Heliograph

About Heliograph

Heliography (in French, héliographie) is the photographic process invented by Joseph Nicéphore Niépce around 1825, and which he used to make the earliest known permanent photograph from nature, View from the Window at Le Gras (c. 1826). The process used bitumen, as a coating on glass or metal, which hardened in relation to exposure to light. When the plate was washed with oil of lavender, only the hardened image area 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.[1]