208 THE INTELLECTUAL RISE IN ELECTRICITY. 



parts of the heavens. But the bit of iron which Pere- 

 grinus placed on his globe was not a compass needle, nor 

 did it point to the Pole star ; nor does he attach to it any 

 theory of control by anything celestial or terrestrial, other 

 than the lodestone itself. It turned to the pole of the 

 round stone, and not only did that, but adjusted itself 

 with such accuracy that its very action was the best means 

 of rinding the pole. 



How the discoverer reasoned over this, we can only 

 conjecture. The bit of iron being already in contact 

 with the stone, he must certainly have remarked that 

 here was a force which did not act to draw the metal to 

 the magnet, but simply to turn it into a new position in a 

 horizontal plane, and that, one always pointing to the 

 pole. 



This, however, was not all. In Peregnnus' third 

 method the needle is turned, tilted, in a vertical plane. 

 If nothing but attraction were involved, it ought simply 

 to be drawn to the stone in any position, sidewise or end- 

 wise. But here it is turned endwise and then inclined 

 until perpendicular. Here then was another force acting 

 to make one end of the needle move downward and so to 

 point to the pole beneath. 



Of course the needle or bit of iron which Peregrinus 

 used was itself a magnet ; or became one immediately by 

 induction from the lodestone globe. 



Now what had he shown? First, the existence of the 

 field of force around the stone, in which he had seen the 

 needle deflect both laterally and vertically in order to point 

 directly at the pole second, he had marked out lines of 

 force and determined their direction and that they ended 

 in the poles for these were the meridians which he traced 

 on his globe : and he had also seen that they existed at 

 considerable distances from the pole for, in order to dis- 

 cover the place where his needle would stand perpendicu- 

 lar he must have moved it to other places where it was 

 simply more or less inclined. 



