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Rh mathematical and astronomical problems, discovering for himself the method of fluxions. For a long time he believed himself its originator, being unaware of the controversy between Newton and Leibnitz for that great honor. “What a mind was here!” said Dr. Benjamin Rush, later, in a burst of enthusiastic admiration. “Without literary friends or society, and with but two or three books, he became, before he had reached his four-and-twentieth year, the rival of two of the greatest mathematicians of Europe.”

He mastered the Principia of Newton in an English translation, and became so engrossed in the study of optics that he wrote of himself in 1756, during the French and Indian war, that should the enemy invade his neighborhood, he would probably be slain making a telescope, as was Archimedes while tracing geometrical figures on the sand. In 1751, the Rev. Thomas Barton, of Lancaster County, an alumnus of Trinity College, Dublin, who afterward married the sister of Rittenhouse, and became a professor in the University of Pennsylvania, went to Norriton to teach school, and making the acquaintance of the young philosopher and clock maker, they became warm friends. Barton supplied him with books from which he obtained a knowledge of the Latin and Greek languages, and two years later brought to him from Europe a number of scientific works. Though his clocks had become celebrated for their accuracy, and he had obtained a local reputation for astronomical information, it seems to have been through Barton that the attention of men of learning was first drawn to him. Among these were Dr. William Smith, provost of the University, John Lukens, surveyor-general (another Pennsylvania Dutchman, whose direct paternal ancestor, Jan Lucken, settled in Germantown in 1683), and Richard Peters, provincial secretary. Through