One summer morning in the upper North Platte country I rose from my blankets, performed the pious acts of sun-worship by yawning toward the east, kicked together the parted embers of my camp-fire, and bethought me of water for my ablutions.  We had gone into bivouac late in the night on the open plain, and without any clear notion of where we were.  There were a half-dozen of us, our chief on a tour of inspection of the new military posts in Wyoming.  I accompanied the expedition as surveyor.  Having an aspiration for water I naturally looked about to see what might be the prospect of obtaining it, and to my surprise and delight saw a long line of willows, apparently some three hundred yards away.  Willows implied water, and snatching up a camp-kettle I started forward without taking the trouble to put on my coat and hat.  For the first mile or two I preserved a certain cheerful hopefulness; but when the sun had risen farther toward the meridian and began to affect my bare head most uncomfortably, and the picketed horses at the camp were hull down on the horizon in the rear, and the willows in front increased their pace out of all proportion to mine, I began to grow discouraged and sat down on a stone to wish myself back.  Perceiving that the willows also had halted for breath I determined to make a dash at them, leaving the camp-kettle behind to make its way back to camp as best it could.  I was now traveling “flying light,” and had no doubt of my ability to overtake the enemy, which had, however, disappeared over the crest of a low sandhill.  Ascending this I was treated to a surprise.  Right ahead of me lay a barren waste of sand extending to the right and left as far as I could see.  Its width in the direction that I was going I judged to be about twenty miles.  On its farther border the cactus plain began again, sloping gradually upward to the horizon, along which was a fringe of cedar trees—­the willows of my vision!  In that country a cedar will not grow within thirty miles of water if it knows it.

On my return journey I coldly ignored the appeals of the camp-kettle, and when I met the rescuing party which had been for some hours trailing me made no allusion to the real purpose of my excursion.  When the chief asked if I purposed to enter a plea of temporary insanity I replied that I would reserve my defense for the present; and in fact I never did disclose it until now.

I had afterward the satisfaction of seeing the chief, an experienced plainsman, consume a full hour, rifle in hand, working round to the leeward of a dead coyote in the sure and certain hope of bagging a sleeping buffalo.  Mirage or no mirage, you must not too implicitly trust your eyes in the fantastic atmosphere of the high plains.

I remember that one forenoon I looked forward to the base of the Big Horn Mountains and selected a most engaging nook for the night’s camp.  My good opinion of it was confirmed when we reached it three days later.  The deception in this instance was due to nothing but the marvelous lucidity of the atmosphere and the absence of objects of known dimensions, and these sources of error are sometimes sufficient of themselves to produce the most incredible illusions.  When they are in alliance with the mirage the combination’s pranks are bewildering.