[Drawn for this work by L. W. Truesdell, Tinman, Owego, N. Y.]

Fig. 1.

How To Find The Circumference Of Any Diameter 1

From the centre C describe a circle AB, having the required diameter; then place the corner of the square at the centre C, and draw the lines CD and CE; then draw the chord DE : three times the diameter added to the distance from the middle of the chord DFE to the middle of the subtending arc DGE, will be the circumference sought.