GILBERT'S TERRELLA. 277 



and probably tested every experiment thereto relating of 

 which he could find record, but made a remarkable num- 

 ber of new discoveries. More than this, he took up, for 

 the first time for systematic study, the phenomenon of 

 the amber not primarily for the purpose of inquiring 

 into its nature, but really as a digression, and with the ob- 

 ject of showing that it was totally different from that of 

 the magnet. 



The research begins with a comparison of the poles of 

 the heavens, the poles of the earth and the poles of the 

 lodestone; and the proposition is at once laid down that 

 the poles of a magnet on the earth look toward the poles 

 of the earth, move toward them and are subject to them. 

 This was the first statement of the truth that the compass 

 needle is governed not by the heavens nor by the Pole 

 star, nor by the poles of the heavens but by the mag- 

 netic quality of the globe itself. 



GILBERT'S 



In order to prove the like nature of the earth and the 

 lodestone, Gilbert carved a piece of the stone into spheri- 

 cal form; because, as he says, that shape is the most per- 

 fect, agrees best with the earth, which is a globe, and is 



the first edition of his treatise De Magnete. A and B repre- 

 sent the earth's poles, F the earth's centre and D and E pivoted com- 

 pass needles applied to the lodestone ball. 



