There was a story about a guy who trained himself to lucid dream about a hundred years ago while he was riding a train, and letting the shadows play off of his

There was a story about a guy who trained himself to lucid dream about a hundred years ago while he was riding a train, and letting the shadows play off of his closed eyes....anyone know what I'm talking about? Having a hard time googling it, but I wonder if that same technique could be used for improving mental imagery instead of eye rubbing.