Monsieur Joseph Jérôme Lefrançois de Lalande et Les Dames

The cliché concept of a Frenchman is of the prime example of a chauvinist and the eighteenth century is not renowned as a period of equality for women, so it might come as somewhat of a surprise that an eighteenth century Frenchman very much championed the positive role of women in astronomy; that man was Joseph Jérôme Lefrançois de Lalande (1732–1807).


Jérôme Lalande after Joseph Ducreux Source: Wikimedia Commons

Jérôme Lalande illustrates rather well something that is fundamentally wrong with the way that much history of science is conceived and presented. I have a moderately large collection of general reference works on the history of science and the history of astronomy, encyclopaedia, dictionaries, and lexica. In this works Jérôme Lalande almost never appears and if at all usually just as a minor footnote to somebody or something else. However, although he never made a major astronomical discovery, and thus his absence from the reference works, he was in the second half of the eighteenth century a leading figure in the astronomical community, not just in France but throughout the whole of Europe, as a organiser, coordinator, communicator, educator and populariser, all activities very necessary to the evolution of any scientific discipline.

He was born 11 July 1832 in Bourge-en-Bresse and was educated at a Jesuit academy. He went to Paris to study law but having got to know Joseph-Nicolas Delisle (1644­–1720) he became an ardent astronomer and a pupil of both Delisle and Charles Le Monnier (1715–1799).


Joseph Nicolas Delisle by Konrad Westermayr Source: Wikipedia Commons

Despite this passion, he completed his law degree and was about to return to Bourge-en-Bresse to become a lawyer when Lemonnier sent him to Berlin to measure lunar parallax together with Nicolas-Louis de Lacaille (1732–1762) in South Africa. The success of this operation led to his election to the Academy of Berlin, as well as the French Academy of Science. He now devoted his life to astronomy. Over the years he was successively elected to the Royal Swedish Academy of Science and The American Academy of Arts and Sciences. In 1762 he was appointed Delisle’s successor as professor of astronomy at the Collège de France. Amongst his most famous students were Jean-Baptiste Joseph Delambre (1749–1822), Giuseppe Piazzi (1746–1826), Pierre Méchain (1744–1804) and his nephew Michel Lefrançois de Lalande (1766–1839). In 1773 he edited more that 250 articles on astronomy for the supplement to Diderot’s and d’Alembert’s legendary encyclopaedia. From 1760 to 1776 he was editor of the Connaissance des tempsthe official French astronomical year book. From 1795 he also became the director of the Paris observatory in which role he issued a star catalogue of 30,000 stars later expanded to 41,000. As an astronomer his principle activity of the years consisted of carrying out the mathematical calculation of orbits, the paths of comets, solar eclipses and the astronomical unit based on the observations of the Transit of Venus in 1761 and 69, as well as the orbit of Venus.  It was here that the lady astronomers entered his life and his work.

As a young man he assisted Alexis-Claude Clairaut in the recalculation of the orbit of Comet Halley. Lalande was ably assisted in this tedious but complex mathematical work by Nicole-Reine Lepaute (1723–1788). In his publication Clairaut did not acknowledge Lepaute’s contribution, which angered Lalande, who honoured her work so:

We calculated from morning to night for six months…Mme. Lépaute’s help was such that I would not have been able to tackle the enormous task without her.


Taken from Winterburn The Quite Revolution of Caroline Herschel see footnote 1

Nicole-Reine Étable de la Briere was born 5 January 1723 in Paris began to take an interest in mathematics and astronomy in around the time she married her husband Jean-André Lepaute the royal clock maker. Together with her husband she designed and constructed an astronomical clock, which was presented to the French Academy of Science in 1753. She, her husband and Lalande worked on a book entitled Traite d’horologerie(Treatise on Clockmaking) that was published under her husbands name in 1755. Although she was not mentioned as author Lalande honoured her contribution as follows:

“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.”

Following her work with Lalande on Comet Halley, she again collaborated with him on the ephemeris for the 1761 Transit of Venus.  She also collaborated with Lalande for fifteen years on the calculations for the Connaissance des temps. In 1762 she calculated the exact time for a solar eclipse that occurred on 1 April 1764. She also wrote an article on the eclipse with an eclipse map. She produced star catalogues and calculated an ephemeris of the sun, moon and the planets from 1774 to 1784. Although childless she adopted and trained he husband nephew, Joseph Lepaute Dagelet (175116788) in astronomy and mathematics. He went on to become professor of mathematics at the French Military School and later deputy astronomer at the French Academy of Science, where he had a distinguished career. A comet and a crater on the moon are named in her honour.

