270 THE INTELLECTUAL RISE IN ELECTRICITY. 



earth be regarded as the motionless centre of the universe 

 (a notion which had occurred long before to the Venetian 

 Benedetti, the first clear refuter of Aristotle's mechanics) 

 and which Burton quaintly describes as so great that u an 

 arrow out of a bow must go seventeen times about the 

 earth whilst a man can say an Ave Maria." l Such earlier 

 objections as this to the Ptolemaic system he epitomizes 

 with characteristic perspicuity; but when he undertakes 

 to present affirmatively his own supposed magnetic proof 

 of the earth's motion, he becomes both doubtful and ob- 

 scure; doubtful, inasmuch as he leaves it questionable 

 whether he intends to accept the idea of an annual motion 

 of the earth about the sun, and obscure, in his explanation 

 of the manner in which the magnetic quality of the earth 

 in his belief causes the diurnal movement on its axis. 



In developing his cosmical theory, Gilbert, following 

 the precedent of earlier co-believers, makes his main point 

 of attack the theory of Aristotle, that the earth is spheri- 

 cal and has its center coincident with the center of the 

 universe about which the heavens revolve: and more par- 

 ticularly the Peripatetic argument that the earth does not 

 move, first, because it is at the center of the universe, to 

 which all heavy bodies gravitate to find a position of rest, 

 and second, because a rotary motion would not belong 

 naturally to the earth itself, but would pertain equally to 

 each portion of the earth, whereas such is obviously not 

 true, all of these portions being carried in a straight line 

 to the center. 2 Against this Gilbert maintains that the 

 earth is not a chaotic spherical mass, but one having de- 

 finite poles which are not merely mathematical expres- 

 sions, but which, on the contrary, are set at fixed points, 

 whereat the greatest verticity of the earth is manifested, 

 and whereon, he holds it is magnetically demonstrable, 

 the earth revolves. This rotation is diurnal, for none else 

 will account for the attending phenomena. The existence 



1 Anatomy of Melancholy, part 2, \ 2, Mem. 3, 

 a Aristotle: De Ccelo, ii., chap. xiv. 



