Chap, i o.] Green Colour of the Sea. i$\ 



rays than of the reft, the fun's light tranfmitted through 

 it inclines towards yellow, orange, or red, efpccially 

 when it pafles through a long tract of air ; and in this 

 manner the fun's horizontal light is tinctured with a 

 deep orange, and even red, and the colour becomes 

 ftill deeper after fun-fet; hence he concludes, that the 

 clouds, according to their different altitudes, may af- 

 fume all the variety of colours at fun-rifing and letting, 

 by barely reflecting the fun's incident light as they re- 

 ceive it. 



The green colour of the fea may alfo be accounted 

 for in the fame manner. Sir Ifaac Newton, and others, 

 have fuppoleel that this effect was produced by the re- 

 flective power of the water; but that this is not the 

 cafe is manifeft ; for when fea water is admitted into a 

 reiervoir, which does not exceed a few inches in depth, 

 it appears pellucid aud colourlefs. 



Dr. Halley, in the diving- bell *, obfcrved, that when 

 he was funk many fathoms deep into the fea, the up- 

 per part of his hand, on which the fun fhone directly 

 through the water, was red, and the lower part a blue- 

 ifh green. On thefe phenomena Mr. Delaval obferves, 

 that the fea water abounds with heterogeneous particles, 

 many of which approach fo near in denfity to the wa- 

 ter itfelf, that their reflective power muft be very weak, 

 though, as they are not quite of the lame denfity, they 

 ftill muft have fome degree of refle6tive power. Al- 

 though thefe, therefore, may be invifible when fepa- 

 rately viewed, yet when the forces of a great number 

 of fuch minute bodies are united, their action on the 

 rays of light becomes perceptible, fome rays being re- 

 flected by them, whilft others are tranfmitted through 

 their intervals, according to the quantity of reflective 



* Newton's Opt. 1. i. Part ad. 



U 2 matter 



