30 



that's it ; 



These northern and southern 

 lights, when in their greatest 

 perfection, consist of a well-de- 

 fined arc of white light, and lu- 

 minous streams of coloured light 

 flowing therefrom. The arc is 

 not permanent, as in the rainbow, 

 but bends and twists in all direc- 



176. 



tions, like a ribbon agitated by 

 the wind. These lights are be- 

 lieved to be connected with mag- 

 netism and electricity ; but thej 

 are imperfectly understood. Elec- 

 tricity can scarcely be called an at- 



13 



177. 



mospheric phenomenon, since it is 

 one of the chief forces in nature, 



and prevails everywhere ; but its 

 atmospheric manifestations are 

 most familiar to us. Lightning, 

 13, is the effect of violent electri- 

 cal action. It is to electricity 

 what the flash of a gun is to the 

 force of its discharge — an effect, 

 not a cause. Electricity is one 

 of the mightiest agents in nature. 

 It not only strikes the living 

 dead, and crumbles the strongest 

 temples erected by man, but 

 sometimes rends the earth, and 

 appears to convulse the system 

 of nature. About forty years 

 ago, electricity tore open a cliff 

 in Colombia, and precipitated 

 an enormous mass of earth and 

 rock into the river Hullaga, the 

 course of which was obstructed 

 thereby. 



The atmosphere is the prime 

 element of life ; for even those 

 creatures that dwell in the sea 

 and rivers are dependent upon, 

 and could not exist without it. 

 Among its tenants are the most 



14 



178. 



beautiful of living things; wit- 

 ness the infinite variety of birds 



