THE ARCTIC SEAS. 127 
tudes, the process of congelation is always going 
on at the surface of the sea. If the wind is high, 
the crystals cannot readily unite into a solid form, 
but form a spongy mass, called sludge: when this 
has become somewhat thick, however, the wind can 
no longer act upon the water, so as to raise little 
ripples upon it, and the sludge now begins “to 
catch ;” but the swell prevents one uniform surface 
being yet formed, and the consequence is, that small 
rounded plates of ice are produced, called “pan- 
cakes,” the edges of which are raised slightly, by 
the constant pressure of one against another. The 
cakes in the centre of the freezing mass now begin 
to adhere to each other, and thus a solid surface 
is produced, which gradually extends both its dia- 
meter and its depth. The individual pieces of 
which such ice is composed are distinctly to be 
traced, even when perfectly consolidated, and pre- 
sent an appearance resembling pavement. But in 
calm weather, a thin pellicle of ice is simulta- 
neously produced over the whole surface of the 
sea, and the formation of the ice-field is much 
more direct and obvious. Single fields have been 
‘seen many leagues in length, and occupying an 
area of several hundred square miles; being at 
the same time from three to six feet high, and 
from ten to twenty deep. The waves produced 
by storms break up these fields into smaller pieces, 
called floes, and driving one against another with 
violence, the edge of one is often lifted upon the 
other by the force of the pressure, and hummocks 
or hills, of various shapes and sizes, are raised upon 
