Henry's Big Mistake

Monday, February 01, 1999
RELATED TAGS: ARCHAEOLOGY
When Henry VIII divorced Catherine of Aragon--the first of six unfortunate wives--he broke with the pope, anointed himself supreme head of the Church of England, and shut down England's monasteries. He may also have unwittingly delayed the industrial revolution. For one of the monasteries he closed--Rievaulx Abbey in North Yorkshire--was apparently the site of a prototype blast furnace built about 200 years before later blast furnaces ushered in the industrial revolution.

After Henry expelled the Cistercian monks from the abbey in 1538, his emissaries inventoried the abbey's contents. Examining these old lists, Gerry McDonnell, an archeometallurgist at the University of Bradford, became curious about two items, a "bloomsmithy" at Laskill, about four miles from the abbey, and a "hammersmithy" at Rievaulx itself. What exactly were they?

McDonnell set out to explore the debris of Laskill and Rievaulx. From the records, he suspected that the monks had built a furnace to extract iron from ore. But what kind of furnace? The most ancient type, in use since the Iron Age, was typically a six-foot-tall, three-foot-wide cylindrical stack of clay. Charcoal and iron ore were loaded into the top. Air, pumped in with hand or foot bellows, helped feed the fire that separated pasty lumps of iron from the ore. This crude iron was further heated and squeezed to remove mineral impurities called slag.

The slag of a primitive furnace typically contains lots of iron--such furnaces don't generate high enough temperatures to separate all the iron from the ore. But the slag McDonnell analyzed at Laskill had a low iron content--it resembled the slag produced by a blast furnace, whose higher temperatures remove more iron from the ore.

McDonnell was further convinced that the monks had built such a furnace when he discovered a square, 15-foot-wide brick structure below the ground, as well as traces of a stream that may have driven the furnace's bellows. The larger size of the furnace and the greater power of water-driven bellows would have allowed the monks to reach blast-furnace temperatures.

McDonnell isn't sure of the purpose of the other furnace--the "hammersmithy" at Rievaulx--but suspects it may have been used to forge iron bars from the iron produced at Laskill. "The monks would have used quite a lot of iron--they had 14,000 sheep to shear, so they needed sheep shears," he says. "We know that the Cistercians were innovators, and technologically they were very astute." If Henry hadn't expelled the monks, he adds, the industrial revolution might have started at the abbey in North Yorkshire.

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