A contribution to the history of kinematics—I

The present paper is the first part of a contribution to the history of kinematics consisting of two parts. The paper deals with the invention of Watt's approximate straight-line linkages in 1784 and the early French contributions to the theory of the planar 4-bar coupler curve by de Prony, Hachette and Vincent. In addition to this the paper treats the way in which Peaucellier discovered the first exact planar straight-line linkage.