Adam Mosley

Appendices: Related Texts and Translations

This chapter presents Rothmanns successive letters to Landgrave Wilhelm IV of Hesse-Kassel, allowing for both the reconstruction of the precise course of observation of the comet and the genesis of Rothmanns treatise on it, the Dialexis Cometae. In the first letter, which must have been written, at the latest, on 9 October, Rothmann describes the successive positions of the comet in longitude and latitude, as well as its daily motion in both longitude and latitude. He also points out that he has determined the successive distances in relation to two reference stars, which form part of the basic system of reference in the stellar catalogue under preparation. The mathematicus indicates that the comet appears to bear a relation with Saturn, towards which it runs in a straight line and with which it will foreseeably conjoin in a period of eight days.Keywords: Christoph Rothmann; comet; Dialexis Cometae; Landgrave Wilhelm IV of Hesse-Kassel

Dialexis Cometae qui Anno Christi M.D.LXXXV mensibus Octobri et Novembri apparuit

This chapter deals with observations and significance of the comet. Sextant is a new instrument used for measuring the distances from two fixed stars. Aristotle thinks that a comet is a fiery something occurring in the air. The motion of the comet can be detected both in longitude and latitude. It has been observed that comets generally follow and seek in the motion some planet with which it can cognate in quality. It appears from its speed of motion that it is located in the sphere of Jupiter rather than that of Saturn, since the motion of Jupiter is faster than that of Saturn. When the Sun is carefully observed through a quadrant, it is found that the ray of the Sun transmitted through an aperture of the same size fills a larger circle in winter and a smaller one in summer.Keywords: Aristotle; comet; Jupiter; Saturn; sextant

Christoph Rothmann's Discourse on the Comet of 1585: An Edition and Translation with Accompanying Essays

Christoph Rothmann’s Discourse on the Comet of 1585 offers the first edition of the Latin treatise after it was published in 1619. It is accompanied by an English translation and a full introduction and commentary.