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The Celestial Planisphere in the Tiles of Coimbra

Four tiles, now belonging to the Machado de Castro National Museum collection, were part of a disappeared celestial planisphere, displaying the northern and southern hemispheres.

In the last decade of the 17th century, the Jesuits’ effort to expand the courses offered at the universities of Coimbra and Évora contributed to the inclusion of mathematical sciences in the complex decorative programs of the schools of these cities.

Everything indicates that the tiles were part of the massive renovation undertaken during the rectorate of Nuno da Silva Teles, when the sculptor Claude Laprade made the doorways of the Aulas dos Gerais and the sculptures with allegorical representations of the faculties between the years 1700 and 1702.

In addition to the well-known tiles with the illustration of Euclid’s theorems, four others, now belonging to the Machado de Castro National Museum collection, were part of a celestial planisphere, displaying the northern and southern hemispheres.

As proposed by Francisco Gil’s study, we can reconstitute the set if we superimpose the tiles on the constellations charts created by Johannes Hevelius (1611-1687), a Polish astronomer whose work achieved great recognition in the second half of the 17th century.

Johannes Hevelius, Prodromus Astronomia, volume III: Firmamentum Sobiescianum, sive Uranographia, plate 56: Southern hemisphere (upside down), 1690. Carol la Haye after Andreas Stech.
Johannes Hevelius, Prodromus Astronomia, volume III: Firmamentum Sobiescianum, sive Uranographia, plate 56: Southern hemisphere (upside down), 1690. Carol la Haye after Andreas Stech. Machado de Castro National Museum tiles collection.

With a didactic sense and an eclectic approach characteristic of Jesuit thinkers, various schemes of the universe were added to the celestial charts on the tile panels.

In the remaining tiles, we can identify the Ptolemaic system and that of Copernicus, with the stars arranged in the last sky, right after that of Saturn, exactly as exposed in the work of Athanasius Kircher, the most outstanding Jesuit philosopher of the time. It is likely that, in the lower part of the northern hemisphere, there was still a representation of the two models associated with the ideas of the astronomer Tycho Brahe.

Johannes Hevelius, Prodromus Astronomia, volume III: Firmamentum Sobiescianum, sive Uranographia, plate 55: Northern hemisphere, 1690. Carol la Haye after Andreas Stech. Machado de Castro National Museum tiles collection.
Johannes Hevelius, Prodromus Astronomia, volume III: Firmamentum Sobiescianum, sive Uranographia, plate 55: Northern hemisphere, 1690. Carol la Haye after Andreas Stech. Machado de Castro National Museum tiles collection.

As a last curiosity, one of the tiles identifies the comet C/1652 Y1, first sighted in Brazil in 1652, which was used in a comparative study on the tails of these celestial bodies in the treatise of astronomer Johannes Hevelius.

Although probably it was not used as a didactic instrument in classes, it is undeniable that the planisphere constitutes an affirmation of mathematics as an erudite language and that these ideas accompany the evolution of astronomical knowledge of the time, as taught by the Jesuits.

ESSENTIAL BIBLIOGRAPHY

DUARTE, António Leal; SIMÕES, Carlota & GIL, Francisco. Azulejos que testemunham o ensino das ciências nos colégios jesuítas em Coimbra. https://doi.org/10.14195/978-989-26-1871-5_7

KIRCHER, Athanasius. Iesu Itinerarium exstaticum: quo mundi opificium. Roma: Vitalis Mascardi, 1656.

MANGUCCI, António Celso. História da azulejaria portuguesa, iconografia e retórica. Tese de doutoramento, Universidade de Évora, 2020. http://hdl.handle.net/10174/28727

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