Evening Republican, Volume 21, Number 305, Rensselaer, Jasper County, 31 December 1917 — Photographic Lens and the Human Eye Are Quite Alike. [ARTICLE]

Photographic Lens and the Human Eye Are Quite Alike.

That the human eye and the photographic lens are very much alike in design and operation is a well-known Jfact. If you look through a photographic lens you will see nothing clearly. To perceive the image, says the Popular Science Monthly, a piece of ground glass or a plate or film Is necessary. A plate Is a piece of plain glass which acts as a support for an emulsion. This emulsion decomposes when struck by light, and the decomposition is made visible by a process called development With an ordinary photographic plate only one such impression, or image, can be obtained. With the motion-picture film, however,' a fresh piece of film is continually exposed to the lens. Just s>ch an arrangement exists in the human eye. An emulsion called visual purple acts as a film of great

latitude, renewing itself as soon as it is struck by the light and discolored. It adapts itself to various intensities of light, protecting the retina from too brilliant a glare at all times.