When she is about to become a mother, she enlarges this breathing hole so as to make it into a perpendicular tunnel. She then, with the sharp nails of her fore-paws, or flippers, scoops away the snow in a dome-like form, as shown in the illustration, taking the snow down with her through the ice, and allowing it to be carried away by the water. By degrees she makes a tolerably large excavation of a hemispherical shape, and when her young is born she deposits it on the ice-ledge around the tunnel. From ordinary foes the young Seal is safe, and nothing can discover the position of the house unless guided by the sense of smell. How the Polar Bear and the Esquimaux hunter discover the dwelling and capture the inmates we have already described in the chapter treating of War and Hunting. Our present business is with the dwelling itself. Comparatively few of these snow-houses, or _igloos_, as they are called, are discovered, and they remain intact until the summer sun melts the roof and exposes the habitation. By this time, however, the young Seal has grown sufficiently to shift for itself, and no longer needs the shelter of a dwelling. * * * * * THE winter hut, or igloo, of the Esquimaux is made of exactly the same shape and of similar materials to the dwelling of the Seal, the chief difference being that it is built instead of excavated. In order to save time, the igloo is generally erected by two men, one of whom supplies the material, and the other acts as bricklayer and architect in one. Each begins by tracing a suitably sized circle in the snow, which he clears away to some depth, so as to preserve a firm surface, either as a floor or as the material for the wall. In this work both men are equally valuable, for the skill required to cut the slabs of snow into such a shape that they can be formed into a hemispherical dome is quite as much as that which is needed for putting them together. I will call them the cutter and the builder. Sometimes a young hand is employed by way of labourer, and passes the snow slabs to the builder as fast as they are cut. The builder receives the slabs, and arranges them in regular order, always taking care to “break the joints,” just as do our bricklayers of the present day. Always remaining within the circle, he gradually builds himself in, and when he has quite finished the house, he cuts a hole through the side, emerges, and, by the help of his partner, puts on the finishing touches. He usually also adds a sort of tunnel to the door, through which any one must creep on his hands and knees if he wishes to enter the igloo. This part of Esquimaux architecture will presently be noticed more in full.