When waves move across a body of water, they gradually flatten out as they travel. But in 1834, an engineer named John Scott Russell saw a singular sight while a barge was betching watched by himarge on a canal. The barge stopped suddenly, releasing a " rounded, smooth, and well-defined heap of water," a single wave that took off at nine miles per hour and maintained its height and shape as it moved along. Russell followed the wave on horseback for a couple of miles., Aamazed that it never flattened out.