ITS PROPERTIES AND DIVISIONS. SOI 



To the above we have only to add, that ihe common foundation 

 of all those clusters of islands which modern navigators have disco- 

 vered in the Pacific Ocean, and to which the name of Polynesia has 

 been given as well as of those which belong to Australasia or New 

 South Wales, and perhaps of New South Wales itself, is evidently 

 of coral structure, immense reefs of which shoot out in every di- 

 rection. And it is a circumstance peculiarly singular, that noUuth. 

 standing this prodigious quantity of lime in the form of coral, not a 

 single bed, and scarcely a pariirle of chalk, has hitherto been met 

 with either in the islands or on the continent. 



There are other islands which are occasionally raised by the vio- 

 lent agency of the subterraneous volcanos. These, however, are 

 comparatively but few in number, and in mass of matter bear no 

 proportion to those which we have reason to believe are perpetually 

 forming by the silent but persevering efforts of the sea-worms we 

 are now more immediately adverting to : and as we have already 

 given instances of such occasional disruptions from the bowels of the 

 earth we need not enlarge upon them in the present place. 



\_Editor.~] 



SECTION IV. 



Supposed Isthmus between Calais and Dover; occasional At- 

 tempts to unite Sea icith Sea ; and the Conjecture of a 

 North.West Passage. 



GEOGRAPHY has had its fancies as well as every other science, 

 and among the more prominent of these may be reckoned the hy* 

 pothesis and hypothetical attempts which we have enumerated at 

 the head of this Section. 



It was ouce a favourite opinion, that Great Britain and France 

 had many years ago been united by an isthmus, or narrow neck of 

 land, stretching across what is now the passage between Dover and 

 Calais; and that this isthmus had been broken down and carried 

 away by some violent force of the circumambient sea, before the 

 commencement of any historical records. In the Philosophical 

 Transactions, we have three or four papers upon this visionary sub. 

 ject. Two of them were written by Dr. Wallis, within two years of 



