Science, experimentation and measurement

  • Replica Carolingian astrolabe

    Record number: 9164
    Date: Last quarter of the 10th century
    Geographical specifications: Catalonia
    Dimensions: 17 x 16 x 1 cm
    ​Weight: 600 g

    An astrolabe is a flat representation of the celestial sphere. The engraved lines can be used to establish and predict the progression of the celestial bodies. This one in particular is built according to the Barcelona meridian and is important because of its numbering system, using Latin letters that nonetheless correspond to Arabic numerals.

    It has two sides, one of them set deeper, with two engraved discs known as timpani, on which the different latitudes are marked. Each of them has a stereographic projection at the top of the circles of the celestial sphere: theoretical horizon, visual horizon, meridian, tropics, equator and, on the lower semicircle, the lines for the odd-numbered hours. The spider is superimposed onto the timpani, a kind of engraved chart of the heavens, with a projection of the ecliptic and eighteen stars (ten boreal and eight austral), without any name engraved. One of the timpani bears the names ROME and FRANCE, in capital letters. According to the historian Julio Samsó, these provide fairly clear proof of its provenance, as Ifranja was the name used by the Arabs before the 12th century to refer to the Christian states of the north-east of the Iberian peninsula. The letters are also similar to those used in the late 10th century in Latin manuscripts produced in the region of Catalonia.