Sundial altitude ring dial - miniature

Altitude sundial. Takes this name because the parameter of its construction is based on Sun’s altitude. They were very popular on 16th-17th centuries.This brass made model is available for two different latitudes: 40º or 50º.On15th century mariners found a way to estimate their latitude to find their location in the sea. It was based on a well-known fact: the height of celestial bodies depends on the latitude. Soon various instruments joined the quadrant, the nautical astrolabe and the cross-staff or ballastella