THE ELECTRICS AND NON-ELECTRICS. 305 



they failed to move the versorium, are emerald, agate, car- 

 nelian, pearls, jasper, chalcedony, alabaster, porphyry, 

 coral, marbles, coal, flint, bloodstone, emery, bone, ivory, 

 hard woods (such as ebony, cedar, juniper, cypress), the 

 lodestone, silver, gold, copper and iron. 



It is no reproach to say that such experimenting was 

 merely empirical. In the nature of things at the time, it 

 could not have been otherwise. 1 He, doubtless, tried 

 every available substance over and over again, making 

 many an inconclusive test, until he discovered that a body 

 might appear as an electric at one time and not at another, 

 and that changes even in atmospheric conditions might 

 easily lead to its entry into or exclusion from the electric 

 category. Nor could he have found a much worse place 

 for such researches than foggy London, where the prevail- 

 ing dampness probably many a time frustrated his most 

 careful efforts. At last, however, he learns that the best 

 electrical effects are obtained when the weather is cold, the 

 sky clear and the wind in the east, and that on overcast 

 days when the breeze is southerly the indications of the 

 quivering versorium are not to be trusted. 



The unexpected revelation of so many substances par- 

 taking of the amber property made it plain that the field 

 upon which Gilbert was how entering was wholly new and 

 untrodden. < That he had reached its border through the 

 devious ways of his magnetic hypotheses, that his further 

 advancement upon it would be but a digression from his 

 chosen main path, that he had come to it in pursuit of a 

 special object all these considerations are immaterial. To 

 all intents and purposes his advent as the first explorer 

 might have been owing to any other influences, or to none, 

 save the merest arbitrary selection of the amber attraction 

 as an inviting subject for inquiry. Thus we reach a per- 

 ception of the simple fact, clear of its surroundings, that 



1 The history of the development of some modern electric appliances is 

 not altogether free from instances of a similar course commending itself 

 to the nineteenth-century intellect. 

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