Lalande’s second lady ‘computer’ (the term used for the people, usually women, employed to do the often complex but tedious and repetitious astronomical calculations was Elisabeth Louise Félicité du Pierry, née Pourra de la Madeleine, who was born 1746 but who’s date of death is unknown/disputed, possibly 1807. She met Lalande in 1779 and began to study astronomy under him after the death of her husband. Her main work was on eclipses of the sun and moon based on historical data that she collected. Lalande based his own lunar orbit work on her research. She is said to have been the first woman to have offered lecture courses at a French university when she lectured at the Sorbonne on astronomy for women­–Cours d´astronomie ouvert pour les dames et mis à leur portée. Lalande dedicated his book, Astronomie des Dames(of which more later) to her stating: “She represents a model for all women through her high intellectual qualities.” She later dropped out of astronomy and took up chemistry instead.

Lalande’s third lady computer was his own illegitimate daughter Marie-Jeanne-Amélie Harley (1768–1832), who married his nephew Michel Lefrançois de Lalande. The young couple studied astronomy together under Lalande and were his assistants at the Paris Observatory helping to calculate and complete the star catalogues. Marie-Jeanne-Amélie work very closely with her father contributing to many of his publications. Gauss is reputed to have said that he knew only one French women working in science, Madame Lefrançois de Lalande. She had two children, a daughter named Caroline after Caroline Herschel and a son named Isaac after Newton. The De Lalande crater on the moon is named after her.

In the naming of his grand daughter we get a strong clue that Lalande’s respect for female astronomers was not restricted to his own assistants and family. In fact Lalande was one of the strongest male supporters of Caroline Herschel, who he respected immensely, which is reflected by her writing directly to him rather than communicating through her brother William, although William was a close colleague and friend of Lalande’s.


Caroline Herschel Source: Wikimedia Commons

Without a doubt Lalande’s greatest contribution to the support of women in astronomy was his Astronomie des Dames published in 1785 with two further updated and expanded editions in 1795 and 1806,which explains various aspects of astronomy for the female reader and praises the work of famous female astronomers beginning with Hypatia, including his own co-workers and going up to Caroline Herschel, who was added in the second edition. Lalande was a renowned and successful author of popular books on astronomy so his decision to write about female astronomers in a laudatory manner had quite a lot of impact. The second editions from 1795 covers the following women:

Hypatia (the ancient Greek philosopher)

Maria Cunitz

Maria-Claire Eimart Muller

Jeanne Dumée

Hevelius’s wife (this is how he describes her, not by name but by association)

Manfredi’s sisters (as above)

Kirch’s thre sisters and his wife, née Winkelmann

La Marquise de Châtelet

Madame Lapute

Mrs Edwards (from the Nautical Almanacin England)

Madam du Piery

His niece Lefrançois de Lalande

Miss Caroline Herschel[1]

 (you can read about Maria Cunitz, Maria Kirch née Winkelmann, Elisabeth Koopman Hevelius and Maria Clara Eimart here)

As Emily Winterburn explains (see footnote 1) Lalande’s book follows in a tradition of popular science books written specifically for ladies. This starts with Bernard Le Bovier de Fontenelle’s Entretiens sur la pluralité des mondes(Conversations on the Plurality of Worlds) (1686) and includes John Harris’ Astronomical Dialogues Between a Gentleman and a Lady(1719), Benjamin Martin’s Gentlemen and Ladies Philosophy(1759) and Francesco Algarotti’s Il newtonianismo per le dame(1737) (Sir Isaac Newton’s Philosophy Explained for the use of Ladies, in six dialogues on Light and Colour(1739)). Lalande acknowledges Fontenelle’s influence on his own work.

Although with Lalande we still have a man employing women in a subservient position and then writing about them rather than women working for and writing about themselves, we have in the way that he supported, acknowledged and praised women in his work a major advance on nearly everything that had gone before.







[1]This list is taken from Emily Winterburn’s excellent The Quite Revolution of Caroline Herschel:The Lost Heroine of Astronomy, The History Press, Stroud, 2017 pp. 221-222, which I reviewed here. Winterburn’s book together with a tweet from RAS Women in STEM @RAS_Women about Marie-Jeanne-AmélieLefrançois de Lalande inspired this blog post.


1 Comment

Filed under History of Astronomy, Ladies of Science

One response to “Monsieur Joseph Jérôme Lefrançois de Lalande et Les Dames

  1. donnamariadigiuseppe

    Thank you for examining these women forgotten by history.

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