| Answer | Crossword Clue |
|---|---|
| heliograms | HELIOGRAM, a message sent by reflecting the sun's rays with a mirror |
| heliogram | a message sent by reflecting the sun's rays with a mirror |
| heliostat | instrument consisting of a mirror moved by clockwork, for reflecting the sun's rays in a fixed direction |
| heliogram | A message sent by reflecting sunlight in flashes from a movable mirror |
