THE MISSISSIPPI VALLEY. 33 



The analysis of the tabulated results for 1846, shows that the total drainage 

 of the Ohio river for that year was — 



879,1 19,000,000 cubic feet ; 



and the average daily discharge — 



2,409,000,000 cubic feet. 



If the discharge had been uniform throughout the year, the depth of the water 

 on the bar at Wheeling would have been constantly 9T'Tnr feet. 



The drainage from the whole surface of the country was, for the year, ItWit 

 feet ; or, 



ISt/o inches. 



The greatest monthly drainage was in March, and amounted to — 



3| inches ; 

 and the least monthly drainage again in September, when it amounted to — 



ttV of an inch. 



The practical results of the inquiry for this year, also, are exceedingly inter- 

 esting. We find, by reference to the table of heights on the bar, that in the 

 beginning of the month of January, as at the close of the previous December, 

 the water fell to 3^ feet in the channel, and the river was then closed by ice. 

 But experience has shown that this river never freezes at Wheeling, excepting 

 when the water falls so low that the ice grounds on the bars and chokes the 

 channel. Consequently, if the proper depth of water were maintained in the 

 river, so that the ice, instead of lodging, would be carried by a brisk current 

 over the bars, it could not jam and form dams, behind which the still water 

 could freeze and the floating particles collect. 



The whole period of low water, and consequent stoppage of the navigation in 

 December, 1845, and January, 1846, was but 14 days; and the whole quantity 

 of water which would have been required, over and above the actual flow, was 

 but 660,000,000 cubic feet per diem, or 9,240,000,000 altogether, for the 14 days, 

 to have maintained a depth of six feet constantly in the channel. 



Now, there are many places upon the upper tributaries of the Ohio, where a 

 dam 45 feet high would form a suflicient reservoir to furnish this quantity ; and 

 an inspection of the records in this paper will show that such a reservoir may be 

 emptied many times during every winter, with full confidence that it will be 

 promptly replenished by the rains and melted snows. 



But we observe by the table of heights for 1846, that the river was not only 

 low at the end of December and the beginning of January, when a discharge of 

 water was needed to carry off" the ice and restore the navigation ; but that it rose 

 and fell also in February, so as again to require aid from the artificial store : 

 that it was down also in March as low as 3i feet — a depth too little for the first 



