The Solar Dial in the Olsztyn Castle: Its Construction and Relation to Copernicus

The article discusses the construction, function, and origin of the solar dial in the Olsztyn Castle, traditionally attributed to Copernicus. The dial, preserved partially on the wall of the cloister and presumably designed to determine the time of equinoxes, served as an astronomical instrument mapping the daily paths of the sun in the sky. The article provides a comprehensive mathematical model of the instrument, taking into account the astronomical and architectural factors which affected its functioning. The analysis allows to alienate the essential properties of the dial as an observational instrument and to contend that measurements were recorded indelibly on the wall and averaged by interpolation. Furthermore, it reconsiders the arguments which support the hypothesis ascribing the construction of the Olsztyn instrument to Copernicus. (Some mathematical appendices appear only in the online issue of the journal.