Henry Clemens (Mark Twain's Brother) Dies While Working on Steamboat

While training, Samuel convinced his younger brother Henry to work with him. Henry was killed on June 21, 1858, when the steamboat he was working on, the Pennsylvania, exploded. Twain had foreseen this death in a detailed dream a month earlier, which inspired his interest in parapsychology; he was an early member of the Society for Psychical Research.

http://en.wikipedia.org/wiki/Mark_Twain