_"See the sage Rittenhouse with ardent eye Lift the long tube and pierce the starry sky! He marks what laws the eccentric wanderers bind, Copies creation in his forming mind, And bids beneath his hand in semblance rise With mimic orbs the labors of the skies."_ This was Barlow's way of telling of the achievement of David Rittenhouse, the colonial astronomer, in fashioning the marvellous orrery, the mechanical representation of the movements of the planetary system. Thomas Jefferson's prose description was a little more readable: "A machine far surpassing in ingenuity of contrivance, accuracy and utility anything of the kind ever before constructed.... He has not indeed made a world, but he has by imitation approached more its Maker than any man who has lived from the creation to this day." The father of the maker of the orrery was a paper manufacturer near Germantown, but when David was three years old he moved to a little farm in Norriton, nineteen miles from Philadelphia, where, in 1749, he built the stone house in which his son spent the rest of his life. It was his purpose to make a farmer of David, and he might have succeeded if he had not invested in a few mathematical books. The twelve-year-old boy was fascinated by these volumes. Samuel W. Pennypacker has told the result: "The handles of his plough, and even the fences around the fields, he covered with mathematical calculations.... At seventeen he made a wooden clock, and afterward one in metal. Having thus tested his ability in an art in which he had never received any instruction, he secured from his somewhat reluctant father money enough to buy in Philadelphia the necessary tools, and after holding a shop by the roadside, set up in business as a clock and mathematical instrument maker." Dr. Benjamin Rush once said that "without library, 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."