Dunnington, G. Waldo (2004). Carl Friedrich Gauss: Titan of Science. New York: The Mathematical Association of America. pp.122–127. ISBN 0-88385-547-X.

A big enough mirror that can comfortably fit in your hands. A two-by-three-inch size is good enough as long as it has a small hole in the middle for you to see where you're focusing your signal. This way, you'll be better placed to capture the eye of a search team. Or, if you are ever in a situation where you will need to be rescued, start practicing with the signal mirror before you see any rescue planes. That way, when a plane does fly over, you will be ready to signal to it with the mirror. The manoeuvre part of MSM can be many things from roundabouts, junctions, changing lanes or parking up to mention just a few. The manoeuvre part is often extended into Position, Speed and Look making MSPSL to further aid learner drivers.When improvising a mirror, hold up your thumb and index finger in a V-shape and angle your reflective material. It ensures that most of the light goes through the V as this will help find the bead of light. The German professor Carl Friedrich Gauss of the University of Göttingen developed and used a predecessor of the heliograph (the heliotrope) in 1821. [2] [11] His device directed a controlled beam of sunlight to a distant station to be used as a marker for geodetic survey work, and was suggested as a means of telegraphic communications. [12] This is the first reliably documented heliographic device, [13] despite much speculation about possible ancient incidents of sun-flash signalling, and the documented existence of other forms of ancient optical telegraphy.

Place your target between your two spread-out fingers while angling the mirror so that the reflected light remains between them. The major difference between this signal mirror and so many on the market today is that this signal mirror is made of high-quality glass. This means its reflectivity is higher than Lexan or plastic versions. We offer this high-quality signal mirror in both 2" x 3" and 3" x 5" sizes with instructions printed on rear of the signal mirror.

How do you use a signal mirror?

a b c d e f W. N. Millar (1920), Canadian Forestry Service. Methods of Communication Adapted to Forest Protection Google Books. Retrieved on 1 June 2008. pp. 160-181 are devoted to the heliograph, with diagrams of the British, American, and Godwin type.