Hi BOOK OP NATURE LAID OPES. 



To a spectator on land, the sea appears to be 

 higher than the spot on which he stands ; this, how- 

 ever, is by no means the case, as is demonstrated 

 by the same experiment by which the globular form 

 of the earth is proved ; namely, the sinking of the 

 hull of a ship in the horizon, as she recedes from our 

 view, before the sails and higher parts disappear. 

 This illusion is occasioned by that refraction in the 

 atmosphere, or property of vision, by which objects 

 are made to rise in the landscape in proportion to 

 their distance from us, by which means our horizon 

 is increased and objects longer kept in view, which 

 otherwise must have been extremely limited, and 

 our prospects of short duration. 



We labour also under a deception in regard to 

 the colour of the sea; for although when viewed 

 from a precipice its waters afford a muddy greenish 

 hue, arising from the depth and position of the eye ; 

 when beheld from a shelving beach it assumes the 

 colour of the sky ; although it is dark and black in 

 the deep abyss, white and foaming in a storm, cloud- 

 ed with the most beautiful colours when the rays of 

 the setting sun shine upon it, or puts on the appear- 

 ance of a beautiful green, when beheld from a boat 

 in a sun-shine day, over a sandy bottom ; yet there 

 can be no doubt but the sea-water is of itself trans- 

 parent and colourless, and that the various appear- 

 ances it puts on must be entirely owipg to accidental 

 causes : and, indeed, how could it be otherwise, but 

 that the medium of vision to so many living crea- 

 tures should have remained in such a transparent 



