CARPENTRY, the art of combining pieces of timber to support a weight or sus tain pressure. The work of the carpenter is intended to give stability to a structure; that of the joiner is applied to finishing and decora tion. The scientific principles of carpentry are founded on the doctrines of the composition and resolution of mechanical forces, and a knowledge of these doctrines, either theoretical or practical, is indispensable to the skilled car penter. To go into the principles of the art would be merely to explain a particular appli cation of these mechanical forces, which would be beyond the scope and limits of this work. An explanation of the terms employed in car pentry may, however, be useful to the general reader. The term °frame* is applied to any assemblage of pieces of timber firmly con nected together. Thepoints of meeting of the of timber in a frame are called *joints" s a beam is uniting pieces of tim ber into one length by joining their extremities. When neatness is not required this is done by °fishing.* In this mode the ends of the beams are abutted together, and a piece of timber placed on each side and secured by bolts passed through the whole. Sometimes the parts are indented together, and pieces termed °keys* are notched into the beams and side pieces. When it is desirable to maintain the same depth and width throughout the beam, °scarfing" is em ployed. This is cutting from each beam a part of the thickness of the timber, of the length of the intended joint, and on opposite sides, so that the pieces may be jointed together and bolted or hooped. In bolting scarfs, side plates of iron are used to protect the wood. When greater strength is required than can be pro duced by a single beam, "building' and °truss ing* beams are resorted to. Building beams is combining two or more beams in depth so as to have the effect of one. In trussing the beam is cut in two in the direction of its length, and supported with cross-beams, as in roofing. °Mortise* and °tenon* is a mode of jointing timber. An excavation called a mortise is made in one piece and a projecting tongue to fit it, called a tenon, in the other. The tenon is confined in the mortise by a pin penetrating it laterally through the side of the mortised beam, or by an external strap of iron passing round the mortised beam and rivetted in the one terminating in the tenon. The timber frame-work of floors is called °naked flooring.' It is of three kinds — single, double and framed. Single flooring consists of a series of joists stretching across the whole void from wall to wall, without an intermediate support. The flooring boards are laid on the top of these, and the ceiling of the lower story fixed to the under side. Double flooring consists in laying binding joists across the floor about six feet apart, crossed above by bridging joists and also crossed below by the ceiling joists. Framed flooring is provided with girders or beams in addition to the binding, bridging and ceiling joists. To prevent the transmission of sound, a double ceiling of lath and plaster is some times used, but generally pugging is inserted between the roof and the ceiling. °Cornice
bracketing' consists in rough wooden profiles of the room cornices, which are afterward lathed around and plastered. Partitions, when not required to bear weight, are formed by lay ing along the floor a piece of timber called a °sill,* together with a corresponding piece along the ceiling joists, the space within being filled with vertical pieces called '"quarters,' to which the lath is nailed. When the partition has weight to support, it has to be trussed with posts and braces. The timbers which support the steps of a wooden staircase are termed the carnage.' They consist of two pieces of tim ber inclined to the °rake,* or projection of the steps, and termed °rough strings,' which may rest upon a piece of timber projecting horizon tally from the upper wall, called a °pitching* or *apron* piece, which also supports the joists of the landing or °half pace.' The °roof* is the framework by which the covering of a building is supported. It may consist of a series of timbers which are called °rafters° with the ends resting on the opposite walls, and the other ends meeting in a point. When loaded with the weight of the covering, this frame work would be apt to thrust out the roof ; a third piece is consequently added, which, like a string, connects the lower extremities of the rafters and prevents them from spreading. This is called a °ties and the whole frame a °cou ple.* When the tie is of such a length that it is apt to droop in the middle, or °sag,* by its own weight, a fourth piece is added to unite it directly with the apex of the rafters; this is called the °king-post? If the rafters, too, are liable to sag, cross pieces called °struts* are introduced, uniting their centres with the centre of the tie. Instead of the king-posts and struts, the centre of each rafter may be joined to the tie by a piece falling perpendicularly on the latter, and to each other by a piece running across parallel to and above the tie, forming a parallelogram with the perpendiculars and the section of the tie enclosed by them. The suspending pieces are called °queen-posts,* and the horizontal one a The whole frame, constructed in either way, is called a truss. The trussed frames are placed at in tervals of about 18 feet apart, and support hori zontal pieces called upurlins,* which run the whole length of the roof and support the com mon rafters with their covering. Ship carpen try is a special form of carpentry. The tim bers are larger and heavier and of the harder kinds of wood. These must be shaped to the curved lines of the vessel and properly beveled to make close joints. This branch of carpen try is now confined to small vessels such as yachts, coasting schooners, barges, scows, etc.
The principal instruments used in carpentry are saws, as the circular-, band- and tenon saws; planes, as the jack-plane, smoothing plane, molding-plane, etc.; chisels, gouges, brad-awls, gimlets, descriptions of which will be found in their places. See Bun-DING; CABI