Members of the expedition
In addition to Pierre Louis Moreau de Maupertuis, the expedition consisted of seven full members and seven servants. The academics were all young men. Only Réginald Outhier was over 40 years old.
Pierre Louis Moreau de Maupertuis
Maupertuis, 38, led the northern degree-measuring expedition. Maupertuis’s social talent and ambition were advantageous in the role of fieldwork leader, in which he had no previous experience.
Alexis Claude Clairaut
Clairaut was a young 23-year-old mathematician when the expedition was working in the Torne Valley. His mathematical skills were so phenomenal that he could be called the expedition’s living calculator.
Alexis Claude Clairaut (1713–1765) was nearsighted. However, he was such a skilled mathematician that myopia was a minor problem. Maupertuis was keen to take Clairaut on an expedition.
Clairaut was responsible for the calculations of the expedition.
In 1743 Clairaut published a summary of his theories on the shape of the Earth in his book Théorie de la figure de la Terre.
This theorem of Clairaut’s deals with the relationship between the flattening of the Earth, the gravitational force acting on the Equator and the poles, and the centrifugal force on the Equator. Applying the theorem, Clairaut calculated extreme values for the flattening of the Earth.
Clairaut’s theorem had a major impact on geodesy. Observations related to gravity complemented the astronomical and geodetic observations and calculations.
Clairaut helped mathematician, the Marquise Émilie du Châtelet, translate Isaac Newton’s Principia (Philosophiæ naturalis principia mathematica, 1687) and published it in 1759, ten years after the death of du Châtelet.
Charles Étienne Louis Camus
Camus was a 36-year-old mathematician and mechanic in charge of the expedition’s measuring instruments. He had also talent for medicine, which was needed during the trip.
Charles Étienne Louis Camus (1699–1768) was Maupertuis’s contemporary, aged 36. He was the only one of the expedition who was married at the time.
Camus had already shown mathematical and mechanical talent as a child.
Camus was very familiar with the mechanics of clocks and other instruments. He was responsible for the calibration, maintenance and operation of the expedition’s measuring equipment.
Camus was elected a member of the French Academy of Sciences having successfully participated in a prize competition organized by the Academy on the optimal way to mast a ship.
Camus was the expedition’s doctor and as such he also became known in the Torne Valley.
Camus’s father was a doctor and Camus had learned his skills from him.
After his expedition to the Torne Valley, Camus was appointed professor of mathematics at the Académie d’architecture in Paris. During his career, he also trained military engineers. He was an assistant engineer at the Académie des sciences.
Camus’s best-known work is Cours de mathématiques (1753).
Pierre-Charles Le Monnier
The 21-year-old astronomer was the youngest member of the expedition. He devoted his whole life to astronomical observations.
Pierre-Charles Le Monnier (1715–1799) was the youngest of the academics, aged 21. He had been elected a member of the Academy of Sciences just before the expedition set off.
Le Monnier started making astronomical observations at a young age. He made his career as a Professor of Astronomy at the Collège royal.
The floor of Saint Sulpice, the second largest church in Paris, bears the meridian line defined by Le Monnier in 1743. The bronze line is a part of the sundial, whose Christian purpose was to determine the vernal equinox, which was needed to determine the time of Easter. The sundial was also used for scientific purposes.
Le Monnier’s most important publication was Institutions astronomiques (1746), in which he complemented the Scotsman John Keill’s introductory course to astronomy. Le Monnier focused his career on observing the movements of the moon – something he did for nearly 50 years.
For the last eight years of his life, Le Monnier was paralysed. He died at the age of 84.
Réginald Outhier
The 42-year-old priest was an experienced surveyor and cartographer whose vividly written travel book Journal of a voyage to the North (Journal d’un voyage au Nord) keeps the story of the expedition still alive.
Abbé Réginald Outhier (1694–1774), a priest, was the oldest member of the expedition at the age of 42.
Unlike the rest of the expedition, he had experience in surveying and cartography. Outhier had participated in Jacques Cassini’s surveys between Caen and Saint-Malo in 1733.
Outhier’s role as a member of the expedition was not primarily spiritual. Outhier took part in measurements, drew maps and wrote a journal.
Outhier was ordained a priest in the early 1720s. He probably learned the basics of astronomy from the Jesuit brotherhood. Because of his astronomical merits, he was invited to become a corresponding member of the Académie des sciences.
Outhier was selected to join the expedition by the minister of the marine, Count de Maurepas.
Outhier’s Journal d’un voyage au Nord was published seven years after the expedition in 1744.
The Finnish historian of science Osmo Pekonen has written a doctoral thesis in French about Outhier, La Rencontre des religions autour du voyage de l’abbé Réginald Outhier en Suede en 1736–1737.
In honour of Outhier, who had fell into oblivion, and due to the impact of Pekonen’s dissertation at the University of Lapland, a monument was erected in his home village of La Marre in the Jura Mountains of France.
