tion several treatises, none of which have ever been printed, among which was one on trigonometry, which he had thought of dedicating to King Frederick II., one on the Copernican system, which he suppressed when he saw how badly the Prutenic tables agreed with the observations,[1] and a treatise on spherical and practical astronomy, which is still preserved in MS. at Cassel.[2]
Tycho and his guest must have had plenty of subjects for conversation, and the host no doubt did his best to entertain the man with whom he had for years exchanged ideas, though they had never yet met. It appears from the diary that several foreign visitors came and went during Rothmann's stay at Hveen, and these as well as the above-mentioned trip to Scania to see Sophia Brahe and her garden lent variety to the visit. There were even some fine auroræ to be looked at and discussed. The many interesting objects to be seen at Hveen, and the scenery, so charming in summer-time, ought to have made Rothmann's stay at Uraniborg very pleasant; but unluckily Tycho seems to have belaboured him with arguments against the Copernican system which must have become somewhat tiresome in the end. In a lengthy note which Tycho has inserted among his printed letters,[3] he states that, during the weeks he had Rothmann with him he pleaded his cause with this generally very obstinate man so well, that Rothmann began to waver, and finally declared himself convinced, and assured Tycho that he had only held to his opinion for the sake of argument; he even added that he had not published, and never would publish, anything in that direction. Doubtless Rothmann was glad to end a dispute which could lead to nothing, and both these skilful observers knew well that
