218 Memoir of M. D' Aiibuisson de Voisins. 



had devoted his attention, more or less directly, for ten years; 

 and then also he gave to the scientific world his Treatise on 

 the Movement of Water in Pipes or Conduits, which he after- 

 wards remodelled in a more general work. The epoch of 

 1830 now arrived ; the life of M. D'Aubuisson, entirely de- 

 voted to objects of utility and science, the liberality of mind 

 which he united to firmness in maintaining his principles, his 

 absence of ambition, and finally, the eminent services he had 

 rendered to the city, gave grounds to expect that, apart from 

 all political considerations, he would again be called upon 

 for his services as a town-councillor. Such, however, was 

 not the case. Naturally involved in "the downfal of the 

 council of which he formed a part, M. D'Aubuisson was not 

 a man to court suffrages in order to be reinstated ; he felt 

 that the moment was come when his part as a public man, 

 and his influence in the affairs of the town, must cease. He 

 profited by this, as it procured him more leisure, and he gave 

 himself up with more complete absti'action to his favourite 

 studies. Science must gain by this laborious repose : this 

 was, in fact, the time when he composed his hydraulic trea- 

 tise, intended to contain, besides his own researches, a view 

 of our knowledge, the most general and precise, on the move- 

 ments of water and air, and on the calculation of the effect of 

 the machines which these two elements put in motion. This 

 was his last work ; it is likewise, w^e believe, his chief work, 

 imdoubtedly constituting the most positive and durable title 

 to the gratitude of both scientific and practical men. It 

 would be superfluous to speak at length of the Traite Hydrau- 

 lique ; eulogium would likewise be superfluous ; every engi- 

 neer has the book in his hands, and it will long continue to 

 form their guide. They will always delight in that clearness 

 of exposition found in it, which vivifies and colours the driest 

 subjects, and illuminates the most obscure ; they will be 

 pleased with that simplicity of calculation which goes before 

 the efforts of the mind, so to speak, rather than embarrasses 

 it ; they will love that subordination of theory to experience, as 

 Avell as that richness and weight of facts which always pre- 

 dominate in the writings of this author. We may add, that 

 in this treatise, which embraces all the parts of so difficult 



