“This river is three hundred yards wide at the point where it receives the waters of Medicine (Sun) River, which is one hundred and thirty-seven yards in width.  The united current continues three hundred and twenty-eight poles to a small rapid on the north side, from which it gradually widens to fourteen hundred yards, and at the distance of five hundred and forty-eight poles reaches the head of the rapids, narrowing as it approaches them.  Here the hills on the north, which had withdrawn from the bank, closely border the river, which, for the space of three hundred and twenty poles, makes its way over the rocks, with a descent of thirty feet.  In this course the current is contracted to five hundred and eighty yards, and after throwing itself over a small pitch of five feet, forms a beautiful cascade of twenty-six feet five inches; this does not, however, fall immediately or perpendicularly, being stopped by a part of the rock, which projects at about one-third of the distance.  After descending this fall, and passing the cottonwood island on which the eagle has fixed her nest, the river goes on for five hundred and thirty-two poles over rapids and little falls, the estimated descent of which is thirteen and one-half feet, till it is joined by a large fountain boiling up underneath the rocks near the edge of the river, into which it falls with a cascade of eight feet.  The water of this fountain is of the most perfect clearness, and of rather a bluish cast; and, even after falling into the Missouri, it preserves its color for half a mile.  From the fountain the river descends with increased rapidity for the distance of two hundred and fourteen poles, during which the estimated descent is five feet; and from this, for a distance of one hundred and thirty-five poles, it descends fourteen feet seven inches, including a perpendicular fall of six feet seven inches.  The Missouri has now become pressed into a space of four hundred and seventy-three yards, and here forms a grand cataract, by falling over a plain rock the whole distance across the river, to the depth of forty-seven feet eight inches.  After recovering itself, it then proceeds with an estimated descent of three feet, till, at the distance of one hundred and two poles, it is precipitated down the Crooked Falls nineteen feet perpendicular.  Below this, at the mouth of a deep ravine, is a fall of five feet; after which, for the distance of nine hundred and seventy poles, the descent is much more gradual, not being more than ten feet, and then succeeds a handsome level plain for the space of one hundred and seventy-eight poles, with a computed descent of three feet, the river making a bend towards the north.  Thence it descends, for four hundred and eighty poles, about eighteen and one-half feet, when it makes a perpendicular fall of two feet, which is ninety poles beyond the great cataract; in approaching which, it descends thirteen feet within two hundred yards, and, gathering strength from its confined channel, which is only two hundred and eighty yards wide, rushes over the fall to the depth of eighty-seven feet.