Military Mk V Heliograph Signalling Mirror in Original Tin.
The heliograph is a wireless telegraph that signals by flashes of sunlight reflected by a mirror. the flashes are produced by momentarily pivoting the mirror or by interrupting the light beam with a shutter. The mirror flashes can be seen up to 20 miles away.
Contained in the tin are two mirrors.
Signalling was key to a successful military operation. Early methods of signalling included flags, lamps and heliographs.
A small but important item of military history.
Size 14cm diameter. 1.5cm high.