prince, he prepared their horoscopes, predicting their fates. He also worked as a cartographer with his former tutor Anders Sørensen Vedel on mapping out all of the Danish realm. An ally of the king and friendly with Queen Sophie (both his mother Beate Bille and adoptive mother Inger Oxe had been her court maids), he secured a promise from the King that ownership of Hven and Uraniborg would pass to his heirs. Publications, correspondence and scientific disputes In 1588, Tycho's royal benefactor died, and a volume of Tycho's great two-volume work Astronomiae Instauratae Progymnasmata (Introduction to the New Astronomy) was published. The first volume, devoted to the new star of 1572, was not ready, because the reduction of the observations of 1572–73 involved much research to correct the stars' positions for refraction, precession, the motion of the Sun etc., and was not completed in Tycho's lifetime (it was published in Prague in 1602/03), but the second volume, titled De Mundi Aetherei Recentioribus Phaenomenis Liber Secundus (Second Book About Recent Phenomena in the Celestial World) and devoted to the comet of 1577, was printed at Uraniborg and some copies were issued in 1588. Besides the comet observations, it included an account of Tycho's system of the world. The third volume was intended to treat the comets of 1580 and following years in a similar manner, but it was never published, nor even written, though a great deal of material about the comet of 1585 was put together and first published in 1845 with the observations of this comet. While at Uraniborg, Tycho maintained correspondence with scientists and astronomers across Europe. He inquired about other astronomers' observations and shared his own technological advances to help them achieve more accurate observations. Thus, his correspondence was crucial to his research. Often, correspondence was not just private communication between scholars, but also a way to disseminate results and arguments and to build progress and scientific consensus. Through correspondence, Tycho was involved in several personal disputes with critics of his theories. Prominent among them were John Craig, a Scottish physician who was a strong believer in the authority of the Aristotelian worldview, and Nicolaus Reimers Baer, known as Ursus, an astronomer at the Imperial court in Prague, whom Tycho accused of having plagiarized his cosmological model. Craig refused to accept Tycho's conclusion that the comet of 1577 had to be located within the aetherial sphere rather