90 wiscoxsiisr academy sciences, arts, and letters. 



precisely upon the plan of our own lake shore harbors. Parallel 

 dykes are carried out to a depth where the action of the waves 

 cease to disturb the bottom, which is in about eighteen feet, the 

 channel is cleared by dredging and the natural current of the river 

 maintains the same, the detsitus moved down by the river is car- 

 ried off by the littorral current into deep water. The question as 

 to how long these artificial structures will serve their purpose, is a 

 matter not j'et determined. Operations were carried on for many 

 years at the mouth of the Rhone by dykes and jetties, which plan 

 had finally to be abandoned. It was hoped that by closing the 

 lateral outlets, and by confining the channel between contracted 

 banks that a sufficient depth might be obtained, but the works 

 were not carried out to a sufficient depth, and the mass of allu- 

 vium carried down, left the outlet in about the same condition as it 

 was before the improvement. Finally, a canal was constructed to 

 the " Gulf de Fos " so called from a former canal constructed by 

 Marius. This canal (St. Louis) is entirely sufficient for the require- 

 ments of commerce. In connection with this canal there is a very 

 extensive basin to serve the purpose of trans-shipment to the steam- 

 ers navagating the shallow portions of the river. 



It appears that a system of jettees is the plan that has most gen- 

 erally been resorted to by engineers for the improvement of the 

 mouths of rivers. In some cases they have been attended with 

 partial success, and in others the enormous expense involved did 

 not warrant the completion of the experiment. 



An attempt was made about 1857 to improve the Southwest 

 Pass of the Mississippi, but a tempest swept away a jettee of over 

 a mile in length. 



In reviewing the subject, we may safely conclude that the jetty 

 system would give but temporary relief in working rivers, although 

 the plan has succeeded admirably in the majority of our inland 

 harbors where the same was applied. 



Returning directlj"- to our own subject, we find the Mississippi 

 one of the most active working-rivers in the world. The South 

 Pass increases at the rate of one hundred feet annually, and the 

 other principal passes even more. 



From the manner in which it is brought before the public we 

 know that it is obstructed to a great degree and requires a remedy. 

 For years the government has been engaged, and with considerable 



