86 wiscoKsi^sr academy sciences, arts, axd letteks. 



onl}'' vegetation is a species of tall reed, the fibrous roots of whicli 

 give a little cohesion to the ooze, and prevent its being dissolved 

 and washed away by the succession of tides. Farther down the reeds 

 disappear, and the banks of mud form, are washed away and form 

 again, wandering, so to speak, between the river and the sea, at the 

 will of the winds and tide. On the left bank of the southwest pas- 

 sage, which is used for the largest ships, the plank built huts of a 

 small pilots village have been fixed as delicately as possible. These 

 constructions are so light, and the ground that carries them is so 

 unstable, that they have been compelled to anchor them like ships, 

 fearing that a hurricane might blow them away; still, the force of 

 the wind often makes them drag on their anchors. Below, the 

 banks of the Mississippi are reduced to a mere belt of reddish mud, 

 cut through at intervals by wide cross streams; still farther down 

 even this narrow belt comes to an end, and the banks of the river 

 are indicated by nothing but islets, which rise at increasing dis- 

 tances from one another, like the crests of submarine dunes. Soon 

 the summits of these islets assume the appearance of a thin, yellow 

 palm floating on the surface of the v-^ater. Then all is mud; the 

 land is so inundated with water that it resembles the sea, and the 

 seals so saturated with mud that it resembles the land. Finally, all 

 trace of the banks disappears, and the thick water spreads freely 

 over the ocean. After getting clear of the bar, the sheet of water 

 which was the Mississippi preserves, during floods, the yellowish 

 color by which it can be distinguished for about twenty miles, but 

 it loses in depth all that it gains in extent, and, gradually deposit- 

 ing the earthy matter which it holds in suspension, becomes ulti- 

 mately mingled with the sea." 



This beautiful illustration gives one at once an idea of the difS- 

 culties of navigating the Delta, which in storms and dark weather 

 becomes uncertain and dangerous even with the assistance of expert 

 pilots. Now, in connection with the above, if we consider the in- 

 sufiicient depth of channel, our problem at once becomes manifest. 

 Before however entering upon the solution of the problem, we will 

 examine the working of rivers, and the means applied to remove 

 the resulting obstruction in the deltas and mouths of rivers. 



The amount of alluvion brought down and deposited in the gulf 

 annually is estimated equal to a mass one mile square and 268 feet 

 high. The " Hoangho," which probably carries more alluvium than 



