292 Lieut. Maury on Magnetism and the Trade Winds. 



current leaves the helix, and likewise for the ' north pole of 

 the magnet opposed.' " * 



Attentively considering the experiments of the Professor 

 of Greifswald, we may trace an analogy between his spirals 

 and the spirals which the currents of the wind in " his 

 circuits" describe about the earth. At the south polar 

 calms, the atmospherical spiral is with the hand of the watch, 

 and as in the case of a spiral so wound about its helix the 

 magnetism is south polar ; and so, mutatis mutandis^ for the 

 regions of north polar calms. 



May we not therefore look to find about the north and 

 south magnetic poles these atmospherical nodes or calm re- 

 gions, which I have theoretically pointed out there \ In other 

 words, are not the magnetic poles of the earth in those at- 

 mospherical nodes, the two standing in the relation of cause 

 and eflfect. the oiie to the other \ 



And have we not a clue already placed in our hands, by 

 which the motion of the circular storms of the northern he- 

 misphere, which travel against, and those of the southern 

 which travel with, the hands of a watch, seems to be con- 

 nected with the like motion of the wind of each hemisphere 

 in its circuit about its pole \ and will not this clue, when 

 followed up, lead us into the labyrinths of atmospherical 

 magnetism for the solution of the mystery \ 



Indeed, so wide for speculation is the field presented by 

 these discoveries, that we may in some respects regard this 

 gi^eat globe itself, with its " cups" and spiral wires of air, 

 earth and water, as an immense " pile" and helix, which, 

 being excited by the natural batteries in the sea and atmo- 

 sphere of the tropics, excites in turn its oxygen, and imparts 

 to atmospherical matter the properties of magnetism. 



Thus, though it be not proved as a mathematical truth, 

 that magnetism is the power which guides the storm from 

 right to left, and from left to right, which conducts the moist 

 and the dry air each in its appointed paths, and which regu- 

 lates the '* wind in his circuits," yet, that it is such a power, 

 is rendered so very probable, that the onus is now shifted, and 

 it remains not to prove, but to disprove that such is its agency. 



* Page 49, 50, Phil. Mag. 



