248 EXPEDITION TO THE 



the surveys in Ohio, that the descent between the moutii 

 of the Muskingum and Cincinnati, a distance nearly double 

 that of the portion just mentioned, is no more than one 

 hundred and twenty-seven feet. Hence also we may assume 

 six hundred and eighty feet as the elevation of the Ohio, 

 at Pittsburg, above tide-water ; and that the aggregate fall 

 of the Ohio, below that place, is about thi-ee hundred and 

 eighty feet, while that of the Mississippi, below the mouth 

 of the former, is about three hundred feet. If we suppose 

 the plane of Lake Erie extended westwardly, its coinci- 

 dence with the bed of the Illinois or rather of the Des 

 Plaines, will probably take place at a point about twenty 

 miles above the entrance of the Kankakee.* The same 

 plane extended would intersect the Mississippi in or near 

 the De Moyen rapids, probably at their head. The surfaces 

 of Lakes Huron and Michigan may be regarded as hav- 

 ing an elevation of six feet, and that of Lake Superior of 

 thirty feet, above the plane above mentioned. 



The writer above alluded to advances a doctrine, to the 

 correctness of which we feel considerable reluctance in 

 yielding our assent, viz. that the surface of the Gulf of 

 Mexico is elevated one hundred and twenty-five feet 

 above that of Chesapeake Bay, or in other words, that the 

 gulf stream is occasioned in a great measure, if not exclu- 

 sively, by a declivity in the Atlantic Ocean, correspond- 

 ing to the velocity and direction of its current. Until the 

 truth of this proposition be satisfactorily established, we 

 shall content ourselves with the assumption that the level 



• In Vol. II. pag-e 382, of tlie Account of an Expedition from Pitts- 

 burg' to tlie Rocky Mountains, a mistake lias been committed, wbich 

 we here take occasion to rectify. Instead of four luindred and fifty 

 feet, which is there stated as tlie altitude of the head of the Illinois 

 above tide-water, it should have been five hundred and fifty feet. 



