REPORT ON HYDRAULICS. PART II. 455 



Neither do the results of his experiments on the amount of 

 expenditure correspond with those deducible from the rate of 

 inclination of the surface. 



The uniform motion which he has supposed in rivers scarcely 

 exists in nature. 



The article on rivers contained in the fourth volume of the 

 Architecture Hydraulique, by Belidor, published in 17^9, is 

 compiled from the works of Guglielmini and Michelini. 



Th^QNoiiveaux PrincipesiV Hydraiiliqi(,eoi'Bc\'v\dxdi,^\i\iY\&hQ^ 

 in the year l787j contains much that is valuable relative to the 

 origin, formation, and establishment of rivers. 



His theory of the efflux of water from the sides of a prismatic 

 vessel and along an inclined channel, and the pressure sustained 

 by a diaphragm placed at one of its extremities, is founded upon 

 the principles of Bernoulli, D'Alembert, Bossut, and Dubuat ; 

 the practical applications are derived from Guglielmini and other 

 writers. His observations on the inclinations and velocities of 

 several of the rivers in France, such as the Saone, the Durance, 

 the Rhone, led him to conclude, that there existed no precise 

 rules in these respects. In several, the mean velocity was found 

 to be |ths of the depth. 



According to Lalande, all rivers increase the height of their 

 waters as they approach their embouchures; the Saone was 

 observed to swell higher at its confluence with the Rhone, at 

 Lyons, than a league above it. 



Bernard concludes with Frisi, that the gravels found in the 

 beds of rivers are not owing to the attrition of rocks and larger 

 stones in the upper parts of the beds of rivers, but that they 

 exhibit themselves accidentally, accordingly as they are traversed 

 by the rivers. The swell and consequent action of rivers are 

 greatest at their points of junction. Inundations are greater in 

 the superior than in the inferior parts of rivers, on account of 

 the pressure of the upper waters, although the velocity of the 

 lower waters be greatest. The same had J)een remarked by 

 Castelli and other writers. 



The banks of the Po are 20 feet in height at 50 or 60 miles 

 distance from the sea,whei'eas at 10 or 12 miles distance from the 

 sea the banks are only 12 feet in height, whilst the breadth of 

 the river is the same in both places. 



Amongst the subsequent writers of the French, German, and 

 Dutch schools, may be mentioned Fabre, Lecreulx, Sturm, 

 Leupold, Meyer, and Brunnings. 



All of them merit attention, from the many vakiable observa- 

 tions with which they abound relative to the natural phenomena 

 of rivers, but it is doubtful whether they have advanced the 

 science. 



