I've seen instructions on using a sextant mirror as a signal mirror, but this is the first account I've seen of a signal mirror used as a sextant!

After their ship was torpedoed in 1944, 3rd officer F.L. Newal cobbled up a sextant from a protractor, a biscuit tin, chewing gum, and a metal signal mirror, and headed for Diego Suarez, Madagascar, more than 1200 miles away.

After 42 days, a ship picked them up just 60 miles short of their goal.

Story and side view of homemade sextant

Story and top view of homemade sextant