LARGE FIELDS OF CORAL. 253 



hurricane tear up its thousand huge fragments ; 

 yet what will that tell against the accumulated la- 

 bour of myriads of architects at work night and 

 day, month after month 1 Thus do we see the soft 

 and gelatinous body of a polypus, through the 

 agency of the vital laws, conquering the gi'eat me- 

 chanical power of the waves of an ocean which 

 neither the art of man nor the inanimate works of 

 nature could successfully resist. 



We did not return on board till late in the even- 

 ing, for we stayed a long time in the lagoon, ex- 

 amining the fields of coral and the gigantic shells 

 of the chama, into which, if a man were to put his 

 hand, he would not, as long as the animal lived, be 

 able to withdraw it. Near the head of the lagoon, 

 I was much surprised to find a wide area, consid- 

 erably more than a mile squai'e, covered with a 

 forest of delicately branching corals, which, though 

 standing upright, were all dead and rotten. At 

 first I was quite at a loss to understand the cause ; 

 afterwards it occuiTed to me that it was owing to 

 the following rather curious combination of circum- 

 stances. It should, however, first be stated, that 

 corals are not able to sui-vive even a short exposure 

 in the air to the sun's rays, so that their upward 

 limit of growth is determined by that of lowest 

 water at spring tides. It appears, from some old 

 charts, that the long island to windward was for- 

 merly separated by wide channels into several 

 islets ; this fact is likewise indicated by the trees 

 being younger on these portions. Under the for- 

 mer condition of the reef, a strong breeze, by 

 throwing more water over the ban-ier, would tend 

 to raise the level of the lagoon. Now it acts in a 

 directly contrary manner ; for the water within the 

 lagoon not only is not inci-eased by currents from 

 the outside, but is itself blowm outwards by the 

 II.— Y 



