Poly technique was likely to give him. Although he 

 embraced a part of Borgnis' approach, adopting 

 rkeptcurs, communicateurs, and operateurs, Coriolis indi- 

 cated by the title of his book that he was more con- 

 cerned with forces than with relative displacements. 

 However, the attractively simple three-element scheme 

 of Coriolis became well fixed in French thinking.'* 



Michel Chasles (1793-1880), another graduate of 

 the Ecole Polytechnique, contributed some incisive 

 ideas in his papers on instant centers*^ published 

 during the 1830's, but their tremendous importance 

 in kinematic analysis was not recognized until much 

 later. 



^^ The renowned Jean Victor Poncelet lent weight to this 

 scheme. (See Franz Reuleaux, Theoretische Kinematik: Grund- 

 Zilge einer Theorie des Maschinenwesens, Braunschweig, 1875, 

 translated by Alexander B. W. Kennedy as The Kinematics of 

 Machinery: Outlines of a Theory of Machines, London, 1876, 

 pp. 11, 487. I have used the Kennedy translation in the 

 Reuleaux references throughout the present work.) 



^^ The instant center was probably first lecognized by Jean 

 Bernoulli (1667-1748) in his "De Centro Spontaneo Rota- 

 tionis" {Johannis Bernoulli . . . Opera Omr.ia .... Lausanne, 

 1742, vol. 4, p. 265fr.). 



Figure 29. — Robert Willis (1800- 1875), J^^k- 

 sonian Professor, Cambridge University, and 

 author of Principles of Mechanism, one of the 

 landmark books in the development of kine- 

 matics of mechanisms. Photo courtesy Gon- 

 ville and Caius College, Cambridge University. 



governors), and operateurs, which produced the final 

 effect.^' 



The brilliant Gaspard-Gustave de Coriolis (1792- 

 1843) — remem.bered mainly for a paper of a dozen 

 pages explaining the nature of the acceleration that 

 bears his name ^' — was another graduate of the Ecole 

 Polytechnique who wrote on the subject of machines. 

 His book,*'' published in 1829, was provoked by his 

 recognition that the designer of machines needed more 

 knowledge than his undergraduate work at the Ecole 



'^ Giuseppe Antonio Borgnis, Theorie de la mecanique usuelle 

 in Traiie complet de mecanique appliquee aux arts, Paris, 1818, 

 vol. 1, pp. xiv-xvi. 



'* Gaspard-Gustave de Coriolis, "Memoire sur les equations 

 du mouvement relatif des systemes de corps," Journal de 

 VEcole Polytechnique, i835, vol. 15, pp. 142-154. 



" Gaspard-Gustave de Coriolis, De Calcul de I'ejet des machines, 

 Paris, 1829. In this book Coriolis proposed the now generally 

 accepted equation, work = force X distance (pp. iii, 2). 



Figure 30. — Franz Reuleaux (i 829-1 905). His 

 Theoretische Kinematik, published in 1875, pro- 

 vided the basis for modern kinematic analysis. 

 Photo courtesy Deutsches Museum, Munich. 



PAPER 27: KINEMATICS FROM THE TIME OF WATT 



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