Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/550

Rh 490 BUILDING [JOINERY. are not the true bevels ; but they are those generally used, and are very nearly true when the columns are not much diminished. The same method may be adopted for form ing large pillars for tables, &e. If a column have flutes, with fillets the joints should be in the fillets, in order to make the column as strong as possible ; also, if a column be intended to have a swell in the middle, proper thickness of wood should be allowed for it. When columns are small they may be made of dry wood, and turned in a lathe, when they can be moulded at the same time. Balusters for stairs are made thus. To secure small columns against splitting, a hole should bo bored down the axis of each column If a piece of wood be boiled in water for a eertain time, and then taken out and immediately bent into any particular form, and it be retained in that form till it be dry, a permanent change takes place in the mechanical relations of its parts ; so that though, when relieved, it will spring back a little, yet it will not return to its natural form The same effect may be produced by steaming wood; but though both these methods have been long practised to a considerable extent in the art of ship-building, we are not aware that any general principles have been discovered either by experiment or otherwise, that will enable us to apply them in joinery, where so much precision is required. They do not seem to have been tried ; and before they can be rendered extensively useful, the relation between the curvature to which the wood is bent, and that which it assumes when relieved, should be determined, and also the degree of curvature which may be given to a piece of a given thickness. The time that a piece of wood should be boiled or steamed, in order that it may be in the best state for bending, should be made the subject of experiments ; and this being determined, the relation between the time and the bulk of the piece should be ascertained. A novel and very simple and effective way of boiling sash-bars or thin articles has been adopted, Fio. 79. Boiling Sash-bars. as shown in fig. 79. Take a piece of common cast-iron pipe of sufficient diameter, stop up one end with a plug of wood driven tight, fill the pipe with water, raise one end in a sloping position, leaning it on a pile of bricks, and kindle a fire under the pipe. For the joiner s purposes the process might perhaps be greatly improved by saturating the convex side of each piece with a strong solution of glue immediately after bending it. By filling, in this manner, the extended pores, and allowing the glue to harden thoroughly before relieving the pieces, they would retain their shape better. The object in framing is, to reduce the wood into narrow pieces so that the work may not be sensibly affected by its shrinkage ; and, at the same time, it enables us to vary the surface without much labour. Besides this, as the strains from the grain of the wood are in different directions, the work is prevented from winding on its face. From this view of the subject, the joiner will readily per ceive that neither the parts of the frame nor the panels should be wide. And as the frame should be composed of narrow pieces, it follows that the panels should not be very long, otherwise the frame will want strength. The panels of framing should not be more than 15 inches wide and 4 feet long, and panels so large as this should be avoided as much as possible. The width of the framing is commonly about one-third of the width of the panel. Frames in joinery are usually connected by mortise and tenon joints, with grooves to receive the panels. Wainscoting, doors, window-shutters, &c,, are framed in this manner. In framing or framed work, the outer vertical bars which are mortised are called styles ; and the transverse, those on whose ends the tenons are formed are called rails (Plate XXVI. fig. 2). In doors the open spaces or squares formed internally by the rails and styles are divided in the width by bars parallel to the styles. These are tenoned into the rails, and are called rnunnions or mountings, or, vulgarly, muntins. The frame being formed by trying up, settiug up, mortising, and tenoning, the inner or face edges of the styles, and of the highest and lowest rails, and both edges of the muntins and of the inner rails, are grooved with the plough to receive the edges and ends of the filling-in parts or panels of the framework. Panels are either flat, raised, or flush (Plate XXVI. fig. 3). Flat panels are no thicker than the grooves into which they are fitted, and consequently their faces are as much below the surface of the framing as the groove is in from each side of the styles and rails. Raised panels are thicker than the groove in the framing, but are not so thick as to reach the surface ; nor is the panel thickened through its whole extent. It fits exactly into the groove, and thickens gradually for an inch or two, and then sets off at a right angle with the surface, increasing suddenly three or four sixteenths of an inch. A panel may be raised on one side only, or on both sides. Flush panels are rebated down from one face to the distance the plough groove is in from the surface of the framing ; and the back of a panel thus rebated on one side is worked down to be even with the other edge of the groove, leaving a tongue to fit it exactly ; for if it be required to make panels flush on both sides, this is generally effected by filling in on the back or flattened side with an extraneous piece. Panels of external doors and shutters may be rendered more secure by boring them, and inserting iron wires, as noticed in the Transactions of the Society of Arts, vol. xxv. p. 106. Fram ing is not, however, often finished in the manner above described, especially with raised and flush panels; mouldings are generally introduced, and are either struck or worked in the solid substance of the framing, or are in separate pieces or slips, and laid in with brads. If a moulding be struck or laid in on one side only, and the other is left plain, the framing is described as moulded and square, a flat panel being in that case understood ; if the panel be raised the framing will be described as moulded with a raised panel on one side, and square or flush on the other. It may be moulded with a flat panel, or moulded with a raised panel, on both sides ; and the moulding may, as before intimated, be either struck in the solid or laid in any of the preceding cases. Mouldings which are laid in round the panels of framing are neatly mitred at the angles, and bradded, to appear as much as possible as if they were struck in the solid. In nailing or bradding the mouldings, the brads should be driven into the framework, and not into the panels. Framing with sunk panels, in some kinds of work, has the edges of the rails and styles either stop- chamfered or slightly curved. With a flush panel the moulding is always either a bead, or a series of beads called reeds ; and is, in the case of a single bead, which is most common, always struck on the solid frame, and the work is called bead-flush ; but reeds are generally struck on the panel in the direction of the grain, and laid in on the panel across it, or along the ends ; this is termed reed-flush.