A 19th century brass surveyor’s circumferentor or sighting compass, manufactured by the firm of Alexander Adie and Sons, Edinburgh. The instrument is constructed primarily of brass with a dark aged patina. The central rotating plate is engraved with the maker’s name distributed across the quadrants as Alexr Sons Adie Edinburgh. The main circular dial is graduated on its outer edge from 0 to 360 degrees in ten-degree increments. An inner rotating brass plate features twin vernier scales graduated from 0 to 60. A long cross-arm or alidade is mounted to the central axis, featuring an integrated housing for a spirit level and vertical sighting vanes at each extremity for taking bearings. The underside is fitted with a substantial mounting assembly comprising a ball-and-socket joint, two large brass levelling thumbwheels, and a threaded base for attachment to a tripod. The reverse of the main body is marked with inventory numbers in white ink, including 30/32.
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