‎VARIGNON, Pierre‎
‎Projet d'une nouvelle méchanique avec un examen de l'opinion de M. Borelli, sur les propriétés des poids suspendus par des cordes.‎

‎Paris, Veuve d'Edme Martin, Boudot, Estienne Martin, 1687.‎

Reference : 17936

‎ Première édition. Premier ouvrage de Pierre Varignon (1654-1722). Il y annonce la règle de la composition des forces par le parallélogramme. Quelques rousseurs habituelles. Dos de la reliure un peu usé, avec début de fente aux charnières, mais la reliure est solide. Ex-libris Bibliotheca Mechanica. /// In-4 de (18), 133, (3) pp., 13 planches h.-t. Veau marbré, dos à nerfs orné, tranches mouchetées. (Reliure de l'époque.) //// First edition. First book of Pierre Varignon (1654-1722), published in the same year as the 'Principia'. "The technique of composing forces by the rule of the parallelogram had undergone more than a century of development when it was published, simultaneously, in 1687 in Newton's Principia, Varignon's Projet, and the second edition of Lamy's Traitez de méchanique. (...) The simultaneous publication of the principle makes difficult any judgement regarding priority. Nevertheless, it was Varignon alone who grasped two importants points. The first is that the law of the lever does not hold a privileged position in statics, and that the unification of "mechanics" (the science of simple machines) was to be carried out on the basis of the compositions of forces. The second concerns the inclinated plane: that the real reason for the the equilibrium observed is that the resultant of the applied forces is orthogonal to the possible displacement. These two points provide a good indication of Varignon's contribution to the development of the principle of virtual velocities." (DSB 13, 585). "In discussing Guidobaldo's Mechanicorum liber, Varignon grasped two important points : the law of levers did not hold a privileged position in statics and the unification of mechanics was to be carried out on the basis of the composition of forces; and second, the real reason for the equilibrium on the inclined plane was that the resultant of the applied forces is orthogonal to the possible displacement" (Roberts & Trent,p. 337, this copy with Ex-libris Bibliotheca Mechanica. /// PLUS DE PHOTOS SUR WWW.LATUDE.NET‎