This flood also prompted the Massachusetts city of Lowell to install a modern (albeit temporary) flood control gate comprising square steel beams at the site of the historic Francis Gate, a 19th and 20th-century wooden flood gate. When lowered, the Francis gate seals the city's canal system off from its source on the Merrimack. The Great Gate, as it is also called, was built in 1850 under the direction of James B. Francis. Considered unnecessary when it was first constructed, "Francis' Folly" first saved the city in 1852 and subsequently in 1936.