SUCCESSORS OF NEWTON IN ASTRONOMY 



during the eighteenth century. D'Alembert, who 

 became one of the best - known men of science of 

 his day, and whose services were eagerly sought 

 by the rulers of Europe, began life as a found- 

 ling, having been exposed in one of the markets of 

 Paris. The sickly infant was adopted and cared for 

 in the family of a poor glazier, and treated as a mem- 

 ber of the family. In later years, however, after the 

 foundling had become famous throughout Europe, his 

 mother, Madame Tencin, sent for him, and acknowl- 

 edged her relationship. It is more than likely that 

 the great philosopher believed her story, but if so he 

 did not allow her the satisfaction of knowing his be- 

 lief, declaring always that Madame Tencin could "not 

 be nearer than a step-mother to him, since his mother 

 was the wife of the glazier." 



D'Alembert did much for the cause of science by his 

 example as well as by his discoveries. By living a 

 plain but honest life, declining magnificent offers of 

 positions from royal patrons, at the same time refusing 

 to grovel before nobility, he set a worthy example to 

 other philosophers whose cringing and pusillanimous 

 attitude towards persons of wealth or position had 

 hitherto earned them the contempt of the upper 

 classes. 



His direct additions to astronomy are several, among 

 others the determination of the mutation of the axis 

 of the earth. He also determined the ratio of the at- 

 tractive forces of the sun and moon, which he found 

 to be about as seven to three. From this he reached 

 the conclusion that the earth must be seventy times 

 greater than the moon. The first two volumes of his 



