The illustration demonstrates the process of constructing an igloo from blocks of hard-packed snow.
Overall, the construction involves two main stages: cutting appropriately sized snow blocks and arranging them in a circular formation, before placing a final capstone block at the top to complete the dome structure.
In the first stage, hard-packed snow is identified as the building material. Using a snow saw, rectangular blocks are cut from the compacted snow. The diagram indicates that the ideal block measures approximately 3 inches in thickness, 8 inches in width and 15 inches in height. Larger blocks are positioned at the base to provide structural stability. These blocks are arranged in a circular pattern, forming the foundation of the igloo. As construction progresses, additional rows of blocks are placed on top of the base layer, with each successive layer slightly angled inward to create a gradually narrowing dome shape.
In the second stage, the structure nears completion as a small opening remains at the top. A final block, described as being slightly too large for the opening, is carefully positioned above the gap and lowered into place. This final piece, often referred to as the capstone, secures the surrounding blocks and stabilises the entire dome. Once inserted, the igloo forms a self-supporting, enclosed shelter constructed entirely from interlocking snow blocks.