heliograph

== English == === Etymology === From helio- +‎ -graph. === Pronunciation === (US) IPA(key): /ˈhiː.li.əˌɡɹæf/ === Noun === heliograph (plural heliographs) An apparatus for signalling by means of a moveable mirror which reflects flashes of sunlight. A heliogram. An instrument for measuring the intensity of sunlight. A device for photographing the sun. (obsolete) A photograph. ==== Derived terms ==== === Verb === heliograph (third-person singular simple present heliographs, present participle heliographing, simple past and past participle heliographed) (transitive) To send a message by heliograph. (intransitive) To send a heliograph. (transitive, dated) To photograph by sunlight. === Further reading === heliograph on Wikipedia.Wikipedia