a HISTORIC hydro-electric scheme once used to power a sanatorium is be revived by a Highland community after 70 years.  Kingussie Community Development Company was yesterday given the go-ahead by the Cairngorms National Park authority to redevelop the 100-year-old scheme on the Gynack Burn.  The GBP180,000 project will use the archimedes Screw method, a system that has been used since ancient times to lift water to higher levels.  Remains of the old scheme, which was last used in the 1930s, are visible less than a mile upstream of the point where the main street in Kingussie crosses the burn.  It originally provided power for St Vincent's Sanatorium to the south, and a plaque has been erected to explain the link between the old scheme and St Vincent's.  The electricity from the new scheme will be fed to the national grid and the community is set to receive income of about GBP15,000 a year to fund other local projects.  The devel