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Classification of the Sci
41

houses of wood, brick, and stone are subdivisible into frame houses, balloon-frame houses, and houses supported by piers of stone or brick. Men do not, however, devote their lives to studying how to make caves, snow-houses, or submerged houses; nor is the construction of glass-houses very important, and the making of tents is a secondary branch of the sailmaker's art. Sky-scrapers and other enormous structures, such as cathedrals, are not constructed scientifically unless they are entrusted to civil engineers; and engineering is not a science principally ministrant to the House-instinct. We therefore restrict ourselves, after all, to the consideration of ordinary houses. Every properly built house rests, if possible, on foundations of stone and brick. Otherwise, it usually rests on piles. Neither masonry nor pile-driving are confined to house-buildings; and the fact that their work is to belong to a house makes no particular difference in regard to the science of doing it. Consequently, these sciences are to be relegated to Engineering. It is otherwise