9781422277584

Nineteenth-Century Improvements By the mid-nineteenth century, the military and civil use of explosives was enormous; in 1851–53 some 100 tons were used in New York Harbor alone to destroy Pot Rock, a large rock near the confluence of the East River and Harlem River. This last example deserves to be noted. High explosives are usually thought of as military weapons, but they also have immensely beneficial uses in mining, quarrying, and civil engineering. Surprisingly, UNDERWATER EXPLOSIONS Until the mid-nineteenth century, it was difficult for ships traveling the Atlantic Ocean to land at New York Harbor. To reach the city, they had to sail up Long Island Sound, passing through a narrow channel that was known as Hell Gate. This strait was near the point where the East River and the Harlem River met, and was characterized by strong currents. Several large underwater rocks in this area—known as Pot Rock, the Frying Pan, and Way’s Reef—added to the danger. The currents and rocks of Hell Gate were notorious for causing ships to lose control and run aground or sink. By the 1850s, about 1,000 ships a year were damaged or sunk in Hell Gate. The blasting of these rocks was one of the earliest examples within the U.S. Office of Coast Survey (now the National Oceanic and Atmospheric Administration, or NOAA) of a desire to modify the environment for human benefit. In 1848, Charles Henry Davis and David Dixon Porter suggested that Way’s Reef, Pot Rock, and other rocks be removed from Hell Gate. Acting on this suggestion, a group of New York citizens hired a European engineer, Benjamin Maillefert, to blast rocks out of the channel. Between blasts, a Coast Survey hydrographic crew measured the changing depths and configuration of the rocks in the blasted areas. The nautical chart pictured here is the

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