D'ALEMBEET. 413 



1747, but part of it had been read in August. He 

 asserts positively in a note ('Mem.,' 1745, p. 335,) 

 that though Euler's first paper had been sent in the 

 same year, he had never seen it till after his solution 

 was obtained ; therefore, Lalande had no right to state 

 in his note to the very bad edition of Montucla which 

 he published, that Fontaine always said that Clairaut 

 was enabled to obtain his solution by the paper of 

 Euler, (Vol. iv. p. 66.) 



At the time that Clairaut was engaged in this in- 

 vestigation, D'Alembert, unknown to him, was working 

 upon the same subject. Their papers were presented 

 on the same day, and Clairaut's solution was unknown 

 to D'Alembert; but so neither could D'Alembert's 

 solution have been known to Clairaut, because the 

 paper is general on the problem, and the section appli- 

 cable to the moon's orbit was added after the rest was 

 first read, and was never read at all to the Academy. 

 Nothing, therefore, can be more clear than that neither 

 of these great geometricians borrowed from the other, or 

 from Euler. It is just possible that Euler in his com- 

 plete solution of 1752 might have had the advantage 

 of their previous ones ; but as it clearly flowed from 

 his earlier paper, there is no doubt also of his entire 

 originality. Nevertheless, when D'Alembert's name 

 became mixed up with the party proceedings among 

 the literary and fashionable circles of Paris, there were 

 not wanting those who insisted that the whole fame of 

 this great inquiry belonged to Clairaut; and it is 

 painful to reflect on the needless uneasiness which such 

 insinuations gave to D'Alembert. We shall recur to 

 the subject afterwards, and now must continue the 

 history of this problem. 



Thus, in investigating this famous " Problem of the 

 Three Bodies," all the three geometricians, without 

 communicating together, took the same general course 

 in the field, like three navigators of consummate skill 

 and most practised experience tracing the pathless 



