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Portable telescope
The telescope barrel is covered with rayskin (shagreen) that has been dyed green. There are four draw tubes made of green vellum with stop lines (shown by rings of black dots) that indicate the optimum working length of the telescope. The brass fittings include a screw-on objective lens cap and a sliding eyepiece cover.
The telescope has an achromatic objective lens. The achromatic lens was first patented in 1758 by John Dollond (1706–61). It was his son, Peter (1731–1820), who founded the company whose name is engraved on one of the draw tubes: 'DOLLOND / LONDON'.
The telescope has an achromatic objective lens. The achromatic lens was first patented in 1758 by John Dollond (1706–61). It was his son, Peter (1731–1820), who founded the company whose name is engraved on one of the draw tubes: 'DOLLOND / LONDON'.
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Object Details
| ID: | NAV1512 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Portable telescope |
| Display location: | Not on display |
| Creator: | Dollond, Peter |
| Date made: | circa 1790 |
| Credit: | National Maritime Museum, Greenwich, London, Caird Collection |
| Measurements: | Length: 450 mm (closed, with cap), 1702 mm (open to stop lines, max.); Diameter: 56 mm (barrel) |
| Parts: | Portable telescope |