Unknown, 1740 c.
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Photo

photo - whole telescope
Basic Info

Maker: Unknown

Year: 1740 c.

Year Range: -

Year Notes:

Manufacturing Location: Italy

Signature:

Signature Notes:

Inscriptions:

No stand present.

Collection: National Maritime Museum

Accession #: NAV1497

Sources:

Royal Museums Greenwich. "HAnd-held telescope". http://collections.rmg.co.uk/collections/objects/43709.html [Accessed: June 2016].

Public Notes:

"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" (Royal Museums Greenwich).

Provenance:

Caird Collection

Length (open): 1750 mm (open to stop lines, approx.)

Length (closed): 483 mm

F-ratio:

Exit pupil:

Object status:

Optical Basics

Objective type: singlet

Optical style

Physical style

Functional style

Materials: leather, paper, gold tooling, glass, pasteboard

Optical/Lab Data

Drawtube data:

Drawtube notes:

Objective Data

Eyepieces

Notes:

WavelengthParaxial70%Whole
575 ± 0 ± ±
652 ± 5.2 ± 1.4 ± ±
482 ± -12.5 ± 1.6 ± ±