600 IMPROVEMENTS IN NOETH AMEEICAN HTDROGEAPHY. 



Improvements in Worth American Hydrogra/phy. 



We are riot yet well enougli acquainted with the geography of 

 Central Africa, or of the interior of South America, to conjecture 

 what hydrographical revolutions might there be wrought ; but 

 from the fact that many important rivers in both continents drain 

 extensive table-lands of moderate elevation and inchnation, there 

 is reason to suppose that important changes in the course of those 

 rivers might be accomphshed. Our knowledge of the drainage 

 of l^orth America is much more complete, and it is certain that 

 there are numerous points within our territory where the courses 

 of great rivers, or the discharge of considerable lakes, might be 

 completely diverted, or at least partially directed into different 

 channels. 



The surface of Lake Erie is 565 feet above that of the Hudson 

 at Albany, and it is so near the level of the great plain lying east 

 of it, that if was found practicable to supply the western section 

 of the canal, which unites it with the Hudson, with water from 

 the lake, or rather from the I^iagara which flows out of it. The 

 greatest depth of water yet sounded in Lake Erie is but two hun- 

 dred and seventy feet, the mean depth one hundred and twenty. 

 Open canals parallel with the ^Niagara, or directly towards the 

 Genesee, might be executed upon a scale which would exercise 

 an important influence on the drainage of the lake, if there were 

 any adequate motive for such an undertaking. Still easier would 

 it be to enlarge the outlet for the waters of Lake Superior at the 

 Sault St. Mary — where the river which drains the lake descends 

 twenty-two feet in a single mile — and thus to produce incalcida- 

 ble effects, both upon that lake and upon the great chain of in- 

 land waters which communicate with it. 



The sumjnit level between the surface of Lake Michigan at its 

 mean height and that of the river Des Plaines, a tributary of 

 the niinois, at a point some ten miles west of Chicago, is but ten 

 and a half feet above the lake. The lake once discharged a part 

 or the whole of its waters into the valley of the Des Plaines. A 



Rhine rose to the level of the railway station at Sargans, and for some days 

 there was fear of the giving way of the barrier and the diversion of the cur- 

 rent of the river into the lake. 



