G4 THE BOTTOM OF THE SEA. 



(^numerated do not modify it in various ways, and 

 if the bottom of the sea itself does not further 

 complicate the phenomenon by sii|)erimposing upon 

 the colour of the water its own reflected hue. 



If the bottom be of a more intense colour than the 

 sea, its reflected hue will not be much affected. 

 Thus, while a yellowish sand will change the tint of 

 the blue water to green, a very bright yellow will 

 make the water itself appear of that tint, because the 

 lesser intensity of the blue does not affect the yellow 

 sufficiently to make a green. Tnckey observed, at 

 Loaiigo, that the sea was of the colour of blood ; 

 the bottom was very red. In other places, where 

 the bottom might be of a similar but less lively 

 colour, the sea would not appear red, but orange, or 

 even yellow. 



The irifluence of the bottom on the tint of the sea 

 would appear to be limited to those cases in which 

 the depth is very slight. In fact, the water of the 

 sea absorbs so rapidly the rays of light, that in no 

 great degree of thickness it becomes opaque. There 

 are, indeed, instances which seem to imply the con- 

 trary. Among other observations, the following, 

 made by M. de Tessan near Cape Agulhas, on the 

 southern coast of Africa, seems to show, that even in 

 the case of great depths the bottom may have a 

 sensible influence on the colour of the water : — ** The 



