Heliography

He·li·og·ra·phy

Heliography

n.
  1. The description of the sun.
  2. The system, art, or practice of telegraphing, or signaling, with the heliograph.
  3. An early photographic process invented by Nicéphore Niepce, and still used in photo-engraving. It consists essentially in exposing under a design or in a camera a polished metal plate coated with a preparation of asphalt, and subsequently treating the plate with a suitable solvent. The light renders insoluble those parts of the film which is strikes, and so a permanent image is formed, which can be etched upon the plate by the use of acid.
  4. Photography. [Archaic.]