To what shall we attribute this surprising difference, 

 this amazing disproportion? Not, certainly, to the al- 

 luvion brought down by the current of the river Po. 

 If its waters had been rendered turbid with mud or jil- 

 luvion, from one end of the year to the other, for the 

 space, of two hundred years, which is a case unheard 

 of or unknown, we could scarcely believe, that it 

 would afford a sufficient quantity to produce that dif- 

 ference ; for it must be recollected, that as the delta 

 advances into the Adriatic, or any other sea, the depth 

 of the water is very much increased, and, particularly, 

 when we advance to the distance of twenty-one miles 

 from the shore ; at least it is so in most seas. 



M. de Prony has attempted to account for this rapid 

 increase of annual deposites, by two causes. 



First, the cultivation of the southern slope of the 

 Alps, and the districts on the borders of the Po, and, 

 consequently, by the facility with which the moun- 

 tain torrents, which flowed into the rivers, conveyed 

 away the soil. 



It is very natural to suppose that these circumstances 

 would tend much indeed, to increase the quantity of 

 alluvion, since but very little is ever seen to be carried 

 away from uncleared, or uncultivated lauds, although 

 exposed to the full force of torrents of rain. 



In a country covered with forest trees, and a bed of 

 leaves, or upon, land covered with a thick sward, the 

 water, during a torrent of rain, .is seen to run off in 

 all directions, almost as clear as it fell from the clouds. 

 This may be observed, in such situations at all times 



