Chase.] g'^g [February. 



others local in their origin. They all, however, have this com- 

 mon feature : each is capable of occasioning fluid currents. 



v. Every disturbance of terrestrial magnetism is accompa- 

 nied by a disturbance of terrestrial gravitation. 



8. The gravitating atmospheric currents, which are origi- 

 nated simultaneously with the magnetic disturbances, become, 

 in their turn, the source of secondary disturbances. 



9. However the disturbance is produced, be it primary or 

 secondary, periodical or occasional, there is an immediate 

 tendency to equilibrium, and that tendency is in the direction 

 of the terrestrial gravitation of fluids. 



10. The regular disturbances by the sun's heat and attrac- 

 tion, combined with the rotation and attraction of the earth, 

 produce revolving currents, analogous in form to those which 

 circulate around ordinary magnets. 



11. Similar revolving currents must be excited about the 

 sun, and about every other rotating celestial body. Such bod- 

 ies, therefore, may become, like the earth, electro-magnets, or 

 the seats of a specific magnetism. 



12. If the specific magnetism is to be measured by the in- 

 tensity of the exciting disturbance, the sun may be, relatively, 

 the weakest magnet in our system ; if it is to be measured by 

 the intensity of the equilibrating force, it is probably propor- 

 tioned to the force of gravitation at the surface of the magnet- 

 ized orb. 



13. It seems probable that the specific cosmical magnetism, 

 like that of a permanent magnet or of an ordinary electro-mag- 

 net, reacts inductively. But I know of no good reasons for 

 supposing that such induction is other than a comparatively 

 unimportant, secondary, and subordinate action. 



14. The lunar primary disturbances, so far as has hitherto 

 been ascertained, appear to belong exclusively to the first class 

 of periodical disturbances, those which are due to change of 

 relative position. It seems most likely, however, that there 

 may also be lunar periodical disturbances of the second class. 



15. The resemblance of the lunar diurnal magnetic curves to 

 the normal tidal curve, indicates a close correspondence be- 

 tween lunar magnetism and lunar gravitation. 



16. Magnetism does not seem to be, strictly speaking, a 

 simple or independent force, but, like the central force of an 

 eddy, the resultant of revolving currents, moving with a speed 



