Dondi, Giovanni

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Dondi, Giovanni

(b. Chioggia, Italy, 1318; d. Milan, Italy, 22 June 1389)

horology, astronomy, medicine.

Dondi was the son of Jacopo (Giacomo) de’Dondi dall’Orologio, municipal physician at Chioggia; his work parallels closely that of his father, with whom he has often been confused. When the family moved to Padua in 1349, Giovanni Dondi became physician to Emperor Charles IV. In 1350 or 1352 he was appointed professor of astronomy at the University of Padua and later was a member of each of the four faculties of medicine, astrology, philosophy, and logic. He lectured on medicine at Florence around 1367–1370. He was ambassador to Venice in 1371; the following year he was a member of a committee of five citizens appointed to establish boundaries between Carrara and the Venetian Republic. Later he was befriended by Gian Galeazzo Visconti of Pavia and from 1379 to 1388 was connected with the University of Pavia; in 1382 he was living in the Visconti palace.

Dondi wrote, probably before 1371, a brief treatise, De modo vivendi tempore pestilentiali, mostly concerning diet during times of plague. After 1372 he followed his father’s interest in balneology with a treatise describing the hot springs near Padua and methods of salt extraction, De fontibus calidus agri Patavini consideratio ad magistrum Vicentium. He also wrote Quaestiones aliquae in physica et medica. A friend of Petrarch and Cola di Rienzo, Dondi shared their interest in the ruins and inscriptions of ancient Rome.

Dondi’s father, Jacopo, had designed a clock (hence the “dall’Orologio” added to the family name) which was installed in 1344 in the Torre dei Signori of the Palazzo del Capitanio at Padua. Giovanni Dondi’s fame rests on an elaborate astronomical clock which he designed and spent sixteen years constructing, completing it in 1364. Petrarch, praising Dondi’s astronomical attainments in his will, referred to this “planetarium,” and there are early descriptions of it by Dondi’s friends Phillippe de Mézières (in his Songe du vieil pèlerin, written between 1383 and 1388) and Giovanni Manzini, podestà of Pisa (letter to Dondi 11 July 1388). Dondi himself wrote a detailed description of his planetary clock, a treatise known as the Tractatus astrarii or Tractatus planetarii, copiously illustrated with diagrams of the dials, wheels, and other components. In this treatise, Dondi says, “I derived the first notion of this project and invention from the subtle and ingenious idea propounded by Campanus [of Novara] in his construction of equatoria, which he taught in his Theorica planetarum”; the astrarium is one of the earliest geared equatoria, driven by clockwork. A heptagonal frame bears dials for the sun, moon, Mercury, Venus, Mars, Jupiter, and Saturn; below, there are dials or displays showing the twenty-four hours, the times of sunrise and sunset, fixed feasts, movable feasts, and the nodes of the moon’s orbit. The astrarium was acquired by Gian Galeazzo Visconti and installed in 1381 in the ducal library in the Castello Visconteo in Pavia. Regiomontanus, who saw the astrarium in 1463 and mentioned it in his introductory lecture on the mathematical sciences at the University of Pavia, said in 1474 that he had such a mechanism under construction in his workshop at Nuremberg. The existence of the astrarium is last recorded when it was offered in 1529 or 1530 to that lover of clocks, Emperor Charles V; it was then so dilapidated that Gianello Torriano (later the emperor’s clockmaker) considered it beyond repair and undertook to make a similar device. Two modern replicas of the astrarium have been completed; that now in the Museum of History and Technology, Washington, D.C., is 4′4″ in overall height, 1′6″ in maximum diameter, and contains 297 parts, of which 107 are wheels and pinions.

Dondi’s treatise is of great importance in the history of medieval horology and technology; the only known earlier detailed description of any sort of clock is that by Richard of Wallingford of his astronomical clock installed in St. Albans Abbey (about 1330). Both treatises, written within a century of the invention of the mechanical clock escapement, demonstrate the rapid development of clockwork and the constant concern to mechanize astronomical demonstrational instruments that is so evident in the long tradition of European public astronomical clocks.


I. Original Works. Dondi’s works include De modo vivendi tempore pestilentiali, Karl Sudhoff ed., in Archiv für Geschichte der Medizin, 5 (1911), 351–354; and De fontibus calidus agri Patavini consideratio ad magistrum Vicentium, printed in De Balneis (Venice, 1553), with Jacopo de’Dondi’s brief treatise on the extraction of salt from the hot springs near Padua. Eleven manuscripts have survived of the treatise on the astrarium; these are Padua, Bibl. Capitolare Vescovile, D. 39; Venice, Bibl. Naz. Marciana, 85. Cl. Lat. VIII. 17; Milan, Bibl. Ambrosiana, C. 221 inf. and C. 139 inf.; Padua, Bibl. Civica, CM 631; Oxford, Bodleian, Laud Misc. 620; London, Wellcome Historical Medical Library, 248; Cracow, Bibl. Universytetu Jagiellońskiego, 577 and 589; Eton College, 172. Bi a. 1; Salamanca, Universidad, 2621, item 12, 25r-72v (? fragments). A twelfth MS, Turin, Bibl. Naz. XLV, was destroyed by fire in 1904. The MS Padua, Bibl. Capitolare Vescovile, D. 39, has been reproduced in facsimile with transcription and commentary in Dondi’s Tractatus Astrarii, trans., with introduction and glossary, by Antonio Barzon, Enrico Morpurgo, Armando Petrucci, and Giuseppe Francescato (Vatican City, 1960). Illustrations reproduced from other manuscripts, especially Bodleian, Laud Misc. 620, may be found in works cited below.

II. Secondary Literature. On Jacopo and Giovanni de’Dondi and their works, see George Sarton, Introduction to the History of Science, III (Baltimore, 1948), 1669–1671, 1672–1677; Lynn Thorndike, A History of Magic and Experimental Science, III (New York, 1934), 386–397; and Giovanni Dondi dall’Orologio, medico, scienziato e letterato (Padua, 1969). Silvio A. Bedini and Francis Maddison discuss the history of the astrarium and its antecedents, list the MSS, and give a full bibliography in “Mechanical Universe. The Astrarium of Giovanni de’Dondi,” in Transactions of the American Philosophical Society, n.s. 56 , pt. 5 (1966). Also see G. H. Baillie, “Giovanni de’Dondi and his Planetarium Clock in 1364,” in Horological Journal (April-May 1934); H. Alan Lloyd, “Giovanni de’Dondi’s Horological Masterpiece 1364,” in La Suisse horlogère, international ed., no. 2 (July 1955), 49–71; and H. A. Lloyd, Some Outstanding Clocks Over Seven Hundred Years, 1250–1950 (London, 1958), pp. 9–24, which describe the construction and appearance of the astrarium.

Francis Maddison