Those strange ruined towers that cling to the cliff tops in Cornwall were once the Power houses of Britain's greatest industrial county. They housed the engines that Powered the pumps and hauled up the tin from mines that reached out under the Atlantic Ocean. William Crago was 9 years old when he first went to work down the mine. He left behind a diary which tells the story of the day he climbed 1,600 feet down a rung ladder to the dark pit streaming with water which was to be his place of work for the next ten years.