·add. ·vt To photograph by sunlight.
II. Heliograph ·noun A picture taken by heliography; a photograph.
III. Heliograph ·noun An instrument for taking photographs of the sun.
IV. Heliograph ·add. ·vt To telegraph, or signal, with a heliograph.
V. Heliograph ·noun An apparatus for telegraphing by means of the sun's rays. ·see Heliotrope, 3.