xxiv Contents 



PAGE 



The flying-fish is held to travel through the air by 

 virtue of a not clearly specified impulse from the tail, 

 and this view is strongly maintained, in spite of the 

 fact that the flying-fish does not describe in the air the 

 trajectory of a projectile. It, in fact, supports itself 

 against the attraction of gravity, travelling at a low speed 

 along a horizontal path only a few feet above the sea, 

 and it maintains itself in the air often for twenty seconds 

 and even longer, as I have myself frequently observed. 



The fallacy of the statement that the apparent blue 

 colour of the sea is not its own but is borrowed by reflec- 

 tion from the sky is dealt with in the text of the paper. 



The colour of the sea has occupied my attention at 

 intervals for more than forty years . . . .124 



Green water first met with in the voyage of the 

 "Challenger" in Antarctic waters. 



The green colour due to the abundance of diatoms 

 living in the water. 



They also furnish the diatom-ooze which is formed 

 at the bottom of the green water. 



Green water due to the presence of diatoms occurs 

 occasionally in equatorial regions . . . .125 



Ultramarine, indigo and olive-green are the funda- 

 mental colour-types of the water of the ocean. 



Precautions necessary in judging the colour of the sea. 



Importance of the " screw- well " of older steamships 

 for judging the true colour of the sea. 



It always converts those who think that the blue 

 colour is due to reflection from the sky . . .126 



Experiments made in the Pacific for colour and 

 transparency of the water . . . . . .127 



Use of the water-glass in such observations. 



Green water on the Morocco coast has abnormally 

 low temperature . . . . . . . .128 



Its density shows that it rises from the deeper strata 

 of the ocean. 



Shells and corals from the bottom have the same 

 green colour, which was shown by Prof. W. N. Hartley 

 to be due to chlorophyll . . . . . .129 



Green water occurs in other parts of the ocean, as 

 on the Pacific coast of South America . . . .130 

 on the same coast of North America . . .131 



on the Atlantic coast of North America . . .132 



