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NATURE FOE ITS OWN SAKE 



in the Arctic seas, are accounted for in this way. 

 But these are mere patches of surface-color in 

 isolated regions. The general hue of sea-water 

 is controlled largely by the matter of depth. 

 It requires a great mass of air-particles to pro- 

 duce a blue sky, and it takes a great depth of sea- 

 water and much reflection from salt-particles to 

 produce " the deep blue sea." It is safe to say, 

 then, that the greatest depths are the bluest, 

 that the shallower depths incline to green, and 

 the shallowest waters the waters near shore 

 are the ones that show the browns, reds, or yel- 

 lows. 



All of these colors are peculiarly beautiful for 

 a reason we seldom take into consideration 

 namely, their transparency. The ordinary 

 colors of nature as shown in grass, flowers, 

 trees, fields, mountains, are opaque. The hue 

 is on the surface, and is only a veneer an outer 

 coating so far as our eyes are concerned. But 

 the sky in its interminable height and the sea 

 in its vast depth are blue by virtue of super- 

 imposed layers or strata of transparent sub- 

 stances. It is not until stratum has been 

 heaped upon stratum in countless numbers that 

 the color begins to show. We see into them as 

 into open space, the quality of the color breaks 



