Miniature Astronomical Ring Dial - Hemisferium
Although it is known as the Astronomic Ring Dial (Annulus Atronomicus), the complete name of this instrument used to determine the solar time and to make other astronomical measurements is the Universal Equinoctial Ring Sundial. Its principle is the Universal Equatorial Solar Quadrant.
Several kinds of astronomic dials existed, and the larger ones could indicate the hour to the minute and for a long time were the only way to know if mechanical clocks were functioning correctly without having to rely on an astronomical observatory.
In this model, Latitude is fixed to: 40, 4º .
Height: 5.1" / Diameter: 1.77" / Thickness: 0.2"