1*8 COSMOS. 



and total force, were appended to these observations, which 

 also give the position of the magnetic equator and of the line 

 of no variation, and belong to the most distinguished and 

 comprehensive that had been drawn up in modern times. 



1845 1850. Faraday's brilliant physical discoveries : (1) 

 In relation to the axial, or equatorial (diamagnetic 74 ) direction 

 assumed by freely oscillating bodies under external magnetic 

 influences (Phil. Transact., for 1846, 2420, and Phil. 

 Transact, for 1851, pfc. i, 27182796) ; (2) Begarding the 

 relation of electro-magnetism to a ray of polarized light, 

 and the rotation of the latter by means of the altered mo- 

 lecular condition of the bodies through which the ray of 

 polarized light and the magnetic current have both been 

 transmitted (Phil. Transact, for 1846, pt. i, 2195 and 

 2215 2221; (3) Regarding the remarkable property 

 which oxygen (the only gas which is paramagnetic) exerts 

 on the elements of terrestrial magnetism, namely that like 

 soft iron, although in a much weaker degree, it assumes con- 

 ditions of polarity through the diffused action of the body of 

 the earth, which represents a permanently present magnet 7 * 

 (Phil. Transact, for 1851, pt. i, 22972967). 



74 See Cosmos, vol. iv, p. 396. Diamagnetic repulsion and an 

 equatorial, that is to say, an east and west position in respect to a 

 powerful magnet, are exhibited by bismuth, antimony, silver, phos- 

 phorus, rock salt, ivory, wood, apple-shavings, and leather. Oxygen gas, 

 either pure or when mixed with other gases, or when condensed in the 

 interstices of charcoal, is paramagnetic. See in reference to crystallised 

 bodies the ingenious observations made by Plucker concerning the 

 position of certain axes (Poggend. Annal. Bd. Ixxiii, s. 178, and Phil. 

 Transact, for 1851, 2836 2842). The repulsion by bismuth was 

 first recognised by Brngmans, in 1778, next by Le Bailiff, in 1827, and 

 finally, more thoroughly tested by Seebeck, in 1828. Faraday himself 

 ( 24292431), Reich, and Wilhelm Weber, who, from the year 1836, 

 has shown himself so incessantly active in his endeavours to promote 

 the progress of terrestrial magnetism, have all endeavoured to exhibit 

 the connection of diamagnetic phenomena with those of induction 

 (Poggend. Annalen, Bd. Ixxiii, s. 241 253). Weber has, moreover, 

 tried to prove that diamagnetism derives its source from Ampere's 

 molecular currents. (Wilh. Weber, A bhandlungen uber electro- dynaniischv 

 Maassbestimmungen, 1852, s. 545 570.) 



' 5 In order to excite this polarity, the magnetic fluids in every par- 

 ticle of oxygen must be separated, to a certain extent, by the actio in 

 distans of the earth in a definite direction, and with a definite force. 

 Every particle of oxygen thus represents a small magnet, and all these 

 small magnets react upon one another as well as upon the earth, and 



