All night long, at brief intervals, our mules were scared by a dull, distant noise like a musket-shot. A soldier told me it was a mud volcano which he had seen the day we arrived. I then found it marked on Hayden's map, but learned that it had not been seen by him, and was only so located on information received from hunters. On the morning of August 1st I persuaded the major to walk over and look for the volcano. We crossed the valley, and, guided by the frequent explosions, climbed the hills to the east, and, descending on the far side, came into a small valley full of sluggish, ill-smelling rills, among which we found the remarkable crater, which, as it has not been hitherto examined by any save hunters, I shall describe at some length. A gradual rising ground made up of soft sulphureous and calcareous earth was crowned by a more abrupt rise some thirty-five feet high, composed of tough gray clay. This was pierced by a cone of regular form about thirty feet across at top and five feet at the bottom. On the west, about one-third of the circumference was wanting from a point six feet above the lowest level, thus enabling one to be at a distance or to stand close by, and yet see to the bottom of the pit. The ground all around and the shrubs and trees were dotted thick with flakes of dry mud, which gave, at a distance, a curious stippled look to the mud-spattered surfaces. As I stood watching the volcano I could see through the clouds of steam it steadily emitted that the bottom was full of dark gray clay mud, thicker than a good mush, and that, apparently, there were two or more vents. The outbreak of imprisoned steam at intervals of a half minute or more threw the mud in small fig-like masses from five to forty feet in air with a dull, booming sound, sometimes loud enough to be heard for miles through the awful stillness of these lonely hills. It is clear, from the fact of our finding these mud-patches at least one hundred yards from the crater, that at times much more violent explosions take place. The constant plastering of the slopes of the crater which these explosions cause tends to seal up its vent, but the greater explosions cleanse it at times, and all the while the steam softens the masses on the sides, so that they slip back into the boiling cauldron below. As one faces the slit in the cone there lies to the right a pool of creamy thin mud, white and yellow, feebly boiling. It is some thirty feet wide, and must be not more than twenty feet from the crater: its level I guessed at sixteen feet above that of the bottom of the crater.