Nevil Maskelyne

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Nevil Maskelyne

Nevil Maskelyne (born October 6, 1732 in London , † February 9, 1811 in Greenwich ) was a mathematician and astronomer and from 1765 to 1811 British court astronomer ("Astronomer Royal").


Maskelyne was the third son of Edmund Maskelyne and his wife Elizabeth Booth. Deeply impressed by the solar eclipse that he observed on July 25th, 1748, Maskelyne decided to devote his life to astronomy. He went to Cambridge in 1749 , where he graduated from Trinity College in 1754 and obtained further degrees in 1757, 1768, and 1777. From 1755 he was in close contact with James Bradley , whom he supported in calculating his refraction table. In 1758 he became a member of the Royal Society , which commissioned him in 1761 to observe the transit of Venus on June 6th on St. Helena .

His proposals of 1760 to have the parallaxes of Sirius and the moon observed at the same time were not accepted. The desired observations were not possible anyway because the sky was overcast, but the device was also defective. A technical improvement that Maskelyne subsequently developed was soon widely used. On the way there and back he dealt with studies to determine the geographical longitude at sea using lunar distances . Appointed by the Board of Longitude to review John Harrison's Model 4, he took part in the test drive to Barbados in 1763 as a ship's chaplain on the HMS Louisa , accompanied by Charles Green, assistant at the observatory , the results of which he presented to the Royal Society in December 1764.

On February 26, 1765 Maskelyne followed the late Nathaniel Bliss as the fifth "Astronomer Royal" and was entrusted with the creation of the 1763 proposed Nautical Almanac himself . The first, for 1767, was published in 1766, and Maskelyne was to look after another 45 issues. A calculation scheme designed by him for the safe use of the tables sold 10,000 copies immediately and was reprinted twice by 1802. He also successfully recommended that the government declare observations made by the observatory to be public property and publish them annually. From 1776 to 1811, previous observations appeared in four volumes and could henceforth be used worldwide. Thanks to his talent for organization, he managed the work in the observatory (cataloging around 90,000 notes) with a single assistant. He limited himself to the sun , moon , planets and 36 selected fixed stars , which he recorded in a reference catalog until 1790. Practical improvements, such as the determination of meridian passages with an accuracy of tenths of a second, the acquisition of achromatic lens systems, both from 1792 onwards, went back to Maskelyne's instigation. He also found a technical improvement for Hadley's Quadrant , the forerunner of the sextant invented in 1731 , which was later retained.

In 1772 he proposed the Schiehallion experiment to the Royal Society in order to determine the density of the earth through the mass attraction of a mountain acting on two pendulums , and carried out it in 1774 in months of work on the Scottish mountain Schiehallion , which in 1775 gave him the Copley Entered medal . Maskelyne also dealt with geodetic studies, in particular with the measurement of the minute of longitude in Maryland and Pennsylvania , which Charles Mason and Jeremiah Dixon carried out in the years 1766 to 1768, and with debates about the longitudes and latitudes of the observatories in Paris and Greenwich .

Maskelyne's tomb in Purton, Wiltshire

He corrected Tobias Mayer's moon tables based on the results of Manson's survey work and published the final version in 1787. His essay on the equation of time appeared in Daniel Bernoulli's Recueil pour les astronomes (1771). His 1769 transit observations were submitted to the American Philosophical Society , Philadelphia , in 1770 . In 1792 he published Brook Taylor's log tables, and in 1806 Thomas Earnshaw's remarks on the construction of chronometers . The data published because of Maskelyne's insistence were based, for example, on the solar tables by Jean-Baptiste Joseph Delambre and Burg's moon tables from 1806 and a later work by John Herschel . In 1788 Maskelyne was elected to the American Academy of Arts and Sciences , in 1802 he was elected one of eight foreign members of the French Académie des Sciences . Since 1776 he was an honorary member of the Russian Academy of Sciences in St. Petersburg and since 1784 a member of the Royal Society of Edinburgh . The almost indefatigable Maskelyne died at the age of 79 on February 9, 1811 in the observatory.

Maskelyne had married in 1785, had a daughter and was the grandfather of Nevil Story Maskelyne , Professor of Mineralogy at Oxford from 1856 to 1895, and of John Nevil Maskelyne , the most famous English magician of the day. A sister of Nevil Maskelyne married Lord Clive .

The Maskelyne lunar crater is named after him.

Maskelyne and the longitude problem

Today's global use satellite location (eg. As GPS ) proves that navigation since the solution of the length problem today is still based on precise time measurement to the end of the 18th century (today means time measurement by atomic clocks ). Nevil Maskelyne went down in history as one of the members of the longitude commission to which Sir Isaac Newton previously belonged, and which has blocked this knowledge for almost half a century since about 1720: the watchmaker and innovator John Harrison was joined by Nevil Maskelyne and the commission By all means put obstacles in the way, which only decades later through the personal intervention of King George III. could be eliminated.

Maskelyne did not even shy away from preventing test drives with Harrison's already working chronometers and ultimately having all clocks and construction plans confiscated from him in old age and then asking him in a cynical way to have to build more clocks. Until recently, Maskelyne and the Commission relied on the determination of longitude by determining lunar distances. And that, although with z. B. could not be navigated with cloudy skies even then. Maskelyne also changed the interpretation of the longitude commission's tender several times to Harrison's disadvantage, especially after he had become "Royal Astronomer" in 1765. This commission, through the British Parliament, had the task of providing prize money to those who developed methods for precise longitude determination, which were better than 0.5 or 1 degree max. Deviation would be.

The behavior of Nevil Maskelyne and the commission, which was supposed to help solve the problem of longitude measurement, resulted in seafarers and sea travelers being exposed to the often deadly risk of incorrect navigation for more than half a century and the development of modern navigation slowed down delayed half a century.

He seems to have largely evaded the attacks that he was actually exposed to because of his skepticism about Harrison's solution to the length problem. Nevil Maskelyne himself contributed to the fact that Harrison's high technology remained unaffordable for decades through his decades of obstruction because he prevented improved production and thus cost reductions from occurring.

In part, Dava Sobel's book Längengrad (Original: Longitude ) gave him the reputation of the spiteful bad-ass maker .


  • A Proposal for Discovering the Annual Parallax of Sirius , 1760
  • Work on the observations of the passage of Venus, 1761/1769
  • About tides in St Helena, which he had been watching closely for ten months. 1762
  • The British Mariner's Guide . London 1763. This edition contained Maskelyne's proposal to publish tables calculated in advance for one year at a time in order to facilitate position determination at sea, and it was the cornerstone of the Nautical Almanac.
  • About various astronomical observations on St. Helena and Barbados. 1764
  • Nautical Almanac (for 1767) 1766; 45 more vintages.


The largest lunar crater with a diameter of 23 kilometers in Mare Tranquillitatis (2 ° 12 'N 30 ° 06' E) was named after Maskelyne. The same applies to the Maskelyne Passage in Antarctica.


  • Howse, Derek: Nevil Maskelyne. The Seaman's Astronomer. Cambridge 1989.
  • Lane Hall, AW: Nevil Maskelyne. In: Journal of the British Astronomical Association. Vol. 43 (1932), pp. 67-77.

Individual evidence

  1. ^ Fellows Directory. Biographical Index: Former RSE Fellows 1783–2002. (PDF file) Royal Society of Edinburgh, accessed March 20, 2020 .
  2. Macaulay's Critical and Historical Essays. German by J. Moellenhoff. Fourth volume: Lord Clive. Publishing house Philipp Reclam jun. (Universal Library No. 1591), Leipzig (around 1914), 120 pp.