Engineer James B. Francis knew that the city of Lowell needed protection from floods. He studied the Merrimack River and understood the dangers of flooding introduced by the canals flowing through the city. The Guard Locks controlled the normal flow of water into the Pawtucket Canal, but Francis knew that the early dam could never contain the potential fury of a Merrimack swollen by melting snow and springtime torrents.
In 1850, he constructed the Great Gate, an extraordinary wooden structure measuring 25 feet by 27 feet and held up by an iron shackle. Critics called the massive floodgate "Francis' Folly." Two years later, at 3:30 A.M. on April 22, 1852, workers used hammer and chisel to drop the gate before the rampaging river flooded downtown Lowell, thus "saving" the city.
Caption, large picture: The flood of 1936, seen here at the University Bridge, left most of Lowell's downtown unscathed. This monumental event so affected young Jack Kerouac that he invoked it as a symbol for nature's power in his novel Dr. Sax (1959).
Caption, small picture: In 1936, for the second time, workers (left) dropped the Great Gate. They cut the iron shackle and the massive 20-ton gate descended, shaking dishes in a cottage nearby.
Newspaper quotation, top right: The inhabitants of Lowell as well as the proprietors of the mills, have great cause to thank the gentleman (James B. Francis) who so promptly decided to take measures against what everyone considered a remote contingency, by what many considered a useless expenditure of money. Boston Daily Advertiser, April 28, 1852