A HISTORY OF SCIENCE 



Researches on the Systems of the World, published in 

 1754, are largely devoted to mathematical and astro- 

 nomical problems, many of them of little importance 

 now, but of great interest to astronomers at that 

 time. 



Another great contemporary of D'Alembert, whose 

 name is closely associated and frequently confounded 

 with his, was Jean Baptiste Joseph Delambre (1749- 

 1822). More fortunate in birth as also in his educa- 

 tional advantages, Delambre as a youth began his 

 studies under the celebrated poet Delille. Later he was 

 obliged to struggle against poverty, supporting himself 

 for a time by making translations from Latin, Greek, 

 Italian, and English, and acting as tutor in private 

 families. The turning-point of his fortune came when 

 the attention of Lalande was called to the young man 

 by his remarkable memory, and Lalande soon showed 

 his admiration by giving Delambre certain difficult 

 astronomical problems to solve. By performing these 

 tasks successfully his future as an astronomer be- 

 came assured. At that time the planet Uranus had 

 just been discovered by Herschel, and the Acad- 

 emy of Sciences offered as the subject for one of 

 its prizes the determination of the planet's orbit. 

 Delambre made this determination and won the 

 prize a feat that brought him at once into prom- 

 inence. 



By his writings he probably did as much towards 

 perfecting modern astronomy as any one man. His 

 History of Astronomy is not merely a narrative of prog- 

 ress of astronomy but a complete abstract of all the 

 celebrated works written on the subject. Thus he 



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