power for the propulsion of boats.  He was firm in the belief that the greatest future for the steamboat was on the great rivers that tied together the rapidly growing commonwealths of the middle west, and he undertook this voyage for the purpose of studying the channel and the current of the rivers, with the view to putting a steamer on them.  Wise men assured him that on the upper river his scheme was destined to failure.  Could a boat laden with a heavy engine be made of so light a draught as to pass over the shallows of the Ohio?  Could it run the falls at Louisville, or be dragged around them as the flatboats often were?  Clearly not.  The only really serviceable type of river craft was the flatboat, for it would go where there was water enough for a muskrat to swim in, would glide unscathed over the concealed snag or, thrusting its corner into the soft mud of some protruding bank, swing around and go on as well stern first as before.  The flatboat was the sum of human ingenuity applied to river navigation.  Even barges were proving failures and passing into disuse, as the cost of poling them upstream was greater than any profit to be reaped from the voyage.  Could a boat laden with thousands of pounds of machinery make her way northward against that swift current?  And if not, could steamboat men be continually taking expensive engines down to New Orleans and abandoning them there, as the old-time river men did their rafts and scows?  Clearly not.  So Roosevelt’s appearance on the river did not in any way disquiet the flatboatmen, though it portended their disappearance as a class.  Roosevelt, however, was in no wise discouraged.  Week after week he drifted along the Ohio and Mississippi, taking detailed soundings, studying the course of the current, noting the supply of fuel along the banks, observing the course of the rafts and flatboats as they drifted along at the mercy of the tide.  Nothing escaped his attention, and yet it may well be doubted whether the mass of data he collected was in fact of any practical value, for the great river is the least understandable of streams.  Its channel is as shifting as the mists above Niagara.  Where yesterday the biggest boat on the river, deep laden with cotton, might pass with safety, there may be to-day a sand-bar scarcely hidden beneath the tide.  Its banks change over night in form and in appearance.  In time of flood it cuts new channels for itself, leaving in a few days river towns far in the interior, and suddenly giving a water frontage to some plantation whose owner had for years mourned over his distance from the river bank.  Capricious and irresistible, working insidiously night and day, seldom showing the progress of its endeavors until some huge slice of land, acres in extent, crumbles into the flood, or some gully or cut-off all at once appears as the main channel, the Mississippi, even now when the Government is at all times on the alert to hold it in bounds, is not to be lightly learned nor long trusted.