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We may further observe, that the extreme interest 

 which he took in it seems to have made him some- 

 what susceptible, when he conceived others had not 

 done justice to his labours in this favourite department 

 of science. Not only is he anxious, perhaps beyond 

 what is altogether beseeming the calm and disinterested 

 love of investigation, to secure the admission of his 

 claims as the original discoverer; but we sometimes 

 find him even querulous, as to the remarks of others, 

 and complaining of them for not rendering him justice. 

 In the * Opuscula,' torn, i., p. 158, we have not only an 

 anxious statement of his having been the first to use 

 the method employed in the ' fissai sur la Resistance 

 des Fluides,' and adding, that " great geometricians 

 had so much valued it as to apply it in their inquiries ;" 

 but he objects to their having maintained that his 

 theory was capable of greater extension than he had 

 given it, and observes that he had turned it to other 

 inquiries which had escaped them. In the able and 

 learned article Hydrodynamique, in the * Diet. Encyc.,' 

 vol. viii., p. 373, he attacks Euler for supposing, in his 

 'Memoire Acad. de Berlin,' 1755, that D'Alembert's 

 method in his Essai was not general; and he adds, 

 " II me semble que M. Euler auroit du rendre plus de 

 justice a mon travail sur ce sujet et convenir de 

 1'utilite qu'il en avoit three." Assuredly if ever man 

 was above all suspicion of either usurping iipon others 

 or overrating his own discoveries, it was this most 

 illustrious geometrician, whose inherent richness of 

 invention made him even blameably careless of his 

 own claims to originality. No one can have contem- 

 plated the different periods of D'Alembert's life without 

 being assured that such feelings of jealousy and irrita- 

 tion as appear in the passages just now cited, were 

 not congenial to his nature and to his earlier habits, 

 when his darling science maintained undisputed pos- 

 session of his mind, excluded all anxiety save in the 

 search after truth, and calmed every temporary ruffling- 



