Circle Center in Seconds #familyhandymanstuff
From The Family HandymanReader William Baker's geometry axiom will help you find the center of any large circle. Draw two straight lines at least a foot long (lines 1 and 2) anywhere on the circle's periphery. Find the center of lines 1 and 2, and, with a framing square, draw perpendicular lines (lines 3 and 4) across the circle. The intersection of 3 and 4 is dead center.