The "official photographer" had been equally successful. One day, while up on the levee trying to take a satisfactory picture of an elusive "mackerel sky," which was changing from moment to moment, he met a stranger. This stranger was sitting on a log that projected into the river, holding a rod and line, and landing fish with an accustomed skill. "What in blazes are you trying to photograph?" he said after a while, as he watched the lad focussing his camera earthwards on what looked like a piece of black glass, which projected from the stand. "Clouds, sir," answered Ralph. "When I try to photograph clouds I look at the sky, not on the ground," the stranger remarked. "What's that contrivance you've got on your camera stand, anyway?" "It's just a broken piece of looking glass," said the boy, "but I painted it on the back with black enamel." "What for?" "So that I could get at the clouds easier, sir," the boy replied. "I read how to do that in a book I've got." "I don't see why black glass should make any difference," said the fisherman, getting up from the log and coming over to where the boy was standing. "It does, sir. If you look on the glass," said Ralph, "you'll see. The clouds are ever so much sharper." The stranger looked in. Even the fleecy white clouds, scarcely visible in the blue sky overhead, stood out a clear white against the blackness of the mirror. The blue sky was not reflected in the glass. "That's queer," said the stranger, "the blue hardly shows at all. I wonder why?" "It said in the book," Ralph explained, "that the blue didn't show up so much because it was partly polarized. I couldn't quite understand what that meant. As far as I could make out, the blue color of the sky is due to waves that are scattered sideways instead of coming straight down like the white light does." "I suppose it is polarized," said the fisherman, "but it hadn't ever occurred to me that the sky wouldn't be reflected in a black mirror. You're right, though. The clouds do stand out well! You ought to be able to get some good pictures from your mirror." "I have got a lot, sir," said Ralph. "I've made three cloud photographs every day, rain or shine, for over two months now." "Every day?" "Yes, sir, before breakfast, after dinner, and just before I begin my evening chores." "What's the idea of that?" Finding a ready listener, Ralph plunged into the story of the Mississippi Weather League and of his crippled friend, Anton. "It's a mighty useful piece of work," the fisherman commented, when the lad had finished, "and I'm especially interested in these cloud photographs of yours. I need some. Have you any prints of them?" "Yes, sir," was the reply, "heaps." "If they're really any good, I might be able to use a few," the fisherman continued. "I'm writing a series of articles for an outdoor magazine and I want some Mississippi River pictures pretty badly. Mine haven't come out particularly well."