VOL. XLVIII.J PHILOSOPHICAL TRANSACTIONS. 325 



learn, behind them? Two causes of this fact occurred while Mr. B. was at 

 Scilly, which may perhaps satisfy these inquiries: the manifest incroachments of 

 the sea, and as manifest a subsidence of some parts of the land. 



The sea is the insatiable monster, which devours these little islands, gorges 

 itself with the earth, sand, clay, and all the yielding parts, and leaves nothing, 

 where it can reach, but the skeleton, the bared rock. The continual advances 

 which the sea makes on the low lands, are obvious, and within the last 30 years 

 have been very considerable. What we see happening every day may assure us 

 of what has happened in former times; and from the banks of sand and earth 

 giving way to the sea, and the breaches becoming still more open, and irrecover- 

 able, it appears that repeated tempests have occasioned a gradual dissolution 

 of the solids for many ages, and as gradual progressive ascendency of the 

 fluids. 



Again, the flats, which stretch from one island to another, are plain evidences 

 of a former union subsisting between many now distinct islands. The flats be- 

 tween Trescaw, Brehar, and Sampson, are quite dry at a spring tide, and men 

 easily pass dry-shod from one island to another, over sand banks, (where, on the 

 shifting of the sands, walls, and ruins are frequently discovered) on which at 

 full sea there are 10 and 12 feet of water. History confirms their former union. 

 " The isles Cassiterides, says Strabo, are 10 in number, close to one another; 

 one of them, is desert and unpeopled, the rest are inhabited." But see how the 

 sea has multiplied these islands: there are now reckoned 140; into so many frag- 

 ments are they divided, and yet there are but 6 inhabited. 



But no circumstance can show the great alterations which have happened in 

 the number and extent of these islands more than this, viz. that the isle of 

 Scilly, from which the little cluster of these cyclades takes its name, is no more 

 at present than a high rock, of about a furlong over, whose clifTs hardly any 

 thing but birds can mount, and whose barrenness could never suffer any thing 

 but sea-birds to inhabit it. 



It has been mentioned before, that on shifting of the sands in the channel, 

 walls and ruins are frequently seen; there are several phenomena of the same 

 nature, and owing to the same cause, to be seen on these shores. Here then 

 we have the foundations, which were probably 6 feet above high-water mark, 

 now 10 feet under, which together make a difference as to the level of l6 feet. 

 To account for this, the slow advances and depredations of the sea will by no 

 means suffice; we must either allow, that the lands inclosed by these fences have 

 sunk so much lower than they were before; or else we must allow, that since 

 these lands were inclosed, the whole ocean has been raised l6 feet perpendicular; 

 -which last will appear much the harder and less tenable supposition of the two. 

 Here then was a great sudsibence ; the land between Sampson and Trescaw sunk 



