Beckley Furnace operated from 1847 until 1919, making it one of the last iron furnaces of its kind to operate in the United States. The site originally included several buildings that changed over time, including a large brick casting shed with a curved metal roof where molten iron was removed from the furnace and cast into ingots called pigs, named for molds resembling piglets nursing. These ingots were shipped to industries both nearby and far away for a wide variety of iron goods, including railroad car wheels that were especially resistant to cracking and were used in great numbers during the industrial expansion of the second half of the nineteenth century. On the far side of the building, a water turbine and related machinery forced air into the furnace to aid combustion of the charcoal fuel, and an oven preheated that air, improving efficiency by using waste gas from the furnace as fuel in an early example of industrial recycling. The ironmaking process also created slag, a glasslike waste product formed from minerals in the ore, especially silicon. Over the years of operation, the furnace produced an enormous quantity of slag, with the heap across the river estimated at 900,000 cubic yards in 1920. Some slag was crushed and mixed with cement to make slag concrete, and some was exported for use in New England buildings, while its use in road surfacing proved unsuccessful; in time, the forest reclaimed the abandoned slag piles. Beckley Furnace was designated by the State of Connecticut as an Industrial Monument, the first site in the state to receive that status. Furnaces like this were commonly built into hillsides so workers could reach the top of the stone tower by bridge. The furnace itself consisted of the stack, the bosh, and the crucible. A charcoal fire heated the interior, iron ore and limestone were added at the top, and hot air was forced in under pressure through tuyeres in a hot blast that improved efficiency. Carbon monoxide from the charcoal fire reduced the ore to pure iron, which collected in the crucible until workers tapped the furnace and let the liquid metal flow into sand molds to harden, while the lighter molten slag was drawn off separately and discarded. Production was continuous except when severe drought cut off power for the air blast or when the furnace broke down, and furnaces of this type were used for iron production throughout the United States.

Photo: Michael Herrick

Photo: Michael Herrick

Photo: Michael Herrick