Mariner's astrolabe

The astrolabe is a nautical instrument consisting of a crown fixed to a central ring with four thick spokes. The instrument was thicker at the bottom in order to lower the center of gravity and enable the horizontal diameter to coincide with the horizon when the astrolabe was suspended by the ring. It was used to measure the altitude of the sun, or the Pole Star, in order to deduce the latitude of the location.

This example, made from bronze, was recovered from a Spanish ship wrecked near the Cape San Antonio, forming the northwestern extremity of Cuba.