renewed pressure bursts upward like a volcano. All the winter the
drifting pack changes--grows by freezing, thickens by rafting, and
corrugates by pressure. If, finally, in its drift it impinges on a
coast, such as the western shore of the Weddell Sea, terrific pressure
is set up and an inferno of ice-blocks, ridges, and hedgerows results,
extending possibly for 150 or 200 miles off shore. Sections of
pressure ice may drift away subsequently and become embedded in new ice.

I have given this brief explanation here in order that the reader may
understand the nature of the ice through which we pushed our way for
many hundreds of miles. Another point that may require to be explained
was the delay caused by wind while we were in the pack. When a strong
breeze or moderate gale was blowing the ship could not safely work
through any except young ice, up to about two feet in thickness. As
ice of that nature never extended for more than a mile or so, it
followed that in a gale in the pack we had always to lie to. The ship
was 3 ft. 3 in. down by the stern, and while this saved the propeller
and rudder a good deal, it made the 'Endurance' practically
unmanageable in close pack when the wind attained a force of six miles
an hour from ahead, since the air currents had such a big surface
forward to act upon. The pressure of wind on bows and the yards of the
foremast would cause the bows to fall away, and in these conditions the
ship could not be steered into the narrow lanes and leads through which
we had to thread our way. The falling away of the bows, moreover,
would tend to bring the stern against the ice, compelling us to stop
the engines in order to save the propeller. Then the ship would become
unmanageable and drift away, with the possibility of getting excessive
sternway on her and so damaging rudder or propeller, the Achilles' heel
of a ship in pack-ice.