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Recent excavations at a site in London's Gresham Street have produced evidence of a remarkable mechanical engineering feat by the ancient Romans to lift water from wells. A team of engineers, archeologists and timber framers have been hard at work to recreate the water wheel. A current exhibition at the London Museum displays the results, built offsite by McCurdy & Co. and assembled and working in the museum's courtyard. Demonstrations of the machine are scheduled once per day during the week and several times on the weekends.

What the excavations found were preserved wooden buckets and the connecting iron links from two bucket chains in a deep well that had been dug around 108 AD. According to the Museum's explanatory material, "Each oak bucket would have weighed 7 kg (about 15.4 lbs) and contained up to 7 litres of water... Engineering analysis shows that there could have been as many as 30 buckets in a continuous loop which, when primed with water, would have weighed up to 500 kg (half a ton)." The engineers figure that the water-lifting machine could have delivered water at the rate of 2 litres per second, and could therefore raise 7,200 litres (1,500 gallons) per hour, and possibly have supplied at least 8,000 people with water -– perhaps one-third of the estimated population of Londinium in the 2nd century.

The description continues, "From ancient examples it is know that such chains were drven either by man-powered treadwheels or by man- or animal-powered horizontal capstan gears. From the scale of machine discovered, engineers believe that .3 horsepower is required to operate it. This is more than one person can achieve and engineers opt for the capstan together with gears as a logical solution."

If you get a chance to visit London, be sure to add this exhibit to your itinerary. For more information, visit the Museum's Web site. -- Janice Wormington.

Photos by Brian Wormington