This paper examines Robert Willis's science of 'mechanism', its relation to the later mechanics textbooks of William Whewell, and its promotion as the key to appreciating, understanding and contriving machinery in Victorian Britain. Responsive, first, to the Society for the Diffusion of Useful Knowledge and later to student audiences at Cambridge, Willis constructed a science of 'mechanism' in both words in print and works in practice. With Whewell's sanction in the Philosophy of the Inductive Sciences (1840), Willis's Principles of Mechanism (1841) elaborated a science of kinematics expressing geometry in motion without considerations of force. With Willis's approval, Whewell's Mechanics of Engineering (1841) began to complete and systematize a projected science of machinery, now separated from previous accounts of mechanics. Their joint project put 'mechanism' and the 'mechanics of engineering' into print in Britain as adjuncts to a liberal education in Cambridge; further, with the rapid expansion of academic provision for practical engineers from 1838 to 1841, these two Fellows offered their progeny as essential fodder further afield. Reactions to this two-pronged attack varied. But it was, perhaps, Willis's work with elaborate demonstration lectures, using special apparatus built by London mechanists and marketed by educational entrepreneurs, that effectively disseminated the new science.