Mr. P. E. Chase on Gravity and Magnetic Inclination. 335 



differences of specific gravity. Even the experiments of Barlow 

 and others, to which I have just referred, as well as the electro- 

 magnetic currents which are generated by chemical solution, 

 involve such differences ; the thermal aerial currents which har- 

 monize with and increase the effects of simple gravitation 

 toward the sun, are caused solely by the greater centripetal 

 tendency of the cold dense air, which has the greatest specific 

 gravity; and the recent investigations in thermodynamics, 

 together with the experiments of Fusinieri and Peltier *, confirm 

 the natural conviction that the imponderable agents can only be 

 manifested through their influence on ponderable matter, and 

 therefore under tendencies to equilibrium with the force of gra- 

 vitation. I already find a curious approximate coincidence, to 

 which I attach little importance so long as it is unsupported by 

 corroborative evidence ; but I refer to it as an indication of the 

 very character that we might reasonably expect, and one that 

 may possibly become valuable in the course of future research. 

 The last edition of the Encyclopaedia Britannica, article " Heat/' 

 gives for the expansion and consequent diminution of specific 

 gravity between 32° and 212° Fahr., of 



Iron ¥19 



Air ........ | 



If we suppose their specific magnetisms to be inversely pro- 

 portioned to the disturbance of their specific gravities, we have, 

 assuming the specific magnetism of iron as the unit, 

 a • _l • • i • _i_ 



"8 ' 819 ' ' x ' 3 7> 



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

 querel (3-3-2) and Plucker (^stH- ^ ms resu ^ would be somewhat 

 modified 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 conduc- 

 tion polarity of oxygen (2933, 2934) ; but that polarity is con- 

 veyed in lines strikingly analogous to the thermal gravitation- 

 currents (see Experimental Researches, 2787, and III. plate 4, 

 fig. 6), which, in their turn, accurately represent the hypotheti- 

 cal indirect action of the sun on the needle, through the atmo- 

 spheric affection of the lines of force (2936). 



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

 explanation of the various magnetic perturbations as the illus- 

 trious Fullerian Professor; arid as his hypotheses appear to me 



* Taylor's e Scientific Memoirs,' vol. iii. p. 394. 



t Professor Frazer has kindly referred me to the coefficients of dilata- 

 tion for iron, in the 'Artizan' of December 1, I860, and to the experi- 

 ments of Regnault on the dilatation of air (see Journ. of Frankl. Instit. 

 S. 3. vol. xv. p. 281). According to these data, the theoretical specific 

 magnetism of oxygen would be between ^j and 3-^-. 



