heliograph

noun

1. An apparatus for signalling by means of a moveable mirror which reflects flashes of sunlight.

   “Now Jones had left his new-wed bride to keep his house in order, / And hied away to the Hurrum Hills above the Afghan border, / To sit on a rock with a heliograph; but ere he left he taught / His wife the working of the Code that sets the miles at naught. / And Love had made him very sage, as Nature made her fair; / So Cupid and Apollo linked, per heliograph, the pair.”

   “It was a lieutenant and a couple of privates of the 8th Hussars, with a stand like a theodolite, which the artilleryman told me was a heliograph.”

   “when we stood up at nightfall we saw, in the sunset, the sparkle of the heliograph above cities, on the far side of the horizon.”

2. A heliogram.
3. An instrument for measuring the intensity of sunlight.
4. A device for photographing the sun.
5. (obsolete)A photograph.

verb

1. (transitive)To send a message by heliograph.

   “With damnatory dot and dash he heliographed his wife / Some interesting details of the General's private life.”

2. (intransitive)To send a heliograph.
3. (dated, transitive)To photograph by sunlight.