The holograph letter was received by First Lord of the Admiralty, Sir Charles Wager on 7 November 1734 (letter dated 6 November 1734). Wager was one of Whiston's patrons for finding a method to solve the problem of longitude at sea. He begins by referring to his 'Description of Mr. Whiston's Reflecting Telescope, for the Discovery of the Longitude at Sea' 22 October 1730; and proceeds to discuss reflecting telescopes and finding longitude by the occultations of the moons of Jupiter.

Related Material the <a href="http://cudl.lib.cam.ac.uk/view/MS-MSS-00079-00130-00002/1">Board of Longitude Digital Archive</a> for a digitised copy of this item.

Administrative / biographical background
William Whitson suceeded Isaac Newton as Lucasian Professor of Mathematics at Cambridge University in May 1702. He was instrumental in forming the Board of Longitude in 1714 and for the next forty years made persevering efforts to solve the longitude problem. Whiston was interested in this problem since his days as Lucasian professor and offered several methods; the first being co-written with Ditton and entitled, 'A New Method for Discovering the Longitude both at Sea and Land' in 1714. Amongst his methods include his 1724 proposal using solar eclipses and a fourth method involved the observation of the eclipses of Jupiter's satellites (The Longitude Discovered by the Eclipses, Occultations, and Conjunctions of Jupiter's Planets, 1738) , for which he attempted to improve the design of reflecting telescopes.