AT NIGHT, FROM THE EARTH, ETC. 
205 
Table (Continued). 
Seneral state 
of the sky 
during the 
ight previous 
o reading the 
instruments. 
Situation of the thermometer. 
The mean yearly excess, according to the state of the sky, of the reading'of a self- 
registering minimum thermometer placed in air at the height of 4 feet, and protected 
from radiation, above that of a similar thermometer placed on different substances. 
1843. 
1844. 
1843 and 1844. 
Number 
of 
nights. 
Sum of 
excesses. 
Mean 
excess. 
Number 
of 
nights. 
Sum of 
excesses. 
Mean 
excess. 
Whole 
number 
of 
nights. 
Whole 
sum of 
excesses. 
Mean 
excess. 
Principally 
On long grass exposed to Jths of the sky 
37 
178-5 
4°-8 
o 
o 
37 
178-5 
o 
4-8 
clear. 
On long grass fully exposed to the sky 
22 
1 79-2 
8-1 
55 
195-2 
9-0 
77 
374-4 
4-9 
On short grass 
61 
410-7 
6-7 
55 
427-7 
7-8 
116 
838-4 
7-2 
On garden mould 
17 
55-6 
3-3 
17 
55'6 
3-3 
One inch above grass 
52 
368-3 
7-1 
52 
368-3 
7-1 
Three inches above grass 
41 
295-1 
7-1 
41 
295-1 
7-2 
Six inches above grass 
6 
18-7 
3-2 
6 
18-7 
3-1 
On white raw wool 
14 
122-6 
8-8 
35 
299-7 
8-6 
49 
422-3 
3-6 
On fine flax 
9 
82-6 
9-2 
54 
482-2 
8-9 
63 
564-8 
9 0 
On coarse flax 
12 
100-2 
8-3 
12 
100-2 
8-4 
On white unwrought cotton wool 
7 
57-2 
8-2 
1 
7 
57-2 
8-2 
On lead 
11 
61-1 
5-5 
1 1 
61-1 
5-6 
On blackened tin 
5 
29-6 
5-9 
13 
97-8 
7-5 
18 
127-4 
7-1 
On white tin 
5 
24-3 
4-9 
13 
91-9 
7-1 
18 
116-2 
6-4 
In focus of metallic reflector 
78 
591-1 
7-6 
55 
374-4 
6-8 
133 
965-5 
7-3 
Cloudless. 
On long grass exposed to fths of the sky 
22 
143-6 
6-5 
22 
143-6 
6*5 
On long grass fully exposed to the sky 
21 
203-0 
9-7 
100 
920-2 
9-2 
121 
1123-2 
9-3 
On short grass 
47 
322-1 
6-9 
98 
866-1 
8-9 
145 
1188-2 
8-2 
On garden mould 
13 
73-8 
5-7 
13 
73-8 
5*7 
One inch above grass 
38 
341-2 
5-7 
38 
341-2 
9-0 
c 
Three inches above grass 
29 
214-0 
7-4 
29 
214-0 
7-4 
Six inches above grass 
1 
5-2 
5-2 
1 
5-2 
5-2 
On white raw wool 
13 
153-5 
11-8 
60 
726-2 
12-1 
73 
879-7 
12-1 
On fine flax 
17 
146-6 
8-6 
91 
1123-6 
12-3 
108 
1270-2 
11-8 
On coarse flax 
12 
131-7 
11-0 
12 
131-7 
10-9 
On white unwrought cotton wool 
11 
113-1 
10-3 
11 
113-1 
10-3 
On lead 
29 
245-8 
8-5 
29 
245-8 
8-5 
On blackened tin 
5 
40-1 
8-0 
5 
40-1 
8-0 
On white tin 
5 
39-8 
8-0 
5 
39-8 
7-9 
In focus of metallic reflector 
81 
768-1 
9-5 
99 
770-1 
7-8 
180 
1538-2 
8-5 
An examination of this Table shows, that on cloudy nights the results derived from 
every substance, with the single exception of garden mould, are nearly the same ; 
and on partially cloudy nights they are different ; the greatest differences occurring on 
cloudless nights. The reading of the thermometer on garden mould was always the 
nearest to the reading of the thermometer in the air ; those on raw wool and on flax 
departed the most from it ; and those placed, at the distance of one inch to two inches 
above the top of grass, on a sheet of lead or tin, were all higher than that on garden 
mould and less than that on wool ; and they were all nearly identical with that of the 
thermometer in the reflector, notwithstanding much heat during the course of a 
whole night must have passed from the earth to the surface of the lead and tin, which 
were placed on it. 
