in the Atlantic before their dissolution, under the influence of a
warmer climate, but for the intervention of other causes. It frequently
happens that two masses are propelled against each other, and are both
shivered into fragments by the violence of the concussion. The ordinary
swell of the ocean also acts with tremendous power upon a large tract,
especially when it has been so thawed as to have become thin, and breaks
it up into a thousand smaller pieces in a very short period. The danger
of being entrapped between two ice-fields coming into contact with each
other is one of the perils which the navigator has frequently to
encounter in the northern seas; and fatal to his vessel and his life has
the occurrence often been, while in a vast number of instances escape
has seemed almost miraculous.

"At half-past six," says Captain Ross, relating to his first voyage of
discovery, in the Isabella, to the arctic regions, with Captain Parry,
in the Alexander, "the ice began to move, and, the wind increasing to a
gale, the only chance left for us was to endeavor to force the ship
through it to the north, where it partially opened; but the channel was
so much obstructed by heavy fragments, that our utmost efforts were
ineffectual; the ice closed in upon us, and at noon we felt its pressure
most severely. A large floe, which lay on one side of the Isabella,
appeared to be fixed; while, on the other side, another of considerable
bulk was passing along with a rapid motion, assuming a somewhat circular
direction, in consequence of one side having struck on the fixed field.
The pressure continuing to increase, it became doubtful whether the ship
would be able to sustain it; every support threatened to give way, the
beams in the hold began to bend, and the iron tanks settled together.

"At this critical moment, when it seemed impossible for us to bear the
accumulating pressure much longer, the hull rose several feet; while the