Epistolarum astronomicarum libriDuncan Liddel visited Tycho Brahe at his observatory on the island of Hven in Denmark in 1587 and again in 1588 having first met the famous astronomer at Rostock. Brahe printed and published a number of works at the printing press he established at Uraniborg, on paper made at the observatory’s own paper mill.

Tycho Brahe seems to have only given his privately printed books to acquaintances and this volume contains his and De mundi aetherei recentioribus phaenomenis. Liddel made only some minor annotations in this volume, one being the latitude of the island of Hven on the title page.

It was through Tycho Brahe that Liddel was able to make a copy of the Commentariolus and the two men seem to have had an amicable relationship until Tycho Brahe accused Liddel of plagiarism. Brahe had formulated his own system of planetary motion, whereby the sun and moon orbited the earth with the other planets orbiting the sun. Brahe reacted angrily when some other astronomers claimed versions of the theory as their own. Liddel did, famously, teach all three theories of cosmic motion: Ptolemaic, Copernican and Tychonian and had, with Brahe’s knowledge, made several mathematical corrections and additions to Brahe’s geoheliocentric theory. Tycho, however, suspected that Liddel was teaching his theory without properly crediting him for it and this led to the accusation of plagiarism. Although Liddel wrote to Brahe to confirm that he had always credited Brahe in his teachings, Brahe never accepted Liddel’s claims.