132 Proceedings of the Poyal Society of Edinburgh. [Sess. 
1918, and February 8-11, 1919. During these periods hard frost took 
place each night, and the day temperature seldom rose above 32° F. 
The soil under the moss and grass has never frozen all winter, and it 
is interesting to note that the only occasion when it was near it was on 
February 5, 1919, after snow and rain, with a relatively high grass 
minimum of 28° F. 
Table V. 
Date. 
Grass 
mini- 
mum . 
Open 
soil. 
Soil 
covered 
\ in. fallen 
leaves. 
Soil covered | in. moss 
and longish grass. 
Remarks. 
1918. 
December 15 
26-5 
Frozen to 
Not frozen 
Not frozen 
Minimum 
„ 16 
26-0 
depth of 
Temperatures — 
surface tem- 
„ 17 
26*0 
3 in. 
(a) Just under moss 330 
perature of 
„ 18 
26-5 
(6) 2 in. depth 34*5 
open soil, 
19 
25-0 
(c) 4 in. „ 36-0 
28*5 
„ 20 
24*5 
„ 21 
27-5 
„ 22 
25-0 
December 23 
32-0 
Frozen to 
Not frozen 
Not frozen 
„ 24 
29-0 
depth of 
Temperatures — 
„ 25 
30-0 
2 in. 
(a) Just under moss 34*0 
„ 26 
25’5 
( b ) 2 in. depth 36’0 
(c) 4 in. „ 37*5 
1919. 
February 5 
28-0 
Frozen to 
Frozen 
Not frozen but on point 
After snow 
depth of 
of freezing 
and rain on 
i in. 
previous 
afternoon 
February 17 
26-0 
Frozen to 
Not frozen 
Not frozen 
Very cold 
depth of 
N.E. wind 
fin. 
— a freeze 
February 8 
26*0 
Frozen to 
Frozen to 
Not frozen 
Minimum 
55 9 
17-5 
depth of 
depth of 
Temperatures — 
surface tem- 
,5 10 
15-0 
4 in. 
^ in., but 
(a) Just under moss 32’25 
perature of 
„ 11 
22-0 
not till 
( b ) 2 in. depth 33*0 
open soil, 
open sur- 
(c) 4 in. „ 34 - 0 
22-0 
face fell 
to 25-0 
The maximum thermal efficiency of the various coverings seems to 
be as follows: — 
°F. 
(1) Loose raked soil 
3*0 
(2) Ashes 
6*0 
(3) Manure 
6-5 
(4) Fallen leaves 
7-0 
(5) Natural moss and grass 
100 
