I recently came across the story of an eccentric inventor, Harry Grindell Matthews, who for several years during the 1920's teased the world with announcements of his 'death ray'. He failed to produce the promised weapon but did create a machine capable of projecting advertising messages onto the underside of clouds. This was his Sky Projector, and a commercial flop. However it looks so cool, and surely a machine that projects an intense light beam has some offensive use, however limited. Here it is:


Anyone fancy building one? Here is the man himself and he just looks like a boffin.
