Love a river story:
Gen. George Washington needed a great idea. He got it from an English-born patriot named Thomas Machin.
Machin knew water. He had been an apprentice canal builder in England, and, as a captain in an artillery company he was called by Washington to help defend the river at the Hudson Highlands. The river was narrow there, and since ancient times armies had placed sharpened logs, scuttled ships, and other debris in a narrows to block passage. But here the river was too deep. Machin had his a-ha moment: Why not forge an iron chain and float it across the river, anchoring it at either shore?
Lake Levels 