Georgetown University

This guide to Georgetown University's Observatory in Washington, D.C. follows the Irish Jesuit priest James Curley, who arrived in 1825 to teach mathematics and, by 1841, talked his superiors into building an observatory on the hilltop. It traces the problem he set himself in the 1840s: fixing the precise coordinates of the young capital's White House and Capitol using nothing but nightly readings of the moon. Decades later, engineers with a transatlantic telegraph cable checked his arithmetic against instant time signals from Greenwich.