Heliography

Heliography (in French, héliographie) is the photographic process invented by Joseph Nicéphore Niépce around 1822, which he used to make the earliest known surviving photograph from nature, View from the Window at Le Gras (1826 or 1827). The process used Bitumen of Judea, a naturally occurring asphalt, as a coating on glass or metal. It hardened in proportion to its exposure to light. When the plate was washed with oil of lavender, only the hardened areas remained.

The word has also been used to refer to other phenomena: for description of the sun (cf. geography), for photography in general, for signalling by heliograph (a device less commonly called a heliotrope or helio-telegraph), and for photography of the sun.

The abbreviations héliog. or héliogr., found on old reproductions, may stand for the French word héliogravure, and can then refer to any form of photogravure.

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