Tony Moss wrote: > Peter Mayer contributed > > > > My recollection is that they were > >used by military forces in the 19th century in places like India. (I have > >a half-baked recollection that Kipling refers to one in a poem...¿Is that a > >source?!) > > > In my impecunious searches of WWII 'surplus' stores back in the 1950s I came > across a "Portable Heliograph Set' in a pouch. It was simply a mirror about > four inches across with a sighting hole in the middle. A length of cord > attached it to a short rod with a bead on top. > > In use the mirror was held in one hand near to the operator's eye. The cord > was then stretched tight and the 'bead' used to 'sight' the target. If the > mirror was then rotated until a sunray coincided with the bead above the > other outstretched hand a flash of sunlight would be directed at the target. > > It all seems rather 'iffy' but I suppose was intended as an emergency device. > > Has anyone any experience of it? >
Tony, This sounds like a "signal mirror" which were also contained in life jackets etc as survival gear. The more modern are quite effective and are great for annoying people on the beach. It uses double internal reflection in the hole to give a virtual image of the sun and so it is easy to hit what you are aiming at even though you are to far away to see the actual reflection on the opject that you are trying to hit. Bob San Diego
