A the Heart of the Continent Captain Clark continued his observations up the long series of rapids and falls until he came to a group of three small islands to which he gave the name of White Bear Islands, from his having seen numerous white, or grizzly, bears on them.
On the nineteenth of June, Captain Clark, after a careful survey of the country on both sides of the stream, decided that the best place for a portage was on the south, or lower, side of the river, the length of the portage being estimated to be about eighteen miles, over which the canoes and supplies must be carried.
Next day he proceeded to mark out the exact route of the portage, or carry, by driving stakes along its lines and angles.
From the survey and drawing which he made, the party now had a clear and accurate view of the falls, cascades, and rapids of the Missouri; and, it may be added, this draught, which is reproduced on another page of this book, is still so correct in all its measurements that when a Montana manufacturing company undertook to build a dam at Black Eagle Falls, nearly one hundred years afterwards, they discovered that their surveys and those of Captain Clark were precisely alike.
The total fall of the river, from the White Bear Islands, as Lewis and Clark called them, to the foot of the Great Falls, is four hundred twelve and five-tenths feet; the sheer drop of the Great Fall is seventy-five and five-tenths feet.
The wild, trackless prairie of Lewis and Clark's time is now the site of the thriving town of Great Falls, which has a population of ten thousand.
Here is a lucid and connected account of the falls and rapids, discovered and described by Lewis and Clark:
"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 Here the hills on the north, which had withdrawn from the bank, closely border the river, which, for the space of three hundred and twenty poles, makes its way over the rocks, with a descent of thirty feet.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 ****** 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.
"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, added to the decline during that distance, 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 in four hundred poles is thirteen feet; within two hundred and forty poles, another descent of eighteen feet; thence, in one hundred and sixty poles, a descent of six feet; after which, to the mouth of Portage Creek, a distance of two hundred and eighty poles, the descent is ten feet.
From this survey and estimate, it results that the river experiences a descent of three hundred and fifty-two feet in the distance of two and three quarter miles, from the commencement of the rapids to the mouth of Portage Creek, exclusive of the almost impassable rapids which extend for a mile below its entrance."