1 example sentence using heliograph.
Heliograph used in a sentence
Heliograph in a sentence as a noun
Not to take anything away from his legacy, but isn't it a stretch to talk about the "invention" of email when we had telex, telegrams, heliography, scrolls of vellum carried by Roman messenger, and so on?
Heliograph definitions
noun
an apparatus for sending telegraphic messages by using a mirror to turn the sun's rays off and on
verb
signal by means of a mirror and the using the sun's rays