heliógrafo

Heliograph: The two tripods held by the two soldiers at right comprise a US Army Signal Corps heliograph - a tripod-mounted device for sending messages by flashes of sunlight using Morse or Myer code, with a range up 30 miles or so. This heliograph is set up in duplex, or "dual-mirror" mode, the mode used when the sun was behind the signalers. The job of the dark-suited soldier at the extreme right was to keep the sun beam reflected by the dual 4.5 inch square mirrors on his tripod in constant alignment on the target as the sun moved, using vernier elevation and azimuth screws. The job of the light-suited soldier in the middle was to open and close the shutter flap on his tripod to produce the dots and dashes of the code. A diagram showing this heliograph (albeit in single-mirror mode), taken from [1], is here (click on the thumbnail to magnify), and see [1] for the dual-mirror mode diagram. An 1893 photograph of this type of heliograph (albeit in single-mirror mode), taken from [2], is here (click on the thumbnail to magnify) To learn more about heliographs, you can read [1] and [2], as well as this Wikipedia article: en.wikipedia.org/wiki/Heliograph You can also see this Flickr gallery (click on the thumbnail): [http://www.flickr.com/photos/signalmirror/galleries/72157630246445306/] and this set (click on the thumbnail) : (Historical Photographs of American Heliographs) [http://www.flickr.com/photos/signalmirror/sets/72157631040759962/] [ 1 ] Annual Report of the Chief Signal Officer of the Army to the Secretary of War for the Year 1888, Government Printing Office, 1889 The new standard heliograph is discussed in Appendix I, pp. 42-47, and depicted on page 46, here: books.google.com/books?id=E2nPAAAAMAAJ&pg=PA46&dq... [2] "The Heliograph", The Compass, Vol. II, No. 11, June 1, 1893, page 161 books.google.com/books?id=tX0SAAAAYAAJ&pg=PA161

signal mirror Thanks for the great information!

Kings African Rifles

This photo of Kings African Rifles signallers shows seven Caucasians (centre row) and 14 native troops (six seated in front with flags, six standing in back with flags, and two standing on either end with 5" diameter circular mirrors mounted on tripods). The tripod-mounted mirror instruments are 5" Mance Heliographs set up in simplex (signal-mirror) mode, with the leather carrying cases slung on the tripods, per standard practice. Heliographs were used to flash messages by Morse Code at ranges up to 30 miles or more, and saw heavy use in Africa by British, German and Boer forces from the late 1870s through WWI, with use continuing into WWII. For more on heliographs, see: Wikipedia:Heliograph Below is another photo of K.A.R.. signallers with a heliograph (believed to be from the 4th Kings African Rifles in Uganda); There's a very nice video held at the Imperial War Museum about the signallers of the Kings African Rifles with several segments showing heliographs in action (including footage of a 12" heliograph mirror in use - very rare footage) that can be viewed on the web at this link: K.A.R SIGNALS : a film of routine in remote places I've posted some other photos of Mance heliographs on Flickr here: [http://www.flickr.com/photos/signalmirror/sets/72157631978269679/]