Now comes the part that requires practice to accomplish successfully. The expert will, with a few thrusts of his knife in just the right places, split off the snow-block and lift it carefully out to await removal to its position on the wall. The tyro will almost inevitably break the block into two or three pieces, utterly unfit for the use of the builder. When two men are building an igloo, one cuts the blocks and the other erects the walls. When sufficient blocks have been cut out to commence work with, the builder marks with his eye, or perhaps draws a line with his knife describing the circumference of the building, usually a circle about ten or twelve feet in diameter. The first row of blocks is then arranged, the blocks placed so as to incline inward and resting against each other at the ends, thus affording mutual support. When this row is completed the builder cuts away the first and second blocks, slanting them from the ground upward, so that the second tier resting upon the edges of the first row can be continued on and around spirally, and by gradually increasing the inward slant a perfect dome is constructed of such strength that the builder can lie flat on the outside while chinking the interstices between the blocks. The chinking is, however, usually done by the women and children as the building progresses, and additional protection secured from the winds in very cold weather by banking up a large wooden snow shovel, the snow at the base often being piled to the depth of three or four feet. This makes the igloo perfectly impervious to the wind in the most tempestuous weather. When the house is completed, the builders are walled in. Then a small hole about two feet square is cut in the wall, on the side away from where the entrance is to be located, and is used to pass in the lamps and bedding. It is then walled up and the regular door cut, about two feet high, and nitched at the top. It would bring bad luck to carry the bedding into the igloo by the same door it would be taken out. Before the door is opened the bed is constructed, of snow-blocks, and made from one to three or four feet high, and occupies about three-fourths of the entire space. The higher the bed and the lower the door, the warmer the igloo will be.