MULTUM E PARVO. 



lead ran out to eleven hundred and forty-five 

 fathoms, (six thousand eight hundred and seventy 

 feet) without reaching bottom. Within three- 

 quarters of a mile of the southern point of this 

 island, the lead had another throw, and, after 

 running out for a while, brought up for an instant 

 at three hundred and fifty fathoms, and then 

 dropped off* again and descended to six hundred 

 fathoms without reaching bottom. The lagoons 

 are generally shallow, though in the larger islands 

 soundings gave twenty to thirty-five, and even 

 fifty and sixty fathoms."* 



The rate at which coral structures are formed is 

 an interesting subject of inquiry, and various 

 opinions have been formed on the point, some 

 affirming that no perceptible increase takes place 

 in several years, others that the process is so 

 rapid, that the Pacific is fast filling up. Darwin's 

 theory of subsidence negatives this conclusion, in- 

 dependently of the ratio of growth. There are 

 facts on record, however, which imply that, in 

 certain circumstances, the process is rapid. A 

 channel that had been dug through the reef of 

 Keeling Atoll for the passage of a schooner, that 

 had been built on the island, from the lagoon into 

 the sea, was found ten years afterwards to be 

 almost choked up with living coral. An interest- 

 ing experiment was tried at Madagascar, by secur- 

 ing several masses of living coral by stakes three 

 feet below the surface. Seven months afterwards 

 they were found nearly reaching to the surface, 

 firmly cemented to the rock, and extended later- 

 ally several feet; a remarkably rapid growth! 



An ingenious inquiry has been started, whether 



the coral polypes may not yet be employed by 



man for the construction of sea-walls and reefs, in 



* Cheever's "Sandwich Islands," p. 152. 



95 



