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Date: |
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Description: | ?Parkinson and Frodsham ?[illegible] .. London?
The sextant has a polished brass straight-bar pattern pillar frame, with twenty pillars, and a wooden handle. The tangent screw and clamping screw are located on the back of the index arm. The instrument has four shades, two red and two grey, and three horizon shades, one red and two grey. Index-glass adjustment is made by a screw and on the horizon glass by capstan screws.
Attached to the sextant is a magnifier on an 80mm swivelling arm, with a frosted glass shade. There is also a threaded telescope bracket in two parts, fitted for correcting collimation error. It has perpendicular adjustment made by a rising-piece and a milled knob. The telescope is 184 mm in length with an inverted image. A second telescope is 81 mm long with an inverted image and four cross wires. An extra drawtube is 49 mm long with an erect image. A third telescope is 68 mm long with an erect image (star finder) that does not fit in the telescope bracket. The sight-tube is 82 mm in length with six shaded eyepieces, three red, one orange, one green, and one grey. One part of the sight-tube is missing; this is probably a magnifying glass.
The instrument has a polished brass limb with an inlaid silver scale from -5 to 150� by 10 arcminutes, measuring to 129�. The sextant has a silver vernier measuring to 10 arcseconds, with zero at the right.
The sextant is contained in a square fitted wooden box, which is probably not original to this instrument.
A figure of a sextant, made of inlaid wood, is found in the lid of the box, with shipping company house flags on either side, also of inlaid wood. These are for the Australian Steam Shipping Co Ltd, London, on the left, and for Manchester Liners Ltd, Manchester, on the right. Edward Troughton patented the pillar and plate frame (no. 1644 of 1788).
AUDIT - Object needs marking with NAV number and 11 items part numbered.
caption: Sextant - Front
caption: Sextant - Back
caption: Sextant - Inscription
caption: Sextant - Box
caption: Sextant - Box Lid
caption: unavailable | Publisher: | "http://collections.rmg.co.uk/" | Rights holder: | "Royal Museums Greenwich" | Subjects: | Sextant Vernier sextants | Source: | Royal Museums Greenwich | Identifier: | http://collections.rmg.co.uk/collections... | Go to resource |
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