Gin gang

A gin gang, wheelhouse, roundhouse or horse−engine house, is a structure built to enclose a horse mill, usually circular but sometimes square or octagonal, attached to a threshing barn. Most were built in England in the late 18th and early 19th centuries. The threshing barn held a small threshing machine which was connected to the gin gang via wooden gears, drive shafts and drive belt, and was powered by a horse which walked round and round inside the gin gang.