The lengths of the links comply with the conditions: B͞P=B͞Q and C͞P=C͞Q. Figure BQCP is a rhomboid linkage. Links 1 and 2 turn about fixed axis A which is the centre of inversion transformation. Links 4 and 3 are connected by turning pairs B to each other and to link 2, and by turning pairs P and Q to links 5 and 6. Links 5 and 6 are connected by turning pairs C to each other and to link 1. For any configuration of the mechanism, points A, P and Q lie on a single straight line. When point P or Q travels along any arbitrary curve, the other point describes a curve which is the inversion of the first curve. Thus, the mechanism accomplishes inversion transformations of the form A͞P×A͞Q=A͞B²-B͞P²=A͞C²-C͞P²= const. The mechanism also accomplishes translational displacement of straight line BC which is perpendicular to straight line APQ.
$739$LW,GI$