Franklin, Dufay and Ampere. 479 



filaments extend themselves and move apart, as if actuated by 

 a repulsive power: also when iron filings are so managed as 

 to obey the influence of the poles of a powerful magnet (51), 

 they arrange themselves in a manner resembling that of the 

 electrified hair. There is, moreover, this additional analogy, 

 that tiiere is an attraction between two portions of hair differ- 

 ently electrified, like that which arises between filings differ- 

 ently magnetized ; yet the properties of the electrified hair 

 and magnetizetl filings are, in some respects, utterly dissimilar. 

 A conducting communication between differently electrified 

 portions of hair would entirely neutralize the respective elec- 

 trical states; so that all the electrical phaenomena displayed by 

 them would cease. Yet such a communication made between 

 the poles, exciting the filings, by any non-magnetic conductor, 

 does not in the slightest degree lessen their polar affections 

 and consequent power of reciprocal influence. Upon the 

 electrified hair, the proximity or the contact of a steel magnet 

 has no more effect than would result under like circumstances 

 from any other metallic mass similarl}^ employed; but by the 

 approximation, and still more, the contact, of such a magnet, 

 the affection of the filings may be enhanced, lessened, or nul- 

 lified, according to the mode of its employment. In the case 

 of the hair, the affection is superficial, and the requisite char- 

 ging power must be in proportion to the extent of surface. In 

 the case of the magnetized ferruginous particles, it is the mass 

 which is affected, and, cceteris paribus, the more metal, the 

 greater the capacity for magnetic power. In the instance of 

 the electrified hair, as in every other of frictional excitement, 

 the electrical power resides in imponderable cethereo-electric 

 atmospheres which adhere superficially to the masses, being 

 liable to be unequally distributed upon them in opposite states 

 of polarity, consequent to a superficial polarization of the ex- 

 citing or excited ponderable masses ; but in the instance 

 of bodies permanently magnetic, or those rendered transiently 

 magnetic by galvanic influence, the sethereo-electric matter 

 and the ponderable atoms are inferred to be in a state of com- 

 bination, forming aethereo-ponderable atoms; so that both 

 may become j)arties to the movements and affections of which 

 the positive and negative waves consist. 



63. Thus an explanation is afforded of the hitherto myste- 

 rious diversity of the powers of a gold leaf electroscope and 

 galvanoscopes, allliough both are to a miraculous degree sen- 

 sitive; the latter to the most feeble galvanic discharge, the 

 former to the slightest statical excitement; yet neither is in 

 the most minute degree affected by the polarization which 

 affects tlie other. 



