The often heavy charge is lifted as the individual inside the treadwheel crane walks. The building for the treadwheel and other new buildings were designed by George Allen Underwood. This included the installation of a treadwheel for those sentenced to hard labour. The Ancient Romans used a treadwheel or polyspaston crane for manipulating heavy objects. A treadwheel, or treadmill, is a form of engine typically powered by humans. The king ordered that his wife be put in a treadwheel crane. The prison treadwheel was a long wooden cylinder with metal framing. Another son, Smith Griffin, is credited with building a treadwheel in 1810. This same technology was later adapted to create rotary grain mills and the treadwheel crane. The site contains the shell of the Victorian treadwheel house - a rare survivor. The terms "treadmill" and "treadwheel" were used interchangeably for the power and punishment mechanisms. A treadwheel crane survives at Guildford, Surrey, United Kingdom. A treadwheel crane survives at Harwich, Essex, United Kingdom. It is the only double wheel treadwheel crane in the United Kingdom. The treadwheel dates from the early 17th century.