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Reflecting circle made by Edward Troughton, London, about 1823. Signed on the index arm: Troughton | 219 | London. Polished brass limb with inlaid silver scale from 140° to 0° to 140°; the entire circle is divided every 20'. Three silver verniers reading to 20", zeros at the left. Circular lacquered brass frame with a wooden handle. A detached U-shaped bracket holds a second handle with a brass-lined threaded hole for a third handle, which can also be screwed on the front of the frame. Three rigidly connected index arms on the back of the frame, a double-ended tangent screw and clamping screw are on the back of one of the arms. Three shades (two red, one green); three horizon shades ( two red, one green). Index glass without adjustment; adjustment of the horizon glass by a screw and a capstan screw. One detached magnifier on a 55 mm swivelling arm, for all three verniers. Threaded telescope bracket in two parts, fitted for correcting collimation error; perpendicular adjustment by rising-piece and a milled collar. Telescope (77 mm) erect image; telescope (179 mm) inverted image two parallel cross-wires; extra draw tube (90 mm) inverted image; extra draw tube (90 mm) inverted image, two parallel cross-wires. Sight tube (132 mm); sight tube (131 mm, probably from a different instrument); three shaded eyepieces (one red, two orange); a magnifying glass. Three unidentified parts. Box not seen WMB. The circle is mounted on a lacquered brass column on a tripod stand with three milled levelling screws. The counterbalanced swinging mount can be locked into the desired position by milled screws.

Brass framed reflecting circle with case.

1820-1825