GILBERT'S ERRORS. 273 



in every electrical apparatus in which mechanical motion 

 is caused by the reaction of fixed and moving fields of 

 force. It cannot, of course, be affirmed that Gilbert con- 

 ceived of the rotation of the earth in the fields of the sun 

 and moon in any such way as we regard the rotation of an 

 armature in a magnetic field ; but that he certainly did 

 regard the earth's diurnal rotation as somehow due to 

 the confederacy and conspiracy of the earth's effused Form 

 acting on, and being acted upon by, the effused Forms of 

 other celestial bodies is plain. 



Of course all this probably intensified the obscurity of 

 Gilbert's theory at the time of its production. And an 

 obscure hypothesis, intended to substantiate another which, 

 according to prevalent opinion, was not philosophical ar- 

 gument, but pestilent, soul-destroying heresy, had not 

 much way-making power even among those who disputed 

 theological conclusions and were inclined to tolerate truth 

 regardless of the finger-posts at Rome. Hence it may 

 readily be imagined that even to the Copernicans them- 

 selves Gilbert may have seemed a doubtful auxiliary, while 

 there was manifestly not much heart of grace to be taken 

 from his long category of experiments and arguments, 

 however individually true and interesting they might be, 

 so long as they seemed in respect to their aim and object 

 merely a ladder leading nowhere. 



There was a more serious trouble in Gilbert's work, 

 however, than even the advocacy of proscribed astronomi- 

 cal doctrines, and that lay in his erroneous notions con- 

 cerning the dip and variation of the compass. At the time 

 he gave these to the world, the English seaman was rapidly 

 merging the pirate in the merchant adventurer, the naval 

 supremacy of England was established, there were no 

 more Invincible Armadas to be feared, a great trade was 

 to be wrested from Spain and Portugal and Italy, and the 

 exploits and discoveries of Drake and Raleigh and Fro- 

 bisher were setting the heart beating and the fancy 

 aflame of every youth in whose veins ran the blood of the 

 18 