Anders Celsius
Under the influence of a 35-year-old Swedish Professor of Astronomy, the expedition headed to the Torne Valley. Celsius later developed the Celsius centigrade-scale for the thermometer.
The role of Anders Celsius (1701–1744) in the French expedition ending up in the Torne Valley was decisive. 35-year-old Celsius was on his grand tour visiting European observatories when he met Maupertuis in Paris.
Celsius had been the Professor of Astronomy at the University of Uppsala in Sweden since 1730. The level of mathematics and astronomy in Sweden was modest, so it was necessary to seek knowledge elsewhere.
Anders Celsius was born in Uppsala to a family of scientists from Hälsingland. Both of his grandfathers were professors: on his father's side, Magnus Celsius (1621–1679) was a mathematician, and his maternal grandfather Anders Spole (1630–1699) specialised in astronomy. Anders' father Nils Celsius (1658–1724) was also a Professor of Astronomy.
Anders Celsius was also very talented in mathematics from an early age.
When Celsius continued his study trip from Paris to England, he was given the task of procuring astronomical instruments from London for the expedition.
In addition to assisting the expedition with equipment, Celsius requested and received approval from the Swedish Crown for the expedition.
Celsius originally proposed that the measurements be made on islands in the bottom of the Bay of Bothnia. Once the expedition reached the islands, it turned out that the islands were too low to get a proper line of sight between them.
As a reward for his work for the French Académie royale des sciences, King Louis XV of France granted Celsius a pension of one thousand livres.
Celsius was the Professor of Astronomy at the University of Uppsala from 1730–1744. His research focused mainly on meteorology, aurora borealis and Earth's magnetism.
Participating in the expedition made Celsius famous and facilitated fundraising for the construction of a modern observatory. Celsius founded the first "Celsius Observatory" in Uppsala in 1741.
Celsius' name has gone down in history as a unit of the temperature scale, the degree Celsius. Celsius also made observations on temperature on the expedition's journey to the Torne Valley.
The centigrade scale was presented to the Swedish Academy of Sciences for the first time in 1742. According to the scale, the freezing point of water was 100 degrees Celsius, while water boiled at zero degrees Celsius.
Later, the scale was reversed. These so-called new degrees were initially called Celsius Novum.
Celsius died of tuberculosis in 1744 at the age of 42.
Antoine-Étienne d’Herbelot
The 25-year-old artist recorded images of plants, animals and habitats on the way and took full part in the measurements.
Sommeraux
Sommereux was the secretary and treasurer of the expedition. No biographical information is known about him. Outhier often mentions Sommereux in his journal, but he doesn't say much about him in particular.
During the winter, when the French stayed in Tornio for a long time, Sommereux and Maupertuis stayed with the mayor Pipping's brother.
Servants
Maupertuis and Outhier did not make many entries in their texts about the members of the expedition.
Outhier mentions that a total of five servants from France went with the expedition. One of them had lived in Stockholm and spoke Swedish, which was useful for the travellers.
In Stockholm, the number of servants increased by two. One of the servants of the French ambassador de Casteja joined the team, and Maupertuis hired another Swedish and French-speaking servant.
Outhier mentions only one servant by name, Pedre. Pedre was credited with extinguishing a forest fire in Iso-Horila (Horilankero).
Sources:
Clairaut: http://www.clairaut.com/n18avril1736po3pf.html
Outhier, Réginald. Matka Pohjan perille. Maupertuis Foundation and Väyläkirjat, 2011 (orig. 1744).
Pekonen, Osmo. La rencontre des religions autour du voyage de l’abbé Réginald Outhier en Suède en 1736–1737. Lapin yliopistokustannus, Rovaniemi, 2010.
Pekonen, Osmo. “Johdanto: Maan muotoa mittaamassa”. Maan muoto ynnä muita kirjoituksia Lapista. Ed. Osmo Pekonen. Väyläkirjat, 2019.
Pekonen, Osmo. “Esseitä. Viisi akateemikko Lapissa”. Maan muoto ynnä muita kirjoituksia Lapista. Ed. Osmo Pekonen. Väyläkirjat, 2019.
Terrall, Mary. Maupertuis. Maapallon muodon mittaaja. Trans. Osmo Pekonen. Väyläkirjat, Tornio, 2015 (orig. 2002).
Tobé, Erik. Anders Celsius och den franska gradmätningen i Tornedalen 1736–1737. Acta Universitatis Upsaliensis, 2003.
Tobé, Erik. Fransysk visit i Tornedalen 1736–1737. Om en gradmätningsexpedition och dess nyckelpersoner. Tornedalica, Luleå, 1986.
Wikipedia: https://fi.wikipedia.org/wiki/Saint-Sulpicen_kirkko
Wikipedia: https://en.wikipedia.org/wiki/Francesco_Algarotti