In good carpentry everything depends on accuracy of measurement of parts, and fitting the parts together at right angles, or at the required angle or bevel. For the attainment of these most necessary requisites, tools of guidance and direction of various kinds are used, without which it would be impossible even for a skilled carpenter or joiner to do his work, and fit the various pieces together with the nicety that is essential in all operations of this nature. Thus, for setting out a long, straight line in ripping a slip of wood from a board, a line and reel is required; and for the measurement of any length into parts, or to measure any required length, breadth, and thickness, the carpenter's rule is needful. For cutting off the end of a board at right angles to the edge, or for mortising, etc., the square must be used, and for cutting wood at any given angle to the edge, the proper line of direction for the saw must be marked by aid of the bevel. For cutting notches in wood or for cutting or planing down pieces of wood to the same thickness, the necessary guide lines must be marked by a marking gauge, while in mortising the mortise gauge is used.

For joining pieces of wood at right angles, as in making a picture-frame, recourse must be had to the mitre box; and for subdividing any given space into smaller spaces, or marking out circles and sweeps of various diameters the compasses must be used. In turning, to make sure of having the diameter of various parts of the work in harmony with the pattern, these diameters must one and all be tried and regulated by the callipers as the work goes on. In bringing horizontal bars, shelves, etc., to a true level, the spirit level must be used; and in fixing a post in the ground, or a piece of quartering to the wall, the upright level with cord and plumb-bob. A straight-edge is useful for testing the nicety and accuracy with which wood has been planed up, and for other purposes. We name these, though the amateur is not likely to need them all. There are many miscellaneous tools and appliances used in carpentry and joinery which are not subject to classification. Among these we may include the screwdriver, the nail-punch, the reamer or rymer, the scriber, the cramp, the glue-pot, and the oil-can. Sand-paper and emery-paper must also be noticed. There is another appliance called the bench holdfast, which is used to hold wood firmly down on the carpenter's bench when necessary.

These tools are so simple and easily obtained that a description of each is not necessary. In their selection cheapness is not to be considered, but accuracy and convenience.