Nevil Maskelyne FRS FRSE, Astronomer Royal From 1765 to 1811, Nevil Maskelyne FRS FRSE was the fifth British Astronomer Royal. He held the office for 46 years. His work was central to the reorganisation of the Royal Observatory at Greenwich, and, among other achievements, he was the first person to scientifically measure the mass of planet Earth, determining its density to be approximately 4.5 times that of water. Maskelyne was also the first person to make time measurements accurate to the nearest tenth of a second. In 1758, Maskelyne was admitted to the Royal Society. Three years later, in 1761 the Society sent him to the island of St Helena, in the South Atlantic, to observe the transit of Venus. He used the voyage as an opportunity to experiment with the determination of longitude at sea by observing the moon's position. In 1763, he published an explanation of this method in The British Mariner’s Guide and adamantly believed that it was an astronomical method such as this that would solve the problem of longitude. As a result of his bias towards an astronomical rather than a mechanical solution, he did not support – and even undermined – the efforts of the clockmaker John Harrison, who eventually solved the problem with the creation of his groundbreaking H4 chronometer. Today, Maskelyne is remembered mainly as Harrison’s nemesis. In her book Longitude, author and science reporter, Dava Sobel provides a complete account of their tempestuous professional relationship and Maskelyne’s role in the race to solve the problem of longitude.[1] You can also learn more about this topic by visiting the John Harrison exhibit here on Clocktime. In recent years, Maskelyne’s posthumous reputation has been rehabilitated by historians, and it should be borne in mind that he was much admired in his day.[2] He enjoyed a long and lauded career in which he championed and advanced the fields of numerous subjects, including navigation, astronomy and cartography. End Notes [1] Sobel 2011, 111–175. [2] Royal Museums Greenwich has published an informative series of blogs on the rehabilitation of Maskelyne’s reputation and why the lunar method seemed to be a viable solution. Go to https://www.rmg.co.uk/stories/blogs and search for ‘Maskelyne’. Reference Maskelyne, N. 1763. The British Mariner’s Guide: Containing complete and easy instructions for discovery of the longitude at sea and land, within a degree, by observations of the distance of the moon from the sun and stars, taken with Hadley’s quadrant: to which are added, an appendix, containing a variety of interesting rules and directions, tending to the improvement of practical navigation in general. And a sett of correct astronomical Tables. Published by the author. Sobel, D. 2011. Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. London: Harper Perennial. Further Reading Royal Museums Greenwich. ‘Longitude found: Nevil Maskelyne and the lunar method.’ https://www.rmg.co.uk/stories/topics/longitude-found-nevil-maskelyne-lunar-method. Image Credit Dr. Maskelyne FRS Astronomer Royal. Published by J. Asperne at the Bible Crown & Constitution Cornhill 1 March 1804, Museum number 1865,0520.107 © The Trustees of the British Museum, CC BY-NC-SA 4.0, https://www.britishmuseum.org/collection/object/P_1865-0520-107
