Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/554

Rh 492 the same straight line, as any defect in this respect will produce a considerable strain upon the hinges every time the hanging part is moved, will prevent it from moving freely, and is injurious to the hinges. In hanging doors, centres are often used instead, of hinges j but, on account of the small quantity of friction in centres, a door moves too easily, so that a slight draught of air accelerates it so much in falling to, that it shakes the building, and is dis agreeable. This may be in some degree remedied by placing a small spring to receive the shock of the door. The greatest difficulty, in hanging doors, is to make them to clear a carpet, and be close at the bottom when shut. To do this, that part of the floor which is under the door when shut, or the width of the jambs, may have a piece of wood about a quarter of an inch thick above the general level of the floor, which, with placing the hinges so as to cause the door to rise as it opens, will be sufficient unless the carpet should be a very thick one. Several mechanical contrivances have been used for either raising the door, or adding a part to spring close to a floor as the door shuts. The best method now in use. and the simplest, is the invention of the rising or skew-butt hinge. The parts of this which bear on each other are mnde with a double bevel, so that, if more than half opened, the door falls against the wall by its own weight; if less than half open, it closes itself. Various kinds of hinges are in use. Sometimes they are concealed, as in the kinds of joints called rule joints ; others project, and are intended to let a door fold back over projecting mouldings, as on pulpit doors and outside folding shutters. When hinges project, the weight of the door acts with an increased leverage upon them, and they soon get out of order, unless they be strong and well fixed. The door of a room should be hung so that, in opening the door, the interior of the room cannot be seen through the joint. This may be done by making the joint according to fig. 84. The bead should be continued round the door, and a common butt-hinge answers for it Fid. 84. Door-Joint. FIG. 85. Bevel for Edee of Door. The proper bevel for the edge of a door or sash may be found by drawing a line from the centre of motion C (fig. 85) to e, the interior angle of the rebate ; e d drawn perpendicular to C e gives the bevel required. In practice the bevel is usually made less, leaving an open space in the joint when the door is shut ; this is done on account of the interior angle of the rebate often being filled with paint. The extension of the principle of ploughing and tonguing work together is one of the most important of the improvements that have been introduced by modern joiners. It is an easy, simple, and effectual method of combination, and one that provides against the greatest defect of timber-work, its shrinkage. By means of this method, the bold mouldings of mediaeval architecture can be executed with a comparatively small quantity of material ; and even in the mouldings of modern architecture it saves much labour. For example, the moulded part of an architrave may be joined with the plain part, as shown by fig. 86. If this method be compared with the old method of glueing one piece upon another, its advantage will be more evident FIG. 86. Joining of Architrave. [JOINERY. Architraves and pilasters are variously sunk and moulded Archi- according to the fancy of the designer. They are fixed to traves - the grounds with their internal edges exactly fitting to the rebates in the jambs, and they form the enriched margin or moulding of the frame in which the door is set. Archi traves are mitred at the upper angle, but pilasters have generally a console or an enriched block or cap resting on them, to which they fit with a square joint ; both the one and the other either run down and are scribed to the floor, or rest on squared blocks or bases, which may be the height of the skirting board, or of the whole base. The architraves, skirtings, and surbase mouldings, are Fixing fixed to pieces of wood called grounds, as A, fig. 86 ; and as S rom&amp;gt;tls - the straightness and accuracy of these mouldings depend upon the care that has been taken to fix the grounds truly, it will appear that fixing grounds, which is a part often left to inferior workmen, in reality requires skill and attention ; besides, they are almost always the guide for the plasterer. Where the plasterer s work joins the grounds, they should have a small groove ploughed in the edge to form a key for the plaster. In old work the ground was generally hidden, but in modern work it is frequently shown, which is a saving of stuff; thus, instead of architraves being prepared A FIG. 87. Door-Jamb and Ground. FIG. 88. Ground and Moul dings. as in fig. 86, they are made as shown in fig. 87, where A is the rebated and beaded door-jamb, and B the ground, which is generally splayed at the back as a key to the plastering instead of being grooved. On this a thin piece of stuff is bradded to form the double-faced architrave, instead of sinking out of the solid, and on this the ogee or ovolo moulding is nailed. Again with base mouldings, A (fig. 88) is the ground fixed against the wall, on the top of which is nailed the upper moulding B, and C shows the skirting and lower moulding, fixed against a fillet on the floor. We have thus far spoken chiefly of joinery as per- Fixing formed at the bench ; but by far the most important part J oiners remains to be considered ; for, however well a piece of w work may have been prepared, if it be not properly fixed, it cannot fulfil its intended purpose. As in the preceding part, the general principles will be stated that ought to be made the basis of practice ; and these illustrated by par ticular examples. When the carcass of a building is ready for the joiner, the first thing to be done is to cut the bond timber out of the openings, set the sash frames, and fill them with old sashes or with oiled paper on frames, to exclude the weather, but admit light. The flooring joists are then proved with straight-edges, and any inequalities in them are removed with the adze ; the flooring boards are next cut down to their places, and are turned with their faces downwards until the ceilings are done. First, how ever, the pugging is done, if any be intended. This is to prevent sound passing through the floor when finished, and is sometimes called deafening sound-boarding. It is effected by nailing fillets to each side of the joists, near the bottom, and laying on these pieces of rough boards across