Southern shield., 1858-08-28

l organ grinder the better for himself and party.-N 0. Crese''f,
 HELENA, Aug. IS, 1858.
 MR. Q. K. UNDERwooD-I last week gave my views as to the cost of cut-offs and le- wees. This time propose to give my views as'to the effect upon the current, channel, &c. Some oppose cut-offs on account of their influence upon the current of the river. That the effect will be to increase it there can not be doubt, but as to how much, it is impossible for me to tell. The question is as to the effect of that increase. The ad- vocates for levees claim that they will in- crease the current, and say if the levees are made strong enough to 'shold the water to | its work" the consequence will be that in 8 sr fe1r uears the food-level of the water will l sink below the banks.7 l contend that the | effect of the increased current will be worse with the levees than the cut offs, for the reason that the increased current will do the greatest amount of damage in the bends l ! ed fact that the bends cave much worse than the straight places. The cut-offs will do in one Year what the levees will be yeGfs doing, and during this suspense there will be little or no immigration, but, on the con- trary, planters will move away from their lands, as many are doing now.
 4 gentleman found fault with with mo for advocating offs, because. as he thought, was unsettling the banks by cut offs. He seemed to think that the banks were settled and would cave little or none, ] if we only made levees. l think the only l fact settled about Mississippi banks is that they have always caved, from the time the river was first seen by white man, and do not think he or any one else can show me place five miles long from Cairo to the E4outh. where the banks have not cayed in the last year, either on one side Or the other. By quickening the current, either by cut offs or levees, the cavin@ is made greater for q time, and by cut offs places are made to cave that did not previously. But should dislike to insure any place from caving, as we often see places commence caving anl be ruin-l in few years, that the owners thought per- fectlv secure. The effect of a cut off is to change the channel of the river and to make the current strike the banks at different places from where it did previously. Gen. erallv the current leaves the old bed of the river below the cut off and strikes the point opposite, and is thrown back into the old bend of the river some miles below, form ing bar in the old bed, and washing away one on the opposite point. This, in most instances, can be avoided, at least partially, by varying the ditch for the cut of. For instance, at any proposed cutoff, the engi- neer should examine the points to be cut through above and below and endeavor to make the current through the cut off tako as near the old channel as possible, and by locating the ditches a quarter or half mile one way or the other, the current could be varied without adding much to the cost of the ditch. For instance, had the ditch at the American Cut off been made a quar- ter or half mile nearer the State levec, the water would have gone through in such a course that it would have taken nearly the old channel and the banks would have caved less than previously. And this is the reason 1 am opposed to individuals making cut offs. Individuals make the ditch at the narrowest part of the point to save cost of the ditch, but the State should make the ditch where it would straighten the river most and do the least damage below.
 Many persons apply the term canon to the changing of the current from side to side of the river, saying that the water can- ons from one point to the other. If un- derstand the term it has no more applica- tion to the river than it has to turning over dirt with plough. When the current strikes the bank it does not rebound, but follows the bank until it comes to some abrupt point which gives 1t direction from the bank, and the momentum of the water is in a nearly straight direction until it meets some obstruction, which it either washes away or again changes its course.- There is nothing like the rebound of bill- iard ball in the whole operation.
 As to the amount of quickening of the current a certain increased fall would give, can only conjecture. The current is sup posed to vary from two and a half miles per hour in low water to five miles in high water, with fall of three and half inches per mile. Thereare so many qualifying cir cumstances also that it is almost impossible to estimate the effect of the increased fall upon the banks. There is a certain rate of ONAI SLAU GU NIlOll DOOUOLl uSlbuGF WsiSI6S deeper nor fills up. This has been termed "point stationary" As the bottom of the river will only wash out when the current exceeds the Fpoint stationary,'' and fills up when the current is less, it depends upon how long time and how high the river gets above thls 'spoint." The tendency will be to fill up or wash deeper according to the aver age of the river for the year. And here is point to which should like to call the at- tention of a levee- man, n,-and that is tho effect of confning the water to the channe of the river, instead of letting it waste of into the swamps and making vast reservoirs to keep the river above this 'point" in the lower portion of the river. For example the water wastes out of the river, on this side from fifty miles above Cairo dowr nearly to St. Francis river, thus treating al immense reservoir. This water IS hell 'ln'