Beschreibung:

A rare 19th-Century English lacquered-brass miniature theodolite, signed on the horizontal circle W&S. JONES 30,,Holborn LONDON -- 15cm. (5 7/8in.) high See Colour Illustration The 17.3cm. long telescope has sliding adjustment to the objective lens by means of a small protruding handle. A bubble level is mounted on the top of the telescope tube in the centre. The objective dust cap is lacking. The tube rests on a cradle and is held in place by two shaped clamp bars resting on top and secured by pins (one pin is replaced by an old nail). The cradle is raised on two A-frame supports and incorporates a vertical half-circle. The silvered scale on the outside is graduated 90°-0-60°, labelled every 10° with 1° and ½° subdivisions, and labelled Degrees . On the inside of the half-circle is a scale for links. The edge of the half-circle is racked to fit with the pinion screw mounted on the horizontal circle and reads against a silvered vernier on the outside and a simple brass index on the inside. There is also a screw clamp (defective). The horizontal circle also incorporates a raised and glazed brass compass box. A wind rose is engraved on the base, with initials for eight compass directions, and graduated twice around the circumference: the inner scale is divided in four quadrants of 0-90° labelled every 10° with no subdivisions; the outer scale runs from 0-360°, labelled every 10° with 1° subdivisions. The shaped blued-steel needle has a brass cap and clamp (defective). A silvered scale of 0-360° runs around the bevelled edge of the horizontal circle, labelled every 10° with 1° and ½° subdivisions and is arranged to read off a vernier graduated 0-30°. Fine adjustment is accomplished by a tangent screw. There is a threaded tripod/staff mounting on the underside of the circle, secured by a screw clamp. Into this is threaded a concave triform stand with three adjustable screw feet, attached via three further screws to the circular brass plate from the top of a tripod.