Rivers at work

Modern development of her mountain waters to bring electrical power to Scotland began at Sloy. Like so many Scottish lochs, Sloy drew its water from only a small area of Highland country - not enough in itself for a massive power project. The collecting capacity of Sloy was consequently extended by means of tunnelling through the mountainsides to pipe the waters of neighbouring glens together. When this project was successfully completed, others were undertaken. Narrated by John Grierson. Photography, Arthur Lavis and John Wiles. Editing, John Tanner. Sound, Ron Abbott.