200 A SHORT HISTORY OF SCIENCE 



sun as 1 : 43 : 6937, and the distance from earth to sun according 

 to the method of Aristarchus at about 1200 earth-radii, that 

 is about ^y of the actual. 



Revolutionary as were the theories expounded by Copernicus 

 they were not clothed in such popular form as to occasion imme- 

 diate or general controversy. In dedicating his work to the 

 Pop 4 Copernicus says in substance : 



It seems to me that the church can derive some advantage from 

 my labors. Under Leo X indeed the rectification of the calendar 

 was not possible, since the length of the year and the motions of 

 the sun and moon were not exactly determined. I have sought to 

 determine these more closely. What I have accomplished, I leave 

 to the judgment of your Holiness, and of the learned mathemati- 

 cians. (See Appendix.) 



\ 



Moreover criticism was in considerable measure disarmed by 

 a fraudulent preface inserted by Osiander, a Lutheran theologian 

 of Nuremberg, to whom the care of publication had been par- 

 tially intrusted by Rheticus. In this preface, ostensibly by 

 Copernicus himself, it is stated, 



that though many will take offence at the doctrine of the earth's 

 motion, it will be found on further consideration that the author 

 does not deserve blame. For the object of an astronomer is to 

 put together the history of the celestial motions from careful ob- 

 servations, and then to set forth their causes or hypotheses about 

 them, if he cannot find the real causes, so that those motions can be 

 computed on geometrical principles. But it is not necessary that 

 his hypotheses should be true, they need not even be probable; it 

 is sufficient if the calculations founded on them agree with the obser- 

 vations. Nobody would consider the epicycle of Venus probable, 

 as the diameter of the planet in its perigee ought to be four times as 

 great as in the apogee, which is contradicted by the experience of all 

 times. Science simply does not know the cause of the apparently 

 irregular motions, and an astronomer will prefer the hypothesis which 

 is most easily understood. Let us therefore add the following new 

 hypotheses to the old ones, as they are admirable and simple, but 



