1 42 LEISURE-TIME STUDIES. 



and varies from ten to ninety miles in breadth. If transferred 

 to European seas and extended round European coasts, this 

 reef would reach from Brest across the mouths of the Irish 

 Sea and English Channel, round the western coast of Ireland 

 to Iceland ; whilst if extended in another direction, it would 

 pass round the coasts of Scotland and the Shetland Isles, 

 and terminate on the Norwegian shores. Soundings taken 

 on the seaward face of a barrier reef reveal immense depths 

 and a state of matters very different from that existing in the 

 fringing reef. The seaward aspect of the latter was seen to 

 exist within the limit of depth of the coral-polypes. The 

 barrier reef, on the contrary, is found to rise from depths 

 altogether beyond the sphere of coral life. And whilst the 

 face of the fringing reef is covered with living coral, that of 

 the barrier reef possesses a living incrustation, only in its 

 upper part, and to a depth of 100 feet or more ; all its sub- 

 stance below this limit consisting of dead coral. 



The third variety of reef is named the atoll or lagoon 

 reef. This latter form of reef exists as a more or less circular 

 ring of coral of varying breadth, enclosing a sheet of still 

 water the lagoon. These coral islands are common in the 

 Indian and Pacific Oceans. Keeling or Cocos Atoll, in the 

 former ocean, measures 9^ miles in its greatest width. 

 Bow Island is 30 miles long and 6 miles wide ; whilst in the 

 MaMive Archipelago, atolls of very large size are met with ; 

 one island measuring 88 geographical miles in length, its 

 greatest width being under 20 miles, and its least width 9*^ 

 miles. Beholding a great coral ring, bearing on its surface 

 a low island soil with vegetation, and protecting a quiet lake- 

 haven from the restless ocean without, it is little to be won- 

 dered at that the earlier voyagers recorded their surprise 

 that the apparently insignificant architects of such an erection 

 are able to withstand the force of the waves and to preserve 

 their work amid the continual attacks of the sea. Pyrard de 

 Laval, writing in 1605, well remarks, " It is a marvel to see 

 each of these atollons surrounded on all sides by a great 

 bank of stone walls such as no human hands could build 



