Theodolite, 13 inch horizontal circle and 9 inch vertical circle, by Ertel & Sohn, Munich. Horizontal circle is graduated to 5 minutes and vertical circle to 15 minutes.

It is likely that this is the 'Universal Instrument' by Ertel listed by George Neumayer as part of the instrumentation at Flagstaff Observatory, Melbourne in 1858. The instrument was used to determine the astronomical meridian, to be used as part of Neumayer's measurement of changes in the Earth's magnetic elements.

Physical Description

2 boxes: 1. stand and horizontal circle; 2. telescope and vertical circle.

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