Hemisferium Nocturlabe Miniature - Piece on stand.This nocturnal watch "Horologium Nocturnum" is an astronomical instrument that was used to keep time at night. By observing the stars, it was noted that certain boreal constellations rotated around the Pole Star as if a giant clock hand were keeping time around a celestial sphere of 24 hours. This particular nocturnal is a reproduction of the one made in 1570 and is designed to calculate the time based on the position of the Pole star and Kochab the