Dondi, Giovanni

SUBJECT AREA: Horology

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b. 1318 Chioggia, Italy

d. 22 June 1389 Milan, Italy

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Italian physician and astronomer who produced an elaborate astronomical clock.

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Giovanni was the son of Jacopo de'Dondi dall'-Orologio, a physician who designed a public clock that was installed in Padua in 1344. The careers of both father and son followed similar paths, for Giovanni became Physician to Emperor Charles IV and designed a complicated astronomical clock (astrarium) for which he became famous. Around 1350 he was appointed Professor of Astronomy at the University of Padua. Dondi completed his astrarium in 1381, having worked on it for sixteen years. Unlike the clock of Richard of Wallingford, it used the common form of verge escapement and had no facility for sounding the hours on a bell. It did, however, indicate time on a 24- hour dial and had calendars for both the fixed and movable feasts of the Church. Its principal function was to show the motions of the planets on the Ptolemaic theory, i.e. the Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn. Like the Wallingford clock, it also indicated the position of the nodes, or points where the orbits of the Sun and Moon intersected, so that eclipses could be predicted. The astrarium was acquired by the Duke of Milan and its history can be traced to c.1530, when it was in disrepair. It is now known only from copies of Dondi's manuscript "Tractus astarii". Several modern reconstructions have been made based upon the details in the various manuscripts.

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Bibliography

1987, Astrarium Johannis de Dondis; fac-simile du manuscript de Padoue et traduction française par Emmanuel Poulle, Padua/Paris. For an English translation of Astrarium, see G.H. Baillie, H.A.Lloyd and F.A.B.Ward, 1974, The Planetarium of Giovanni de Dondi, London; however, this translation is less satisfactory as it is a composite of two manuscripts, with illustrations from a third.

Further Reading

S.Bedini and F.Maddison, 1966, "Mechanical universe. The astrarium of Giovanni de"Dondi' Transactions of the American Philosophical Society 56:1–69 (for the history of the clock).

H.A.Lloyd, 1958, Some Outstanding Clocks Over 700 Years, 1250–1950, London, pp. 9–24 (for its construction).

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