Nordenskiöld looked upon Greenland and its icefield as a broad-lipped, shallow vessel with chinks in the lip, the glacier being viscous matter within it. As more is poured in, the matter runs over the edges, taking the lines of the chinks, that is, of the fiords and valleys, as that of its outflow. In other words, the ice floats out by force of the superincumbent weight of snow just as does the grain on the floor of a barn when another sackful is shot on to the top of the heap already there. When the glacier reaches the sea it makes its way along the bottom under water for a considerable distance, in some cases, as near Avigait, for more than a mile. This is where the water is too shallow for it to affect the mass, which forms a breakwater; though as a rule the shore deepens more suddenly and the projection is less. It was long supposed that the berg broke from the glacier by force of gravity, but this is not generally so. The berg is forced off from the parent glacier by the buoyant action of the sea from beneath; the ice groans and creaks; then there is a crashing, then a roar like the discharge of artillery; and with a great regurgitation of the waves the iceberg is launched into life. These huge floating islands of ice are the most conspicuous exports of Greenland; and their true magnitude is not realised until it is remembered that only about an eighth of their bulk appears above the water. Bergs as large as liners we frequently hear of—one such is shown in our illustration—but sometimes they are of much greater freeboard, though the very large ones reported as extending along the horizon are invariably groups of several crowded together. [Illustration: THE ALLAN LINER "SARDINIAN" AMONG ICEBERGS]