440 FOURTH REPORT — 1834. 



fluence of the t\vD rivers were as the square roots of the actual 



heights, the cubes of the heights would be as the squares of 

 the quantities of water wliich are discharged in an equal time 

 by the sections. 



Manfredi deduced that the Reno, which added ^^ part of the 

 whole quantity to the Po, could not raise the height of the Po 

 more than jj part ; but, reflecting afterwards that some expe- 

 riments made on adding or subtracting the water of a drain to 

 and from the Panaro, occasioned no difference in the elevation 

 of the surface of that river, he concluded that the elevation of 

 the Po must be very small for any augmentation which the 

 waters of the Reno could cause in its stream*. The fatal conse- 

 quences which had arisen from dividing the Rhine into so many 

 branches from the frequent bursting of the embankments which 

 maintained them above the adjacent lands, and the continual 

 expenses entailed by them, necessarily excited great interest. 



The great Rhine divides itself near Emmerik into two branches, 

 nearly equal to each other, viz., the Waal and the Rhine : the 

 bed of each of these branches is nearly as large as that of the 

 whole river before its division, and when the waters rise they 

 are at an equal height in both. The second branch divides itself 

 again towards Arnheim to form the Issel, which has nearly the 

 same section as that of the Rhine. 



The first division of all the waters of the Rhine was begun 

 under the Roman generals Drusus and Corbulo : many subdivi- 

 sions were made in subsequent ages. This great multiplicity of 

 channels, although productive of advantages to Holland, occa- 

 sioned many fatal consequences : the waters, divided into so 

 many branches, lost the rapidity and strength necessary for 

 them to push forward the alluvial matter, occasioned a conti- 

 nual rising of the bottom, rendered the draining of the waters 

 from the adjacent lands more difficult, increased the expense of 

 the embankments, and augmented the damages over the exten- 

 sive lands when the dykes broke. 



" To secure that part of Holland which lies between Rotter- 

 dam, Utrecht, Amsterdam, and the ocean, it was proposed in 

 1754," says Frisi, " to form a cut, with sixteeen sluices, in the 

 Leek, which is another branch of the Rhine, by which part of 

 the waters woiUd be discharged into the Meruva, which is the 

 junction between the Waal and the Meuse. M. Gennete op ■ 

 posed the project on the ground that it would not have dimi- 

 nished the height of the floods, but that it would have been pre- 



• See Major-General Gaistin's Translation of Paul Frisi's Work on Rivers 

 and Torrents. 



