FIGURE OF THE EARTH. 313 



The great truth cannounccd by Copernicus, the basis of existing astronomy, 

 encountered at the time more oppon(;nts than partisans ; nor was it possibh^ that, 

 in detect of good instruments and delicate observations, he could corroborate 

 by incontestible facts the surprising revelations of his intellect; he could but 

 consign to after ages the contirmation of his theory. In vain did Tycho Brahe, 

 contrary to what might have been expected from his 'profound knowledge of 

 celestial phenomena, impugn in the name of science, and that so late as the 

 close of the sixteexitli century, the astronomical system of Copernicus ; in vain, 

 at the commencement of the seventeenth, was it sought, in the name of more 

 sacred but ill understood interests, to convert into a stumbling block the public 

 belief in the movement of the earth: the truth wrought its own way, and from 

 Galileo onward, for every adversary there were hundreds who sustained it. 

 At present there is no longer any discussion about it ; he who controverts it 

 is regarded as irrational, and meets in universal indifference the reproof of liis 

 stolid incredulity. 



II. 



If the knowledge, whether certain or presumptive, of the ancient philoso- 

 phers and mathematicians respecting the roundness and rotation of the earth, 

 cannot be considered as the origin or basis of the ideas at present received on 

 both those points, but merely as a remote antecedent completely forgotten at the 

 revival of the discussion in modern times, the same thing nearly may be predi- 

 cated of the researches undertaken to find the value of the radius of the earth's 

 circumference. The analogy, it is true, is not entirely exact, for in these latter 

 researches two things are to be distinguished : the method or principle on which 

 they are founded, and the results finally obtained. The first as devised, two or 

 three centuries before our era, by Eratosthenes and Posidonius, both of the school 

 of Alexandria, is the same with that employed in our own time, as is shown in 

 our Annual for 1862 ; the results of the method, whether from the imperfec- 



lived Eudoxus of Gnidus, a disciple of Plato, usually resident at Cizycum at the entrance of 

 the Euxiup, and one of the most distinguished among the learned of his time in the field, 

 both of theory and practice. To explain the appearances of the heavens, on the hypotiiesis 

 of the repose of the earth, Eudoxus conceived the first idea of crystalline spheres with axes 

 in different directions, and also with different movements. New facts having been discovered, 

 Calippus, a disciple of Eudoxus, in place of 26, admitted 33 spheres, a number which Aris- 

 totle found it necessary to raise to 55. These spheres, supposed at pleasure and symbolical 

 of as many insoluble difficulties in the cosmical system followed by these savants, became 

 established principles in the minds of the philosophers who had imagined them, as well as 

 in those of their disciples, and consequently obtained unquestioned currency in the world. 



Aristotle, taking up anew and analyzing the ideas of his predecessors, and rejecting almost 

 all of them, a proof of their fundamental impracticability, admitted, however; Jst. That the 

 earth is spherical, because such is the apparent form of all the firmameutal bodies ; such also 

 the form which a body, as a drop of water for instance, assimies when left to the free gravi- 

 tation of its panicles; and sitch the form of the earth's shadow in eclipses of the moon. 

 2d. That the dimensions of the earth cannot be extended in an indefinite plane, seeing that 

 with cA-ery change of place there is a change also in the aspect and number of the visible 

 stars ; and 3dly, That it cannot be movable in space, since its hypothetical mobility meets 

 with no reflection in the constant position of other bodies of the universe. The system of 

 Aristotle, based on the observations and conjectures of Eudoxus and his disciples, was that 

 adopted by Euclid, Archimedes, Hipparchus and Ptolemy. 



A o-eneratioR a; er Euclid, who entitled one of his theorems "The earth the centre of the 

 universe," and while the opinions of Aristotle and his followers were in the highest favoi-, 

 there was a formidable protest against them advanced l)y Aristarchus of Samos, who flourished 

 in the earlier half of the third "century before our era, and who was one of the most distin- 

 guished luminaries of his age. Aristarchus exploded all the spheres of Eudoxus and Aris- 

 Totle, set the earth again at'liberty, assigned to the sim and stars their true posiUon, and laid, 

 in a word, the basis of the Copernicau system ; but in opposition to Aristarchus iqipeared 

 Archimedes, on behalf of science, and Cleanthes, chief of the stoic sect, in defence of the 

 faith and religious prepossessions of the age, and the happy conception of tlie suge of Samos 

 remained sunk in oblivion, or passed into the category of dreams, until, in the process of time, 

 it revived with new vitality and brighter evidence in the mind of the recluse of Thorn. 



