Perpetual Calendar Quadrant is in the British Museum

is in the British Museum of London

It's used by measuring the height of a star using the back of the instrument

which means "one who seeks"

Crafted of brass comes complete with wood base and display hook

This instrument is based on the eastern astrolabe now in the collection of the Adler Planetarium in Chicago made by the the famous craftsman Diyal'al Din Muhammad in 1647

Perpetual Calendar Quadrant is in the British MuseumThis calendar starts on January 1st, 1600 and ends December 31st, 2799 it is based on the repeating cycle of 400 years and a solar cycle of 28 years. It works by means of the "Dominical Letter" This beautiful instrument is fashioned of brass and comes complete with wooden base and booklets explaining method of use and historical context. Diameter: 3. 54" Thickness: 0. 24"