Being unable to reconcile his own observations with those of Copernicus, and with the Prutenic Tables, Tycho resolved to obtain new determinations of the latitude of Frauenburg, in Prussia, where Copernicus made his observations, and of Konigsberg, to the meridian of which Rheinhold had adapted his Prutenic Tables. For these purposes he sent one of his assistants, Elias Morsianus, with a proper instrument, under the protection of Bylovius, Ambassador of the Margrave of Anspach, to the King of Denmark, who was returning by sea to Germany; and after receiving the greatest attention and assistance from the noble Canons of Ermeland, he determined, from nearly a month's observations on the sun and stars, that the latitude of Frauenburg was 54 deg. 22-1/2', in place of 54 deg. 19-1/2', as given by Copernicus. In like manner he determined that the latitude of Konigsberg was 54 deg. 43', in place of 54 deg. 17', as adopted by Rheinhold. When Morsianus returned to Huen in July, he brought with him, as a present to Tycho, from John Hannovius, one of the Canons of Ermeland, the Ptolemaic Rules, or the Parallactic Instrument which Copernicus had used and made with his own hands. It consisted of two equal wooden rules, five cubits long, and divided into 1414 parts. Tycho preserved this gift as one peculiarly dear to him, and, on the day of his receiving it, he composed a set of verses in honour of the great astronomer to whom it belonged. Among the distinguished visits which were paid to Tycho, we must enumerate that of Ulric, Duke of Mecklenburg, in 1586. Although his daughter, Sophia, Queen of Denmark, had already paid two visits to Uraniburg in the same year, yet such was her love of astronomy, that she accompanied her father and his wife Elizabeth on this occasion. Ulric was not only fond of science in general, but had for many years devoted himself to chemical pursuits, and he was therefore peculiarly gratified in examining the splendid laboratory and extensive apparatus which Tycho possessed. It has been said by some of the biographers of Tycho, that the Landgrave of Hesse visited Uraniburg about this period; but this opinion is not correct, as it was only his astronomer and optician, Rothman, who made a journey to Huen in 1591 for the recovery of his health. Tycho had long carried on a correspondence with this able astronomer respecting the observations made at the observatory of Hesse-Cassel, and, during the few months which they now spent together, they discussed in the amplest manner all the questions which had previously been agitated. Rothman was astonished at the wonderful apparatus which he saw at Uraniburg, and returned to his native country charmed with the hospitality of the Danish astronomer.