Buot, Jacques

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Buot, Jacques

(d. ca. 1675)

astronomy, physics, geometry.

Buot was a member of the Académie des Sciences of Paris from the time it was founded in 1666; as such he received an annual stipend of 1,200 livers.

Buot probably was present on 16 July 1667 when Huygens observed the exact hour at which the diameter of the ring of Saturn seemed to be parallel to the horizon. From this observation, Huygens calculated the inclination of the ring to the equator as 8°58’ and to the ecliptic as 31°22’; Buot found a value of 31°38’35” for the latter. (As early as 1659, in his Systema Saturnium, Huygens had attempted to determine these values as precisely as possible.) On 15 August 1667 Huygens, Jean Picard, Jean Richer, and Buot repeated the experiment and obtained values of 9°32′50″ and 32°0′.

Buot made a further contribution to astronomy by inventing the équere azimutale, an instrument for finding the intersection of the meridian with a horizontal plane. He was also active as a physicist, once again drawing upon Huygens’ work. In 1667 Huygens and members of the Accademia del Cimento in Florence had made experiments to determine the forces that cause water to expand on congelation. In 1670 Buot repeated these experiments for water and oils and observe that the congealing of water differs from that of oils. In 1669 Buot joined Huygens and others in the discussions on the causes of gravitation that were held by the Academy; in his mémorie of 21 August 1669, he showed himself opposed to the action-at-a-distance theory.

Condorcet wrote that Buot died in 1675. A letter from Olaus Römer to Huygens, dated 30 December 1677, states, however, Dominus Buot post aliquot mensium morbum fato appropinquare creditur—“After an illness of some months Mr. Buot seems to feel that his end is drawing near.” The Comptes des bâtiments gives the date of his last stipend as 10 June 1676.


I. Original Works. Buot’s writings include Usage de la rouë de proportion, avec un traite d’arithmétique (Paris, 1647); and “Équerre azimutale,” in Gallon, ed., Machines et inventions approvées par l’Académie royale des sciences depuis 1666 jusqu’en 1701, I (Paris, 1735), 67–70.

II. Secondary Literature. Works dealing with Buot are Condorcet, Éloges des Académiens de l’Académie royale des sciences, morts depuis jusqu’en 1666 (Paris, 1773), p. 157; J. Guiffrey, Comptes des bâtiments du roi, sous le règne de Louis XIV, I (Paris, 1881), 163, 227, 299, 378, 449, 565, 650, 782, 856; Panckoucke, ed., Histoire de l’Académie royale des sciences 1666 à 1698, I (Paris, 1777), 121; and Oeuvres complètes de Christiaan Huygens, VI (The Hague, 1895), 58–66, 139–142, 143–147; VIII (The Hague, 1899), 54; XV (The Hague, 1925), 43, 93, 94, 478; XIX (The Hague, 1937), 182, 183, 344, 630; E. Maindron, L’Académie des sciences (Paris, 1888), p. 98; and D. Shapeley, “Pre-Huygenian Observations of Saturn’s Rings,” in Isis, 40 (1949), 12–17.

H. L. L. Busard