SUPPLEMENT: 



Being an Extract from the Researches of M. de Prony, 

 on the Hydraulic System of Italy : Containing an 

 Account of the Displacement of that Part of the 

 Coast of the Adriatic which is occupied by the Mouths 

 of the Po. 



JL HAT portion of the shore of the Adriatic which 

 lies between the lake, or rather lagune, of Comma- 

 chio and the lagunes of Venice, has undergone con- 

 siderable alterations since ancient times, as is at- 

 tested by authors worthy of entire credit, and as is 

 still evidenced by the actual state of the soil in the 

 districts near the coast ; but it is impossible now 

 to give any exact detail of the successive progress 

 of these changes, and more especially of their 

 precise measures, during the ages which preceded 

 the twelfth century of our era. 



We are, however, certain, that the city of Ha- 

 now called Mria, was formerly situated on 



