40 PHYSICAL GEOGRAPHY OF 



The discharge of the Ohio, calculated from the data offered in the foregoing 

 record, exhibits for the volume of water which flovred past Wheeling in 1844, a 

 season of more than ordinary drynetss, 



650,982,000,000 cubic feet ; 



and for the average daily discharge, 



1,779,000,000 cubic feet; 



and for the uniform height which this quantity would have maintained upon the 

 bar at Wheehng, 



7/15% feet. 



The drainage of the country for that year was tVt of a foot ; or, 



ll-/inj inches ; 



which is almost precisely the amount ordinarily assumed by engineers as the 

 supply that may be relied on for canal feeders, but by no means that which 

 ought to be uniformly anticipated. There ip, in fact, scarcely an approach to 

 uniformity in the annual discharge of streams in this climate. 



The practical conclusions drawn from the analysis of the record for the year 

 1844 are also important. During a portion of September the water fell below 

 14 inches on Wheeling bar; and both in August and October it was down as 

 low as 3 feet, or less. Yet, the irregular discharge for the month of August 

 was sufficient to have maintained an uniform depth, throughout that month, of 

 4iVTr feet ; and it would have required no greater accession to the natural sup- 

 ply of the stream, if this supply had been properly regulated by art, to maintain 

 an uniform depth of 5 feet, than would be afforded by many of the dams actu- 

 ally erected and in use on the navigable rivers of this country. 



In the month of September the water was down as low as H foot; yet a sin- 

 gle dam on the Alleghany, and one other on the Monongahela — neither being 

 larger than those already built by the Monongahela Navigation company — pro- 

 perly constructed, and supplied with appropriate gates, would have been all- 

 sufficient to have regulated the actual discharge, and maintained an uniform 

 depth of 4 feet throughout that month. 



It may be stated as a general fact, which can be fully demonstrated by these 

 measurements, that two dams, no higher than the Blue Mountain dam on the 

 Schuylkill navigation — one of which should arrest the waters of the Alleghany, 

 and the other those of the Monongahela — could be safely relied on for perma- 

 nently maintaining a depth of 4 teet, and clearing the river effectually of obstruc- 

 tion from ice, so that the navigation for boats of that draught need be subject 

 to no future interruptions. A depth of 4 feei will permit the best class of Pitts- 

 burg and Cincinnati packets to run all the year; and this result could have been 

 easily obtained in 1844 for a sum not exceeding ^300,000. 



