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Maraldi, Giovanni Domenico (Maraldi II)


(b. Perinldo, Imperia, Italy, 17 April 1709; d. Perinaldo, 14 November 1788)

astronomy, geodesy.

Maraldi I was the son of Francesco Maraldi and Angela Cassini, sister of Cassini I, who had helped found the Paris observatory. After finishing his studies of the classics and of mathematics, he was called to Paris in 1687 by his uncle Cassini I. He soon became his devoted collaborator, and eventually assisted his son, Cassini II, as well. He participated in the observatory’s work for thirty years.

Upon arriving in France, Maraldi I started producing a new catalog of the fixed stars, a project he continued throughout his career. This important work, which he almost succeeded in completing, unfortunately was never published, with the exception of certain stellar positions utilized by Deslisle, Manfredi, and Brouckner. An active participant in the daily observations made at the observatory, Maraldi I left behind several unpublished journals. He published many notes in the annual volumes of the Histoire de l’Académie royale des sciences concerning the planets, their satellites, eclipses and variable stars, as well as some more theoretical memoirs. In one of the latter, “Considérations sur la seconde inégalité du mouvement des satellites de Jupiter et l’hypothése du mouvement successif de la lumiére” (Histoire de l’Académie pour l’année 1707 [Paris, 1708], 25–32), he defended the point of view of Cassini I, opposing the hypothesis of the finite velocity of light, conceived by Ole Römer to account for certain irregularities in the movement of Jupiter’s satellites.

In 1700 and 1701 Maraldi I participated with Cassini II, J. M. de Chazelles and Pierre Couplet in the operations directed by Cassini I to extend the meridian of Paris to France’s southern frontier. He then spent two years in Rome, making various astronomical observations—including one on the zodiacal light—and sharing on the determination and construction of the meridian of the Church of the Carthusians. He returned to paris in 1703 and resumed his observations, interrupting them for several months in 1718, to take part, with Cassini II and G. de La Hire, in the extension as far as Dunkirk of the paris-Amiens meridian measured by Jean Picard in 1670.

Maraldi I’s personal work was overly influenced by the conservative ideas of Cassini I and was only of the second rank. But as a steady and scrupulously careful observer he contributed significantly to the smooth operation of the observatory and to the realization of important programs of astronomical and geodesic research. He was successively student (1694), associate (1699), and pensioner (1702) of the Academy of Sciences of Paris.

In 1726 Maraldi brought his nephew Giovanni Domenico (Maraldi II), the son of his brother Gian Domenico and Angela Francesca Mavena, to Paris. Maraldi II, who had studied in San Remo and Pisa, worked first under Cassini II and then under Cassini de Thury (Cassini III), until 1771, when he returned to Italy. He carried out regular astronomical and meteorological observations until 1787 and published many notes drawn from them in the Histoire de l’Académie. He likewise participated in various geodesic operations directed by Cassini II and Cassini III: the triangulation of the west perpendicular to the meridian of Paris (1733); the partial survey of the Atlantic coast (1735); the verification of the Paris meridian (1739–1740); and also an experiment designed to measure the speed of sound in the air (1738). Lastly, he shared in the fundamental work carried out to establish the map of France. The greater part of Maraldi II’s activity, however, was concerned with positional astronomy. Although he published no books of his own, he edited the Connaissance des temps from 1735 to 1759 and also the posthumous work of his friend Lacaille: Coelum australe stelliferum(Paris, 1763). Among the numerous memoirs which he published, the most important were devoted to the observation and theory of the movements of the satellites of Jupiter, in which he made many improvements. We may note that in 1740 he finally accepted Römer’s theory of a finite value of the speed of light

Named adjoint of the Academy of Sciences in 1731, he was promoted to associate in 1733, to pensioner in 1758, and finally to veteran pensioner in 1772. “An industrious and worthy astronomer” and “an assiduous observer of all the phenomena,” Maraldi II “was not content to calculate them; he sought to make them serve the development of his theories.” This judgment of Delambre, an author who generally had little good to say for the Cassini family and its allies, is sufficient testimony to the quality of his work, especially regarding the improvement of the tables of Jupiter’s satellites.


I. Original Works. The works of the Maraldis were almost all published in Histoire de l’ Acedémie royal des sciences; the list of their works in given in successive vols. of Table générale des matières contenues dans I’ Histoire et dans les Mémoires de l’ Académie royal des sciences, I–IV (1729–1734) for Maraldi I and IV–X (1734–1809) for Maraldi II. The most important of these works are also in Poggendorff, II, cols. 37–38 for Maraldi I and col. 38 for Maraldi II; P. Riccardi, Biblioteca matematica italiana, I (Bologna, 1870; repr. Milan, 1952, cols, 98–102 for Maraldi I, cols. 102–105 for Maraldi II; and J. Houzeau and A. Lancaster, Bibliographie générale de l’ astronomie, 3 vols. (Brussels, 1882–1889; repr. London, 1964), see index.

II. Secondary Literature. For studies dealing with both Maraldis see the following (in chronological order): A. Fabroni, Vitae italorum doctrina excellentium, VIII (Pisa, 1781), 293–320; J. J. Bailly, Histoire de l’ astronomiemoderne, 3 vols. (Paris, 1779–1782), see III index; J. D. Cassini IV, Mémoires pour servir à l’histoire des sciences et à celle de l’Observatoire de Paris (Paris, 1810), 348–357; J. J. Weiss, Biographie universelle, new ed., XXVI (Paris, 1861), 410–411; J. B. Delambre, Histoire de l’astronomie au XVIIIe siècle (Paris, 1827), 239–250; F. Hoefer, ed., Nouvelle biographie générale, XXXIII (Paris, 1860), cols. 348–350; C. Wolf, Histoire de l’Observatoire de Paris… (Paris, 1902), see index; F. Boquet, Histoire de l’astronomie (Paris, 1925), 403–404 and 425–426; and N. Nielsen, Gèomètres français du XVIIIe siècle (Copenhagen-Paris, 1935), 297–300.

On Maraldi I, see B. Fontenelle, “Éloge de Jacques-philippe Maraldi,” in Hisitoire de l’Académie royale des sciences pour l’année 1729 (Paris, 1713), 116–120; and C. G. Jöcher in Allgemeines Gelehrtenlexikon, III (Leipzig, 1751), col. 130.

On Maraldi II see J. D. Cassini IV, “Éloge de J. D. Maraldi,” in Magasin encyclopédique, 1 (1810), 268–282; and J. de Lalande, in Bibliographie astronomique (Paris, 1803), see index.

RenÉ Taton

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