34 
A VOYAGE TO SPITZBEBGEN . 
quent chapter, the warm water originates at the Pole. 
This is a question which requires investigation. There 
are many other questions connected with Polar tem¬ 
perature of a very complicated and involved cha¬ 
racter, which cannot be fully entered into here. One 
or two may be alluded to. It is known that the 
mean temperature of the Southern hemisphere is lower 
than that of the North ; and it is a matter of obser¬ 
vation that the Antarctic Pole is more extensively 
ice-clad than the Arctic. This may be in part con- 
jecturally explained by the greater extent of land at 
the South than at the North Pole. It is also known 
that the earth revolves round the sun in an elliptic 
orbit, so that it is at one time nearer the sun than 
at another. At the present time the Poles are farther 
from the sun in summer and winter than in spring 
and autumn. It has already been indicated that the 
North Pole is warmed up during the summer, and 
as the warming of the South Pole occurs under 
similar conditions as regards heat, &c., the South 
Pole should have a similar temperature whereas it is 
the coldest. This is probably indicative of the North 
Pole being for the most part surrounded by water. 
During the spring the heat is being gradually in¬ 
creased by the gradually increasing height of the sun, 
which increase is in part counterbalanced by the 
