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a difference of latitude and an increase of elevation; second, contrariety of direction in some of the streams which constitute the sources of the river; third, the time required for the waters of the Upper Mississippi, of the Missouri, and of other distant regions, to traverse the long distance from the sources to the mouths of this mighty river. The difference of latitude from the mouths to the remotest sources of the Mississippi is about 20 degrees, and the relative elevation not less than 5000 feet. These elements combined would give a winter climate to the sources of the Missouri or Mississippi, equal to that of Labrador, in latitude 61°, on the Atlantic coast. Permanent snows cover the earth in winter, over the Atlantic slope and Mississippi basin, as low as latitude 310, the waters from which, it is obvious, cannot be simultaneously discharged. The general course of the flood being south, the spring advances in a reverse direction, and releases in succession the waters of the lower valley, then those of the Ohio, and last those of the Mississippi proper and the Missouri. Rising in latitude 42° to 50° north, and at an elevation of from 1200 to 5000 feet, the higher sources of the Mississippi are locked in ice and snow long after summer reigns on the Delta. Then the course of the Missouri and Yellowstone Rivers is to the north-east at first, for 500 or 600 miles, from which circumstances, together with the slow movement of the waters, it results that the waters of the upper sources of the Mississippi do not reach the Delta before the beginning of August, about 100 days after the breaking up of winter, and

more than a month after the inundation has been abating. The average height of the floods, below the mouth of the Missouri, is 15 feet. From the Missouri to the Ohio it rises 25 feet, and for a great distance below the mouth of the Ohio it rises 50 feet. Before reaching Natchez, the height of the floods begins to decline. At Baton Rouge it seldom exceeds 30 feet, and at New Orleans 12. This gradual diminution in the flood, in the lower part, has been supposed by some to result from the draining through the numerous effluxes of the river, conveying away such considerable portions of its waters by separate channels to the sea. So greatly does the quantity of snow and rain differ in different years, that it is quite impossible, even for those who have had the longest experience, to anticipate, with an approach to certainty, the elevation which the flood will attain in any given year. Some years the waters do not rise above their channels, and no inundation takes place. As the banks of the river in the Delta, from the cause above noticed, are higher than the general level of the country, constituting an alluvial margin of from half a mile to a mile and a half wide, it becomes important to protect some of the more valuable tracts in the rear from the annual overflow of the river, from which they could not easily be drained. For this purpose an artificial embankment has been raised at great expense upon the margin of the river, called the Levee. On the east side this embankment commences 60 miles above New Orleans, and extends down the river more than 130 miles. On the west side it com

mences 172 miles above New Orleans.

The vast trade of the Valley of the Mississippi centres at New Orleans. Vessels are often from 5 to 30 days ascending the river to this port, unless they employ the steam tow-boats, though they will often descend with a favorable wind in 12 hours. Before the introduction of steamboats it required 8 or 10 weeks to go to the mouth of the Illinois. The use of steamboats has nearly superseded all other vessels for ascending the river. Boats of 40 tons ascend more than 2000 miles, to the Falls of St. Anthony. The passage from Cincinnati to New Orleans and back has been made in 19 days. The first steamboat on the western waters was built at Pittsburg in 1811, and there are now over 300 on the Mississippi and its tributaries, many of them of great burden. By the opening of the Illinois Canal from Chicago to the head of navigation in the Illinois River, a connection has been formed between the waters of the River St. Lawrence and the Mississippi, of sufficient draught to admit the passage of small vessels, laden with their cargoes of merchandise. Some time in the autumn of 1849, the first vessel was reported at New Orleans as having arrived from the St. Lawrence, via the Welland Canal, the great lakes, the Illinois Canal and River, and the Mississippi. Returning by the Atlantic coast, she might then have circumnavigated the United States.

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The sources of this great river take their rise in the Rocky Mountains, and some of their springs are within a mile of other springs which discharge themselves west, through the Columbia River, into the Pacific Ocean. The three principal streams which constitute

the head waters of the Missouri are the Jefferson, the Madison, and the Gallatin, which unite at the same point in latitude 45° 10′ north, and longitude 110° west. From their confluence at this point, the river takes the name Missouri, and flows onward, receiving numerous tributaries in its course, through a distance of more than 3000 miles, to its junction with the Mississippi, in latitude 38° 51′ north, and longitude 90° west. Its course is at first north and north-east, to the mouth of White Earth River, latitude 47° 25′; thence south-east about 220 miles, to the Mandan villages, or Indian settlements. From this point, the river takes a south course, through a distance of several hundred miles; and then, being inflected more to the east, it pursues this general direction to the Mississippi. ALthough it loses its name at its confluence with the Mississippi, it is, before it reaches this point, much the longest and largest river of the two, and, physically considered, is entitled to be denominated the principal, rather than the secondary. The Missouri is already a very large river, when it approaches and passes the sources of its very inferior rival. If it be ranked according to physical preeminence, as including the Mississippi from its confluence with that river to its mouth, it has an entire length of about 4350 miles, and is prob ably the longest river of the earth. Ranking it as a secondary to the Mississippi, and having reference to the area drained by its channel, it is the largest river of that class in the world. A direct line drawn along its valley, from its junction with the Mississippi River

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