Altitude & azimuth instrument, 12 inch circle, made by Troughton & Simms, London, circa 1836

This instrument was used for the Geodetic Survey of Victoria, 1858-71, which established the primary surveying points throughout the colony. Also used at Melbourne Observatory.

Physical Description

Altitude circle 11 inches and azimuth circle 12 inches. Circles graduated on silver every 10 minutes & read by verniers. In two wooden boxes: 1. stand and horizontal circle; 2. telescope and vertical circle.

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