Structures in the Stream by Todd Shallat

Author:Todd Shallat [Shallat, Todd]
Language: eng
Format: epub, pdf
Publisher: University of Texas Press
Published: 1994-05-29T04:00:00+00:00

Amphibious dredge boat, built by Oliver Evans for Philadelphia’s board of health, 1804. Courtesy of the Historical Society of Pennsylvania.

A good illustration of this boom-and-bust funding pattern was a waterway-dredging program that over committed Congress but diversified civil works. Dredging, like snagging, was a steam technology that owed more to Yankee invention than to methodical French science. The first steam dredge on record was also a steam-powered car. Built by Oliver Evans of Philadelphia and tested in 1804, the machine was an amphibious “scow,” a bargelike carriage with a five-horse engine, a stern paddle wheel, and a belt of mechanical buckets to scoop out the mud.103 Two years later the English inventor Samuel Bentham designed a “steam-dredging machine” for His Majesty’s dockyards in London.104 Baltimore, New Orleans, and other port cities conducted their own dredging experiments, mostly with hand-powered equipment. Federal contractors began digging out the Delaware River in 1803, but isolated expenditures followed by years of neglect did nothing to ease navigation. Not until the time of the general surveys, 1824 to 1838, did the Corps have the resources to study the long-term effects of marine excavation.105

The Corps sponsored no formal “contest” for dredging machines, but the rivers and harbors acts of 1824 inspired dozens of strange devices—human-powered treadmills, horse-powered capstans that dragged heavy scoops, grapples suspended from cranes, tubes filled with black powder to blast underwater, and sharp plowlike harrow scrapers that, when towed behind steamboats, stirred up the mud so the current could wash it downstream. Lt. George W. Long, Stephen’s younger brother, invented a conical “diving bell” that lowered men underwater where they drilled and chiseled the rocks. Once rocks had been smashed into rubble, the Corps experimented with a spoonlike “dipper” on a pulley geared to an engine. In 1826 the engineers also spent $2,300 to develop a floating conveyor belt with rows or “ladders” of buckets on a continuous chain, a ladder dredge. On March 2, 1829, after the chief engineer reported success with ladder dredging in New York and North Carolina, Congress spent $139,000 for dredging at ten sites. Soon there were mud-clogged boilers and cracked engines from Lake Ontario to Mobile Bay. Rocks shattered cast-iron buckets. Chains snapped off in the water. In 1833 and 1836, steam dredges sunk off Savannah, blocking the harbor. Still a dredge boat was much less expensive than structures like dikes and wing dams that were used to excavate shoals by the force of current alone. By 1838, when Van Buren and the Twenty-fifth Congress began to dismantle the program, the Corps and the topographical bureau were deeply committed to dredging at about thirty sites.106

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