STUDY IV* 241 



from the winds and currents which are very vio- 

 lent in the (traits of thefe rocks and ifles, and from 

 the difficuky of anchoring in fuch a vaft depth of 

 water, Government has been at the expence of 

 faflening feveral hundreds of ftrong iron rings in 

 the rocks, more than two fathoms above water, by 

 which veflels may be fafely moored. 



Nature has infinitely varied thefe means of pro- 

 tedion, efpecially in the iilands themfelves which 

 proted: the Continent. She has, for example, fur- 

 rounded the We of France with a bank of madre- 

 pores, which opens only at the places where the 

 rivers of that ifland empty themfelves into the Sea. 

 Other illands, feveral of the Antilles in particular, 

 were defended by forefts of mangliers which grow 

 in the fea-water, and break the violence of the 

 waves, by yielding to their motion. To the de- 

 ftrudion, perhaps, of thefe vegetable fortifications, 

 we ought to afcribe the irruptions of the Sea, now 

 fo frequent in feveral iflands, particularly that of 

 Formofa. There are others which confift of pure 

 rock, rifing out of the bofom of the waves, like 

 huge moles ; fuch is the Maritimo, in the Medi- 

 terranean. Others are volcanic, as the Ille of 

 Fuego, one of the Cape de Verd iflands, and fe- 

 veral others, of the fame defcription, in the South 

 Sea, rife like pyramids with fiery fummits, and an- 

 fwer the purpofe of light-houfes to mariners, by 



VOL. I. R their 



