Page 13
THE SEXTANT AS A HELIOGRAPH
You can use the sextant mirror to flash the sun’s rays several miles to attract
attention, or to signal another person who is too far away for your voice to reach.
If you know Morse code, you could even send a message.
1. Hold the sextant so that the index mirror (the larger of the two mirrors) is just
below the eye.
2. With your other arm extended and the thumb held upright, look at the person
you wish to signal.
3. Hold your thumb to a position just below the person, so that your eye (with the
mirror under it), your thumb, and the person are in a straight line (Fig. 18).
4. Using the mirror, flash the sun on your thumb. The sun flashes simultaneously
on the distant person.
Figure 17
Figure 18
Since the sextant does not have a compass, you don’t need to worry about varia-
tion or deviation. However, you must use at least three lines of position.
Summary of Contents for Mark 3
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