PHYSICAL AND LITERARY. 221 



I had occafion, to lee it again on the 23d 

 of 0(5tober laft, in f ravelling from Glaf- 

 gow, northward. When I had alcended 

 a very little out of the fog, fo that my 

 fhadow was projedlied amongft it ; the fun 

 being behind, and alaioil on a level with 

 me i there was a double range of colours, 

 like thofe of the rainbow, formed round 

 the fhadow. The colours of the utter- 

 moft range were broad and very dirtindt, 

 and about two teet diltant troui the iha-* 

 dow every where ; then there was a dark- 

 ifh interval, and after that another nar- 

 rower range of colours, clofely furround- 

 ing the ihadow, which was very much 

 contradled. 



Having feen no account for this phse- 

 nomenon, I fhall now venture to offer my 

 conjedlures. As the fun is a broad lumi- 

 nous furface, the ihadows of bodies mtift 

 be furrounded with a penumbra occafi- 

 oned by the different direction of the rays 

 proceeding from each verge of the fun and 

 from the center ; this becomes very fenfible 

 when you are upon lome eminence with 



the 



