Formed of large sheets of birch-bark, kept in shape by delicate ribs of lance-wood or willow, it was nearly forty feet in length, and sharp at both ends; and the seams where the bark was sewn together were covered by a thick resinous gum, which became hard in the water.  Like the small canoes, it required careful handling; for, having no keel, it was easily turned over.  It was impelled by six or eight paddles,--three or four on one side, and the same number on the other; one man steering with a paddle, as well as paddling.