OTES. 



NOTE A. 



The average volume of water annually flowing down the Ohio is shown in the text to be 

 835,000,000,000 cubic feet. This volume would fill a lake 100 feet deep and 17 J miles square. 



To have regulated the supply of the river in 1848, so as to have kept the depth on the bar at 

 Wheeling uniform throughout the year, would have required reservoirs capable of holding 

 240,000,000,000 cubic feet, which is equivalent to a single lake 100 feet deep and 9J miles square. 



There is no difficulty, on any of the principal tributaries of the Upper Ohio, in obtaining reservoirs 

 capable of holding from twelve to twenty thousand millions of cubic feet. It can scarcely be doubted 

 that twelve or fifteen sites for dams may be selected capacious enough to hold all the excess of water, 

 and equalize the annual discharge so nearly, that the depth may be kept within a very few feet of an 

 invariable height. 



NOTE B. 



It is by no means improbable that a sufficient depth of water may be constantly maintained in the 

 Ohio, above Louisville, to permit boats to ascend the Falls at all times, and thus supersede the 

 necessity of a new and enlarged canal. But the measurements now in the possession of the writer 

 having been all made at Wheeling, and applied to the records kept at that point, he cannot express a 

 positive opinion upon this important question. The results, as far as they go, point to an equalization 

 of the daily discharge of the Ohio as, possibly, the cheapest mode of improving the Falls ; making 

 that work an incidental consequence of a systematic and adequate improvement of the general naviga- 

 tion of this river and its tributaries. 



NOTE C. 



Although there has never been any attempt made, or proposition offered, to su])ply the channels of 

 great navigable rivers from stores of water held in reserve, as is here contemplated, yet experiments 

 have been made, and expedients resorted to, in various practical operations, so analogous to this 

 method, that they ought to have led to some such suggestion. 



It has long been the practice on some of the smaller rivers of Europe, to erect moveable dams, 

 which would retain the water, and overflow the shoals above the dams ; and when the boats have 

 passed the upper shoals, the dam is lowered, and the boats allowed to descend with the water of the 

 pool ; and keeping on the top of the wave, they are thus enabled to pass the shoals below. 



A similar expedient has been long in use on Oil creek, and some of the other tributaries of the 

 Alleghany river. The lumber men there frequently send their lumber from the smaller tributaries 

 into the larger, by opening the sluices of their mill dams, and Creating a flood sufficient to float their 

 rafts into deeper water. 



The Lehigh Navigation Company of Pennsylvania were compelled, for many years before the com- 

 pletion of their improvement, to send their arks, loaded with coal, down the channel of the Lehigh by 

 the same process. The fall of the river was rapid, and the supply of water very insufficient. The arks 

 were floated through the pools formed by (he dams, and passed by locks into the channels below. The 

 water was then drawn through sluices from the pool above the dam, and the coal boats were borne on 

 the top of the wave over the shoals in the channel. 



The Schuylkill Navigation Company have been in the practice for years, when their boats have 

 grounded in the pools from want of water, of increasing the depth by drawing water through sluice 

 gates in the dams above. Even the small dams on that river are so supplied with gates for venting 

 the water, that the stream is kept in complete control during the summer season. By opening the 

 gates the pond above is emptied, and a small flood is produced below. By closing the gates, the 

 supply furnished by the river is held back for many hours, while the empty pool is being replenished. 

 During that time no water reaches the channel below. 



