25 
years ago, is about five- sixths ; and hence, one-sixth of 278°, 
or 45°, will be the aggravation at that date of the winter cold. 
But if this mode of reckoning were sound, it ought to apply 
to the northern and southern hemispheres with the present 
excentricity. In this case the southern winter should be colder 
than the northern in the amount answering to the ratio 
•93507, or 18° F. But in fact there is no such inequality, and 
it would almost appear that the climate, in answering latitudes, 
is slightly warmer than in the northern hemisphere, except in 
the immediate neighbourhood of the pole. 
44. The following extract from Mr. Croll’s table gives his 
conclusions with regard to his two proposed glacial periods, 
and the midwinter temperature of Great Britain at the 
answering periods : — 
Date. 
Excen- 
tricity. 
Perihelion. 
Excess of 
Winter, 
In days. 
Sun’s 
Heat. 
Depression. 
G. B. mid- 
winter. 
880,000 
•0456 
152 ° 33 ' 
21-2 
•884 
32°-2 
6 0- 8 
870,000 
•0607 
180 ° 23 ' 
28’2 
•859 
39°'0 
o°-o 
860,000 
•0708 
209 ° 41 ' 
32-9 
•843 
43°’6 
- 4 °-C 
850,000 
•0747 
239 ° 28 ' 
347 
•837 
45°-3 
- 6°-3 
840,000 
•0698 
269 ° 14 ' 
32-4 
•845 
43°-2 
— 4°‘2 
830,000 
■0623 
298 ° 28 ' 
29-0 
•857 
40°-0 
- l °-0 
820,000 
•0476 
326 ° 4 ' 
22-1 
•881 
33 °'l 
5°\9 
240,000 
•0374 
74 ° 58 ' 
17-4 
•898 
28°‘3 
10°7 
230,000 
•0477 
102 ° 49 ' 
22-2 
•885 
33°-2 
5°-8 
220,000 
•0497 
124 ° 33 ' 
23-2 
•877 
34 °‘l 
4°-9 
210,000 
•0575 
144 ° 55 ' 
267 
•864 
37°7 
l °-3 
200,000 
•0569 
168 ° 18 ' 
26-5 
•865 
37°-4 
l °-6 
190,000 
•0539 
190 ° 4 ' 
247 
•871 
35°7 
3°-3 
ISO , 000 
•0476 
209 ° 22 ' 
227 
•881 
33 0, 1 
5°-9 
170,000 
•0437 
228 ° 7 ' 
20-3 
•887 
31°3 
7°7 
160,000 
•0364 
236 ° 38 ' 
16'9 
•900 
27 0, 8 
11 0, 2 
45. In the following table, the excentricity is reduced by 
the formula e'=f e-f ‘024 to correspond with Mr. StockwelPs 
corrected maximum, '0693888, instead of Leverrier’s '077747. 
The equilibrium of solar heat and radiation is assumed to be 30° 
after the winter solstice, and the law of radiation is taken from 
Dulong and Petit’s experiments. The i’atiol'165 log. = '0663259 
answers to a change of 36° F., or a change of solar distance 
to that amount to 72°. Hence log. radius vector +- i 1 r -^p- 
will give the answering change in degrees. The precession 
at the rate of 50"'3405 a year, or 139° 50' for 10,000 years, is 
combined with the perihelion places of Mr. CrolPs table, to 
give the anomalies at 30° after the solstice. The columns are 
the date (in 10,000’s of years B.C.), excentricities } anomalies , 
