de; describe the circle bei; make df equal to the radius of the circle bei, and join af. Bisect af by a perpendicular, gh, meeting af in h; then, with the radius dg, describe the arc db: dbc will then be the ovolo required.

22. Figure 17 is the section of a concave moulding called a SCOTIA. To form this moulding, describe the circle dabf, and draw cd perpendicular to the fillet. Make cg equal to the radius of the circle to be described, and let e be the centre of that circle: join ge, and bisect ge by the perpendicular df: from d, with the radius dc, describe the arc cb, and cba will be the scotia required.

23. Figure 18 represents the section of a piece of wood when it is said to be rebated Figure 19, the section of a piece of wood said to be grooved. Figure 20, the sections of two pieces grooved and tongued together: where No. 1 shows the tongue, and No. 2 the groove, and these are so adapted to each other that they may be joined closely together. This method is used where it is required to join many boards together, so as to have the effect of one board, and prevent wind or air from coming through the joints between every two boards, without the risk of splitting, which would take place if the boards were glued together. Figure 21 represents the section of a piece of wood said to be rebated and beaded.

FRAMING ANGLES.

24. WHEN the length of a joint at an angle is not considerable, it is sufficient to cut the joint, so that when the parts are joined, the plane of the joint shall bisect the angle. This kind of joint is called a plain mitre, and is shown for different angles by fig. 1, plate XLIV.

25. When an angle of considerable length is to be joined, and the kind of work does not require that the joining should be concealed, fig. 2 is often employed; the small bead renders the appearance of the joint less objectionable, because any irregularities, from shrinkage, are not seen in the shade of the quirk of the bead.

A bead upon an angle, where the nature of the thing does not determine it to be an arris, is attended with many advantages; it is less liable to be injured, and admits of a secure joint, without the appearance of one. Fig. 3 shows a joint of this description. It is the metnod usually adopted for joining linings together at external angles.

26. Figure 4 represents a very good joint for an exterior angle, whether it be a long joint or a short one. It is employed for mitring dado together at external angles. The joint represented by fig. 5 is esteemed superior to it for long joints in the direction of the grain of the pieces, the parts being drawn together by the form of the joint itself, they can be fitted with more accuracy, and joined with more certainty. The angles of pilasters are often joined as in fig. 5. 27. Interior angles are commonly joined as shown by fig. 6. If the upper or lower edge be visible, the joint is mitred, as in fig. 1, at the visible edge only; the other parts of the joint being grooved, as in fig. 6.

In this manner are put together the skirting and dado at the interior angles of rooms, and the backs, and back-linings of windows, the jambs of door-ways, and various other parts of joiners' work.

Figure 7 shows the variation of this method which is used in rougher work, such as joining the angles of troughs, and the like. It is better adapted for a water-tight joint than one with a smaller groove.

28. Figure 8 represents an angle joined by common dovetails; the part AB represents the pins, and CD the dovetails.

29. Figure 9 shows the species called lap dove-tailing, in which the dovetails are concealed; it is used for portable desks, drawer-fronts, and other purposes. Figure 10 is another species of concealed dove-tailing, called mitre dove-tailing, the joint resembling a plain mitred joint. Tea. chests, work-boxes, and any kind of work requiring much neatness, is joined in this manner when it is not to be veneered.

30. Figure 11 shows the mode of joining a mitre-joint with keys: picture-frames and light boxes are frequently put together by this method.

The figures 8, 9, 10, 11, are drawn according to the mode of projection lately invented by Professor Farish, of Cambridge, and which he has so successfully applied to drawings of machinery. He calls it Isometrical Perspective, but it would be more correct to call it Isometrical Projection. In our treatise on PRACTICAL ARCHITECTURE, which will form a volume similar to this, we propose to give a full account of Professor Farish's method.

PRINCIPLES OF FRAMING.

31. THE goodness of Joiners' work depends chiefly upon the care that has been bestowed in joining the materials. In Carpentry, framing owes its strength to the form and position of its parts; but, in joinery, the strength of a frame usually depends wholly upon the strength of the joinings. The importance, therefore, of forming the joints properly, and fitting them together as accurately as possible, is obvious. Hence it is that we expect such accurate workmanship from a good joiner; and he not only should be able to connect his materials with truth and firmness, but also be able to make surfaces perfectly even and smooth, mouldings true and regular, and the parts intended to move, so that they may be used with ease and freedom.

32. Frames, in joinery, are usually connected by mortise and tenon joints, with grooves to receive pannels. Doors, window-shutters, &c. are framed in this manner. 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 the labour of cutting out for the depressed parts. From this view of the subject, the joiner will readily perceive that neither the parts of the frame nor the pannels should be wide. And, as the frame should be composed of narrow pieces, it follows that the pannels should not be very long, otherwise the frame will want strength. The pannels of framing should never be more than about fifteen inches wide, nor more than four feet long, and pannels 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 pannel.

33. It is of the utmost importance in good framing, that the tenons and mortises should be truly made. After a mortise has been made with the mortise-chisel, it should be rendered perfectly even with a float;-an instrument which differs from a single cut, or float-file, only by having larger teeth, capable of being sharpened like a saw. An inexperienced workman often makes his work fit too tight in one place, and too easy in another; hence a mortise is often partially split in first driving the parts together, and the work is never afterwards firm; whereas, if the tenon fill the mortise equally in consequence of every part being accurately formed, the work will go together without using any considerable force in driving, and will be found to be firm and sound.