Silently at first the mountainous mass of ice began to tilt. Then, amid an ever-increasing roar of the agitated water and the crash of detached pieces of the berg, the list grew more and more.
Even now it was a race between the toppling cliffs of ice and the ship, for the latter had not put a safe distance between herself and the berg.
The lads, even in the midst of this new peril, could see the now aroused bear, striving to run up the steeply shelving ice wall which a few moments previously had been almost level.
For a few yards the animal made good progress, then its massive paws began to slip. Struggling in vain for a foothold, the bear slid backwards with increasing speed till, like a stone shot from a catapult, its huge body was flung over the edge of the precipice, to disappear in a moment beneath the foam-crested waves.
The noise of the collapsing berg grew till it rivalled the crash of thunder. The sea, thrashed by huge fragments of dislodged ice, many of them forming small bergs, was churned into a heavy mass of foam.
The Polarity won the race by barely her own length as the topmost pinnacle of the iceberg struck the sea.
"Hold on, men!" roared Captain Stormleigh.
But his voice could not be heard owing to the ear-splitting crashes. Nevertheless, all hands clung on like grim death as a cascade of water, topped by a fringe of foam, burst over the vessel's stern.
Clinging desperately to a life-rail, Leslie and Guy thought that the Polarity was doomed.
Buried ten feet below the waves of icy water, and almost torn from their hold, they knew not whether the vessel were plunging to the bottom or otherwise. Both lads were seized by a frantic desire to release their grasp and strike out for the surface. The water trickled down their mouths and nostrils, its very coldness lacerating their throats and causing them intense pain.