AGUILON, FRANÇOIS d'. - Belgian Jesuit, born in Brussels on 4 January 1567; he entered the novitiate at Tournai in 1586. Ordained priest in 1596, he spent the rest of his life at the college of Antwerp, as professor of theology, vice-rector, and then rector; he died there on 20 May 1617.
He enjoyed a reputation as a distinguished mathematician, especially for his great treatise Opticorum Libri VI (Antwerp 1613, folio, with fine engravings from drawings by Rubens; reprinted at Würzburg in 1685 and at Nuremberg in 1702); the work was intended to comprise three volumes, but remained incomplete. Particularly noteworthy is its study of projections, in the terminology of which he introduced the term stereographic projection. To his efforts is largely due the establishment, at the Society’s college in Antwerp, of a special school of mathematics, inaugurated in 1617 by the eminent geometer Fr. Gregorio di Saint-Vincent, and which achieved a respectable output. D'A. also has his place in the history of art: he drew the plans for the church of the professed house of the Jesuits at Antwerp (now S. Carlo Borromeo), one of the most important monuments of the Baroque in Belgium; but it is difficult to distinguish his contribution from that of the great artist Fr. Pietro Huyssens, who assisted him and continued the construction after the death of his rector.