AT NIGHT, FROM THE EARTH, 
ETC. 
147 
Table XLV. 
The mean excess of the reading of a thermometer placed in air at the height of four 
feet above the soil and protected from the effects of radiation, above those of 
thermometers placed on different substances, or in different situations, fully exposed 
to the shy. 
Situation of the thermometer, its bulb, or the substance under which 
it was placed, being fully exposed to the sky. 
Whole 
number of 
compari- 
sons. 
Whole sum of the 
excesses of the 
readings of the 
thermometer in 
air at the height 
of four feet, above 
those placed as 
stated in the first 
column . 
Mean ex- 
cess of the 
reading of 
the ther- 
mometer in 
air. 
Relative 
excess, that 
of long 
grass being 
represented 
by 1000, or 
compara- 
tive radia- 
ting power. 
Remarks. 
On long grass 
479 
4017-7 
3454-7 
8-39 
1000 
On short grass 
473 
7-30 
870 
One inch below the surface of ground under grass 
273 
- 476 1 
- 1-75 
- 209 
On surface of ground under long grass ... . 
156 
85 0 
0-55 
66 
On surface of ground under short grass .. 
259 
437-3 
1-69 
200 
On long grass covered by white raw wool . 
66 
11-9 
0T8 
22 
On long grass covered bv flax 
61 
20-4 
0-35 
42 
On long grass covered by white tin 
35 
119-3 
3-41 
406 
On long grass covered by white tin one inch high. . 
42 
126-3 
300 
357 
On long grass covered bv blackened tin .. .. 
28 
131-9 
4 71 
561 
On long grass covered by lead 
10 
46-7 
4-67 
556 
On long grass covered by lead six inches high . 
13 
40-1 
3-08 
367 
f nerally simultaneous. 
On long grass covered by glass “ 
127 
727-9 
557-5 
601 
716 
On long grass covered by glass one inch high . 
128 
3-35 
399 
J nerally simultaneous. 
On long grass covered by hare-skin 
18 
13-6 
0-75 
89 
On long grass covered by rabbit-skin 
17 
101 
0-60 
72 
j multaneous. 
One inch high above the top of grass (in air) 
226 
1272-9 
5-63 
671 
Two inches high above the top of grass (in air) 
9 
43-0 
4-78 
570 
Thesefactors, multipliedinto 
Three inches high above the top of grass (in air) 
89 
336 1 
4-00 
477 
the mean radiating power of 
any substance, will show the 
cooling effect of that substance 
upon the air, at that distance 
L above it corresponding to the 
Six inches high above the top of grass (in air) " 
165 
394 1 
2-37 
282 
One foot high above the top of grass (in air) . . 
212 
229-4 
1-08 
129 
Two feet high above the top of grass (in air) 
199 
143-3 
0-72 
86 
Four feet high above the top of grass (in air) 
87 
50-3 
0-58 
69 
factor used. 
SLx feet high above the top of grass (in air/ 
18 
7-9 
044 
52 
Eight feet high above the top of grass (in air) 
96 
13-4 
014 
17 
See simultaneous observa- 
tions at 8 feet and 10 feet. 
J 
Ten feet high above the top of grass (in air) 
9 
80-0 
0-89 
Twelve feet high above the top of grass (in air) 
77 
90 
0 12 
14 
On black-lead in powder on the raised board./. 
138 
808-1 
5-85 
697 
On charcoal in powder on the raised board 
153 
996-2 
6-51 
776 
On whiting in powder on the raised board 
67 
465-5 
694 
827 
On chalk in powder on the raised board 
21 
1421 
705 
840 
On lamp-black in powder on the raised board 
14 
1130 
806 
961 
On unwrought white cotton wool on grass 
228 
2074-6 
910 
1085 
On unwrought wdiite cotton wool on the raised board . . . 
On white raw wool on grass 
15 
357 
1277 
3655 1 
8-52 
10-24 
1222 
j tions. 
On flax on grass 
461 
4563-6 
9-90 
1186 
On flax on the raised hoard 
17 
76-3 
6-94 
j ticns. 
On yellow cotton, jeweller’s wool, on grass 
13 
84-1 
6-46 
770 
On yellow cotton, jeweller’s wool, on the raised board... 
On blue cotton, jeweller’s wool, on grass 
56 
12 
4720 
84-6 
8-43 
7-05 
1005 
840 
j were simultaneous. 
On blue cotton, jeweller’s wool, on the raised board 
On white wadding on grass 
55 
27 
460-3 
223 1 
837 
8-27 
997 
986 
| were simultaneous. 
On black wadding on grass 
20 
166-6 
8-33 
993 
On flannel on grass 
29 
2121 
7-31 
871 
On flannel on raised board 
55 
408-7 
743 
886 
j were simultaneous. 
On raw silk on grass 
32 
2540 
7-84 
934 
On raw silk on the raised board 
50 
464-3 
9-29 
1107 
j were simultaneous. 
On silk from the cocoon 
24 
208-1 
8-67 
1034 
On jet black lambs’ wool 
33 
205-4 
6-22 
741 
On white lambs’ wool 
33 
227-5 
6-89 
821 
On green lambs’ wool 
33 
220-2 
6- 76 
806 
always simultaneous. 
On light blue lambs’ wool 
33 
242-6 
7-35 
876 
On dark blue lambs’ wool 
33 
230-2 
6 98 
832 
The observations in air at the height of ten feet above grass, were made on one night only, viz. on 1844 April 24, and the readings 
were between those of eight feet and twelve feet. 
No certain difference appeared from many simultaneous observations of fine and coarse flax, and consequently their results have 
been combined in the formation of the final values for flax. 
