Longwood Gardens

This guide to the Main Fountain Garden at Longwood Gardens outside Philadelphia opens with Pierre du Pont asking you to guess how many gallons of water roar past every minute when the fountains switch on. It follows how a chemist and MIT-trained engineer who ran DuPont and later General Motors traced his love of fountains back to watching pump displays at Philadelphia's Centennial Exposition as a six-year-old, then spent 1925 working out the hydraulics himself, page after page of pressures, pipe sizes, and pump horsepower. Three one-hundred-horsepower pumps fill a reservoir on the hill above the garden, and booster pumps take over once the sun goes down.