Medieval Mechanical Power

by Friar Thomas Bacon (David Moreno)
Orignally published in the January 2001, A.S. XXXV issue of the Dragonflyre, a publication of the Barony of Vatavia.

When how work was accomplished during the Middles Ages, the usual images are those of the overburden peasant and the lumbering oxen or horse. That is by the exertion of muscle power alone. This is but an oversimplification of reality. One of the sub-themes of the period is the increasing use of mechanical power to accomplish work. It is upon this foundation that the Industrial Revolution was built.

With the exception of the clock escapement and possibly the crank, the basic mechanisms of this tend where known to the ancient Greeks and Romans. It is just that, for the most part, they chose not to make much use of them. The reason for this change is not clear. But one theory finds it in the nature of the Christian religion. Whereas the Greco-Roman intellectuals despised labor, the monks elevated it to a form of worship, and God is the master craftsman. And whereas the older religions were cyclical or static, Christianity looked forward to a spiritual goal. And this translated to a sense of purpose in more material efforts, and an acceptance of things that would allow such goals to be reached. While all things technological were not embraced, neither were they openly discouraged.

The best known of these machines is the water wheel. Of the three major types, the undershot vertical wheel was the most common. The overshot vertical and the horizontal wheel types were also known and occasionally used. The Domesday Book reports that in 1086 there were 5624 mills in England. Till around 1000 AD the primary purpose of these mills was to grind grain. But then they began to be used where heavy repetitive motion was needed. The most common of these alternate uses was for fulling cloth and forging metal. Lessor use was that of an oil press, and later for making paper.

To make use of the motion of the water wheel required the use of gears and cams. These were usually made of wood, frequently elm. Metal versions did not begin appearing till the eleventh century. These gears consisted of a disk with pegs evenly spaced around the edge, upright for a crown gear and outward for a star gear. Often a second disk was added on the other end of the pegs of a crown gear for additional strength. Breakage was often enough that special rights to the forest were granted to gather material for repair. Cams were used to activate various forms of trip hammers. The cam would press down on a lever which would raise the striking device, which would fall under its own weight when the cam moved out of the way.

For those areas, which did not have streams with adequate flow for water wheels, there was the windmill. The origin of the windmill is unknown. There is no evidence that the ancients knew of such a thing. There are Arabs references in the tenth century, but they describe a device much different then that that would appear in Europe later. The first European reference is in a Normandy deed of circa 1180. While they quickly spread throughout Northern Europe, they were still far from universal. If Don Quixote thought windmills were giants, it was in part because they had just newly appeared in La Mancha. These windmills were of a type known as post-mills, where the entire structure, not just the sails, would be turned into the wind. They were only used to grind grain.

Another key invention of unknown origin is the crank. Some archeological remains found on the Nemi ships of the emperor Caligula have been interpreted by some as evidence of a crank, but this is highly disputed. Indisputable evidence of a crank is not to be found till the first half of the ninth century. However, it was until the fifteenth century that it was used beyond the grindstone and the hurdy gurdy. With the invention of the crankshaft, reciprocating and rotary motion could be easily interchanged.

The mechanical clock is purely an invention of the Middle Ages. The key to this invention is the verge escapement by which the motive force of a falling weight could be regulated. This consisted of a pair of weights on outstretched arms that rocked back and forth, each time releasing a tooth on the crown wheel. This method would not be superseded till 1657 by the pendulum escapement. The exact date of invention is not known, only that occurred between 1271 and 1348. They were the high technology of their day, and were a source of civic pride, on par with stone defensive walls and a cathedral. By 1382 the universe was seen a gigantic clock.

By the end of the Middle Ages machines were being used for a wide variety of uses. This had a profound effect on the way people thought. Nature changed from something to be endured to something that could be exploited. That man could conceive and build a machine that could rival or surpass anything in nature. The marvel of the modern world can be found in the writings of such people as Roger Bacon and Francis Bacon. Their technology was just not up to the task. What marks the Industrial Revolution is not a change in the way people saw things, but that in the steam engine people now had a nearly inexhaustible source of power. They now had the means to realize the dreams of the medieval technologists.



Daumas, Maurice. A History of Technology and Invention: Progress through the Ages, Vol. 1. New York: Crown Publishers, 1962.

Hill, Donald. A History of Engineering in Classical and Medieval Times. New York: Barnes & Noble Books, 1997.

White Jr., Lynn. Medieval Religion and Technology. Las Angeles: University of California Press, 1978.

White Jr., Lynn. Medieval Technology and Social Change. London: Oxford University Press, 1962.


Copyright © 1997 - present His Lordship Friar Thomas Bacon (David Moreno). All rights reserved.

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