If a workman has to cut many mortices on pieces of the same size, he frequently constructs a rough mortice gauge with double points, which marks both sides of the mortice at once, like K. A fixed block at K, the right distance from the points, l m, of two nails, is sufficient when all the mortices are to be alike. There is, however, a regular double-pointed gauge, made generally of ebony, plated with brass, and a brass rule to which one of the points is fixed, and which is acted on by a screw at the end, which can be turned by the thumb and finger. This has the effect of separating or closing the two points according to the desired width of the mortice, its distance from the side of the piece being regulated as before by the sliding head fixed by a wedge. This is an expensive tool, and need not be purchased. There are also, let me add, many costly tools of various forms and uses; but let the boy’s motto (and man’s, too, for all that) be, “Do as well as you can without.” You have no idea how a little ingenuity and contrivance will save your pockets, and that, too, without in the least tending to spoil your work. All you require are a few of the most generally useful tools in first-rate condition—chisels, saws, and planes, sharp and well set, and fit for work at any moment.
With regard to uniting two pieces of wood or other material with glue, it must be remembered that if you use this substance in a thick semifluid state, and in quantity, its effect will be lost. Make it a rule to put on as thin a coat as possible, and let it be not thicker than cream, so that it will freely flow into corners, and spread evenly over the surfaces to be united. Make the wood also quite warm, so that the glue shall not be suddenly chilled, and let it be used boiling. Always heat it either in a proper glue-pot, or at any rate, place the vessel which contains it (a small gallipot, for instance) inside another vessel in which water can be kept boiling.
The glue, which should be thin and transparent, being broken into small pieces, should be put into such a vessel as suggested, and covered with cold water, and it should be allowed to remain thus until swollen and softened. Then bring the water in the outer vessel to the boiling point, and do not use the glue until it is entirely dissolved and of one uniform consistence. It should be stirred while boiling with a piece of stick, and a brush used to lay it upon the pieces to be joined. It very generally happens that pieces glued by boys fall apart almost directly. This is almost entirely due to the fact that the glue is used thick and clotty, and in too great quantity, while the wood is never made warm as it should be. If two pieces are properly joined in this way, it is almost impossible to separate them at the joint—the wood itself will give way and split before the glue will yield to the strain. Carpenters use various forms of clamps or vices to hold work together until the glue shall be dry; but for boys by far the best plan, where any such holdfast is needed, is to bind the parts together with twine, and then to set them aside for twelve hours at least. It is seldom that articles once united by glue and separated will unite firmly a second time.
Chapter IV.
The exercise of a boy’s mechanical tastes upon works of practical utility is, of course, far preferable to its expenditure upon mere trifles, made one day to be cast aside and destroyed the next; and as there is scarcely any household that does not need its furniture repaired or added to from time to time, I shall now give directions for the construction of one or two articles that seem to be within fair scope of a young mechanic’s abilities. The first is a plain, useful table, without a drawer, and with square legs, because without a lathe the latter cannot be made ornamental; and lathe work will occupy some future pages, since it is necessary first to give the young mechanic a fair insight into the principles and practice of plain carpentry and joinery.