8 1/2 inch Ebony Sextant by Dollond, London
Dollond, London ebony sextant in box
Type of object:
Sextant
Time period:
Britain rules the waves + France
Place:
London
Date:
1800
Maker / Author:
Probably Peter Dollond , London ( 1730-1820), son of John Dollond optician
Publisher / Printer:
Dollond
Dimensions:
8 1/2 inch radius; 11 x 13¾in. (28 x 35cm.)
Material:
Ebony and Brass in Keystone box with two telescopes
Graduation:
0- 140°
Inscription:
Dollond London
Provenance:
England, Charles Miller
References:
Directory of British scientific Instrumlent makers, pag 87
Description
AN 8½IN. VERNIER SEXTANT BY DOLLOND, LONDON, CIRCA 1800
signed on the cross bar as per title, scale divided to 140º and stamped with Ramsden fouled anchor mark at centre, right-aligned vernier scale with braced index arm, sighting tube mount, shades, mirrors, shaped handle and brass feet, contained within keystone box with two telescopes
Additional information
Wikipedia:
Known for
Achromatic lens
Peter Dollond (24 February 1731 - 2 July 1821 born Kensington, England) was an English maker of optical instruments, the son of John Dollond. He is known for his successful optics business, and for the invention of the apochromat.
[edit] Biography
Working together with his father and subsequently with his younger brother and nephew (George Dollond) he successfully designed and manufactured a number of optical instruments. He is particularly credited with the invention of the triple achromatic lens in 1763, still in wide use today,[1][2] though known as the Cooke triplet after a much later 1893 patent.
Peter Dollond worked at first silk weaving with his father, but his father's passion for optics inspired him so much that in 1750 Peter quit the silk business and opened an optical instruments shop in Kennington, London. After two years, his father gave up silk, too, and joined him.
Dollond telescopes, for sidereal or terrestrial use, were amongst the most popular in both Great Britain and abroad for a period of over one and half centuries. Admiral Lord Nelson himself owned one. Another had sailed with Captain Cook in 1769 to observe the Transit of Venus.
The Peter Dollond compound chest microscope is based on improvements to the Cuff-style microscope introduced by British scientific instrument designers Edward Nairne and Thomas Blunt around 1780. Another design was for the Peter Dollond compound monocular Eriometer around 1790 used to accurately measure the thickness and size of wool fibres.
After successfully defending a legal challenge to the patent he held for the achromatic lens the business prospered and he successfully sued his rivals for patent infringement.[2] Dollond's reputation, especially with his father being a Fellow of the Royal Society as a result of his invention of the achromat, provided the company with the de facto right of refusal on the best optical flint glass.[3] This privilege permitted Dollond to maintain an edge in quality over competitor's telescopes and optical instruments for many years.
