Ironmaking

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Ironmaking

American Production . Extracting iron from ore in the eighteenth century was a process that combined sophisticated water-power technology with the science of metallurgy. English colonists began casting iron in the mid seventeenth century. These were mostly small operations; America had an abundance of raw materials, but ironmaking on a large scale required heavy investments of capital, which the colonies habitually lacked. By 1700 American iron production amounted to no more than 1 percent of the estimated world production. Seventy-five years later, however, that figure had risen to almost 15 percent. What had happened to produce this dramatic change?

British Encouragement . Britain’s growing empire was built largely on its manufactures, which British merchants exchanged for the exotic commodities so much in demand in Europe and America. Britain had been largely stripped of forest, from which charcoal, the required fuel for iron production, was made. On the other hand, American forests seemed endless, and with the discovery of good-quality ore deposits in Connecticut, northern New Jersey, and Pennsylvania all that was lacking was money and management. Britain supplied much of both, forming companies of investors to raise capital and sending English, Dutch, and German experts to America to erect and manage large-scale operations. British legislation such as the Iron Acts of 1750 and 1757 encouraged American production of raw pig iron but at the same time forbade American production of finished iron goods. The idea behind this legislation was to create a dependable American supply of iron while protecting British manufacturers of iron and steel products. British money and imported expertise gave colonial ironmaking the boost it needed: while smaller, all-American operations continued, large-scale ironworks grew in the middle colonies and Maryland. The largest of these was Peter Hasenclever’s ironworks in New Jersey, which in the 1760s ran six great blast furnaces smelting ore into pig iron and seven water-powered forges beating the metal into semifinished bars ready for export.

Making Iron. Even one twenty-foot-high furnace required enormous amounts of fuel, ore, and labor—265 bushels of charcoal and three tons of ore were required to produce one ton of iron. Once begun an ironmaking “campaign” might last thirty or forty weeks, nonstop. Obviously fuel and ore had to be constantly on hand, and gangs of men tended the furnace in shifts. Twice a day the crucible at the bottom of the furnace was tapped, and the molten iron ran out into prepared shallow ditches in the ground, where it sputtered and cooled into one-hundred-pound pigs of raw cast iron. Brittle and full of impurities, the pigs then went to the forge, itself a masterpiece of waterwheel-driven technology. There the pigs were heated again, almost to melting, and beaten into squared bars with half-ton mechanical hammers, squeezing out the impurities with each deafening blow. The entire process called for men with physical strength, skill, and judgment.

The Impact of Revolution. Ironmaking at this scale was an industry, employing men from all over the region to cut wood, make charcoal, mine the ore, tend the furnace, operate the forge, furnish transport, and manage the whole operation. Like any industry, an ironworks changed its community for both better and worse. Forests were quickly cut away to supply the ravenous furnaces, and slag heaps soon piled up around the operations. On the other hand, ironworks frequently invested in local road improvement and supplied relatively well-paying employment. When the Revolution came, American ironworks were able to supply most military needs, but the loss of British investment and markets for American iron put the industry into a decline from which it did not recover until the mid nineteenth century.

DEATH FROM BELOW: THE AMERICAN TURTLE

David Bushnell’s submarine the American Turtle had a “shell” of solid oak, carefully caulked and pitched to be watertight. Its shape was roughly that of a top, with the pointed end weighted so that it floated upright. A small, windowed cupola on top served for a “conning tower,” allowing the operator to see where he was going. For controls, an operator had two screw-type, hand-cranked propellers for horizontal and vertical travel and a rudder, all operated from within the shell. A foot-operated valve allowed water into a compartment for descent while hand pumps served to discharge the same water for surfacing. Instrumentation consisted of a water gauge depth indicator and a compass, both lighted with phosphorus to save air consumption. For armament the Turtle carried an underwater bomb called a “torpedo.” The torpedo, located just over the rudder of the Turtle, had a sharp screw attached, pointing upward, and the entire bomb was spun by another interior hand crank. To deploy the torpedo the operator dove the boat under a ship’s hull, then fastened the bomb to the underside of the hull by turning the crank, which screwed the bomb to the hull. As the boat then pulled away, a clockwork-driven time fuse ignited the torpedo after a set amount of time, blowing a fatal hole in the ship’s hull.