The river, in its unrestrained rambles from bluff to bluff, performs some curious freaks. It develops the most remarkable bends, varying in length from one to thirty miles, with distances across the necks but a small fraction of those around. In time these narrow necks are cut in two, and the river abandons its old course, which soon fills up near the extremities of the bends and leaves crescent-shaped lakes in the middle. This process is a never-ending one, and the channel distances along the river are in a state of never-ending change. There is one bend in the upper river, known from the earliest times as the Great Bend, which was not formed in the way just described. The course of the river here is comparatively permanent, and is evidently the same as that of the original stream bed. The distance around is nearly thirty miles, while that across is only a mile and a half. It was a regular custom with travelers, when the Indians were not too dangerous, to leave the boats at the beginning of this bend and walk across, going on board on the other side. The existence of so many bends increased the length of the channel, but this drawback was more than offset by the reduction of the slope which made the current less strong and enabled steamboats to overcome it with greater ease. The river is like a great spiral stairway leading from the ocean to the mountains. A steamboat at Fort Benton is 2565 feet--two and one-half times the height of the Eiffel tower in Paris--above the level of the sea; yet so gentle is the slope nearly all the way that, in placid weather, the water surface resembles that of a lake. This wonderful evening-up of the slope of the river by the extreme sinuosity of its course is a fact not only interesting as a natural phenomenon, but of the utmost importance in the behavior and use of the stream. [Illustration: CHANGES OF THE CHANNEL OF THE MISSOURI RIVER THROUGH MONONA COUNTY, IOWA. _Present Channel Distance, 44 Miles_ (COMPILED BY MITCHELL VINCENT, ONAWA, IOWA.)] Not only does the general course of the river have these larger windings, but in periods of low water they are multiplied many fold. When a large proportion of the river bed between its banks becomes exposed, as it does in the low-water season, the stream flows back and forth across this bed until its length is largely increased over that at high water. Here again is to be seen the wisdom of nature’s methods. In periods of high water, when it is important to move the floods rapidly down the valley, the river straightens out, shortens its length, increases its slope, and accelerates its velocity of flow. [Sidenote: ANNUAL TONNAGE.]