On 18 in × 24 in paper, draw the four-bar linkage full size, placing A 6 in up from the lower edge and 7 in left of the right edge. (Better utilization of the paper is obtained by tilting the frame through about 15◦ as indicated.) For the coupler link, draw the inflection circle and the cubic of stationary curvature. Choose a coupler point C coincident with the cubic, and plot a portion of its coupler curve in the vicinity of the cubic. Find the conjugate point C

. Draw a circle through C with center at C

, and compare this circle with the actual path of C. Find Ball’s point. Locate a point D on the coupler at Ball’s point, and plot a portion of its path. Compare the result with a straight line.