In some exercises no jointing of the several pieces may be required, as they may be fixed together by glue, nails, or screws. In construction of the great majority of articles made of wood, joints of various sorts are an absolute necessity. In order that sufficient practice may be got in planing, gauging, exact measurement, and cutting to lines preparatory to jointing, it will be advisable to procure a piece of wood about I in. square, and from 12 to 15 in. long. It must be planed correctly on face and edge, and gauged to the greatest size it will stand, either 7/8 in., 3/4 in., or under. When finished, a line must be accurately drawn on each side, at right angles to face or edge, by the square and pencil (observing the advice given at the centre of page 16), and as far from the end as the width of the wood. This part must now be carefully cut off with the dovetail saw, so that each line may be split, and the end left quite square. If not successfully performed at first, the process should be repeated till the cube is exact, after which the same thing should be done by the help of the angular groove, cut on each side, as described on page 17. If unsatisfactory, this, also, should be repeated until the work is without fault.