90 



THE SEA. 



Turning- to another subject, partially discussed before the colour of the sea it may be 

 remarked that by itself as sea water it is really colourless. Its varying- colours are caused by 

 reflection, by the varied bottoms it covers, or by the presence of actual animal, vegetable, and 

 mineral bodies. The ocean, 



" When winds breathe soft along the silent deep," 



is azure blue or ultramarine, becoming- greener in-shore. There are some days when it is 

 generally green, others sombre and grey. A bottom of white sand will give a greyish or 



"THE SOUFFLEUR," ISLAND OF MAURITIUS. 



apple-coloured green ; of chalk, a pure clear green ; if the bottom is brownish-yellow sand, 

 the green is naturally duller in character. In the Bay of Loango the waters appear of a deep 

 red, from the red bottom. The Red Sea owes its colour to actual floating microscopic algse 

 and to red coral bottoms. Sea water, concentrated in the salt marshes of the south of France 

 by the heat of the sun, is also red : this is due to the presence of a red-shelled animal of 

 microscopic size. These minute creatures do not appear till the salt water has attained a 

 certain concentration, while they die when it has reached a further density. Navigators often 

 traverse patches of green, red, white, or yellow-coloured water, their coloration being due to 

 the presence of microscopic crustacaans, medusae, zoophytes, and marin2 plants. 



The pleasing phenomenon known as the phosphorescence of the sea is generally, though 



