1A signalling device by which sunlight is reflected in flashes from a movable mirror.
- ‘A heliograph was a communications system consisting of two mirrors on a tripod used to flash signals with sunlight.’
- ‘When we all got back to camp, our General communicated by heliograph from a distant mountain top with his superiors.’
- ‘Organised divers always carry some means of signalling their position at the surface, whether it be air-horn or flag, flare or heliograph, or combinations of two or more.’
- ‘Although visual signaling - wigwag, sun-powered heliograph, and observation balloons - remained important to the U.S. military, the Spanish-American War found commercial and military telegraph enjoying extensive use.’
- ‘Later, runners, telegraph, semaphore, heliograph and line were used to communicate.’
- 1.1A message sent by heliograph; a heliogram.
2A telescopic apparatus for photographing the sun.
3historical A type of early photographic engraving made using a sensitized silver plate and an asphalt or bitumen varnish.
- ‘An earlier version of the heliograph known as the heliotrope was used during the American civil war.’
- ‘The researchers used infrared spectrometry to analyze the heliograph's bitumen layer, too.’
- ‘The heliograph, ‘View From the Window,’ will be on view at the Ransom Galleries in Austin, Texas.’
1Send (a message) by heliograph.‘the glasses seemed to be heliographing a warning’
- ‘Garfield, just over the shoulder of Bond, was another, and it seemed as if the two were heliographing one to another from golden mirrors.’
- ‘To continue with my trip, the remainder of the summer was spent in patrolling, keeping weather reports, heliographing and reporting fires.’
- ‘Many in your Lordships’ House will be familiar with the story told in James and Jan Morris's great imperial trilogy, of the outpost in Sudan which heliographed to Khartoum.’
- ‘The besieged soldiers, using shaving mirrors, heliographed messages to their comrades based at Fort Pearson near the mouth of the river.’
- ‘In that small boat was the man to whom the signal had been heliographed.’
2historical Take a heliographic photograph of.‘he could only heliograph static subjects in very intense light’