Portable telescope
This non-achromatic telescope has a barrel covered in red leather and decorated with gold-tooled motifs. It has six draw tubes of marbled paper. Handwriting on the inside of many of the draw tubes suggests that they were made of recycled paper.
The eyepiece and objective lenses are both missing. There is a lens cap made of leather, but its gold-tooled decoration is slightly different to that on the barrel, suggesting that it once belonged to another instrument.
Telescopes in this period had to be quite 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 an optimum working length of about 1750 mm.
A label attached to the telescope indicates that it was shown at an exhibition of scientific instruments held at the Musée des Arts Décoratifs in Paris in 1936. A number of objects now held by the National Maritime Museum were shown in this exhibition, including NAV1496.
The eyepiece and objective lenses are both missing. There is a lens cap made of leather, but its gold-tooled decoration is slightly different to that on the barrel, suggesting that it once belonged to another instrument.
Telescopes in this period had to be quite 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 an optimum working length of about 1750 mm.
A label attached to the telescope indicates that it was shown at an exhibition of scientific instruments held at the Musée des Arts Décoratifs in Paris in 1936. A number of objects now held by the National Maritime Museum were shown in this exhibition, including NAV1496.
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Object Details
ID: | NAV1497 |
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Collection: | Astronomical and navigational instruments |
Type: | Portable telescope |
Display location: | Not on display |
Creator: | Unknown |
Date made: | circa 1740 |
People: | Bernard, J. |
Credit: | National Maritime Museum, Greenwich, London, Caird Collection |
Measurements: | Overall: 490 mm; Diameter: 60 mm |
Parts: | Portable telescope |