T BHE DECLINE OF THE CARTESIAN WORLDVIEW in the early decades of the eighteenth century has been described from several vantage points.' As a metaphysical system it reflected the failure of the ontology of substance philosophy.2 The categories substance and modification were too limited in scope; the essences extension and thought so different in kind as to forbid causal interaction. As a methodological system it failed because certain knowledge of the temporal phenomenal world could not be deduced from its logical axioms.3 As a planetary explanation its vortical aethereal motions were shown by Newton to be inconsistent with Kepler's laws, while the gradual demise of these aethereal hypotheses has been recently documented by E. J. Aiton.4 My purpose in this paper is to indicate the inadequacies of the Cartesian worldview in handling problems in terrestrial mechanics. I shall show that although Cartesian presuppositions were used in mechanical problems, the mathematical results supported Leibnizian or Newtonian conclusions. Cartesianism was unable to maintain