astonishment on entering this basin, to see at no great distance before us an immense body of sparkling water, projected suddenly and with terrific force into the air to the height of over one hundred feet.  We had found a real geyser.  In the valley before us were a thousand hot springs of various sizes and character, and five hundred craters jetting forth vapor.  In one place the eye followed through crevices in the crust a stream of hot water of considerable size, running at nearly right angles with the river, and in a direction, not towards, but away from the stream.  We traced the course of this stream by the crevices in the surface for twenty or thirty yards.  It is probable that it eventually flows into the Firehole, but there is nothing on the surface to indicate to the beholder the course of its underground passage to the river.

On the summit of a cone twenty-five feet high was a boiling spring seven feet in diameter, surrounded with beautiful incrustations, on the slope of which we gathered twigs encased in a crust a quarter of an inch in thickness.  On an incrusted hill opposite our camp are four craters from three to five feet in diameter, sending forth steam jets and water to the height of four or five feet.  But the marvelous features of this wonderful basin are its spouting geysers, of which during our brief stay of twenty-two hours we have seen twelve in action.  Six of these threw water to the height of from fifteen to twenty feet, but in the presence of others of immense dimensions they soon ceased to attract attention.

Of the latter six, the one we saw in action on entering the basin ejected from a crevice of irregular form, and about four feet long by three wide, a column of water of corresponding magnitude to the height of one hundred feet.  Around this crevice or mouth the sediment is piled in many capricious shapes, chiefly indented globules from six inches to two feet in diameter.  Little hollows in the crust filled with water contained small white spheres of tufa, of the size of a nutmeg, formed as it seemed to me around some nuclei.[Z]

We gave such names to those of the geysers which we saw in action as we think will best illustrate their peculiarities.  The one I have just described General Washburn has named “Old Faithful,” because of the regularity of its eruptions, the intervals between which being from sixty to sixty-five minutes, the column of water being thrown at each eruption to the height of from eighty to one hundred feet.

The “Fan” has a distorted pipe from which are projected two radiating sheets of water to the height of sixty feet, resembling a feather fan.  Forty feet from this geyser is a vent connected with it, two feet in diameter, which, during the eruption, expels with loud reports dense volumes of vapor to the height of fifty feet.

[Illustration:  OLD FAITHFUL.  NAMED BY GENERAL WASHBURN.]