There is some advantage in this; because these twin-tubs being so small they fit more readily into the boat, and do not strain it so much; whereas, the American tub, nearly three feet in diameter and of proportionate depth, makes a rather bulky freight for a craft whose planks are but one half-inch in thickness; for the bottom of the whale-boat is like critical ice, which will bear up a considerable distributed weight, but not very much of a concentrated one.