Meteors. 115 



green, yellow and red. It always 

 appears in that part of the heavens oppo- 

 site the sun. 



The Halos, are circles somewhat akin 

 to the rainbow, which appear about the 

 sun and moon,and are sometimes various- 

 ly coloured. They never appear in a 

 rainy sky, but in a rimy and frosty one* 

 and are formed by the refraction of the 

 rays of light, without any reflection as in 

 the rainbow* 



Mo.ck-suns and mock-moons are repre- 

 sentations of the face of the true sun an.d. 

 moon by reflection in the clouds. 



The weight and pressure of the atmos- 

 pherical air have been explained in the 

 preceding chapter. We shall now exam- 

 ine the particulars relative to its progres- 

 sive motion, which we denominate wind* 



Wind is a stream or current of air ; as 

 the air is a fluid, its natural state is that 

 of rest, which it endeavours always to 

 keep or retrieve by an universal equilibri- 

 um of all its parts. When, therefore, this 

 natural equilibrium of the atmosphere 

 happens by any means to be destroyed in 

 any part, there necessarily follows a mo- 



