^66 M. Hamboldt cni Isothermal Lines ^ 
southern hemisphere on the isothermal lines of 46^.4 and 50°.0, 
we find summers which in our hemisphere belong only to 
the isothermal lines of 35°.6 and 40^. The mean temperature 
is not precisely known beyond 51 of S. Lat. Navigators do 
not frequent those regions when the sun is in the northern signs, 
and it would be wrong to judge of the rigour of winter, from the 
low temperature of the summer. The eternal snows which in 71 ^ 
of N. Lat. support themselves at the height of 2296 feet above 
the seaj descend even into the plains, both in South Georgia * 
and in Sandwich Land in 54^^ and 58*^ of S. Lat. But these 
phenomena, however striking they may appear, do not by any 
means prove that the isothermal line of 32® is 5® nearer the 
South Pole than the North Pole, in the system of transatlan- 
tic climates, the limit of eternal snow is not at the same altitude 
as in Europe; and in order to compare the two hemispheres, we 
must take into account the difference of longitude. Besides, an 
equal altitude of the snows, does not by any means indicate an 
equal mean temperature of the year. This limit depends par- 
cularly-]- on the coldness of summer, and this again on the quick 
condensations of the vapour caused by the passage of the float- 
ing ice. Near the poles the foggy state of the air diminishes in 
summer the effect of the solar irradiation, and in winter that of 
the radiation of the globe. At the Straits of Magellan, MM. 
Churruca and Galeano have seen snow fall in 53® and 54® of 
S. Lat. in the middle of summer ; and though the day was 18 
hours long, the thermometer seldom rose above 42®. 8 or 44®. 6 
and never above 51°. 8. 
The inequal temperature of the two hemispheres, which, as 
we have now proved, is less the effect of the eccentricity of the 
* It is the more surprising to find in the Island of Georgia snow on the banks 
of the ocean, because 2® 39' nearer the Equator at the Malouine Isles, the mean 
temperature of the summers is 53®. 1, or 9® greater than at the point in our 
hemisphere in 71® of Lat. where the limit of perpetual snow exists at 2296 feet 
of absolute elevation. But we must recollect, 1st, That the Malouine Isles are 
^near a continent which is heated in summer ; 2d, That Georgia is covered with 
mountains, and is placed not only in a sea open to the north, but under the influ- 
ence of the perennial ices of Sandwich Land ; and, 3dly, That in Lapland, 20® of 
Lat. produce in certain local circumstances 10®. 8 of difference in the tempera- 
tures of the summers. 
I Baron Von Buch’s Travels in Lafland^ toI. ii- p. 393,— 120. 
