20 ON CHANGES IN THE DISPOSITION 



change the position of a former one. The bank gene- 

 rated at the mouths of the Nile, by the opposing ac- 

 tions of the stream and of the sea, soon produces an 

 island ; which, united to the shore, and becoming the 

 gradual basis of vegetation, extends the region of the 

 Delta. The Gulf of Pe-tche-lee is similarly filled 

 with islands ; the extensive shoaling of the shores 

 round the mouths of the Amazon, is the prelude to 

 that further extension which the coast is here under- 

 going: while the land advances fifteen leagues in a 

 century under the power of the Mississipi. The Gulf 

 of Mexico is gradually filling up in the same manner ; 

 though the gulf stream here assists, by means of the 

 earth conveyed along the eastern shore : the land 

 having been so far extended, that shells are now found 

 thirty miles in the interior. If the insignificance of 

 our own rivers does not permit us equally to witness 

 these effects, they are still sufficiently sensible every 

 where, and most distinctly so at the mouth of the Tay. 

 With respect to the sea line, if the general effect is 

 to change its form by extending the land, the ultimate 

 practical results are very different. Thus towns, once 

 maritime, are now many miles inland; as Ravenna, a 

 sea port in the time of Augustus, is at present, a league 

 from the sea. And thus, as commerce has been ex- 

 cluded from harbours, and wealthy territories ruined, 

 might physical causes have done for Venice, what 

 moral ones have effected with far greater speed. But 

 if this increase, combined with political and moral ruin, 

 has destroyed many more of the once wealthy ports of 

 the Mediterranean, the same operation, in other places, 

 aided by the rise of empire and by industry, has added 

 to the world, cities and harbours not less populous 

 and flourishing; destined in their turns to submit to 

 the same fate, as nature, ever steady, shall triumph over 



