Apkil 15, 1904.] 



SCIENCE. 



6uy 



culable destruction of property, to say 

 nothing of the cost to build them. 



There is one place where it would be 

 possible, in an imaginative sense, to im- 

 pound a volume of water that would be 

 missed from the river. That place is the 

 St. Francis basin, 6,700 square miles in 

 area. By cutting that area up into sub- 

 divisions by dams crossing it at frequent 

 intervals, and increasing in height progress- 

 ively down stream as rapidly as the slope 

 of the land surface would permit a vast 

 storage of water could be secured, many 

 feet deep at its lower border. But the only 

 material that can be found there to make 

 the dams of is earth. The expense of stone 

 would be scarcely thinkable. And to im- 

 . prison such a volume of water at the head 

 of such a valley as would lie below it with 

 only earthen walls to hold it back would 

 be nothing less than criminal foolhardiness. 

 The best use we can make of the reservoir 

 theory is to keep it to talk about. 



We frequently hear the present large 

 projects for the storage of water for pur- 

 poses of irrigating arid lands in the west 

 spoken of as though valuable aid in the 

 control of the floods of the Mississippi could 

 be obtained from those works. For want 

 of more accurate knowledge of the possible 

 extent of that storage and its locality I can 

 say no more than that while it may help a 

 little, it appears to me that it can be no 

 more than very little. It must be remem- 

 bered that it would be of no advantage to 

 the Mississippi River to diminish its volume 

 at ordinary stages, or even ordinary flood 

 stages. It is only by the power of its vast 

 discharge that its great channel has been 

 produced or can be maintained. A per- 

 manent reduction of its ordinary annual 

 floods would tend to diminish its channel 

 capacity. Better a great channel with a 

 maximum discharge of 2,000,000 cubic feet 

 per second than a less channel with three 

 quarters of that volume, so the water can 



be kept within the banks. If the irriga- 

 tion reservoirs should operate, as I fancy 

 they would, to store a substantially uniform 

 quantity of water each year and distribute 

 it over cultivated lands, to be for the most 

 part evaporated or absorbed, they would 

 serve no useful purpose to the Mississippi 

 except in rare and extreme floods, when it 

 may be said that the smallest reduction is 

 of some value. 



All this emphasizes more and more the 

 main truth that the present levee system 

 has been so thoroughly tested, and has been 

 of such incalculable value, and is so near 

 completion, that it is a sort of treason to 

 turn aside to talk about anything else for 

 any other purpose than to illustrate by 

 contrast the transcendent importance of 

 finishing up what we have in hand. 



Even this phrase needs definition. In a 

 sense the levees of the Mississippi never will 

 be finished. But they can be extended, 

 raised and strengthened until they will hold 

 the water even in such floods as that of last 

 spring. At that period they will be 'fin- 

 ished' in the only sense in which it will 

 ever be possible to apply that word to them. 



It is not necessary, either, to the achieve- 

 ment of 'success' that they shall never be 

 broken by crevasses. I have said that dur- 

 ing the flood of 1903 the existing levees 

 protected from overflow seven eighths of 

 all the lands capable of protection by them 

 if not one had failed. Suppose we should 

 never be able to do better than that. Sup- 

 pose great floods should come once in five 

 years, and we should always save seven 

 eighths of the land from overflow. That 

 would mean that, upon the whole, taking 

 all the years and the whole valley into ac- 

 count, there would be an average annual 

 inundation of two and a half acres out of 

 every hundred. I should call that success. 



Robert S. Taylor. 

 Fort Wayne, Ind. 



