195, find A.B.C.D., the centers of each edge.

Now with the dividers take 12 spaces from the 8-square scale.

Lay off this distance on each side as A' A" from A, B' B" from B, etc.

Now connect A" with B', B" with C', C" with D', D" with A', and the octagon is obtained.
[Illustration: Fig.195.Method of Using the Eight-Square Scale on the Steel-Square.] In making a square piece of timber octagonal, the same method is used on the butt, sawed true.

When the distance from one center is laid off, the marking-gage may be set to the distance from the point thus obtained to the corner of the timber, and the piece gaged from all four corners both ways.