EASTING OF THE TKADE-WINDS, ETC. 167 



these minute bits of ferruginous dust that arrange themselves in 

 lines and curves about magnets ; when we reflect that this great 

 magnet, the earth, is surrounded by a para-magnetic gas, to the 

 molecules of which the finest atom from the file is in comparison 

 gross and ponderous matter ; — that the entire mass of this air is 

 equivalent to a sea of mercury covering the earth around and 

 over to the depth of 30 inches, and that this very subtile mass is 

 in a state of unstable equilibrium, and in perpetual commotion 

 by reason of various and incessant disturbing causes ; — w^hen v/e 

 reflect farther upon the recent discoveries of Schwabe and of 

 Sabine concerning the spots on the sun and the magnetic ele- 

 ments of the earth, which show that if the sun or its spots be 

 not the great fountain of magnetism, there is at least reason to 

 suspect a close alliance between solar and terrestrial magnetism 

 — that certain well-known meteorological phenomena, as the 

 aurora, come also wdthin the category of magnetic phenomena; 

 — that the magnetic poles of the earth and the poles of maximum 

 cold are at or near the same spot ; — that the thermal equator is 

 not parallel to or coincident with either the terrestrial or w'itli 

 that which the direct solar ray w^ould indicate, but that it follow^s-, 

 and in its double curvatures conforms to the magnetic equator ; 

 — moreover, when we reflect upon Barlow's theory and Fox's 

 observations, which go to show that the direction of metallic 

 veins of the northern hemisphere, which g enerally lie north-east 

 and south-westwardly, must have been influenced by the direc- 

 tion of the magnetic meridians of the earth or air ; — finally, I 

 say, when we reflect upon magnetism in all its aspects, we may 

 well inquire whether such a mass of highly magnetic gas as that 

 which surrounds our planet does not intervene, by reason of its 

 magnetism, in influencing the circulation of the atmosphere and 

 the course of the winds. 



348. The needle in its dhmial variations, the barometer in its 

 readings, and tlie atmosjyhere in its electrical tension, all have the same 

 hours for their raaxlma and minima. — This magnetic sea, as tho 

 atmosphere may be called, is continually agitated ; it is dis- 

 turbed in its movements b}' various influences which prevent it 

 from adjusting itself to any permanent magnetic or other dy- 

 namical status ; and its para-magnetic ]3roperties are^'known to 

 vary with every change of pressure or of temperature. The 

 experiments of Faradaj' show that the magnetic force of the air 

 changes with temperature ; that it is least near the equator, and 



