Continuing northward we reach the vast treeless arctic regions, where cold is the great enemy, and the reader wonders what man can do here in the way of architecture. He has done considerable; amongst other things he devised the only true arch found on the continent, and constructed one of the most admirable and unique dwellings in the world. This he built out of the snow which fell about him and prevented him from securing other material. The invention of the snow house by the Eskimo, or Innuit, as they call themselves, was one of the greatest triumphs over environment man has ever accomplished. I refer, of course, to the perfected snow house, the dome-shaped _iglugeak_, commonly called by us _igloo_ or _iglu_. _Iglu_ is the Innuit generic term for “house,” the distinctive name for snow house being _iglugeak_. This snow house is begun by selecting a suitable deep drift that is compact enough to permit homogeneous blocks to be taken from it, with the snow-knife, which is a bone tool shaped like a short sword. Latterly steel saws are employed when they have them. In the pit formed by removal of blocks of snow the builder works at his walls, the bottom of the excavation finally forming the floor of the house. The first block is bevelled down to a wedge shape with the point toward the beginning, and the worker goes on round his circle, and when he comes again to the wedge his wall rises upon the first portion and continues thus in a spiral fashion to the top, constantly narrowing till at last one block fills the opening. It takes two to adjust this, though one may build a small house successfully to that last point. By building spirally and therefore continuously, there is always support on two sides for the last block laid. The edges are slanted at the same time to bring the tiers gradually toward the centre. Joints and holes are filled with snow, though a small hole is left at the top for ventilation. As the heating of this house is done with lamps there is little smoke. For camping purposes a small snow house is built, seven feet diameter and five feet high, in about two hours. When made for permanent use the house is about twelve feet high and fifteen feet diameter. Plenty of light comes through the snow, but a window of ice or seal intestine is often placed over the entrance, which is reached by a more or less extended passage, with vaults for storage, by the way. [Illustration: SECTION OF SNOW IGLU]