22 



HISTORY OF ASTRONOMICAL DISCOVERY. 



pursue a direct course, and afterwards to retrograde again. As an hypothesis, therefore, 

 the Copernican theory had strong presumptive evidence in its favour, accounting for the 

 celestial movements, and being in beautiful congruity with Nature's frugal and simple 

 plan of general operation. Still presumptive evidence is not positive proof, nor could 

 the truth of the theory at that time be demonstrated. It detracts not from the glory of 

 its author, that to others the merit belongs of establishing his leading views as a real 

 expression of the phenomena of the universe. He had not the instruments by which alone 

 this could be done. He seems to have entertained a noble confidence that he had con- 

 ceived the true system, and that future discoveries would remove the mechanical difficulties 

 then in its way, and a more enlarged observation of physical facts place it upon the basis 

 of incontrovertible evidence, a confidence which has been amply justified. 



The sixteenth century, rendered me- 

 morable at its commencement by the 

 foundation being laid of true views re- 

 specting the constitution of the uni- 

 verse, was distinguished at its close 

 by the labours of TYCHO BRAHI, a 

 Dane, born at Knudsthorp, near the 

 Baltic, three years after Copernicus 

 terminated his career. His attention 

 was called to astronomy by a great 

 eclipse of the sun, August 21. 1560, 

 when quite a child. Upon being sent 

 to the university for his education, he 

 was accustomed to watch the constel- 

 lations while his tutor slept. Of noble 

 extraction, and strongly influenced 

 himself by prevailing aristocratic prejudices, he at length conquered the pride of his 

 order, devoted himself to public usefulness in the particular department to which his 

 natural genius was inclined, became a studeift, an author, an astronomical lecturer, and 

 finally completed his offences against the pride of life by marrying a plebeian. This 

 last step, probably, rendered exile desirable, in order to escape from the slights of his 

 relatives. He found a welcome reception at the court of the Landgrave William of 

 Hesse-Cassel, a prince who was himself an ardent student of astronomy, of whom it is 

 related that, while observing the brilliant new star of 1572, 

 his servants ran to tell him that the house was on fire : but 

 he quietly pursued his task to its completion. The fame of 

 Tycho has been obscured by his rejection of the Copernican 

 doctrine, and the construction of a system of his own, combin- 

 ing the elements of the Ptolemaic and Copernican theories. 

 He maintained the earth to be the immoveable centre of the 

 universe, but supposed the planets to revolve round the sun, 

 and to be carried with their centre in revolution round the 

 earth. 



The adoption of this hypothesis has been usually deemed 

 discreditable to Tycho ; but it will be only fair to recollect 

 that the Copernican theory was, in his day, quite incapable of proof. He argued, against 

 the diurnal motion of the earth, that, upon that assumption a stone dropped from the 

 summit of a high tower would not fall at the base, as we see it does, because the velocity 

 of rotation would carry the tower several hundred feet during the descent of the stone, 



