Archimedes' screw screws of decreasing pitch are used for the compaction of waste material. If water is fed into the top of an Archimedes screw, it will force the screw to rotate. The rotating shaft can then be used to drive an electric generator. Such an installation has the same benefits as using the screw for pumping: the ability to handle very dirty water and widely varying rates of flow at high efficiency. Settle Hydro and Torrs Hydro are two reverse screw micro hydro schemes operating in England. The screw works well as a generator at low heads, commonly found in English
SS Archimedes lead to the adoption of screw propulsion by the Navy (see Legacy section below). With the conclusion of the Dover trials, "Archimedes" was placed at the disposal of Captain Chappell for a circumnavigation of Britain, which took place in July 1840. This voyage presented an opportunity to not only conduct further tests, but also to allow inspection of the technology by shipowners, engineers and scientists in ports throughout the country. "Archimedes" completed the 2006-mile voyage at an average speed in excess of 7 mph, and a maximum speed under ideal conditions of 10.9 mph. With the completion of this voyage,