^Biography of M. Le Comte Lagrange. 243 



bim the care of developing the arguments on which his 

 formulas rested. In effect, we notice already in these 

 memoirs this pure analytical step which afterwards charac- 

 terized the great productions of Lagrange. He had found 

 a new theory of the lever. It constituted the third part of 

 a memoir that had much success. Foncenex in return, 

 was put at the head of the navy which the king of Sardinia 

 was then forming. The two first parts seem of the same 

 style and from the same hand. Are they alike from La- 

 grange? He has not positively claimed them. What, 

 however, can direct our conjectures to the real author, 

 is, that Foncenex soon ceased to enrich the collections of 

 the new Academy, and that Montucla, ignorant of what has 

 been revealed to us by Lagrange at his last moments, is 

 astonished that Foncenex, after being so favourably an- 

 nounced, broke off researches that could have obtained for 

 him a great name. 



Lagrange abandoning to his friend isolated solutions, 

 published at the same time under his own name some 

 theories which he promised to follow out and develope. 

 Thus, after having given new^ methods for maxima and 

 minima o^ ever J hind, after having shewn the insufficiency 

 of the known formulas, he announced that he would treat 

 this subject, which otherwise appeared to him interesting, 

 in a work which he was preparing, and in which, too, are 

 seen deduced from the same principles all the mechanics of 

 bodies, whether solids, or fluids. Thus, at twenty three 

 years he had already laid the foundation of great works, 

 which have since excited the wonder of philosophers. 



In the same volume, he brings back to the differential 

 calculus, the theory of recurring series, and the doctrine of 

 chances, which, hitherto, had been treated only by indirect 

 methods, and which he establishes upon the most natural 

 and the most general principles. 



Newton had undertaken to submit to the calculus the 

 motions of fluids : he had made researches on the propaga- 

 tion of sound. His principles were insufficient and even 

 defective ; and his suppositions inconsistent with them- 

 selves : Lagrange demonstrated them to be so. Lagrange 

 founded his new researches on the known laws of dynamics; 

 hy considering in the air only the particles found in a straight 



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