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POPULAR SCIENCE MONTHLY. 



more active as causes than the Edlund currents. It is natural to suj^- 

 pose that any variation of the earth's electrical equilibrium or poten- 

 tial would tend to draw down the atmospheric currents. Here 

 would come in the action of the electrical currents which coincide 



^^ 



with sun spots, and which undoubtedly produce electric storms in 

 summer and auroras in winter. Magnetic disturbances and telluric 

 currents have a known relation to sun spots ; so also must the aurora 

 in its secondary widespread form. 



