Portable telescope

The barrel of this non-achromatic telescope is covered in red leather that is decorated with gold-tooled motifs. There are five draw tubes covered in marbled paper. The other fittings are of turned wood and bone. The objective lens and some of the fittings are now missing.

This telescope is assumed to have been made in France because of an inscription on one of the draw tubes in French.

Telescopes in this period had to be long, since lenses with long focal lengths were used in order to minimise chromatic aberration - the appearance of coloured fringes around the object being viewed. The stop lines drawn onto the draw tubes of this telescope indicate a maximum optimum working length of over 1600 mm.

Object Details

ID: NAV1498
Collection: Astronomical and navigational instruments
Type: Portable telescope
Display location: Not on display
Creator: Unknown
Date made: circa 1740
Credit: National Maritime Museum, Greenwich, London, Caird Collection
Measurements: Overall: 470 mm; Diameter: 60 mm