(1):

(n.) An instrument for taking photographs of the sun.

(2):

(n.) An apparatus for telegraphing by means of the sun's rays. See Heliotrope, 3.

(3):

(n.) A picture taken by heliography; a photograph.

(4):

(v. t.) To telegraph, or signal, with a heliograph.

(5):

(v. t.) To photograph by sunlight.