
PROFESSOR FORBES ON THE TEMPERATURE OF THE EARTH. 207 
POWER OF THE DIFFERENT SOILS OR ROCKS FOR HEAT is very palpable. But to 
submit it to numerical calculation, a more elaborate analysis is necessary. Each 
year has been first considered by itself, and then the whole united. 
C. Thermometric Ranges. 
To ascertain the range for each year, the maximum and minimum points of 
the curves of each thermometer were ascertained graphically by the aid of an 
elastic wire, bent so as to represent a curve which should pass through the zig- 
zags of the temperature curve, and connect the observed points with tolerable 
accuracy. The points of greatest and least temperature in each year were thus 
represented with a certain degree of approximation, and the results are shewn in 
the following table. 
TABLE VILL. SHEWING THE MAXIMUM AND MINIMUM TEMPERATURE AND RANGE 
FOR EACH OF FIVE YEARS. 
Observatory, Trap. Experimental Garden, Sand. Craigleith, Sandstone. 


: ate Range = rae Range, “ oon Range, 
Maxi- Mini- | pahren- || Maxi- Aultievic SRL eaa Maxi- Mino ravens 
mum. mum. wows mum. mum. Tact, mum. mum. heit. 
1837-38 || 56-25 | 37-30 | 18°95 || 57-20 | 37°55 | 19-65 || 55-90 | 37°65 | 14-25 
1838-39 || 53-40 | 35°70 | 17-70 || 55:45 | 35-12 | 20°33 | 53-90| 35:38 | 18:52 
1839-40 |] 53-05 | 38:10| 15-55 || 56-50| 37-50 | 19-00 || 54:30 | 37-85 | 16-45 
1840-41 || 53-87 | 38:95 | 14-92 || 56-35 | 38:10 | 18:25 || 55°10 | 38-95 
1841-42 || 52°85 | 38:88 | 13-97 || 54:50 | 37-85 | 17-65 || 53:15 | 38-25 
1837-38 || 52°30 | 40°40 | 11°90 || 54:65 | 39°70 | 14:95 || 53:80 | 39-90 
1838-39 || 50°90 | 39°70 | 11:20 || 53°20) 38°63 | 14°57 || 52°35 | 38°10 
1839-40 || 50°97 | 40°65 | 10°32 || 53°67 | 39°70 | 13°97 || 52°53 | 39-20 
1840-41 || 51°35 | 41°10] 10°25 || 53°75 | 40°52 | 13 23 || 53°15 | 40.05 
1841-42 || 51:07 | 40°78 52°95 | 39°55 | 13°40 || 51°90 | 38-95 
1837-38 || 49°40 | 43°90 p 50°65 | 43:10] 7:55 || 51:10 | 41-70 
1838-39 || 48°65 | 43°60 : 49°95 | 42°85 : 50°05 | 40°75 
1839-40 || 48:57 | 43°73 ; 50°19 | 43-08 : 49°80 | 41°45 
1840-41 || 48°80 | 44°30 : 50°30 | 43-60 : 50°45 | 42°12 
1841-42 || 49°00 | 44.20 ; 50°40 | 43°50 5 50°30 | 41°60 


1837-38 || 47°85 | 46:40 : 48:25 | 46°15 : 48°50 | 44°40 
1838-39 || 47°45 | 46:20 ; 47°88 | 46-00 3 47°88 | 44:05 
1839-40 || 47°35 | 45°97 ; 47°40 | 45°97 : 47°82 | 43°87 
1840-41 || 47°38 | 46°15 : 48°00 | 46°10; 1: 48°12 | 44°40 
1841-42 || 47°50 | 46:12 : 48°10 | 46°10 : 48°25 | 44°35 












Theory shews, that the annual range ought to decrease in geometrical pro- 
gression, as the depths increase uniformly. In other words, the ranges may be 
represented by the ordinates of a logarithmic curve. And that such is the case 
may be seen from the curves in Plates IX. and X., where the logarithmic curves 
are drawn through points so as to represent, as well as is practicable, the law of 
decreasing range at the different stations. These diagrams were constructed with- 
out any reference to one another; and their general coincidence is highly satis- 
factory. 
