Above this fall, the Missouri bends suddenly to the northward, where, four hundred and seventy-three yards wide, it is suddenly stopped by one shelving rock, which without a single niche, and with an edge as straight and regular as if it had been formed by art, stretches itself across from one side of the river to the other. Over this the Missouri precipitates itself in one even, uninterrupted sheet, of four hundred and seventy-three yards broad to the perpendicular depth of forty-seven feet eight inches; whence, dashing against the rocky bottom, it rushes rapidly down, leaving behind it a spray of the purest foam across the river. At the distance of less than half a mile, another of a similar kind is presented. Here a cascade stretches across the whole river, for a quarter of a mile, with a descent of fourteen feet seven inches, though the perpendicular pitch is only six feet seven inches. For the space of one thousand one hundred and seventy-seven yards above this cascade the river descends fifteen feet. Immediately above this, one of the largest springs in America falls into the river. Its water is cold, of the most perfect clearness, and of a bluish color, which it preserves, even for half a mile after falling into the Missouri, notwithstanding its rapidity. This fountain rises in the plain, twenty-five yards from the river, on the south side. In its course to the river, it falls over some steep, irregular rocks, with a sudden descent of eight feet perpendicular, in one part of its progress. The water boils up from among the rocks, and with such force near the centre that the surface seems higher than the earth on the sides of the fountain, which is a handsome turf of green grass. The water is pleasant to the taste, not being impregnated with lime or any adventitious substance. For the space of a mile and one thousand one hundred and sixty-six yards above the mouth of this spring, the descent of the river is thirteen feet six inches. During the upper part of its course, this river is remarkable for a succession of rapids, cascades, and cataracts, and in a course of about three miles it has a descent of no less than three hundred and fifty-two feet. On the _Mississippi River_ are several sets of rapids. One called _Les Rapides des Moines_, is eleven miles long, and consists of successive ledges and shoals, extending from shore to shore across the bed of the river. One hundred miles higher up is another, about eighteen miles in length, and consisting of a continued chain of rocks, over which the water flows with turbulent rapidity.