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 perpendicular, 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 its nest, the river goes on for five hundred and thirty-two poles over rapids and little falls, the estimated descent of which is thirteen feet six inches 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.  It is of the most perfect clearness and rather of a bluish cast; and even after falling into the Missouri it preserves its colour for half a mile.  From this fountain the river descends with increased rapidity for the distance of two hundred and fourteen poles, during which the estimated descent is five feet from this for a distance of one hundred and thirty-five poles, the river descends fourteen feet seven inches including a perpendicular fall of six feet seven inches.  The river 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 the Missouri then proceeds with an estimated descent of three feet, till at the distance of one hundred and two poles it again is precipitated down the Crooked falls of 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, making a bend towards the north.  Thence it descends during four hundred and eight poles, about eighteen feet and a half, 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 and three quarters of an inch.  After raging among the rocks and losing itself in foam, it is compressed immediately into a bed of ninety-three yards in width:  it continues for three hundred and forty poles to the entrance of a run or deep ravine where there is a fall of three feet, which, joined to the decline of the river during that course, makes the descent six feet.  As it goes on the descent within the next two hundred and forty poles is only four feet:  from this passing a run or deep ravine the descent for four hundred poles is thirteen feet; within two