Editing Hydropower (section)

===Mechanical power===
====Watermills====
{{excerpt|Watermill}}

====Compressed air ====
{{See also|Trompe}}
A plentiful head of water can be made to generate [[compressed air]] directly without moving parts. In these designs, a falling column of water is deliberately mixed with air bubbles generated through turbulence or a [[Venturi effect|venturi]] pressure reducer at the high-level intake. This allows it to fall down a shaft into a subterranean, high-roofed chamber where the now-compressed air separates from the water and becomes trapped. The height of the falling water column maintains compression of the air in the top of the chamber, while an outlet, submerged below the water level in the chamber allows water to flow back to the surface at a lower level than the intake. A separate outlet in the roof of the chamber supplies the compressed air. A facility on this principle was built on the [[Montreal River (Timiskaming District)|Montreal River]] at Ragged Shutes near [[Cobalt, Ontario]], in 1910 and supplied 5,000 horsepower to nearby mines.<ref>{{cite journal|last=Maynard|first=Frank|date=November 1910|title=Five thousand horsepower from air bubbles|journal=Popular Mechanics|page=633|url={{GBurl|-N0DAAAAMBAJ|p=633}} }}</ref>