Manufactured: ca 1870

Description:
Pendulum or gravity sextant with artificial horizon. Graduated from 0°-100° in 30'. Vernier graduated from 0'-30' 1/10'. Two colored shades (red and green). Works without mirrors or lenses.

Item History:
The observer directs the instrument at the celestial body... While moving the frame towards the sky, a weighted 'alidade', through gravity, remains vertical. Designed for land surveying and map making. Uses a free-swinging pendulum to establish vertical reference. More accurately a "quadrant" than a sextant.