"Two outboard motors, one on each side the stern, rigged on a cross plank," said Jesse, never smiling. "Besides, a head sail when the wind is right behind. And a rope if we got a head wind. And the oars and paddles, too. We've paddled hours. Every little." "We could get gas easy," said John. "Lots of towns all along, now." "Easy as shooting fish," drawled Jesse. "I'm making a model of a new flying ship now, though it isn't all done. I can run one of those motors." "What say, Rob?" Uncle Dick turned to the oldest of the three, and the one of soberest judgment, usually. "I shouldn't wonder if it's the answer, sir," said Rob. "How many miles a day must we average?" "As many as we can. Lewis and Clark and their big boat did eight or ten, sometimes fifteen or twenty--the average was about nine miles a day. It took them all summer and fall to get to the Mandans. That's above Mandan, South Dakota--a thousand miles or so, eh?" "Just sixteen hundred and ten miles, sir," said Rob, "according to their figures. Just about nine miles a day, start to finish of that part of the run, here to the Mandans--though the modern estimates only call it fourteen hundred and fifty-two miles." "If we can't beat that average I'll eat the boat," said Jesse, gravely. "Well," said Uncle Dick, beginning to bite his fingers, as he often did when studying some problem, "let's see. A good kicker might do two or three miles an hour, by picking out the water. Two good kickers might put her up to five, good conditions. Some days we might do forty miles." "And some days, on long reaches and the wind O.K., we'd do forty-five or fifty," said Rob. "Of course, we can't figure on top notch all the way. We've got to include bad days, break-downs, accidents, delays we can't figure on at home, but that always get in their work somehow. Look at all our own other trips." "Depends on how many hours you work," said Frank. "We don't belong to the longshoremen's union, you know. Some days we might travel twelve hours, if we'd nothing else to do. And I don't think there's much fishing, and it would be off season for shooting, most of the time." "I'll tell you," said Uncle Dick, after a time. "I doubt if we could do it all the way by boat by September. But I'll see your teacher, here in St. Louis, where we're all going to winter this year, and arrange with him to let you study outside for the first few weeks of the fall term in case we don't get back. You'll have to work while you travel, understand that." The boys all agreed to this and gave their promise to do their best, if only they could be allowed to make this wonderful trip over the first and greatest exploring trail of the West. "It can perhaps be arranged," said Uncle Dick. "You mean, it has been arranged!" said Rob. "You've spoken to our school principal!"