Princeton's Rittenhouse Orrery is the first of two remarkably accurate orreries made by the Pennsylvania clockmaker and self-educated astronomer, David Rittenhouse. He made the second one for the College of Philadelphia, now the University of Pennsylvania. Princeton's orrery was purchased by President Witherspoon and installed in Nassau Hall in 1771. It was damaged during the Revolution and later repaired. It was in active use for about a half-century; thereafter it became merely a curiosity and did not come to attention again until it was exhibited at the World's Fair in Chicago in 1893. Then it disappeared and was thought permanently lost until it was discovered, in 1948, still crated, in the basement of McCosh Hall. Through the generosity of Bernard Peyton '17, it was once more restored and given a place of honor in Firestone Library until Peyton Hall was built. In the restoration one concession was made to the twentieth century: electric motors were added to provide smooth motive power, thus eliminating the damage to the intricate wheelwork, which in earlier days resulted from hasty and irregular turning of the crank that set the orrery in motion.