Oftentimes it becomes necessary to draw a line parallel to the tried edge. This may be done roughly with the rule and pencil, as shown in [Fig. 40]. Grasp the rule in the left hand, with the first finger touching the tried edge of the board, and hold the pencil point against the end of the rule with the right hand. Keeping this position, with a steady hold on the rule and pencil, move your hands along the board. The result will be a line parallel to the tried edge.
At first you may have trouble in making a straight line, but with practice you will be able to hold the rule and pencil steadily.
Fig. 40.—Gauging with Rule and Pencil.
For particular work, where it is necessary to get a perfectly straight and parallel line,
A Marking-gauge should be used. This is nothing more than the above principles combined in a tool. It consists of a graduated shaft, or rule, with a small needle or spur in one end, which slides through a mortise made in a block of wood known as the head.
Fig. 41.—Using the Marking-gauge.