Bobby began chopping off as large pieces as he thought he could conveniently handle.  The ice was exceedingly hard and brittle.  It had frozen centuries before, under the extremely low temperatures of the Arctic regions.  It had its beginning, perhaps, in snow deposited in some far-off Greenland valley.  Other snows had come upon it, and still other snows, until a tremendous weight of snow pressed it, as it froze, into a glass-like hardness.

And all the while the great mass was moving, inch by inch, and slowly, down the long valley toward the sea.  Perhaps a century passed, perhaps two or three, or even more, centuries, before this particular portion of the glacier, as these masses of ice between the hills are called, reached the sea and was at last thrust out beyond the land.

And then, one day, with a report like the report of a cannon, it separated from the mother glacier, slid out into the current, and began its southward voyage.  Months had passed since then—­perhaps a year, or even two or three years—­and all the time it had been wasting away in the water until Bobby and Jimmy found it this July day, off Itigailit Island.

But neither Bobby as he chopped at the ice, nor Jimmy as he sat in the boat, gave that a thought, if indeed they knew it.  They were intent only upon gathering enough of the aged ice to preserve the meat of a polar bear.

Neither did they realize that with each stroke of the ax Bobby was disturbing the center of gravitation of the iceberg, already delicately balanced in the water, until presently Jimmy noticed that the side next him was rising—­very slowly and deliberately at first.

“Bobby!  Look out—­the berg’s turning!” he shouted in a terrified voice.

Up and up went the side of the iceberg.  Bobby was lost to view.  Then came a rush of water, a great deluging wave swamped the skiff, and Jimmy went down with a crash and roar of water and crumbling ice in his ears.

CHAPTER XII

ADRIFT ON THE OPEN SEA

As the iceberg turned, great masses of ice, some of them weighing tons, loosened from the main body, and with loud rumbling and roar crashed into the sea.  Bobby, when he realized what was happening, began with all his energy to scramble up the wall of ice as it rose from the water.

Fortunately it was a small iceberg, and fortunately, also, it turned slowly and with deliberation and but a short distance, when it again reached its equilibrium, and was still.

Bobby’s life had been one of pretty constant peril and adventure, and after the manner of wilderness dwellers he had learned resourcefulness and self-possession.  It is indeed a part of the daily training of every lad of the wilderness, that he acquire these attributes, until at last they become second nature to him, and instinctively he does the thing he should do when he comes suddenly face to face with unexpected dangers.  And so it was with both Bobby and Jimmy, and thus it came about that Bobby did not lose his head when the iceberg began to turn, and when it was again at rest he found himself upon a high pinnacle, with the seething waters all around him.  To be sure, his heart beat faster, and it was but natural that he should be excited, but his nerves were nevertheless under control, and his wits, too.