REPORT ON HYDRAULICS, PART II. 



467 



In the third, by the amount of the high, mean, and ordinary 

 volumes of water. 



The velocity of the waters of the adjoining part of the river 

 must also be considered. 



The advantage of the curvilinear directions is, that the force of 

 the centrifugal projection of the current on the concave side of 

 the river can be more easily counteracted. 



The proper determination of the radii of curvature for the cuts 

 must depend on the inclination and force of the current ; and 

 from careful observations of the lengths of the curves in different 

 parts of the rivers, M. de Fontaine determined the maximum 

 lengths of the radii of curvature at 2200 metres where the depth 

 in the curved part of the river was 15 "36 metres, and where the 

 corrosion did not exceed 11 metres in depth in the curve; he 

 fixed the minimum length of the radius at 1250 metres. 



Declivities of the Rhine, from a series of experiments made 

 with the Stromm Messer of Woltmann, on the velocities of 

 the Rhine in different sections, according to the following 

 Table. 



Velocities at different parts 

 of the Section. 



Number 



turns of 



made by 



the 



Instrument 



in 30 



seconds. 



Space 

 passed 



through 

 in 30 



seconds. 



Velocity 



per 

 second. 



Average 

 Velocity 

 per second. 



Surface 

 of the 



Section of 

 Motion 

 of the 



diffferent 

 Strata. 



Mean 

 Velocity 



of the 

 Section. 



Mean 

 Velocity 

 deduced 

 after the 

 Formulas 

 of that of 

 the Surface. 



Met. 



At the surface 



— 0"10 met. below. 



— 0-20 - 



— 0-30 



_ 0-40 



_ 0-50 



_ 0-60 



_ 0-70 . 



— 0-80 



68 



67t 



65|- 



63|. 



62 



59 



58 



29-308 

 29-020 

 28-111 

 27-345 

 27-024 

 26-291 

 25-429 

 24-998 



Met. 

 l-OOOO 

 0-9769 

 0-9673 

 0-9370 

 0-9115 

 0-9008 

 0-8764 

 0-8476 

 0-8333 



Met. 

 0-9959"! 

 0-9769 

 0-9578 

 0-9388 

 0-9198 

 0-9008 

 0-8817 

 0-8627 

 0-8437 



0-8347 intersec- 

 tion of" the two 

 divisions 



— 0-90 met. below.., 

 _ 1-00 



— 1-10 or 



— 1-10 met. from the 



bottom.... 

 Bottom 



1-0131117 



52-1 

 491- 



22-682 

 21.281 



18-964 



0-7563 

 0-7094 



0-6321 



0-8371 



0-7867 

 0-7094 



0-6321 



0-5548J 



Note. — These velocities have been taken from experiments made over an 

 extent of 60 metres, by means of a float, so suspended that its specific weight 

 did not exceed that of the water. 



2 H 2 



