built up, atom after atom, through unnumbered ages; during which time, no doubt, the geyser hour by hour has faithfully performed its part, without an eye to note its splendor, or a voice to tell its glory to the world.  Old Faithful does not owe its popularity entirely to height or beauty, though it possesses both.  It is beloved for its fidelity.  Whatever irregularities other geysers show, Old Faithful never fails.  Year in, year out, winter and summer, day and night, in cold and heat, in sunshine and in storm, Old Faithful every seventy minutes sends up its silvery cascade to the height of about one hundred and eighty feet.  Of all the geysers known to man this is the most reliable and perfect.  Station yourself before it watch in hand and, punctual to the moment, it will never disappoint you.  Few realize on how large a scale the forces of Nature work here.  At each eruption, Old Faithful pours forth about one million five hundred thousand gallons, or more than thirty-three million gallons in one day!  This geyser alone, therefore, could easily supply with water a city of the size of Boston.

[Illustration:  CASTLE AND OLD FAITHFUL GEYSERS.]

[Illustration:  OLD FAITHFUL IN ACTION.]

Within this area of the active geysers is a place called Hell’s Half Acre.  It is rightly named.  Rough, perpendicular ledges project over a monstrous gulf of unknown depth, from which great clouds of steam are constantly emerging.  When the wind draws back for a moment a portion of this sulphur-laden curtain, the visitor perceives a lake below, seething and boiling from internal heat.  For years no one suspected this to be a geyser; but suddenly, in 1881, the underlying force hurled the entire lake up bodily to the height of two hundred and fifty feet, and even repeated frequently.  After some months the exhibition ceased, and all was calm again for seven years.  In 1888, however, it once more burst forth with prodigious energy, ejecting at each explosion more boiling water than all the other geysers in the Park combined.  Even the surrounding ledges could not withstand this terrible upheaval, and tons of rock were sometimes thrown up, with the water, more than two hundred feet.  It is not strange, therefore, that this is called Excelsior, the King of Geysers.  It is the most tremendous, awe-inspiring fountain in the world.  When it will be again aroused, no one can tell.  Its interval would seem to be from seven to ten years.  Said an enthusiastic traveler to me:  “If the Excelsior ever plays again, I will gladly travel three thousand miles to see it.”

[Illustration:  HELL’S HALF ACRE.]

[Illustration:  THE EXCELSIOR, IN 1888.]

[Illustration:  EVENING IN THE UPPER BASIN.]