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 woodcut figures that draw closely on those from the 1488 edition, also printed in Venice by Joannes Lucilius Santritter and Hieronymus de Sanctis. These illustrations accompany a section of chapter one of Sacrobosco's text which discusses the sphericity of the heavens and the Earth. The first two illustrations argue 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 argues that the sea is spherical.</p>