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Lot 137
George Margetts (1748-1804). A late 18th century book of tables. Margetts's Longitude Tables; For Correcting the Effect of Parallax and Refraction, on the Observed Distance Taken Between the Moon and the Sun, or a Fixed Star whereby the True Distance is Accurately Obtained and the Corresponding Time at Greenwich Ascertained found by Inspection.
13 July 2023, 14:00 BST
London, New Bond StreetSold for £1,280 inc. premium
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George Margetts (1748-1804). A late 18th century book of tables.
Margetts's Longitude Tables; For Correcting the Effect of Parallax and Refraction, on the Observed Distance Taken Between the Moon and the Sun, or a Fixed Star whereby the True Distance is Accurately Obtained and the Corresponding Time at Greenwich Ascertained found by Inspection.
Printed for the Author, No.42, Penton Street, Islington and Sold by Mr Elmsly, Bookseller in the Strand and Messrs Gilbert & Wright, Opticians, Leadenhall Street where the Author will attend in order to give a full Explanation of his Method of finding the Longitude. Featuring full instructions and many tables including a large fold-out plate to the back. Later gilt-tooled leather binding. Circa 1790-93. 29cms x 25cms (11.5ins x 10ins).
Printed for the Author, No.42, Penton Street, Islington and Sold by Mr Elmsly, Bookseller in the Strand and Messrs Gilbert & Wright, Opticians, Leadenhall Street where the Author will attend in order to give a full Explanation of his Method of finding the Longitude. Featuring full instructions and many tables including a large fold-out plate to the back. Later gilt-tooled leather binding. Circa 1790-93. 29cms x 25cms (11.5ins x 10ins).
Footnotes
Finding longitude at sea using the Lunar Distances method was used before chronometers were invented and indeed long after since it was a low-cost system. The calculations to find longitude were however, complex and time consuming. George Margetts's tables provided a solution where calculations were replaced with looking up results using a series of graphic charts and tables.
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0373463300021056