We completed our outfit by making a surveyor's rod out of a straight stick
of wood about 6 feet long. A target or sighting disk was mounted on the
stick. This disk was 6 inches in diameter, and was sawed out of a 6-inch
square hoard by making straight cuts across the corners and then smoothing
off the edge to a perfect circle with a draw-knife. The thickness of the
disk was only 1/2 inch. At the back of the disk we fastened a block of
wood with a slot cut in it to receive the rod, as shown in Fig. 81. To
hold the disk at different heights on the rod a small bolt was used. The
nut on this bolt was slipped into a hole on the block at the bottom of the
slot and held in place by driving in nails about it, as illustrated in
Fig. 82. The bolt was then passed through the hole and threaded through
the nut, with its inner end bearing against the rod. The disk could thus
be held at any desired position by tightening up the bolt. A piece of
white paper was now pasted over the disk. The paper was marked off into
quarters, and opposite quarters were painted black so that it would be
easy to sight, from a distance, the exact center of the target.

[Illustration: Fig. 80. Cutting Out a Disk.]

[Illustration: Fig. 81. The Sighting Disk.]

[Illustration: Fig. 82. Nut Fastened in Block.]



A Simple Method of Surveying.

[Illustration: Fig. 83. Diagram of Our First Lesson in Surveying.]