THE AURORA. 



475 



while local auroras are nearer the earth, of small extent, and due to 

 local disturbances. 



Telluric currents, passing along telegraphic wires, communicating 

 with the earth at both ends, are visihlv and often violentlv affected 



during an aurora, setting electric call-bells ringing, preventing the 

 transmission of messages by throwing the mechanism out of gear, and 

 often proving a sotirce of positive danger. This is not due to, or 



