Portable telescope

This non-achromatic telescope has three draw tubes. The barrel is made of pasteboard and is decorated with hand-painted flowers on a red background. The other fittings are made of turned horn. The objective lens and the screw-on eyepiece cap are now missing.

Early telescope lenses suffered from the appearance of coloured fringes, a problem that could be reduced by using lenses with long focal lengths. This meant, however, that the telescopes had to be very long - the stop lines drawn onto the draw tubes of this telescope indicate an optimum working length of about 918 mm.

Object Details

ID: NAV1495
Collection: Astronomical and navigational instruments
Type: Portable telescope
Display location: Not on display
Creator: Unknown
Date made: circa 1750
Credit: National Maritime Museum, Greenwich, London, Caird Collection
Measurements: Overall: 320 mm; Diameter: 35 mm
Parts: Portable telescope