Nicole-Reine Étable de la Brière
January 5, 1723
|Died||December 6, 1788 (aged 65)|
|Other names||Hortense Lepaute|
|Known for||Halley's Comet|
|Spouse||Jean-André Lepaute (1749-1788)|
|Notable students||Joseph Lepaute Dagelet|
Nicole-Reine Lepaute (French pronunciation: [nikɔl ʁɛn ləpot]) née Étable de la Brière, also erroneously known as Hortense Lepaute, (5 January 1723 – 6 December 1788) was a French astronomer and human computer. Lepaute along with Alexis Clairaut and Jérôme Lalande calculated the date of the return of Halley's Comet. Her other astronomical feats include calculating the 1764 solar eclipse and producing almanacs from 1759 to 1783. She was also a member of the Scientific Académie de Béziers.
Nicole-Reine Lepaute was born on the 5th of January, 1723 in the Luxembourg Palace in Paris as the daughter of Jean Étable, valet in the service of Louise Élisabeth d'Orléans. Her father had worked for the royal family for a long time, both in the service of the duchess de Berry and her sister Louise. She was the sixth of nine children. As a child she was described as precocious and intelligent, being mostly self-taught. She stayed up all night "devouring" books and read every book in the library, with Jérôme Lalande saying of her that even as a child "she had too much spirit not to be curious".
Early career: mathematics of clockmaking
Her marriage gave her the freedom to exercice her scientific skill. At the same time as she kept the household's accounts, she studied astronomy, mathematics, and "she observed, she calculated, and she described the inventions of her husband".
She met Jérôme Lalande, with whom she would work for thirty years, in 1753 when he was called as a representative of the Académie des Sciences to inspect her husband's work on a pendulum of a new type. The three of them worked together on a book titled Traité d'horlogerie (Treatise of Clockmaking) that was published in 1755 under her husband's name. Although she did not receive authorship, Lalande sang her praises later, saying, "Madame Lepaute computed for this book a table of numbers of oscillations for pendulums of different lengths, or the lengths for each given number of vibrations, from that of 18 lignes, that does 18000 vibrations per hour, up to that of 3000 leagues".
In June 1757, she worked together with Jérôme Lalande and Alexis Clairaut to calculate the date of the next passage of Halley's comet, last seen in 1682. Halley couldn't precisely compute the return date beyond "around the end of the year 1758 or the beginning of the next", due to the gravitational pull of Jupiter and Saturn on the comet, which made for a three-body problem that couldn't be solved back then, for which Clairaut had found a solution recently.
In order to solve it, Clairaut, Lalande and Lepaute divided calculations between them and worked in parallel, with Lepaute and Lalande focusing on the attraction of Jupiter and Saturn, while Clairaut calculated the orbit of the comet itself. The team worked for more than six months straight, barely stopping for food, in order to produce a date before the comet arrived. In November 1758, they gave a two-months window for when the comet would reach its perihelion, between the 15th of March and the 15th of May, centered around the 13th of April 1759. The comet ended up arriving on the 13th of March, 1759.
Although this was a tenfold improvement over Halley's initial 2 years period, there was still an error of a few days, which caused the astronomer Jean d'Alembert to ridicule their work and call it "more laborious than deep".
Lepaute's involvement largely went unrecognised, and, while Lalande acknowledged her work in his Théorie des Comètes (Comet Theory), insisting that they could never have done the calculations without her, Clairault removed mentions of her from the book he published in 1760, Théorie du mouvement des comètes, alledgedly to please another woman.
Later mathematical accomplishments
In 1759, Lalande became the Director of the Connaissance des Temps (Knowledge of the times), an astronomical almanach published by the Académie des Sciences, and he appointed Lepaute as his assistant. She did calculations from the computing plans Lalande prepared until 1774 and made various contributions to the almanac, including calculations on a 1762 comet, as well as a table of parallactic angles.
Afterwards, she worked on Éphémerides, annual guides for astronomers and navigators. She calculated the position of Saturn for each day of the year from 1775 to 1784 for the seventh volume, published in 1774, and she calculated on her own the daily positions of the sun, the moon and the planets for the eighth volume (1785-1792, published 1784).
