When members of the Chicago Commercial Club arrived to hear a lecture by the famed electrical inventor Nikola Tesla on May 13, 1899, they were startled by the sight of an artificial lake sitting in the middle of the auditorium. Everyone knew that Tesla--the man who had devised the alternating-current (AC) system that brought electricity into people's homes and businesses--was a master showman. Six years earlier at Chicago's Columbian Exposition, for example, the dapper engineer had dazzled spectators by sending 250,000-volt shocks coursing through his body. Now the audience was abuzz, wondering what Tesla was going to do with his miniature lake and the six-foot boat that floated on its surface.