1H8 COSMOS. 



be expressed by 2-052 (the unit still employed being the in-* 

 tensity which I discovered on the magnetic equator in North- 

 ern Peru), Sabine found it was only 1-624 at the magnetic 

 north pole near Melville Island (74° 27' north lat.), while it 

 is 1-803 at New York, in the United States, which has al- 

 most the same latitude as Naples. 



The brilliant discoveries of QErsted, Arago, and Faraday 

 have established a more intimate connection between the elec- 

 tric tension of the atmosphere and the magnetic tension of our 

 terrestrial globe. While CErsted has discovered that elec- 

 tricity excites magnetism in the neighborhood of the conduct- 

 ing body, Faraday's experiments have elicited electric currents 

 from the liberated magnetism. Magnetism is one of the mani- 

 fold forms under which electricity reveals itself. The ancient 

 vague presentiment of the identity of electric and magnetic 

 attraction has been verified in our own times. " When elec- 

 trum (amber)," says Pliny, in the spirit of the Ionic natural 

 philosophy of Thales,* "is animated by friction and heat, it 

 will attract bark and dry leaves precisely as the loadstone at- 

 tracts iron." The same words may be found in the literature 

 of an Asiatic nation, and occur in a eulogium on the load- 

 stone by the Chinese physicist Kuopho.f I observed with as- 



Mouut Crozier, west-northwest of the south magnetic pole, at a place 

 where Captain .Tames Ross tbund the inclination of the needle to be 87° 

 11' (Sabine, Contributions to Terrestrial Magnetisyn, 1843, No. 5, p. 

 231); the latter, observed by Erman, at 19° 59' S. lat., and 37° 24' W. 

 long, from Paris, 320 miles eastward from the Brazilian coast of Espiritu 

 Santo (Erman, Phys. Beoh., 1841, s. 570), at a point where the inclina- 

 tion is only 7° 55'. The actual ratio of tlie two intensities is therefore 

 as 1 to 2-906. It was long believed that the greatest intensity of the 

 magnetic force was only two and a half times as great as the weakest 

 exhibited on the Earth's surface. (Sabine, Report on Magnetic In- 

 tensity, p. 82.) 



* Of amber (succinum, glessum) Pliny observes (xxxvii., 3), " Gen- 

 era ejus plura. Attritu digitorum accepta caloris anima trahunt in se 

 paleas ac folia arida qute levia sunt, ac ut magnes lapis ferri ramenta 

 quoque." (Plato, ira Timceo, p. 80. Martin, Etude snr le Tim^e, t. ii., 

 p. 343-346. Strabo, xv., p. 703, Casaub. ; Clemens Alex., Strom., ii., 

 p. 370, where, singularly enough, a diffei'ence is made between to 

 aovxiov and to rjXsKTpov.) When Tlmles, in Aristot., de Anima, 1, 2, 

 and Hippias, in Diog. Laert., i., 24, describe the magnet and amber as 

 possessing a soul, they refer only to a moving principle. 



t " The magnet attracts iron as amber does the smallest grain of mus- 

 tard seed. It is like a breath of wind which mysteriously penetrates 

 through both, and communicates itself with the rapidity of an arrow." 

 These are the words of Kuopho, a Chinese panegyrist on the magnet, 

 who wrote in the beginning of the fourth century. (Klaproth.Lef^r.? o 

 M. A. de Humboldt, snr V Inventio7i de la Boussole, 1834, p. 125. ^ 



