REPORt ON HYDRAULICS. — PART II. 46/|f 



Maximum and Minimum Depths under the mean level of the 



JVater. 

 The greatest depths of the Rhine do not exceed, on the ave- 

 rage, four or five metres, except in particular places, such as the 



Rock of Istein, where the depth is 9*70 metres j 



At Rhein Weiller 7'00 — 



At the Spur of Blodelsheim 12-00 — 



At the foot of the volcanic rock of Sponeck . 11*50 — 



At the extremity of ditto 18 "GO — 



At thefoot of the Glasserwoerth 25*00 — 



Plitersdorif 13-60 — 



From which it appears that the influence of corrosion is very 

 great where the current is obstructed, and hence the necessity of 

 the artificial works undertaken by M. de Fontaine. 



Floods. — The floods of the Rhine occur periodically, namely, 

 from the end of May to the middle of September, during the 

 melting of the glaciers, after which the river returns to its 

 ordinary flow. The greatest floods generally happen about 

 March, after the first melting of the snows, but they occasionally 

 occur in other months. The rise of the waters at Basle seldom 

 commences until three days after tlie greatest rains and meltings 

 of the snow ; the greatest rise in 24 hours never having ex- 

 ceeded 2-92 metres at Basle in 22 years ; and at Kehl, 1-38 metres 

 in 27 years. The floods of the aflSuents (between Basle and 

 Lauterbourg,) which descend from the Vosges and Black Forest 

 mountains, are generally over before the arrival of the floods 

 from Switzerland. This phsenomenon arises from the great 

 difference which prevails between the sections at Basle and Kehl : 

 for some time the Rhinometers at the two places indicate nearly 

 equal elevations; but as soon as the floods commence, tlie eleva- 

 tions no longer maintain the same relation to each other ; on the 

 contrary, when the Rhine has risen O'Ol metre at Kehl, it has risen 

 0*016 metre at Basle; and this relation occasionally varies with 

 the changes in the two sections. The years 1801 and 1824 were 

 remarkable for the extreme rises of the waters, not only in the 

 Rhine but in all the rivers of France. 



Tables are added in M. de Fontaine's report showing the maxi- 

 mum and minimum oscillations of the waters at Basle, Kehl, and 

 Lauterbourg, for 22, 27, and 10 years respectively. 



Expeiiditure of the Rhine. 



(From a series of gauges taken at Basle, Vieux Brisach, and 

 Kehl, according to the different states of the river at these 

 places.) 



1834. 2 H 



