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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Heliography
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1992-09-02
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320b
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9 lines
Old method of signalling, used by armies in
the late 19th century, which employed
sunlight reflected from a mirror to pass
messages in Morse code. On a clear day, a
heliograph could send over distances in
excess of 50 km/30 mi. Also, an early
photographic process by which a permanent
image was formed on a glass plate.