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Phillosoph

Survival Heliographs: When the Sun Is Behind You. Part Two

Following on from my post on heliographs one of my regular readers observed:
Aiming a signalling mirror with the sun behind you could be tough but basically if you have the sun behind you and a plane in front, the problem (conceptually) is put the mirror flat between the two.”
He is correct. During my research I came across this informative illustration:

Note that the signaller is using his free hand to aim by directing the reflected spot of light on to it.