OF WATERING PLANTS. 149 



The inhabitants, therefore, found it expedient to put a 

 stop to this levelling system of Nature by embanking the 

 rivers, in order to confine the waters within their beds. 



Caroline. We observed that in Lombardy and in 

 Tuscany the rivers were generally embanked : but I 

 should have thought that such a measure would have af- 

 forded but a temporary remedy ; for those very sands, 

 which Nature would have employed to raise the general 

 level of the plains, being deposited at the bottom of the 

 rivers, would in the course of time, so raise their beds, 

 that the waters would overflow the embankments. 



Mrs. B. Very true ; their only resource was to raise 

 the embankments in proportion as the bed of the rivers 

 were elevated. In consequence of this elevating system 

 of art, in opposition to the levelling one of Nature, the 

 Adige and the Po are higher . than the plains which sep- 

 arate the two rivers ; and it is thought that it will be ul- 

 timately necessary to form new beds for their waters, in 

 order to avoid the ruin they threaten. 



The plains of Holland derive their origin from a similar 

 process ; but they are exposed to still greater dangers 

 than those of Italy, lying so low as to be menaced not 

 only by the overflowing of the Rhine and the Moselle, 

 from the shallowness of their beds, but by inundation of 

 the sea. Every defence which art can afford, such as 

 embankments, dykes, canals, &c., has been achieved by 

 the patient and industrious inhabitants of that enterpri- 

 sing country ; yet the resistless ocean frequently breaks 

 in upon them, and destroys all their labors. 



Emily. What a prodigious quantity of earth and sand 

 these rivers must carry into the sea ! It is well that its 

 bed is too deep, to be affected by such depositions. 



Mrs. B. It is true there is no danger of their occa- 

 sioning an overflowing of the sea : important effects, how- 

 ever, are frequently produced on its shores. The impulse 

 of the rivers is diminished on reaching the sea, by that of 

 the waves they have to encounter. Sometimes their wa- 

 ters are partially repelled back on the shore, where they 



825. What does Caroline observe of the rivers in Lombardy and in 

 Tuscany! 826. What is said of the Adige and the Po 1 ? 827. Of 

 the plains in Holland! 828. How are inundations there prevented? 

 829. What consequences result from rivers losing their velocity on en- 

 countering the waves of the ocean'? 



