleith .. . 52°45 | 234° 39’ "652 Aug. 27:0|| 40:18 538° 00’ 147 Feb. 23:7 
12 FEET. 
Observatory . . 48°85 | 282° 30’ 785 Oct. 14:7]/ 48:86 | 108° 58’ 303 April 21:7 
Experimental Garden 50°23 275° 41’ ‘766 Oct. 77 43°39 109° 15’ -303 April 21°7 
Craigleith .. . 50°14 | 257° 00’ ‘714 Sept. 18°7|| 41-70 77° 00’ *214 Mar. 20:0 
24 FEET. 
Observatory . . 47°53 5° 00’ 014 Jan. 6:0] 46-21 185° 00’ 514 July 7:7 
Experimental Garden 48:01 855° 00’ *986 Dec. 27:0|| 46:17 “75> O0F “486 June 27:3 
Craigleith . . . 48:01 | 303° 00’ "842 Nov. 4:3] 44:18 123° 00’ "342 May 6:0 



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 VIIL., 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. On the Influence of “« Specific Heat” on the Results. 
The quantity which we have, in page 208, called B (after M. QUETELET*) is 
equal to 
ee log e 
Where 7 = 3:1416, ¢ is the base of natural logarithms, and a the symbol used by 
* Annales, &c., vol. iv. p. 112. 
VOL XVI. PART II. ol 
