ON THE HOURLY OBSERVATIONS OF THE THERMOMETER. 201 
Table XIY.—Showing the relation between the Mean Tempe¬ 
rature of each hour and that of the whole day. 
Hours. 
1 
2 
3 
4 
6 
6 
7 
8 
9 
10 
11 
12 
Temp. 
48-80 
48-52 
48-34 
48-14 
48-14 
48-85 
50*18 
52-14 
53*67 
55-14 
56*15 
5(r95 
NH 
a.mJ 
• O 
1 
„ Deviation. 
-3*33 
-3-61 
-379 
-3-99 
-3-99 
-328 
-1*95 
+001 
+ 1*54 
+3-01 
+4-02 
+4-82 
1933 
r Tabl 
P.M. - 
■ Temp. 
57*15 
5686 
56-22 
55*47 
54*32 
53-20 
52*16 
51-38 
50*70 
50-00 
49-65 
49*17 
« 
. Deviation 
+5-02 
+4-72 
+4-09 
+3-34 
+ 2-19 
+ 1-07 
+ 0-03 
-0-75 
-1-43 
-2-13 
-2*48 
- 2*96 
- Temp. 
50-64 
50-26 
49-98 
49-93 
49-88 
50-45 
5178 
53-29 
54-99 
56-39 
57 53 
58*39 
> 
a.mJ 
+3-86 
►— 1 
. Deviation 
-3-03 
-3-41 
-369 
-374 
-3-79 
-3-22 
-1-89 
-0*38 
+ 1-32 
+ 2-72 
+ 472 
co o 
co c5 
' Temp. 
58-85 
58-44 
57*86 
5678 
55*72 
54*69 
53-64 
52-72 
52-21 
51*64 
51-27 
50*95 
P.M. 4 
1 Deviation 
+ 5-18 
+477 
+4-19 
+3*11 
+2*05 
+ 1*02 
-0-03 
-0-95 
-1*46 
-2-03 
-2-40 
-272 
r Temp. 
4972 
49*39 
49-16 
49-03 
1Q-00 
49-65 
50-98 
52-63 
54*33 
55 76 
56-84 
57-67 
A.M. ■< 
> 
£ a; 
L Deviation 
-3-18 
-3-51 
-374 
-3-87 
-3-90 
-3-25 
-1'92 
- 0-27 
+ 1-43 
+2-86 
+3-94 
+477 
O 
Sr 03 
r Temp. 
58-00 
57-68 
57'04 
56-12 
55-02 
53-94 
52-90 
52*05 
51*45 
50-85 
50*54 
50-11 
P.M. 4 
. Deviation 
+ 5-10 
+4-78 
+4*14 
+ 3-22 
+2-12 
+ 1-04 
+o-oo 
-0-85 
-1-45 
-2-05 
-2*36 
-279 
We perceive by this Table that the mean annual temperature of 
any hour in the day never differs more than about 5° from the mean 
annual temperature of the twenty-four hours. Sir David Brewster 
found the difference at Leith much less, viz. about 3° only. He 
also observed that of the two years 1824 and 1825, the devia¬ 
tions were uniformly greater in the warmer year, that is, in 
1825, the mean temperature of which exceeded that of 1824 
by more than 2°. A similar result, however, is not apparent 
at Plymouth, the deviations being less in the warmer year, that 
is, in 1834, the mean temperature of which exceeded that of 
1825 by about a degree and a half: future observations may 
probably lead to some explanation of the cause of this anomaly. 
The mean temperature for Plymouth may be, however, deduced 
from a register containing only one observation in the day, by 
applying, according to its sign, the correction given in the 
preceding table. Thus if the observed mean temperature for 
9 a.m. as deduced by the observations through the whole year, 
was 54*33; then the mean temperature of the whole twenty- 
four hours for the year would be 54*33—1*43, since the mean 
temperature of 9 a.m. exceeds the mean temperature of the 
twenty-four hours by 1*43 ; that is, in applying the respective 
corrections we reverse the signs. 
