Annual Variations for the Temperature of the Air. 
Ixxxv 
178. We may employ tlie monthly means in the 11th column of Table 72, for the purpose of predicting 
the mean temperature for a coming month, the probable error of the predicted temperature for each month as 
deduced approximately from the Table, being as follows :* — 
Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 
2°-0 2°-9 r-1 r-9 l°-9 l°-7 l°-4 l°-5 l°-5 1°-1 r-2 3°-2 
Thus, at Makerstoun, there are equal chances that the mean temperature of any month of March will not 
be more than 1°-1 from 39°-5. The months of March, October, and November, shew the least variation of 
montlily mean temperature ; the months of December, January, and February shew the greatest variation. 
Table 73. — Monthly Means of the Diurnal Ranges of Temperature, as deduced from the 
Observations of the Register Thermometers, for the Years 1843-6. 
Year. 
Jan. 
Feb. 
March. 
April. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Mean. 
1843 
' 9-0 
7-8 
14-1 
15-2 
13-3 
13-6 
16-7 
20-2 
20-8 
13-6 
12-4 
8-1 
13-7 
1844 
10-9 
11-7 
13-1 
18-4 
19-4 
18.2 
18-7 
19-5 
15-9 
134 
8-4 
6-8 
14-5 
1845 
11-9 
12-1 
14-0 
20-2 
14-2 
18-7 
17-1 
17-1 
17-9 
12-0 
12-6 
ll-O 
14-9 
1846 
8-6 
10-6 
14-7 
14-3 
18-1 
24-9 
16-6 
18-8 
19-3 
13-9 
9-0 
110 
15-0 
Mean 
10-1 
10-5 
14-0 
17-0 
16-2 
18-8 
17-3 
18-9 
18-2 
13-2 
10-6 
9-2 
14-5 
179. Annual Variation of the Diurnal Range of Temperature. — From the last line of Table 73, the mean of 
the diurnal ranges of temperature was least in December, and it was greatest in June and August. It appears 
probable, however, that when a sufficient number of years' observations is considered, the mean of the diurnal 
ranges will be found to vary little from April till September. This result is analogous to that obtained for 
the ranges of the mean undisturbed diurnal vaiiations of the magnetic elements. 
The ranges of the monthly mean diurnal variations, from the hourly observations in the two years 1844-5, 
ai'e as follow : — 
Jan. Feb. March. April. May. June. July- Aug. Sept. Oct. Nov. Dec. 
5°-60 7°-05 9°-30 14°-70 ll°-80 12°-15 12°-00 12°-35 12°-60 8°-20 5°-05 3°-70 
These quantities indicate a result quite similar to that obtained from Table 73, though, as might be expected, 
the ranges are considerably smaller. December has the least range, and May, June, and July have rather 
less ranges than April, August, and September. 
Table 74. — Mean Differences of the Daily Mean Temperature from the Monthly Mean for 
each Month in the Years 1843-6. 
Year. 
Jan. 
Feb. 
March. 
April. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Mean. 
1843 
5-45 
4-40 
4-63 
4-21 
2-08 
3-44 
1-57 
2-48 
4-42 
6-98 
4-44 
2-69 
3-90 
1844 
4-30 
4-20 
4-43 
2-62 
2-69 
3-00 
3-33 
1-62 
2-07 
4-50 
3-90 
3-20 
3-32 
1845 
6-02 
3-21 
6-08 
3-97 
2-46 
3-34 
2-16 
1-86 
3-32 
3-04 
4-69 
3-12 
3-61 
1846 
4-21 
4-20 
4-67 
2-85 
2-15 
4-47 
2-57 
2-80 
3-61 
3-87 
4-82 
4-60 
3-73 
Mean 
5-00 
4-00 
4-95 
3-41 
2-34 
3-56 
2-40 
2-19 
3-35 
4-62 
4-46 
3-40 
3-64 
* These numbers divided by 3 v^ill give approximately the probable errors of the monthly means in the 11th column of Table 72 
as the true monthly mean temperatures at Makerstoun. 
