ELEMENTARY COURSE OF CIVIL ENGINEERING. BUILDING MATERIALS. 1. A KNOWLEDGE of the properties of building materials is one of the most important branches of Civil Engineering. An engineer, to be enabled to make a judicious selection of materials, and to apply them so that the ends of sound economy and skilful workmanship shall be equally subserved, must know their ordinary durability under the various circumstances in which they are employed, and the means of increasing it when desirable; their capacity to sustain, without injury to their physical qualities, permanent strains, whether exerted to crush them, tear them asunder, or to break them transversely; their resistance to rupture and wear, from percussion and attrition; and, finally, the time and expense necessary to convert them to the uses for which they may be required. 2. The materials in general use for civil constructions may be arranged under the three following heads: 1st. Those which constitute the more solid components of structures, as Stone, Brick, Wood, and the Metals. 2d. The cements in general, as Mortar, Mastics, Glue, &c., which are used to unite the more solid parts. 3d. The various mixtures and chemical preparations, as solutions of Salts, Paints, Bituminous Substances, &c., employed to coat the more solid parts, and protect them from the chemical and mechanical action of atmospheric changes, and other causes of destructibility. STONE. 3. The term Stone, or Rock, is applied to any aggregation of several mineral substances. Stones, for the convenience of description, may be arranged under three general heads-the sili cious, the argillaceous, and the calcareous. |