Polygonal telescope

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This non-achromatic telescope has an octagonal barrel covered in rayskin. The barrel unscrews into two sections. There is a single draw tube made of vellum, which has stop lines drawn onto it to indicate the different working lengths of the telescope according to the distance of the object being viewed. There is also some tooled decoration on the draw tube. The other fittings are of ivory, although parts of the eyepiece assembly are missing. The objective lens is a modern replacement. The telescope is thought to have belonged to Admiral Augustus Keppel (1725-86).

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Object Details

ID:	NAV1576
Collection:	Astronomical and navigational instruments
Type:	Polygonal telescope
Display location:	Not on display
Creator:	Unknown
Date made:	circa 1750
People:	Keppel, Augustus
Credit:	National Maritime Museum, Greenwich, London
Measurements:	Length: 1447 mm (closed, approx); 1556 mm (open, to stop lines, max); Diameter: 45 mm (barrel); 57 mm (max)
Parts:	Polygonal telescope Draw tube for the telescope (NAV1576.1) Part of telescope barrel (NAV1576.2) Part of the octagonal telescope barrel (NAV1576.3)