equal to ± 45″, the collimation error being − 114″.6.[1] These results are sufficient to show that Tycho's instruments were really made with the great care which he declares he had always bestowed on them,[2] and in connection with the above results as to Tycho's standard stars, they exhibit the vast stride forward which observing astronomy made at Uraniborg, and which but for the invention of the telescope could hardly have been much exceeded by his successors.[3]
It will not be out of place to say a few words here about a time-honoured absurdity which has attributed great carelessness to Tycho Brahe in the adjustment of his instruments in azimuth. In 1671, Picard, when determining the latitude of Uraniborg, measured the azimuths of the principal church spires in Seeland and Scania visible from the site of Uraniborg. At Copenhagen he found among Tycho's manuscripts similar observations which showed considerable differences from his own.[4] Picard did not lay any stress on this discrepancy when mentioning it in the account of
- ↑ By computing the orbit from the sextant observations alone, Peters found the probable error of one distance = 110″.5, which result, however, is less certain than the one given above.
- ↑ "Plura enim hic quam ipsa magnitudo necessaria sunt. Nam et materiæ soliditas, aëris mutationi nihil cedens, & preparationis concinnitas, diuisionum subtilitas, pinnacidiorum atque perpendiculi iusta applicatio, firma fulcra, debita dispositio, conueniens & obsecundans tractatio, accurata collimatio & numeratio: & pleraque eiusmodi, adesse oportet. Quorum tamen vix omnia instrumento ligneo, quantæcunque magnitudinis, competere, aut sane non diu in eo sarta tecta perdurare possunt. Longe igitur præferendum censeo e solida metallica materia confectum instrumentum." . . . Progymn., p. 635.
- ↑ By using verniers, improved pinnules, &c.,Hevelius (without using telescopes) reduced the probable error of a distance measure to 18″, to the amazement both of contemporaries and of posterity (Lindelöf, Ueber die Genauigkeit der von Hevelius gemess. Sternabstände, St. Petersburg Bulletin, 1853).
- ↑ They occur in a rough volume of observations, 1578–81, and are copied into the volume for 1563–81, so often quoted above in Chapter ii. They are entered at the end of the year 1578, but it is not stated when they were made. There are also azimuths measured from a hill and from the church at Hveen, probably with a cross-staff, and they are headed, "Observations geographiæ in insula Huena factæ."
