OF THE HALO, CORONA, CHAP. 2. 19. 



increases its elevation, has been explained by 

 M. Howard in his account of the Vapour Plane, 

 and the cause of the Stackencloud.* 



SECTION XIX. 



Of certain Luminous Appearances which result 

 from the Reflection and Refraction of Light hy 

 Clouds, and which arc commonly called Halos, 

 Rainbows, Parhelia, and Paraselenas. 



EVERY one who is conversant in meteorology 

 must be well acquainted with such luminous 

 appearances, occasionally seen about the sun, 

 moon, and planets, and caused by the refrac- 

 tion of their light through a cloud of peculiar 

 structure, as are usually called Halos, Coronae, 

 Burrs, Glories, &:c. But these phaenomena have 

 hitherto received no definite names whereby 

 they may be distinguished from each other, 

 tliough they differ considerably in appearance. 

 Meteorologists have spoken of Halos and Crowns 

 of light indiscriminately, without distinguish- 

 ing between the Corona or luminous disk, and 

 the Halo or luminous ring. 



* Howard on Clouds, in Phil. Mag. 



