reprinted in his greater work, filling a little more than twenty-seven pages (A to second page of D2). As this is more generally accessible than the other parts of the book, a short abstract will suffice here. Having described how he first saw the star, he quotes the words of Pliny relating to the star of Hipparchus, which many had taken to be a comet; but as it would be absurd to fancy that a great astronomer like Hipparchus should not have known the difference between a star of the æthereal region and a fiery meteor of the air which is called a comet,[1] it must have been a star like the present one which he saw. Since that time no similar star has been seen till now, for the star of the Magi was not a celestial object, but something relating exclusively to them, and only seen and understood by them. How it was created he does not profess to offer an opinion about, but proceeds to treat of its position among the stars. This is illustrated by a diagram of the stars in Cassiopea, and the measured distances of the new star from α, β, and γ Cassiopeæ are given,[2] after which he shows how the rules of spherical trigonometry of Regiomontanus give the longitude and latitude of the star from these data. He adds that the accuracy of the co-ordinates deduced will, of course, depend on that of the positions of the fixed stars he has used; but as he has not any observations of his own to depend on, he is obliged to use the positions given by Copernicus, trusting that God will spare him and enable him to correct the accepted places of the fixed stars by new observations. In order to find the distance of the star from the earth, he has measured its angular distance from Schedir,
- ↑ The expression is remarkable, as it shows that Tycho had not yet shaken himself free from the old Aristotelean opinion of the comets as atmospheric phenomena.
- ↑ Respectively 7° 55′, 5° 21, and 5° 1′; while Progymnasmata, p. 344, gives 7° 50′.5, 5° 19′, and 5° 2′. Tycho remarks (ibid., p. 593) that the latter results are corrected for the error of excentricity, and were made with the improved pinnules which he afterwards adopted.