She also computed in 1762 the exact time of an annular solar eclipse that occurred on the 1st of April, 1764 and published two maps under own name that showed the eclipse's extent: one over Europe, which showed the eclipse's transit in 15-minutes intervals, and one that detailed its successive phases over Paris.
Her work went largely unappreciated and unrewarded despite its importance. While Lalande would eventually become a professor of astronomy and the director of the Paris Observatory, she kept working for him for fifteen years as a human computer. She nonetheless became a member of the distinguished Scientific Academy of Béziers in 1761, for which she calculated the ephemeris of the transit of Venus this year. Lalande always recognised her work, and, after her death, he wrote a brief biography about her contributions to astronomy in his Astronomical Bibliography.
While childless herself, she adopted her husband's nephew, Joseph Lepaute Dagelet in 1768 and trained him in astronomy and advanced mathematics, which Lalande includes in her contributions to astronomy. He travelled south to the Terra Australis in 1773, became a professor of mathematics at Paris' Military School and became inducted in the French Royal Academy of Sciences in 1785. He most likely died in a shipwreck during a scientific expedition led by Jean-François de Lapérouse in 1788.
List of works
- Tables of the length a pendulum must have for a given number of oscillations per hour, in Jean-André Lepaute's Treatise of Clockmaking, Paris, augmented edition of 1767, first edited 1755
- Various contributions to the Connaissance des Temps from 1759 to 1774
- Lost memoirs for the Académie de Béziers from 1761
- Table of parallactic angles for Paris's latitude, La Connaissance des Temps, 1763, p133-144 and Exposition du calcul astronomique, Jérôme Lalande, 1762, Paris
- Ephemerides of Saturn, Ephemerides of celestial movements for the meridian of Paris, volume 7 (1775-1784), 1774
- Ephemerides of the Sun, the moon and the planets, Ephemerides of celestial movements for the meridian of Paris, volume 8 (1785-1792)], 1783
Philibert Commerson attempted to name the Hydrangea flower Lepautia or Peautia after Lepaute. However, the flower's accepted name later became "Hortensia". This led to people believing Lepaute's name was Hortense, but the Larousse remarks that this is erroneous, and that the name probably came from hortus, garden.
- Lynn, W. T. (2 January 1911). "Madame Lepaute". The Observatory. 34: 77–78. Bibcode:1911Obs....34...87L. Retrieved 8 November 2022.
- Bernardi, Gabriella (21 March 2016). The Unforgetten Sisters: Female Astronomers and Scientists before Catherine Herschel. Springer. pp. 121–127. ISBN 9783319261270. Retrieved 12 November 2022.
- De La Lande, Jérôme (1803). Bibliographie astronomique avec l'histoire de l'astronomie depuis 1871 jusqu'à 1802 (in French). Paris: Imprimerie de la République. ISBN 978-2329549170. Archived from the original on 4 May 2010. Retrieved 5 November 2022.
- Connor, Elisabeth (November 1944). "Mme. LePaute, An Eighteenth Century Computer". Astronomical Society of the Pacific Leaflets. 4 (189): 314–321. Bibcode:1944ASPL....4..314C. Retrieved 7 November 2022.
- Grier, David Alan (2005). "The First Anticipated Return: Halley's Comet 1758". When Computers Were Human. Princeton: Princeton University Press. pp. 11–25. ISBN 0-691-09157-9.
- Skinner, David (Spring 2006). "The Age of Female Computers". The New Atlantis (12): 96–103.
- "Madame Lepaute". Saggi di Astronomia Popolare (in French): 118–124. 1912.
- Lalande, de, Jérôme. Éphémérides, volume 7 (1775-84) (in French). p. IV.
- Lalande,de, Jérôme. Éphémérides, volume 8 (1785-92) (in French). p. IV.
- "The fate of La Perouse". Discover Collections. State Library of NSW. Archived from the original on 17 May 2013. Retrieved 7 February 2013.
- "Death certificate". Archives de Paris. 6 December 1788. Retrieved 12 November 2022.
- Boistel, Guy (2004). "Nicole-Reine Lepaute et l'hortensia" (PDF). Cahiers Clairaut (in French) (108).