page_title: Astrarium of Giovanni Dondi dell'Orologio
section_title: The Tractatus astrarii
hierarchical_section_title: Astrarium of Giovanni Dondi dell'Orologio / The Tractatus astrarii
caption_attribution_description: English: Giovanni Dondi dell'Orologio (1330–1388), Tractatus astrarii (manuscript describing the construction of his Astrarium), page showing the dial of Venus; Padova, Biblioteca Capitolare, Ms. D.39: 12v
context_page_description: The Astrarium of Giovanni Dondi dell'Orologio was a complex astronomical clock built between 1348 and 1364 in Padova, Italy, by the doctor and clock-maker Giovanni Dondi dell'Orologio. The Astrarium had seven faces and 107 moving parts; it showed the positions of the sun, the moon and the five planets then known, as well as religious feast days. It was one of the first mechanical clocks to be built in Europe.
context_section_description: Dondi documented the Astrarium in detail in the Tractatus astrarii, which is the earliest complete surviving description of its kind; the St Albans abbey clock designed by Richard of Wallingford predates it, but survives only as fragments (reconstructed by John North). In the introduction, Dondi writes that his machine was built in accordance with the 13th-century Theorica planetarum of Campano di Novara, and to demonstrate the validity of the descriptions of the motion of heavenly bodies of Aristotle and Avicenna. The Tractatus survives in twelve manuscript sources. The autograph in the Biblioteca Capitolare of Padova (MS. D39) and a copy of it, also in Padova, are certainly the work of Dondi. The other sources are rewritten versions of the autograph, to which Dondi's contribution is as yet unclear. The autograph manuscript was published in 1987 in a critical edition with colour facsimile and French translation by Poulle as the first volume of the Opera omnia of Jacopo and Giovanni Dondi.
caption: Page from the Tractatus astrarii showing the dial of Venus; Padova, Biblioteca Capitolare, Ms. D.39: 12v
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