DAVIS Mark 15, 25 Sextant - Manual (Page 21)

Page 19
Note: Since the sextant does not have a compass, you do not need to worry about
variation or deviation. You must use at least three lines of position, however.
Using 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 mir-
rors) 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. 20).
4. Using the mirror, flash the sun on your thumb.
The sun flashes simultaneously on the distant person.
Figure 19
Figure 20
5. Move the tracing paper around on the chart until the lines are posi-
tioned so as to run through the three features.
The point of intersection of the three angles is your position (Fig. 19).