The 1873 discovery, by Willoughby Smith, of the photoconductive property of selenium, is important historically, not so much for any practical value that selenium might have had in the field of optical telephony, (following Bell's and Tainter's work on photophones), but for the glut of schemes and proposals made for distant vision systems in the following years.

Inspec keywords: optical communication; photoconductivity; selenium; telephony

Other keywords: selenium; optical telephony; photoconductive property

Subjects: Optical communication