“This has been an earthquake!” exclaimed Daggett.  “That volcano has been pent up, and the gas is stirring up the rocks beneath the sea.”

“No, sir,” answered Stimson, from the forecastle of his own schooner, “it’s not that, Captain Daggett.  One of them bergs has turned over, like a whale wallowing, and it has set all the others a-rocking.”

This was the true explanation; one that did not occur to the less experienced sealers.  It is a danger, however, of no rare occurrence in the ice, and one that ever needs to be looked to.  The bergs, when they first break loose from their native moorings, which is done by the agency of frosts, as well as by the action of the seasons in the warm months, are usually tabular, and of regular outlines; but this shape is soon lost by the action of the waves on ice of very different degrees of consistency; some being composed of frozen snow; some of the moisture precipitated from the atmosphere in the shape of fogs; and some of pure frozen water.  The first melts soonest; and a berg that drifts for any length of time with one particular face exposed to the sun’s rays, soon loses its equilibrium, and is canted with an inclination to the horizon.  Finally, the centre of gravity gets outside of the base, when the still monstrous mass rolls over in the ocean, coming literally bottom upwards.  There are all degrees and varieties of these ice-slips, if one may so term them, and they bring in their train the many different commotions that such accidents would naturally produce.  That which had just alarmed and astonished our navigators was of the following character.  A mass of ice that was about a quarter of a mile in length, and of fully half that breadth, which floated quite two hundred feet above the surface of the water, and twice that thickness beneath it, was the cause of the disturbance.  It had preserved its outlines unusually well, and stood upright to the last moment; though, owing to numerous strata of snow-ice, its base had melted much more on one of its sides than on the other.  When the precise moment arrived that would have carried a perpendicular line from the centre of gravity without this base, the monster turned leisurely in its lair, producing some such effect as would have been wrought by the falling of a portion of a Swiss mountain into a lake; a sort of accident of which there have been many and remarkable instances.

Stimson’s explanation, while it raised the curtain from all that was mysterious, did not serve very much to quiet apprehensions.  If one berg had performed such an evolution, it was reasonable to suppose that others might do the same thing; and the commotion made by this, which was at a distance, gave some insight into what might be expected from a similar change in another nearer by.  Both Daggett and Gardiner were of opinion that the fall of a berg of equal size within a cable’s length of the schooners might seriously endanger the vessels by dashing them against some wall of ice, if in no other manner.  It was too late, however, to retreat, and the vessels stood on gallantly.