1865.] J]^7 [Chase. 



If we suppose their specific magnetisms to be inversely propor- 

 tioned to the disturbance of their specific gravities, we have, assum- 

 ing the specific magnetism of iron as the unit, 



8 ■ 81^ •• ^ • 3 61 



a value which is intermediate between those given by MM. Becque- 

 rel (ggo) and Pllicker (^g^)-* This result would be somewhat modi- 

 fied by an accurate determination of the ratios of the linear to the 

 cubic expansions of iron in its several forms. 



Faraday disclaims the assumption of any other than a conduction 

 polarity of oxygen (2933, 2934), but that polarity is conveyed in 

 lines strikingly analogous to the thermal gravitation currents (see 

 Exp. Res., '2787, and III, PI. TV, Fig. 6), which, in their turn, ac- 

 curately represent the hypothetical indirect action of the sun on the 

 needle, through the atmospheric affection of the lines of force (2936). 



I know of no physicist who has given so lucid a theoretical expla- 

 nation of the various magnetic perturbations, as the illustrious Ful- 

 lerian Professor, and as his hypotheses appear to me still more satis- 

 factory when viewed in connection with the gravitation disturbances, 

 I will briefly refer to some of the more important points that have 

 helped to confirm me in the various views that I have hitherto ad- 

 vanced. Such are, e. </., the evidences of the identity of helices and 

 magnets (2239); the existence of magnetic repulsion without pola- 

 rity (2274); the relative magnetic position of gases and vapors 

 (2416); the relations of the magnecrystallic, cohesive, and magnetic 

 forces (2479, 2562, 2578); the probable dependence of the magnetic 

 motions of fluids upon their mass and density (2768, 2769, 2781, 

 2863); the magnetic influence of winds and varying atmospheric 

 pressure (2952, 2954) -j-f the supposed velocity of magnetic trans- 

 mission in space or asther (2958); the daily bi-polar minima of cold 

 (3006); the closed circuits and prominent characteristics of the 

 magnetic lines of force (3117, 3278, 3279, 3284); the tendency of 

 all bodies to evolve electric currents, when moving in a magnetic 

 field (3337); the relative diamagnetic and magnetic effects of heat 



* Prof. Frazer has kindly referred me to the coefficients of dilatation 

 for iron, in the "Artisan," of Dec. 1, 1860, and to the experiments of 

 Eegnault on the dilatation of air (See Jour, of F. Inst. [3], XV, 281). 

 According to these data, the theoretical specific magnetism of oxygen 

 would be between ^^^ and ^j^. 



f Humboldt speaks of the accumulation of electricity in the lower 

 equinoctial regions, " at the maximum of heat, and when the barometric 

 tides are near their minimum." Taylor's Scieni. Mem., Ill, 398. 



