SCIENCE 



FRIDAY, AUGUST 24, i{ 



Aside from its economic importance, which cannot be 

 exaggerated. Major Powell's letter to the New Orleans Chamber of 

 Commerce, printed in full on another page of Science, on the relief 

 of the alluvial lands of the lower Mississippi from destructive floods, 

 contains the first formal announcement of a new law in the hydraul- 

 ics of rivers. It is set forth in these words : " The cutting power 

 of a stream increases rapidly with the increase of sedimentary load." 

 This principle was briefly stated by Major Powell in a short oral 

 address before the American Association for the Advancement of 

 Science, about ten years ago, and he has indirectly referred to it 

 two or three times since, in a word or two, in his writings ; but 

 this is the first specific statement of it that he has made, and this 

 he considers as barely more than indicating the line of discussion 

 which he has long intended to pursue in a volume that he proposes 

 to write upon the subject. But the principle is stated in this paper 

 with sufficient detail and illustration to arrest the attention of phy- 

 sicists and engineers, and to give rise to an interesting discussion. 

 This Major Powell invites, and the columns of Science will be 

 gladly placed at the disposal of any of its readers who may desire 

 to express an opinion, either favorable or unfavorable, to the new 

 theory. 



It is cheering to note that another step in advance in the line 

 of statistical science has recently been taken. A year ago Colonel 

 Wright made a marked impression by demanding that statistics be 

 given a place in the collegiate curriculum. Now the American 

 Statistical Association, which possesses a quiet history of forty 

 years in its records, announces a publication, to appear at regular 

 intervals, devoted to the interests of statistics. This association in 

 the past has been practically but a local society of Boston, formerly 

 fostered by the late Dr. Jarvis, so eminent in the field of vital sta- 

 tistics, and at the present time officered by General Walker (its 

 president), and Mr. Edward Atkinson (its corresponding secretary). 

 The association welcomes to membership all who are interested in 

 statistical work, and hopes in the future to be able to issue a repre- 

 sentative journal which may compare favorably with similar Euro- 

 pean publications. There is no reason why this cannot be done. 

 In no country is the utility and application of statistics more gen- 

 erally recognized than in the United States: it only remains to 

 create an intt;lligent interest in their proper collection and tabu- 

 lation. The venture of the publication of a work upon technical 

 statistics, like that of Mr. Pidgin, entitled ' Practical Statistics,' 

 furnishes added testimony to the development in progress. We 

 also understand that during the past year a course upon statistics 

 has been introduced at the University of Michigan, under the direc- 

 tion of Prof. Henry C. Adams. 



PRE\'EXTION OF FLOODS IN THE LOWER MIS- 

 SISSIPPI. 

 POPUL.AR interest in the proposed investigation by the United 

 States Geological Survey, of the problem of storing the waters of 

 the upper Missouri and other Far Western rivers in great reservoirs, 

 and the reclamation by irrigation of vast areas of what are now 

 waste lands, spreads as some of the incidental effects of those great 

 works, should they be undertaken, are beginning to be understood. 

 An illustration of this is a letter from the New Orleans Chamber 

 of Commerce to Director Powell, asking him what the effect of the 



proposed reservoir system will be upon the commercial and agri- 

 cultural interests of the lower Mississippi. In reply he has pre- • 

 pared and forwarded the following paper, which, aside from the 

 economic possibilities it suggests, is an important contribution 10 

 the scientific discussion of the hydraulics of the Mississippi River. 

 The paper is given in full. 



The control of the lower Mississippi is a problem of great mag- 

 nitude, and the conditions are of great complexity. The end 10 

 be attained is to give the channel stability of position, and sufficient 

 depth and breadth to make it a perfect conduit, capable of transport- 

 ing to the sea all the water sent down by floods, thus relieving the 

 adjacent country from danger of overflow. To accomplish this end 

 it is necessary (1) to prevent the choking of the channel by excessive 

 sedimentation, and this is the most important remedy; and (2) to 

 diminish the volume of the floods by the storage of water above at 

 flood-time : this is an accessory but important remedy. The relief 

 of the river from excess of sediment, and the storage of the super- 

 abundant water at flood-time, may be accomplished by the same 

 method, and its accoinplishment may also involve the irrigation of 

 the arid lands on the eastern slope of the Rocky Mountains. All 

 this must be set forth more fully. 



The Mississippi and its tributaries receive and transport to the 

 sea the drainage of about 1,250.000 square miles. To obtain an 

 idea of the work done by this river system, some facts must be 

 understood. 



The volume of drainage passing New Orleans is, on the average, 

 675,000 cubic feet per second, or about 150 cubic miles per year. 

 The average contributions in cubic feet per second of the principal 

 tributaries in the system are, in round numbers, as follows : — 



Cubic Feet per Seconi). 



Upper Mississippi loo.cwa 



Missouri 120,000 



Ohio 160,000 



St. Francis 30.''<» 



Arkansas and White 60,000 



Red 60.003 



A portion of the grand total poured into the valley below Cairo 

 escapes through the Atchafalaya and other bayous even at average • 

 river stages, put probably not less than eighty per cent of that total •■ 

 finds its route to the sea at present by way of the Crescent City. 

 During flood-stage the outflow by the same route rises to about 

 one million cubic feet per second ; but the rate of inflow into the 

 valley may at such stages exceed twice the carrying capacity of the . 

 main branch of the Atchafalaya. Of the three main tributaries, the 

 discharge has been found to rise during floods in the upper Missis- ■ 

 sippi and Missouri to three times, and in the Ohio to seven times,* 

 the average amount. 



Such, in brief, are the most apparent facts as to the volume of 

 drainage discharge. But these do not disclose two other facts 

 which are of prime importance in the engineering problems pre- • 

 sented by the Mississippi ; viz.. that this river is a river of mud fron>- 

 the Missouri to the Gulf, and that the Missouri is the principal 

 source o( mud-supply. 



Much attention has been given recently by the Mississippi River 

 and the Missouri River Commissions to obser\-ations of the- 

 amount of sediment in transport at various points along the Missis- 

 sippi and Missouri. These observations show that near New Or- 

 leans the amount of sediment in transport varies from 5^5 to -^-^ 

 part of the total volume discharged, and averages about y,',-,5 pa^ 

 of that volume. Above the mouth of the Missouri the Mississippi 

 carries much less sediment, the range being from 5^5 to yuo'cisis. w-ithr 

 an average of ^^-Vj part of the volume. The Missouri, on the other 

 hand, is always heavily loaded with sediment. Just above its point 

 of confluence with the Mississippi the amount in transport varies 



