D'ALEMBERT. 441 



of ignorant men to depreciate his labours in the great 

 problem, by representing him as borrowing from Clairaut, 

 instead of only exciting his indignation against the silly 

 propagators of such insinuations, which assuredly had no 

 countenance whatever from Clairaut, as we have already 

 seen, led him to show more heat than beseemed the geo- 

 metrical character in scientific disputes on the subject 

 with that illustrious colleague, whom he shewed an 

 unworthy disposition to differ with. A controversy of 

 some length arose between them, when the principles of 

 the solution respecting the lunar orbit were applied to 

 the construction of lunar tables. D'Aleinbert's were 

 published in his 'Recherches' in 1754, and he soon found 

 their inaccuracy to be considerable; the results of his 

 calculations sometimes differing seven or eight minutes 

 from the observations. He was obliged in 1756 to give 

 a corrected set after further investigation. Clairaut was 

 writing at the same time on this subject, and he had 

 received a prize from the Academy of Petersburgh for 

 his work. D'Alembert, who had been a candidate too, 

 attacked his methods in his ' Recherches/ 1 756. Clairaut 

 gave a criticism of this book and of the author's method 

 in the ' Journal de Sgavans ;' D'Alembert replied in the 

 'Mercure;' and Clairaut rejoined in 1758. The same 

 unworthy spirit broke out on Clairaut having applied his 

 investigation of the disturbing forces to the comet of 

 1682, (Halley's comet,) expected in 1759, but appearing 

 a month earlier than Clairaut foretold, owing to an error 

 of nineteen days in the computation. Anonymous attacks 

 upon him he ascribed to D'Alembert, and a long series 

 of controversial papers in different journals ensued; until 

 Clairaut appeared to silence his adversary by an elabo- 



