April 15, 1904.] 



SCIENCE. 



603 



level; but not very much— not enougli to 

 change any element of the problem, nor to 

 introduce into it any new difficulty except 

 the additional expense necessary to build 

 and maintain the embankments at the 

 higher grades required. The levees have 

 done their work so well and are so far ad- 

 vanced toward completion that the aban- 

 donment of that system for an attempt to 

 protect the alluvial lands in some other way 

 is not to be considered for a moment. The 

 interests involved are too vast to be put in 

 jeopardy by. experiment. To complete the 

 existing system and maintain it is a duty 

 so plain that it is not open to discussion. 

 At the same time there is no reason why 

 the believers in outlets and reservoirs 

 should not continue to advocate their theo- 

 ries, nor why their argiiments should not 

 receive the compliment of polite refutation. 

 There is still great lack of information on 

 the subject in the public mind. The gov- 

 ernment has spent large sums from the 

 United States treasury in aid of levee 

 building, and must continue to do so if they 

 are to be perfected and maintained; and 

 all citizens who care to look into the sub- 

 ject are entitled to know why that method 

 of protection has been and is to be pursued 

 instead of others that are proposed. 



Nothing could be more natural than the 

 suggestion to seek relief from great floods 

 by providing additional channels for the 

 surplus water ; and it takes some close con- 

 sideration of the subject to perceive the 

 fallacy of the proposal. But it is, as I 

 shall attempt to show, a delusive scheme 

 as a means of protection against ovei-flow 

 of general permanent practicability and 

 utility. In the consideration of the sub- 

 ject I shall try to come a little nearer to it 

 than has been heretofore attempted, so far 

 as I know, by locating an outlet system on 

 the only lines upon which it would be avail- 

 able for the advantage of the alluvial valley 

 as a whole, and discussing its feasibility 



and utility from a practical standpoint. 1 

 have indicated such a system by the con- 

 tinuous red lines on the accompanying map. 

 The broken red line is to be disregarded for 

 the present. 



Such a system would necessarily begin in 

 the St. Francis basin. Suppose we should 

 make a group of outlets near the head of 

 that basin and connect them with a channel 

 of sufficient capacity to carry, say, one 

 tenth or one fifth of the combined discharge 

 of the Ohio and the Upper Mississippi dur- 

 ing great floods. The water thus diverted 

 would be returned to the main channel at 

 the foot of the basin, and would produce a 

 flood height there as great as though the 

 same water had come down the main chan- 

 nel. What should we do with it there? 



A possible answer would be to make an- 

 other outlet on the other side of the river 

 into the head of the Yazoo basin, with a 

 channel of like dimensions down that basin 

 to its foot at the mouth of the Yazoo. To 

 follow up the plan it would be necessary 

 to make a third outlet, leading this time 

 into the Tensas basin, with a channel lead- 

 ing down that basin across Red River and 

 through the Atchaf alaya basin to the gulf. 

 We would then have two rivers from the 

 head of the St. Francis basin to the sea, 

 of which one would cross the other twice 

 as a canal sometimes crosses a river in a 

 pool raised by a dam. Those parts of the 

 river in the neighborhood of the crossings 

 would have to carry the whole flood volume 

 and would require levees as high as, or 

 higher than would be required in a levee 

 system without outlets. 



Such a combination would be enormously 

 expensive. The secondary channel would 

 be not less than flve hundred miles long. 

 In order to carry water enoiigh to afford 

 substantial relief from floods of the first 

 magnitude it would need to be of large 

 capacity. It would pass through the cen- 

 tral parts of the fat alluvial basins. To dig 



