42 
A VOYAGE TO SPITZBEBGEJST. 
tionable practical importance originated in apparently 
useless inquiries. 
The phenomena and distribution of Arctic ice are 
subjects worthy of investigation. It does not answer 
our purpose to detail the numerous observations made 
by Arctic voyagers. These observations indicate that 
the icebergs and ice-fields are loosened every summer, 
and sent drifting southward. These masses accumu¬ 
late most where there is most land, and by their 
melting they transfer the cold of higher latitudes to 
these more southern lands, and thus reduce their 
mean temperature. This has the effect of throwing 
the zone of greatest cold towards the south, especially 
where the lands advance far north. Observations 
upon the thickness of ice found each winter. or each 
year at several localities would enable us to define the 
zone of greatest cold, and also infer from the thick¬ 
ness of the ice whether the regions around the Pole 
are warmer than in about 75° N. What are the 
regions of perennial ice ? for that there are such 
regions seems clear from the occurrence of sea ice in 
sheets formed of annual layers. These regions may 
be the true sources of the cold currents of the sea; 
while the warm currents have a temperature of 40° or 
45° F., and flowing from the north, may arise from the 
area where the sea is freed every year from ice by the 
