Brass framed reflecting circle with case.

Reflecting circle made by Charles West, London, 1817-1822. Circular lacquered brass frame and index arm, polished limb, two detachable wooden handles. Signed on the limb: C. West, 5. Cursitor St. Chancery Lane, London. Inlaid silver scale from 0° to 180° (four times) every 20'. Three silver verniers to 10", zeros at the right. The index arm carries the index glass; the telescope arm carries the horizon glass. The tangent screw and clamping screw are on the back of the index arm; two clamping crews are at both ends of the telescope arm. Four index shades (two red, one green); three horizon shades (two red, one green). Index-glass adjustment by screw; adjustment of the horizon glass by screw and capstan screws. Detachable magnifier serving two verniers on a 40 mm swivelling arm; a second, fixed magnifier is on a 25 mm swivelling arm. Threaded telescope bracket in two parts, fitted for correcting collimation error; perpendicular adjustment by rising-piece and a milled collar. Telescope (84 mm) erect image; telescope (152 mm) inverted image, four cross-wires; extra draw tube (57 mm). Sight tube (83 mm); shaded eyepiece (red); adjusting key; adjusting pin. Square fitted mahogany box containing in the lid a broadside of James Allan at no. 12 Blenvitts Buildings, Fetter Lane, London, announcing his new, improved, self-correcting dividing engine, and the prizes he received for this. The broadside was printed after 1811.