20 PHYSICAL GEOGRAPHY OF THE SEA. 



alone must have extended over several square miles. The 

 colour of the water was like that of a river which has flowed 

 through a red clay district, and a strictly defined line separated 

 the red stream from the blue water." 



In the neighbourhood of Callao, the Pacific has an olive-green 

 colour, owing to a greenish matter which is also found at the 

 bottom of the sea, in a depth of 800 feet. In its natural state 

 it has no smell, but when cast on the fire, it emits the odour of 

 burnt animal substances. 



Near Cape Palmas, on the coast of Guinea, Captain Tuckey's 

 ship seemed to sail through milk, a phenomenon which was 

 owing to an immense number of little white animals swimming on 

 the surface, and concealing the natural tint of the water. 



The peculiar colouring of the Eed Sea, from which it has 

 derived its name, is owing to the presence of a microscopic alga, 

 sui generis, floating at the surface of the sea and even less 

 remarkable for its beautiful red colour than for its prodigious 

 fecundity. 



I could add many more examples, where, either from minute 

 algse or from small animals, the deep blue sea suddenly appeared 

 in stripes of white, yellow, green, brown, orange or red. For 

 fear, however, of tiring the reader's patience, I shall merely 

 mention the olive green water, which covers a considerable part 

 of the Greenland seas. It is found between 74° and 80° N. lat., 

 but its position varies with the currents, often forming isolated 

 stripes, and sometimes spreading over two or three degrees of 

 latitude. Small yellowish Medusae, of from one-thirtieth to one- 

 twentieth of an inch in diameter are the principal agents that 

 change the pure ultramarine of the Arctic Ocean into a muddy 

 green. According to Scoresby, they are about one-fourth of 

 an inch asunder, and in this proportion a cubic inch of 

 water must contain 64, a cubic foot 110,592, a cubic fathom 

 23,887,872, and a cubic mile nearly twenty-four thousand 

 billions! From soundings made in the situation where these 

 animals were found, the sea is probably more than a mile deep ; 

 but whether these substances occupy the whole depth is un- 

 certain. Provided, however, the depth to which they extend 

 be about 250 fathoms, the immense number of one species 

 mentioned above may occur in a space of two miles square; 

 and what a stupendous idea must we form of the infinitude of 



