| WHY IS THE SITE HISTORICALLY SIGNIFICANT? |
| During the American colonial period, Principio was a leading iron producer. Principio held Maryland's first blast furnace, operating in 1725, and first refinery forge, constructed in 1728. One of the company's notable partners was Augustine Washington, father of George Washington. In the early Federal period, Principio manufactured cannons and other ordinance until the British destroyed the complex in a raid during the War of 1812. The Whitaker family took control of the site in 1837, and revived Principio as an active iron manufacturing site for much of the nineteenth century. |
| Principio is also significant for the following extant cultural resources: |
| The 1837 charcoal iron furnace together with what was at the time a state-of-the-art hot blast stove, both still have a high degree of integrity Water-powered turbine and blowing engine, the only known example that is still in place Brick beehive charcoal kiln, one of only two of this type still intact in the United States The two story company office, built around 1877-1880, provides an example of the French Second Empire style of architecture Other surviving structures at or near the site, which contribute to the overall integrity of the site Potential archaeological dig sites, especially the sections that relate to the colonial period. "A careful study of the literature, maps, and the Principio Creek below the falls reveals a number of potential furnace and forge locations" (Institute, 22). |
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| COLONIAL IRON MAKING |
| The One Step Process |
| A bloomery produced wrought iron, or bar iron. The ironworker heated iron ore in a hearth and hammered the clump of molten iron to remove slag, the impurities in the iron ore, and then shaped the metal into blooms or bars. Using this one-step method, a bloomery could produce around one hundred pounds of iron a day. |
| The Two Step Process |
| The indirect or two-step process was more expensive to set-up, but yielded a higher daily rate of production and better quality iron. With this process, iron ore was heated for a sustained period of time in a blast furnace, causing a separation of the iron and impurities. A flux, usually lime, was used to aid in the congealing of impurities, making the separation easier. Charcoal provided the source of heat. Water-power was often used to operate large bellows that pumped air into the base of the blast furnace to intensify the heat of the fire. At the top of the blast furnace, workers added iron ore, charcoal, and flux (oyster shells were the usual source of lime in the Chesapeake region). The furnace was usually around thirty feet high, and a hill or a ramp on at least one side of a furnace gave workers access to the top. Periodically workers would add new layers of these materials. If a sufficient amount of resources were gathered in advance, a charge or blast could burn continuously for several months. The blast operators removed accumulations of slag by opening a tap. From a lower level tap at the base, iron was drained from the furnace several times during a twenty-four hour period. |
| Then, the resulting pig iron is refined in a refinery forge. The pig iron would be reheated and hammered a number of times to make the iron more malleable, and then the iron was usually formed into bars that could be reshaped into iron products (Robins, 6-9). |
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