AT NIGHT, FROM THE EARTH, ETC 
157 
the ground immediately under others placed on the top of long and short grass ; all 
the observations thus taken have been copied out, and the difference between every 
consecutive pair of observations has been consulted with respect to the interval 
of time between them. The results of this investigation are contained in the follow- 
ing tables : — 
Table XL VI. 
Showing the quantity and the rapidity of heat conducted from one inch below the 
surface of the soil, to the surface and to the top of grass. 
Year, month and 
day. 
Mean 
reading of 
a thermo- 
meter in 
air at the 
height of 
four feet. 
Long grgss. 
Short 
grass. 
The decrease per hour in the 
reading of a thermometer placed 
Number of hours 
during which the 
readings were 
frequently ex- 
amined and from 
which the results 
were deduced. 
Amount by which the reading of a 
thermometer read less when placed 
On the top 
of long 
grass than 
that in air 
at the 
height of 
four feet. 
On the top 
of long 
grass than 
that on the 
surface of 
ground 
under long 
grass. 
On the top 
of short 
grass than 
that in air 
at the 
height of 
four feet. 
On the top 
of short 
grass than 
that under 
short grass. 
Under 
short grass 
than that 
one inch 
beneath the 
surface of 
ground. 
On the top 
of short 
grass than 
that one 
inch below 
the surface 
immedi- 
ately under. 
On the 
surface of 
ground 
under long 
grass. 
On the 
surface of 
ground 
under short 
grass. 
One inch 
below the 
surface of 
ground 
under short 
grass. 
Long 
grass. 
Short 
grass. 
1843, Dec. 11. 
40-0 
o 
8-2 
100 
7-4 
7-2 
3-7 
10° 9 
0-5 
0-8 
0-6 
h 
6 
h 
5 
14. 
44-9 
60 
3-4 
5-6 
2-6 
1-5 
41 
0-3 
0-4 
0-7 
2 
2 
15. 
45-7 
5-3 
3-5 
5-2 
1-8 
1-2 
3 0 
0-3 
13 
0-7 
13 
i 
15. 
45-7 
... 
0-6 
0-4 
4 
17. 
42-3 
7-7 
7-2 
6-8 
49 
24 
7-3 
0-2 
0-3 
0-4 
io 
10 
1844, Jan. 6. 
43-5 
51 
1-9 
3-4 
5-3 
10 
10 
2 
22. 
35-9 
10 0 
7-5 
8-9 
7'2 
1-8 
90 
ii 
1-2 
0-6 
2 
3 
26. 
42-7 
9-8 
4*5 
7-4 
1-5 
3-3 
4-8 
0-3 
0-6 
0-8 
2 
2 
30. 
44-9 
8-4 
5-5 
6-6 
1*5 
1-4 
2-9 
0-5 
M 
1 
i 
Feb. 1. 
31-7 
7-2 
9-2 
5-5 
6 9 
21 
90 
0-4 
0-4 
0-4 
6 
6 
15. 
34-6 
10-6 
11-5 
7-7 
73 
2-9 
10-2 
0-4 
01 
0-4 
4 
4 
16. 
39-6 
8-7 
7-0 
8-0 
4-9 
1-2 
61 
0-7 
05 
0-8 
6 
5 
20. 
33-4 
6-7 
6-5 
3-0 
9-5 
M 
0-3 
3 
22. 
25-8 
7 5 
13 7 
61 
10-9 
21 
130 
0-3 
02 
0-2 
12 
12 
28. 
35 0 
6-2 
8-0 
... 
03 
7 
March 20. 
30-8 
84 
12-8 
0-3 
9 
21. 
376 
10-8 
9-2 
0-4 
2 
23. 
39-7 
12 5 
1 1-4 
0-3 
1 
April 1. 
420 
9-7 
111 
8-4 
5-8 
5-4 
11-2 
0-6 
6-3 
0-2 
10 
8 
2. 
49-2 
9-7 
8-4 
8-2 
5-4 
3-8 
9-2 
1-8 
10 
1-2 
4 
4 
3. 
47-0 
1 1-4 
8-8 
9-5 
2-5 
3-3 
5-8 
0-4 
01 
0-6 
11 
6 
8. 
44-9 
130 
8-3 
112 
6-8 
3-4 
102 
0-6 
0-4 
0-8 
10 
7 
9. 
52-6 
130 
9-2 
1 1-2 
3-6 
5-3 
8-9 
0-8 
10 
10 
1 
1 
17. 
46-5 
9-4 
75 
90 
40 
5-5 
9-5 
04 
0-3 
0-4 
6 
8 
18. 
42- 1 
119 
12-4 
... 
0-7 
9 
23. 
54-7 
73 
5-5 
7-0 
30 
2-7 
5-7 
1-2 
0-8 
1-6 
2 
1 
24. 
45 5 
150 
13-7 
12-8 
5-4 
7-7 
131 
10 
1-2 
0-3 
3 
3 
25. 
50-2 
100 
9-2 
91 
40 
6 0 
100 
20 
20 
1-5 
12 
10 
27. 
470 
90 
9-9 
6-3 
16-2 
21 
2-2 
2 
29. 
40-8 
8-3 
5-8 
7-3 
7-8 
1-9 
9-7 
i-2 
0-6 
0-2 
2 
4 
May 1. 
460 
11-4 
no 
9-9 
5-8 
61 
11-9 
1-2 
1-2 
1-2 
10 
9 
By taking the mean of the numbers in each column, we find that — 
The mean reading of a thermometer placed on long grass was less than that 
in air by 9 5 
The mean reading of a thermometer placed on short grass was less than that 
in air by 8 0 
The mean reading of a thermometer placed on long grass was less than that 
under long grass by 
87 
