When I was a young lad in the 1930s, our family used to spend the summer holidays at a cottage in Milton Eonan, Glenlyon, Perthshire. There was no electricity and water was pumped up into the cottage from the Milton Burn by a contraption known as the Ram. Powered by the gravity flow of unlimited water from the burn above, it maintained an intermittent jet of water into the attic tank; or rather...