172 H. MOLHOLM HANSEN 
42.3 and 14.2. A comparison between the daily temperature amp- 
litudes for rock and sandy soil shows, for the same depths, apart 
from the uppermost layers, a greater amplitude for the solid than 
for the loose soil. All these figures show that sandy soil is a better 
isolator than rocky soil. 
TABLE 36. Average Diurnal Variation of Temperature 
in different Soils with differing Vegetation. After Th. Homén. 
Nos. 1—3 (1897, p: 48); 4—14 (1894, ip. 231). 
Granite BAN Bog Sunny open heath | Forest-clad heath 
heath 
F 10 = VER 10— 15/, 10 - 13/3 12 13/5 6 SJ, 12— 137, ir 6—8/, 
1893 1893 1893 1892 1892 1892 NP 
1 2 3 4 5 6 7 
0 cm depth.. | 20.20 34.60 21.40 18.49 29.00 7.19 | 6.39 
2 ae 161 19.3 9.6 13.0 132 4.3 3.6 
aes Do 13.8 11.8 2.8 94 9.2 PAST | 2.4 
10 » > T7 7.8 1.9 64 6.2 1.5 1.3 
PAV >: eee 729 3.9 0.4 2.9 Ad 0.7 0.6 
40 » SAGE 3.4 0.7 0.05 0.6 0:4 0.2 0.1 
Re = = - i 
i : Clayey 
Sunny open bog | Forest-clad moor Boggy field =. 
field 
13 — 13/5 c= 8/9 12 —13/, 5—8/9 preserv. | harvest. | 12—13/g 
1892 1892 1892 1892  |12-13/,1892! 68/9 1892 | 1892 
er! a ee Bee nn —— 
24,0 10 IE ieee b> 13 14 
ee ee ae ART LENS PR 
| | | | | 
Oremaädeptlee NT ar 899 749 |. 1209 | 18.00 a 
Din > rl 9.5 | 48 4.1 7.4 9.9 6.9 
a ee ta 291 9 Te 4.7 4.0 
ia Se DEEE JAY eden SE ANR 0.7 11 1.2 eae 
a Vihear perenne nay a 02 02 | 03 03 | 20 
40 » » | 0.04 | 0.04 0.02 +: 0.02 | 0.03 0.03 0.3 
| 
| | | | Il 
If, next, the dry soil, the sandy heath, is compared with the 
damp soil, the bog, the above-mentioned deviations are seen to be con- 
tinual. The surface of the bog only attains a temperature maximum of 
27.7°, owing to a great deal of heat becoming latent by evaporation 
of the water present in the bog. At a depth of 60 cm the maximum 
temperature is only 11.70. The minimum temperature of the sur- 
face is no less than 6.3° and is thus the lowest of the temperatures 
