Ohio Falls . 
163 
shew us that the descending water will not long preserve the 
depth of three feet, but will descend so rapidly as in a little time 
and before it reaches the bottom, be reduced to the depth of a few 
inches ; this consequence uniformly attends water which passes, 
over an inclined plane without obstruction. The rapidity, there- 
fore, and want of depth, would make it of little use. To obviate 
this in a fall like the Ohio, which passes such a quantity of water* 
is easy. For having occasion but for a part of it in the first in- 
stance, the residue is suffered to move on, and is drawn in from 
time to time as you have need of it. If it was all compelled to 
enter the sluice at one time, it would create a fall at the upper 
end, besides overflowing your shute or channel. These lateral 
or tributary dams are therefore introduced, in the first place, to 
check the rapid descent of the water, and to keep up an adequate 
supply : the first it accomplishes by entering the channel at an 
angle in opposition to the current ; the other by the quantity of 
water which it adds to it. At what distance those lateral dams 
might admit of being separated, and yet keep up the requisite sup- 
ply, must depend on several considerations ; but, it is evident, 
that they cannot be too close together, because the lower end of 
the dam at $ is but little higher than the wall of the shute, and 
discharges its water over, it if the shute is full, and by that means 
supplies the dam next below it, if it should require it, which also 
acts in like manner in its turn. These dams, however, are form- 
ed with but little trouble, nature having in all such falls, in a 
great measure, prepared them to your hand in the various curves 
and indenting of the rocks ; nor is it at all necessary that they should 
be made with the regularity of the drawing-all that is necessary 
being to compel it to enter your channel at certain distances by a 
tough but substantial obstruction at any convenient point. And so 
easy is this done, that I have seen in the Susquehanna a counter 
current of more than a quarter of a mile, formed by a dam of 
loose round stones ; the current running directly opposite to the 
natural course of the stream and almost as rapidly. These coun» 
ter currents of the tributary dams will so check the velocity of the 
current in the shute that I make not the least doubt, that if it 
should be executed on this plan, of loaded boats being able to 
ascend with perfect ease. 
With the aid of a small steam boat, which should avail itself 
of the ring bolts placed at certain distances along the shute, and, 
after joining them, draw after it successive a loaded boat. I 
should make no doubt of its ascending the falls with 100 tons. 
