172 " OF THE MISSISSIPPI, 



are great, and they are consequently better fitted for the pur- 

 poses of navigation. The Mississippi is supposed to be naviga- 

 ble (pursuing the western branch or Missouri) 3000 miles at 

 least from the ocean. Those who have studied the theory of 

 rivers inform us, that the stability of the bed of a river de- 

 pends upon a due equilibrium between the velocity of the 

 current and the tenacity of those matters which compose its 

 bottom and sides: the velocity of rivers is greatest at the sur- 

 face, gradually diminishing downwards; hence when the bot- 

 tom is composed of matter of the most yielding nature, the 

 channel will continue to deepen until the velocity at bottom 

 is almost nothing, and the depth of the water will be regulated 

 by those circumstances: the bottom of the bed of the Missis- 

 sippi, within the alluvial country, being composed of the 

 finest sand and lightest earth extremely comminuted, it is not 

 surprising that its depth should be comparatively great; its 

 soundings have (it is believed) never been taken with minute 

 attention, but from New-Orleans to the mouth of the river, 

 its depth is said to be from 50 to 70 fathoms, under the thread 

 of the current, which follows the concave shore; diminishing 

 gradually towards the elbows, where there are frequently con- 

 siderable shallows. The sudden effect of the diminution of the 

 velocity of water is no where more remarkable than at the 

 mouth of this river, for the rolling torrent no sooner arrives at 

 the ocean, than, rinding its bed indefinitely enlarged, it spreads 

 on all hands; the thread of the current diverges into an infi- 

 nite number of filaments like radii from a center ; the velocity 

 of the mass of water rapidly diminishes until, no longer able 

 to propel the matter hitherto suspended and swept along by 

 the swiftness of the stream, it is deposited in form of a crescent, 

 opposing to the mouth of the river, a bar with from 12 to 20 

 feet water. The current being less, immediately to the right 

 and left, than in front, of the mouth of the river, the deposi- 

 tion and accumulation of matter will consequently proceed 

 more rapidly on either side, and the velocity of the current 

 being increased by the contraction of the channel, the bar will 

 be protruded further into the ocean; hence it appears why the 

 mouths of all auuvial rivers terminate in a promontory pro- 



