284 Kaloy cr Corona. [Book III. 



Dr. Langwitb, indeed, once Taw a bow lying on 

 the ground, the colours of which were almoft as lively 

 as thofe of the common rainbow. It was extended 

 feveral hundred yards. It was not round, but ob- 

 long, being, as he conceived, the portion of an hyper- 

 bola. The colours took up lefs fpace, and were much 

 more lively in trnfe parts of the bow which were 

 near him than in thofe which were at a diftance. 



The drops of rain defcend in a globular form, and 

 thence we can eafily account for the effects produced 

 by them on the rays of light ; but in different flutes 

 of the air, inftead of drops of rain vapour falls to the 

 the earth in different forms of fleet, fnow, and hail. 

 In the two latter dates there cannot be a refraction of 

 the rays of light, but in the former ftate, when a drop 

 is partly in a congealed and partly in a fluid form, 

 . jhe rays of light v/ili be differently affected, both from 

 the form of the drop and its various refracting powers. 

 Jrlence we may expect a variety of curious appc-arances 

 in the heavens, and to thefe drops, in different dates, 

 we may attribute the formation of haios, parhelia, and 

 many orher phenomena, detailed in the phiiofophical 

 tranfactions, or in the hiftories of every country. 



The HALO, or CORONA, is a luminous circle fur- 

 rounding the fun, the moon, a planrt, or a fixed ftar. 

 ItTs fometimes quite white, and fometimes coloured like 

 the rainbow. Tiu;fe which have been obferved round 

 the moon or ftars are but of a very fmall diameter ; 

 thofe round the fun are of different magnitudes, and 

 fometimes immenfely great- When coloured, the co- 

 lours are fainter than thofe of the rainbow, and ap- 

 pear in a different order, according to their fize. In 

 thofe which Sir Ifaac Newton o'ofervcd in 1692, the 

 order of 'the colours, from the infide next the fun, was 

 jn the innermoft, blue, white, red ; in the middle, pur- 



