heliograph
noun /ˈhiːliəɡrɑːf/
/ˈhiːliəɡræf/
- a device that gives signals by reflecting flashes of light from the sun
- (also heliograma message that is sent using signals from a heliograph/ˈhiːliəɡræm//ˈhiːliəɡræm/)
- a special camera that takes photographs of the sun