348 THE INTELLECTUAL RISE IN ELECTRICITY. 



stone will sustain, he applies to them, in the form of 

 separable pieces, numerous bits of iron which, with the 

 anchors, aggregated a weight greater than the stone's sus- 

 taining power, as he carefully adds "in the condition in 

 which I sent it": thus guarding against an apprehended 

 possibility that the stone will not behave in Florence in 

 the hands of others as well as it has acted in Padua in his 

 own. 



He provides the stone also with a strengthening 

 piece, apparently arranged so that the armatures cannot 

 be placed anywhere except at the proper places. Then he 

 says that both armatures had better be applied at once, 

 because he has found, to his great surprise, that u an iron 

 so heavy that by itself it will not be governed by one pole, 

 will become attached thereto if another iron is applied to 

 the opposite pole." He also sends with the stone two ex- 

 tra pieces of iron, one of which is to be in the form of a 

 cylinder and to be placed upon a smooth table, and the 

 other to be applied to the stone at a marked point; and 

 this cylinder, in some way which he does not very clearly 

 describe, is to be first repelled by the magnet brought near 

 it, and then attracted a result evidently depending upon 

 variations in the distance intervening between the strong 

 lodestone and the rolling cylinder which, by induction, it 

 weakly magnetizes. And then he adds the first announce- 

 ment of the true effect of the armature as a keeper in 

 actually invigorating and retaining the strength of the 

 magnet, by being allowed to remain in contact with the 

 poles, and suggests the provision of a support, so arranged 

 that the armatures may always remain attached and in 

 place. Finally he says that not only will the stone sustain 

 its own weight, but a load four times greater, which, in a 

 magnet of such large proportions, he regards as marvelous, 

 and he expresses the opinion that if it were cut up into 

 small pieces the latter might be made to hold iron aggre- 

 gating six or eight times their weight. 



Such were the interesting results of the study which 





