National Maritime Museum Manuscripts : Correspondence from Nevil Maskelyne

National Maritime Museum Manuscripts

<p>Two documents composed by <a href='/search?keyword=Nevil%20Maskelyne'>Nevil Maskelyne</a>, who served as Astronomer Royal from 1765-1811, as well as serving as a Commissioner on the Board of Longitude. As Astronomer Royal, much of Maskelyne's time was spent managing the production of the Nautical Almanac - an annual publication of the position on the Earth's surface at which various celestial landmarks (the sun, moon, planets, etc.) are overhead, for each hour of the year. It was under Maskelyne's guidance that the first Nautical Almanac was published in 1767.</p> <p>Maskelyne hoped that the Nautical Almanac could be incorporated into use by seamen while on board ships, largely for the purpose of finding their longitude. Like timekeepers, however, getting them to work on ships was not terribly easy. Indeed, in his 'List of instruments and books delivered to Capt. Cook on May 22 1776' (for <a href='/search?keyword=James%20Cook%27s'>James Cook's</a> final and ultimately fatal voyage on board <a href='/search?keyword=HMS%20Resolution'>HMS Resolution</a>), we see that Maskelyne desired Cook to carry and use an enormous amount of hardware, some of which - the two Hadley's sextants by the instrument makers <a href='/search?keyword=Jesse%20Ramsden'>Jesse Ramsden</a> and <a href='/search?keyword=John%20Dolland'>John Dolland</a>, for example - were crucial for the purpose of taking the necessary measurements for working out longitude by the Nautical Almanac. However, the others - including the achromatic telescope, the transit instrument, and the theodolite - remind us that much of the accuracy of finding longitude by celestial observation still relied heavily on land-based observing.</p> <p>Having such a large cargo of expensive instruments wasn't just an economic burden for the Board of Longitude and for Cook. Many of the items were also incredibly fragile. In his letter to <a href='/search?keyword=John%20Nourse'>John Nourse</a> on 3 Jan 1767, for example, Maskelyne demonstrates that even books carried on ships could be damaged. This was of particular importance for the success of the Nautical Almanac, and thus Maskelyne was very concerned that Nourse, the publisher to the King, took 'great care…in the stitching' of the Nautical Almanac, so that it didn't get damaged. In the same way that timekeepers and telescopes could be easily damaged by the effects of temperature and water on a long-distance voyage, so could paper and print. We can see that Maskelyne was also concerned with problems that could arise when attempting to replicate documents. In his letter to Nourse we see him being clear to ensure that there were no basic printing errors - problems that could render the enormous amount of effort spent by Maskelyne and his assistants at Greenwich and across the globe redundant.</p> <p>Eóin Phillips<br />History and Philosophy of Science<br />University of Cambridge<br /> </p>

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