48 PIONEERS OF SCIENCE IN AMERICA. 



family of ten children. When he was a few months old, his 

 father quit paper-making and went to farming at Norriton, 

 about twenty miles from Philadelphia. David was early put 

 to work on the farm, and was ploughing at fourteen years of 

 age. An uncle dying had left him a chest of tools and a few 

 books on arithmetic and geometry, with some manuscript 

 mathematical calculations. These furnished palatable food to 

 his mind, and his biographers tell of his having covered the 

 handle of his plough and the fences around the field with his 

 workings of the problems which they set before him. As the 

 uncle mentioned above was his mother's brother, it is inferred 

 that he inherited his genius from his mother's side. His 

 mechanical talent was shown in his construction of a complete 

 water wheel in miniature when eight years old, a wooden clock 

 when seventeen, and a clock with metallic works at a later 

 age. His father was not disposed at first to favour the youth's 

 tastes, but eventually he furnished him with money enough to 

 buy a set of clock-making tools; and David built a workshop 

 at Norriton, where he carried on the clock-making business for 

 several years. He at the same time pursued his studies so 

 diligently that he impaired his constitution, and contracted an 

 internal pain that afflicted him all his life. Astronomy ap- 

 peared to be his favourite study; and he was interested in 

 optics and mechanical science. He discovered himself, inde- 

 pendently, the method of fluxions, of .which, in his imperfect 

 knowledge of what Newton and Leibnitz had done, he believed 

 himself to be the originator; and mastered the English trans- 

 lation by Motte of Newton's Principia. 



The acquaintance which he formed in 1751 with Thomas 

 Barton, who afterward married his sister, had an important in- 

 fluence in shaping his career. Rittenhouse, according to Wil- 

 liam Barton, "possessed a sublime native genius; which, how- 

 ever, was yet but very imperfectly cultivated for want of indis- 

 pensable means of extending the bounds of natural knowl- 

 edge." Barton had enjoyed these means, and had acquired 

 the reputation of being a man of learning. He found Ritten- 

 house's society profitable, and Rittenhouse found his equally 

 so. Barton aided Rittenhouse greatly by helping him to the 

 books he needed. Partly through his instrumentality a cir- 

 culating library was established at Norriton ; and he bought 

 books for Rittenhouse when he went to Europe. 



