PRINCIPLES OP BUILDING, Are those parts of geometry, mechanics, mensuration, and chemistry, which shew how to design and construct the parts of a building, so as to be the most durable, the destination, situation, and other fixed data of the intended structure, being known. These parts of the sciences are the foundation of' the art of constriction.
Construction may in general be divided into two parts, the science of masonry, and that of carpentry ; though there are other branches, as slatery, plumber?,.. ke. sometimes also employed as constituent parts ; but these may be considered as ra ther adventitious.
The science of masonry shews how to construct walls and vaults. A wall should be built so as to resist a given force, either acting uniformly over the whole, or par tially upon the surface : such as to resist the pressure of vaults or roofs nrestrai it ed t'rom the want of tie beams, acting along one continued butment, as in plain vaulting ; or to resist different forces, act ing at intermitted points, as in groin vault ing ; or to resist the forc:e of the wind, acting uniformly over the whole surface. An arch should be so constructed as to balance itself equally on all parts of the intrados, whether it be of uniform thick ness, or to support a given load.
The science of carpentry comprehends the sizing, cutting, disposition, and join ing of timbers. lly chemistry we are en abled to judge of the quality of materials, such as stone, mortar, wood, iron, slate, lead, &c.
Taste. Taste consists in introducing such forms in the construction and em bellishments, as appear agreeable to the eye of the beholder. The arrangement of the plan, figure of rooms, and contour of the whole building-, and character, as to its destined purpose, depend much on taste.
Invention. Invention is the art of com bining or arranging the various apart ments in the most convenient order.
Basements. A basement is the lower story of a building on which an order. is placed ; its height will therefore be vans ble, according as it is the cellar story or the ground story ; or, when it is the ground story, according as Ciere are prin cipal rooms in both stories, or only in one of them. It is proper, however, to make the basement no higher than the order of the next story ; for this wo.ild he making
the base more principal in the composi tion titan the body to be supported. If the cellar story is the basement, and if the height does not exceed five or six feet at the niost, it may be plain, or with rustics, or formed into a continued pedes tal; but if the basement is on the ground story, the usual manner of decorating it is with rustics supported on a base, and sur tnounted with a crowning string-course : the base may either be a plinth alone, or w:th mouldings over it: in like manner the string-course may either be a plat band, or with mouldings under it ; or it may forma confee. The rustics arc either made of a rectangubir or triangular sec tion, by imagining one of the sides of these sections to be a line extending across the front of the joint. l'he joints of the rustics may be from an eighth to a tenth part of their height l'he depth of the joint of the triangular rustic may be half of its breadth, that is, making the two planes by which it is formed a right an gle, and the depth of the rectangular sec., tioneci rustics from one-fourth to one-third of their breadth. The ancients always marked both directions of the joints of the rustics; whereas the moderns not on ly employ the ancient manner, but they sometimes make them with horizontal joints alone. Those with horizontal joints represent rather a boarded surfiice than that of a stone wall, which must have two directions of joints. lite height of the string-course should not exceed the height of a rustic with its joint : the plinth, or zocholo, ought not to be less than the height of the string.course. Witen the basement is perforated with arcades, the imposts of the arches may be a platband, which may be equal to the height of a rustic, exclusive of die joint. When the string-course is a cormce, the base may be moulded, and the projection of the cornice may be two-thirds of its height ; so as to be less prominent than that which finishes the building. The height of the cornice may be about one eighteenth part of the height of the base ment, and that of the base about twice as much, divided into six parts, of which the lower five-sixths form the plinth, and the upper sixth the mouldings.