Tycho Brahe’s Quadrans Muralis – A detailed review

Abstract

Tycho Brahe’s Quadrans Muralis – the mural quadrant – is without doubt his most famous astronomical instrument, not least due to the illustration of the quadrant as it appears in the Astronomiæ Instauratæ Mechanica, Tycho’s description of his astronomical instruments. This quadrant was permanently installed on the western wall of the south-western room in Tycho’s castle Uraniborg on the island of Hven. Apart from Tycho’s own description in Mechanica, the Quadrans Muralis has hitherto not been subjected to a detailed evaluation of all important aspects of the instrument. In this report, properties such as construction, number and type of observations, accuracy and precision as well as limitations of use are described.