138 THEORY OP THE EARTH. 



some day become united to the main land, in spite 

 of every effort to preserve her insular situation.* 



We learn from Strabo, that Ravenna stood 

 among lagunes, in the time of Augustus, as Ve- 

 nice does now; but Ravenna is now at the dis- 

 tance of a league from the sea. Spina had been 

 originally built by the Greeks on the sea-coast ; 

 but in the time of Strabo the sea was removed to 

 the distance of ninety stadia. This city has been 

 long since destroyed. Adria, which gave name to 

 the Adriatic, was, somewhat more than twenty 

 centuries ago, the chief port of that sea, from 

 which it is now at the distance of six leagues. 

 The Abbe Fortis has even produced strong evi- 

 dence for believing that the Euganian hills may 

 have been islands, at a period somewhat more 

 remote. 



M. de Prony, a learned member of the Insti- 

 tute, and inspector-general of bridges and high- 

 ways, has communicated to me some very valu- 

 able observations, to explain the changes which 

 have taken place on the flat shores usually deno- 

 minated the Littoral of the Adriatic, and which 

 will be found appended to this Essay. Having 

 been directed by government to examine and re- 

 port upon the precautions which might be em- 



See a Memoir qn the Lagunes of Venice, by M. Forfait. 



