1884.] ^^ [Carson. 



enormous mass of facts and data was collected and tabulated, showing the 

 length, slope, dimensions of cross-sections, discharge, area of basin, down- 

 fall of rain, and drainage of the Mississippi and its tributaries. In this 

 way all of the important facts connected with the various physical condi- 

 tions of the river were ascertained, reduced and digested ; the laws unit- 

 ing them were determined, and out of seeming chaos the beautiful results 

 of science were evolved, leading to simple and practical conclusions, and 

 the great problem of protection against inundation was solved. Various 

 suggestions, theories, and expedients, which had been much discussed in 

 Europe, and broached in this country by Charles Ellet, were disproved 

 and condemned. In the language of the Report: "It has been demon- 

 strated that no advantage can be derived either from diverting tributaries 

 or constructing reservoirs, and that the plans of cut-ofis and of new or 

 enlarged outlets to the Gulf, are too costly and too dangerous to be 

 attempted." 



The decision was in favor of the system of levees. 



The question of the protection of the valley from inundation having 

 been satisfactorily determined, attention was next directed to the improve- 

 ment of navigation by the deepening of the mouths of the river. The 

 first problem was one of national, the second of international, importance. 

 In the same thorough way the facts relating to the delta were collected 

 and studied, as well as those relating to the mouths of the river and their 

 bars, and a plan was reported for increasing the depth of water on the 

 bars. A ship canal was urged to obviate the difficulties and dangers 

 of the passes, while the temporary and fallacious expedient of jetties was 

 strongly condemned. 



The spirit in which the entire work was executed is that of the well- 

 chosen motto of the title page— the words of Franklin to Abbe Souliave — 

 "I approve much more your method of philosophizing, which proceeds 

 upon actual observations, makes a collection of facts, and concludes no 

 further than those facts will warrant." 



In addition to the purely scientific features of the work, it contains 

 chapters of the utmost historic value. In chapter iii, the state of the 

 science of hydraulics, as applied to rivers, is exhaustively considered. A 

 complete chronological list is given of all the works bearing upon it, with 

 a resume of their contents. It sets forth all that was previously known 

 about river hydraulics, both in Europe and in this country ; whh special 

 studies, in part conducted by General Humphreys when in Europe, of 

 the Nile, Neva, Rhine, Rhone, Garonne and the Po. The phenomena of 

 great floods from 1718 to 1859 are fully stated, and a succinct account is 

 given of the progress of the levee system in the Mississippi valley. 



Finally, in elaborate appendices, each one of which is systematic and 

 complete, the statistics are given upon which all computations are based. 

 It is needless to state that the mathematical features, together with the 

 maps and diagrams, are as elaborate as the other portions of the work. 



A political lesson of the utmost consequence in its relations to the Fed- 



