ALEMBERT. 



fliematics ; but they soon perceived that 

 his growing attachment to this science 

 was likely to disappoint the hopes they 

 had formed with respect to his future des- 

 tination . they therefore endeavoured to 

 divert him from the pursuit ; but their 

 endeavours were fruitless. 



On his quitting- the college, finding 

 himself alone, and unconnected in the 

 world, he sought an asylum in the house 

 of his nurse, who was the wife of a gla- 

 zier. He hoped that his fortune, though 

 not ample, would enlarge the subsistence, 

 and better the condition of her family, 

 which was the only one that he could 

 consider as his own. It was here, there- 

 fore, that he fixed his residence, resolving 

 to apply himself entirely to the study of 

 geometry. And here he lived, during the 

 space of 30 years, with the greatest sim- 

 plicity, discovering the augmentation of 

 his means only by increasing displays of 

 his beneficence, concealing his growing 

 reputation and celebrity from these ho- 

 nest people, and mak'ng their plain and 

 uncouth manners the subject of good- 

 natured pleasantry and philosophical ob- 

 servation. His good nurse perceived his 

 ardent activity ; heard him mentioned as 

 the writer of many books ; and beheld 

 him with a kind of compassion : " You 

 will never," said she to him one day, 

 "be any thing but a philosopher and 

 what is a philosopher? a fool, who toils 

 and plagues himself all his life, that peo- 

 ple may talk of him when he is dead." 



As D' Alembert's fortune did not far 

 exceed the demands of necessity, his 

 friends advised him to think of some pro- 

 fession that might enable him to increase 

 "it. He accordingly turned his views to 

 the law, and took his degrees in that fa- 

 culty, which he soon after abandoned, 

 and applied himself to the study of me- 

 dicine. Geometry, however, was always 

 drawing him back to his former pursuits : 

 so that, after many ineffectual struggles 

 to resist its attractions, he renounced all 

 views of a lucrative profession, and gave 

 himself up entirely to mathematics and 

 poverty. In the year 1741, he was ad- 

 mitted a member of the Academy of Sci- 

 ences ; for which distinguished literary 

 promotion, at so early an age (24,) he 

 had prepared the way, by correcting the 

 errors of the "Analyse Demontree" of 

 Reyneau, which was highly esteemed in 

 France in the line of analytics. He after- 

 wards set himself to examine, with atten- 

 tion and assiduity, what must be the mo- 

 tion and path of a body, which passes 

 from one fluid into another denser fluid, 



VOL. I. 



in a direction oblique to the surface be- 

 tween the two fluids. Two years after 

 his election to a place in the academy, he 

 published his "Treatise on Dynam cs." 

 The new principle developed in this 

 treatise consisted in establishing an equal- 

 ity, at each instant, between the changes 

 that the motion of a body has undergone, 

 and the forces orpowers which have been 

 employed to produce them; or, to ex- 

 press the same thing otherwise, in sepa- 

 rating into two parts the action of the 

 moving powers, and considering the one 

 as producing alone the motion of the bo- 

 dy in the second instant, and the other 

 as employed to destroy that which it had 

 in the first. 



So early as the year 1744, D'Alembert 

 had applied this principle to the theory of 

 the equilibrium, and the motion of fluids ; 

 and all the problems before resolved in 

 physics became in some measure its corol- 

 laries. The discovery of this new prin- 

 ciple was followed by that of a new calcu- 

 lus, the first essays of which were pub- 

 lished in a " Discourse on the General 

 Theory of the Winds:" to this the prize- 

 medal was adjudged by the Academy of 

 Berlin, in the year 1746, which proved a 

 new and brilliant addition to the fame of 

 D'Alembert. This new calculus of " Par- 

 tial Differences" he applied, the year fol- 

 lowing, to the problem of vibrating 

 chords, the resolution of which, as well 

 as the theory of the oscillations of the air, 

 and the propagation of sound, had been 

 but imperfectly given by the mathemati- 

 cians who preceded him ; and these were 

 his masters or his rivals. In the year 

 1749, he furnished a method of apply- 

 ing his principle to the motion of any 

 body of a given figure. He also re- 

 solved the problem of the precession of 

 the equinoxes : determining* its quantity, 

 and explaining the phenomenon of the 

 nutation of the terrestrial axis discovered. 

 by Dr. Bradley. 



In 1752, D'Alembert published a trea- 

 tise on the " Resistance of Fluids," to 

 which he gave the modest title of an 

 " Essay;" though it contains a multitude 

 of original ideas and new obvervations. 

 About the same time he published, in the 

 Memoirs of the Academy of Berlin, "Re- 

 searches concerning the Integral Calcu- 

 lus," which is greatly indebted to him for 

 the rapid progress it has made in the pre- 

 sent century. 



While the studies of D'Alembert were 

 confi nedto mere mathematics, he waslittle 

 known or celebrated in his native country. 

 His connections were limited to a small 



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