ON THE FORMATION OF THE SHUTTING JOINTS OF DOORS, &c.

95

69. Another mode of hanging a door on centres is shown by fig. 9, plate LI. To find the place for the centre, join AB, and bisect it by the perpendicular DC. Make EAC an angle of 45 degrees, and then the point in which DC intersects AC will be the centre required.

70. The door of a room should be so formed and hung, 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. 8. The bead should be continued round the door, and a common but-hinge answers for a joint of this kind.

On the Formation of the Shutting Joints of Doors, Shutters, &c.

71. THE proper bevel for the edge of a door or sash may be found by drawing a line from the centre of motion a, fig. 1, plate LIII, to b, the interior angle of the rebate, and drawing be perpendicular to ab, which gives the bevel required. In practice, the bevel is usually made a little 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 becoming filled with paint.

72. Figure 2, on the same plate, represents the section of a pair of folding-doors with jambs, upon a straight plan. Here we must suppose that one of the doors is shut, while the other opens. Let the half which is shut be edcbhgf, and let aedcb be the other half, which opens. Draw the line dc, parallel to the face of the door, bisecting the thickness, so that the middle of cd may be in the middle of the breadth of the door. Draw the line ad, and draw de perpendicular to ad; also draw the line ab; taking the bottom of the quirk of the bead for the point b, and make bc perpendicular to ab, then will edeb be the form of the joint.

The principle of the operation is evident; since no length can be applied in a place shorter than itself. The most remote point of the thickness in the moving part must, in the act of opening, pass every other part of the rebate that is stationary. The principle, therefore, amounts to this: that, since in the opening every point in the edge of the moving door describes the circumference of a circle, no line drawn from the point a to the line bc, should be less than the line ab; and, because the angle abc is a right angle, every line drawn from a, to meet the line bc, will be the hypothenuse of a right-angled triangle, of which one of the legs is the line ab; therefore, ab is shorter than any line that can be drawn from the point a to the line be; consequently, the point b, in the act of opening, would fall within the extremities of every line drawn from a to the line bc.

It may, also, be shown that, if any point be taken in be, and a line be drawn from that point to the point a, the line thus drawn will be less than any other line drawn from a to any other point of the line bc, between the former point and the point c.

In the same manner, because ade, fig. 2, is a right-angle, the line ad is less than any other line that can be drawn from a to any point of the line de, between d and e; and every other line drawn from a, to any point between d and e, will be less than any other line drawn from a to any other point in de, between that point and the point e.

Having thus shown the reason of the method, its application in figures 3, 4, 5, 6, will be evident on inspection; or, at least, by comparing it with the former part of this description; and it only remains to add, that the angle may be as much greater than is given by this method as the appearance of the work requires, as in fig. 3 and 4.

73. Figure 7 is a section of the jambs of a pair of folding-doors, with part of the section of the door, adapted for folding back against the wall: fig. 8 is the section of the meeting-stiles of the doors; the dotted line in the stile shows the place for the lock.

OF THE CONSTRUCTION OF DOORS.

74. Doors are of various kinds, and are usually described by the number of pannels, and the kind of framing.

Figure 1 represents a SIX-PANNELED DOOR, having an ovolo and fillet on the stiles, with plain pannels.

Figure 2 is a section of part of a stile and pannel moulded with a quirk-ovolo and fillet; the pannel being flat on both sides.

Figure 3 represents FOLDING DOORS, which meet together with a lap-joint, exhibiting a bead on both sides of the door.

Figure 4 exhibits a one-pannel or dwarf door, with BEAD and BUT framing.

Figure 5 shows one with BEAD and FLUSH framing. The difference between bead and but and bead and flush is this: In bead and but, the bead is run on the edges of the pannel, in the direction of the grain only; but, in bead and flush, the bead is run round all the four edges of the frame. Sometimes beads are inserted across the ends of the pannels.

Figure 6, section of part of the stile and pannel of square framing.

Figure 7, section of part of a stile and pannel, having quirked ovolo and bead on the framing, with square pannel.

Figure 8, section of a part of the stile and pannel of a door, with quirked cyma-reversa on the framing.

75. External doors for houses should not be less then 14 inches thick, when finished, in order to be firm and durable. They should be made of yellow deal or oak, framed with pannels, and may be moulded, or the external face may be plain with a flush-bead round each pannel, (called bead and flush,) with a substantial oak or yellow fir frame. The height and width of external single doors are made in various proportions; they should never be less than 6 feet 8 inches in height, nor narrower than 2 feet 10 inches; and large doors should be avoided, because they lessen the apparent magnitude of a building. When folding-doors are employed, there should be space to admit one person to enter when only one of the doors is open, and therefore they should never have less than two feet clear opening when one door is open, and the height to this width may be about 8 or 9 feet.

76. Internal doors are made of various kinds of materials, but most commonly of yellow fir or white deal, the latter should be preferred. Doors of principal apartments are often made of oak, and sometimes of mahogany, and other expensive woods. Mahogany acquires a dull heavy colour with age, which gives a room a gloomy appearance, when it is employed in large masses, as in doors; therefore, when it is used, means should be used to prevent it turning dark. Good varnishing with copal varnish is, perhaps, the most effectual.

The proportions of internal doors, depend, in some degree, on the size of the apartments; in a small room, a large door always gives it a diminutive appearance. With regard to the proportions of the doors themselves, if we take a door, 2 feet wide and 6 feet 3 inches high, as a standard, and then for any other width add half the difference between 2 feet and that width to 6 feet 3 inches, will give the height required. The height should never be less than is given by this rule, and we wish it to be understood, that it is given rather to assist than to direct the taste of the builder. Writers on Architecture observe, that doors should never have more height than double their width, nor less than the diagonal of a square formed on the width.*

• Alberti's Architecture, Vol. I p. 12.