Fig. 40.
Fig. 41.
Another Method.—Stick a pin in each corner of a square board [(Fig. 41)], and look diagonally across them, first in the direction of the line to which you wish to run at right angles, and then for the new line sight across the other two pins.
A SIMPLE LEVELLING INSTRUMENT.
Fasten a common carpenter’s square in a slit to the top of a stake by means of a screw, and then tie a plumb-line at the angle so that it may hang along the short arm, when the plumb-line hangs vertically and sights may be taken over it. A carpenter’s spirit-level set on an adjustable stand will do as well. The other arm will then be a level [(Fig. 42)].
Fig. 42.