casional fields.

"Of course," said John, after a time, "we know this spot, and know why
you and Mr. Billy brought us here. It's the Fort Rock of Meriwether
Lewis--it couldn't be anything else!"

Uncle Dick smiled and nodded.

"That's what she is," nodded Billy. "Right here's where Cap'n Lewis
stood and where he said was a good place for a fort--so high, you see,
so no Indians could jump them easy. But they never did build the first
fur fort here; that was higher up, on the Jefferson, little ways.

"Up yonder's the Gallatin--we're up her valley a little way. My ranch is
up in ten miles. Yonder used to be quite a little town like, right down
below us. Yon's the railroad, heading for the divide, where we came over
from Prickly Pear. Other way, upstream, is the railroad to Butte. Yon
way lies the Madison; she heads off southeast, for Yellowstone Park. And
yon's the main Jefferson; and the Madison joins her just a little way
up. And you've seen the Gallatin come in--the swiftest of the three.

"Now what would you do, if you was Lewis?" he added. "And which way
would you head if you wanted to find the head of the true Missouri and
get on across the Rockies?

"You see, we're in a big pocket of the Rockies here--the great
Continental Divide sweeps away down south in a big curve here--made just
so these three rivers and their hundred creeks could fan out in here.
She's plumb handsome even now, and she was plumb wild then. What would
you do? Which river would you take?"

"I'd scout her out," said John.

"They did. You look in your book and you'll find that, while Lewis was
in here Clark was nigh about forty miles above here; he plumb wore his
men out, twenty-five miles the first day above the Forks, twelve miles
the next. That was up the Jefferson, you see; they picked it for the
real Missouri, you see, because it was fuller and quieter.

"They didn't waste any time, either of them, on the Gallatin. That left
the Madison. So Clark comes back down the Jefferson and they forded her,
away above the Forks--no horses, on foot, you see--and near drowned that
trifling fellow Chaboneau, the Indian girl's husband.

"Then Clark--he wasn't never afraid of getting lost or getting drowned,
and he never did get lost once--he strikes off across the ridges,
southeast, heading straight for the Madison, just him and his men, and
I'll bet they was good and tired by now, for they'd walked all the way
from Great Falls, hunting Indians, an