SCIENTIFIC TRACTS. 



NUMBER XIV. 



METEORS. 



THAT department of physical science which treats of 

 atmospherical phenomena is called Meteorology. This 

 term includes all the various phenomena of the atmo- 

 sphere, as winds, cloud?, rain, hail, snow, dew, thunder, 

 lightning, and the fiery meteors. 



The word Meteors is almost exclusively confined to 

 those luminous bodies, which occasionally appear in the 

 sky, and which are not governed by any known laws. 

 They may be arranged in three general classes. I. Au- 

 rora Borealis, or Northern Lights. II. Shooting Stars. 

 III. Ignes Fatui, usually termed Will o' the Wisps, ot 

 Jack o' Lanterns. 



I. Aurora Borealis. When walking in a cloudless 

 evening, the eye is frequently directed to luminous ap- 

 pearances in the northern part of the heavens, called 

 Aurora Borealis, or Northern Lights. They are irregu- 

 lar in their appearance, assuming different forms and of 

 different degrees of brilliancy. Sometimes they con- 

 tinue for several successive days and nights ; and again 

 they are of but a few moments' duration. Sometimes 

 there is a pale illumination spread over a large extent of 

 sky ; again large flames waving to and fro, and sweeping 

 from one point of the heavens to the other. Sometimes 

 they assume the form of pillars of fire, and at other times 

 appear like slender fibrous rays of light, majestically 

 moving along the horizon. These movements are occa- 

 sionally accompanied with a hissing noise, or a low 



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