Euclid in tiles: the mathematical azulejos of the Jesuit college in Coimbra

Abstract

The mathematical glazed tiles (azulejos) of the Jesuit college in the city of Coimbra, in Portugal, are remarkable and unique artifacts. They seem to be the only known example of glazed tiles for classroom use displaying geometrical diagrams of true mathematical (Euclidian) demonstrations. Scientific motifs as decorative elements in buildings were widely used in Europe and, in particular, in spaces built by the Society of Jesus.1 Panels of azulejos using ornamental mathematical motifs are well known in Portugal and elsewhere. But the mathematical azulejos of Coimbra are unique in that they are genuine didactical aids to the teaching of mathematics and not merely decorative artifacts. Azulejos (painted, glazed, ceramic tiles) are an ancient technique of decorative surface cover used in architecture and other forms of artistic expression. The technique has been known since Antiquity and some remarkable Babylonian examples are still extant. Azulejos were widely used in the Muslim world and introduced into Portugal around the fifteenth century. Since then they became a very popular decorative element in Portuguese architecture and are widely employed even today.2 Besides their