CORAL AND CORAL REEFS 405 



sand ; growing upon that beach you have vegetation, which 

 takes, of course, the shape of the circular land ; and then, 

 in the interior of the circle, there is a pool of water, which 

 Is not very deep probably in this case not more than eight 

 or nine fathoms and which forms a strange and beautiful 

 contrast to the deep blue water outside. This circular 

 island, or atoll, with a lagoon in the middle, is not a com- 

 plete circle ; upon one side of it there is a break, exactly 

 like the entrance into a dock ; and, as a matter of course, 

 these circular islets, or atolls, form most efficient break- 

 waters, for if you can only get inside your ship is in perfect 

 safety, with admirable anchorage in the interior. If the 

 ship were lying within a mile of that beach, the water 

 would be one or two thousand feet deep ; therefore, a 

 section of that atoll, with the soundings as deep as this all 

 round, would give you the notion of a great cone, cut off 

 at the top, and with a shallow cup in the middle of it. 

 Now, what a very singular fact this is, that we should have 

 rising from the bottom of the deep ocean a great pyramid, 

 beside which all human pyramids sink into the most utter 

 insignificance ! These singular coral limestone structures 

 are very beautiful, especially when crowned with cocoa-nut 

 trees. There ^ou see the long line of land, covered with 

 vegetation cocoa-nut trees and you have the sea upon 

 the inner and outer sides, with a vessel very comfortably 

 riding at anchor. That is one of the remarkable forms of 

 reef in the Pacific. Another is a sort of half-way house, 

 between the atoll and the fringing reef ; it is what is called 

 an " encircling reef." In this case you see an island rising 

 out of the sea, and at two or three miles distance, or more, 

 and separated by a deep channel, which may be eight to 

 twelve fathoms deep, there is a reef, which encircles it 

 like a great girdle ; and outside that again the water is 

 one or two thousand feet deep. I spent three or four years 

 of my life in cruising about a modification of one of these 

 encircling reefs, called a " barrier reef," upon the east 

 coast of Australia one of the most wonderful accumulations 

 of coral rock in the world. It is about 1,100 miles long, and 

 varies in width from one or two to many miles. It is 

 separated from the coast of Australia by a channel of about 

 25 fathoms deep ; while outside, looking toward America, 

 the water is two or three thousand feet deep at a mile from 

 the edge of the reef. This is an accumulation of limestone 

 rock, built up by corals, to which we have no parallel any- 



