Astronomical Images : Sphericity of the Earth and sea

Johannes Sacrobosco

Astronomical Images

<p style='text-align: justify;'>Very little is known about Johannes Sacrobosco except that he was probably British, taught astronomy at Paris University, and died there in the second quarter of the thirteenth century. <i>Sphaera mundi</i>, his major work, was an extraordinarily popular astronomical textbook for several generations. Manuscripts of it circulated through all the main European centres of learning. It was first published in 1472 in Ferrara, and went through dozens of editions up to the mid-seventeenth century. This edition of Sacrobosco's <i>Sphaera mundi</i> was printed with Georg Peuerbach's <i>Theoricae novae planetarum</i> and Johannes Regiomontanus's <i>Disputationes contra Cremonensia deliramenta.</i> It is illustrated throughout with woodcuts, some of which were coloured. These illustrations accompany a section of chapter one of Sacrobosco's text that discusses the sphericity of the heavens and the Earth. The first two illustrations demonstrate that the Earth is round on the basis of 1) the hour of lunar eclipses and 2) polar altitude (demonstrated by travellers walking northward and southward). The third illustration shows that the sea is spherical.</p>