I have made the drawings of the three principal dovetailed joints so plain as to render special description almost unnecessary after the remarks already made. The second and third, however, may need a few words, as they differ slightly from that used in the drawer, of which a description has been given, chiefly because the piece in which the dovetails are, is, in this case, as thick as that used for the sockets.
Suppose the dovetails and pins marked out ready to be cut. Take your marking-gauge and set the slide about a quarter of an inch from the point, and run a line across the ends of the two pieces at A B, and at C D, and also at E F. Stop at A B when you cut the sockets, and take care to get the bottoms of these quite square and even. Cut the dovetails or pins as directed in making the drawer, but stop on the lines e f and g h (the latter also to be made with the gauge on both edges of the work), thus the two pieces will, of necessity, fit nicely together, and only a single line will appear a little way from one corner. If all lines are made with gauge and square, this form of dovetail may require neatness and care, but will not be beyond the skill even of a young mechanic. I should indeed advise that every opportunity be taken of joining pieces of wood with tenon or with dovetail, because, after all, these are the chief difficulties to be encountered. If you can square up your work, and make true-fitting joints, there is little in carpentry and joinery that you cannot accomplish.
The third example is worked exactly like the second, but instead of leaving square the pieces projecting beyond the dovetails and pins, these are sloped off or bevelled carefully from the extreme corners down to the pins and sockets. The result is, that when put together, no joint appears, as it is exactly upon the angle. There is no neater or stronger method than this of joining the sides of drawers, boxes, trays, and such like articles. The cabinetmaker employs no other for heavy work; only when it is very light does he make use of a plan, the appearance of which is (when finished) like the last-described, but it is less trouble to make, and less strong, yet sufficiently so for many purposes. This method is called mitring, and is accomplished in the following way.
The wood (let it be for a small tray) is prepared as usual, truly and evenly, and the ends exactly square to the sides. If you use stuff about a quarter or half an inch thick, or even an eighth (the first or last being suitable for such light work), you can make a mitred joint with the help of the gauge alone, but frequently a mitre-board or mitre-box is used, which saves some trouble in measuring and marking. It is well, however, that you should begin with this trouble, and take up the easier method afterwards; especially as it will in this case give you a simple lesson in mathematics, and teach you some of the properties of the figure called a square. Let us commence with this lesson.
A, B, C, D, Fig. 31, is a square; the lines at the opposite sides are parallel,—that is, they are exactly the same distance apart from one end to the other. To make this clear, E and F are given, which are not parallel, for they are further apart at one end than they are at the other. And as A B is parallel to C D, and A C parallel to B D, so A B is perpendicular to B D and to A C, or what we have called square to it, as you would find with your square, which is made, as you know, to prove your work in this respect. The consequence is, that the angles (or corners) are all alike, and are called right angles. Understand what is meant by angles being the same size or alike. M and H are alike, though the lines of one are a great deal longer than those of the other; but though the lines of K and H are the same length, the angle K is much smaller than that at H.
Fig. 31.
As I have gone a little into this subject, I will go a little further, for it is as well that you should learn all about the sizes of angles, and I only know of one way in which to make the matter clear.
Every circle, no matter how small or large, is supposed to be divided into 360 equal parts, called degrees. That large circle which forms the circumference of the earth is considered to be so divided. Now, if we draw lines from all these divisions to the centre, they will meet there, and form a number of equal angles. I have not divided the circle P all round, because it would make so many angles that you could not see them clearly; but I have put 360 at the top, and then 45, which means, that if I had marked all the divisions, there would be 45 up to that point. Then at 45 more I have marked 90, and so on, marking each 45th division, and from these I have drawn lines to the centre of the circle. Now, if you understand me so far, we shall get on famously. Look at the line from 360 to the centre, and that from 90°, and see where they join. This is a right angle, and this is the angle at each corner of a square. At N, I have drawn this separately to make it clear, and you see I have taken a quarter of the circle, or the quadrant, as it is called, of 90°. And you now see that I might extend the lines beyond the circle to any extent, but it would make no difference,—we should still have 90° of a circle, only the circle would be larger, as those which are partly drawn with the dotted lines.