322 THE POPULAR SCIENCE MONTHLY 



that lie greatly simplified the theory of planetary motion by this step . . . which 

 he worked out mathematically . . . and, that by means of his simpler theory 

 and more exact planetary tables, he reduced to some sort of order the confused 

 chaos of the Ptolemaic system, whose accumulations of complexity and of out- 

 standing errors threatened to render astronomy impossible by the mere burden 

 of its detail. There are many imperfections in his system, it is true, but his 

 great merit is that he dared to look at the facts of nature with his own eyes 

 unhampered by the prejudice of centuries. A system, venerable with age and 

 supported by great names, was universally believed and had been believed for 

 centuries. To doubt this system, and to seek after another and better one, at a 

 time when all men's minds were governed by tradition and authority, and when 

 to doubt was sin — this required a great mind and a high character. Such a 

 mind and such a character had this monk of Franenburg. 



Mr. E. J. C. Morton in a biography of Copernic says: 



Kopernicus can not be said to have flooded with light the dark places of 

 nature — in the way that one stupendous mind subsequently did — but still, as 

 we look back through the long vista of the history of science, the dim, Titanic 

 figure of the old monk seems to rear itself out of the dull flats around it, pierces 

 with its head the mists that overshadow them, and catches the first gleam of 

 the rising sun, 



"... like some iron peak, by the Creator 

 Fired with the red glow of the rushing morn." 



It is not to be supposed that there were not weighty objections to 

 be urged against the Copernican system. • Of these three may be noted : 



1. If it be true that the earth moves, why do not the configurations 

 of the stars change with the changing seasons? It is evident that the 

 grouping of the stars depends upon the distance of the earth from them, 

 and if the earth moves the groups of stars in front of the earth's motion 

 should appear to open out while those behind should appear to close 

 up. We now know the correct answer, that is, that the 184 millions 

 of miles making up the diameter of the earth's orbit is lost in the 

 immensity of stellar space and its effect can only be detected by the 

 most refined of modern methods. 



2. If the earth moves about the sun, Mercury and Venus should 

 show phases as does the moon. 



The only answer Copernicus could make was that, were the powers 

 of man's eyesight sufficiently increased, this would doubtless be found 

 to be the case. Seventy years later, Galileo furnished the required 

 proof. 



Before looking so far ahead, two important workers must be noted. 

 The first of these is the Danish astronomer, Tycho Brahe (1545—1601), 

 who is well called the father of instrumental astronomy. His aid in the 

 solution of the present problem did not consist in the advocacy of the 

 Copernican system — for he rejected it — but in his patient, faithful gath- 

 ering of data. His tables of planetary motions and his star tables were 

 the most extensive and the most accurate of his time. Even when 



