234 KEPOET UNITED STATES GEOLOGICAL SURVEY. 



throwing up jets a few feet into the air, exciting hopes that it was about to perform, 

 and bringing those who were in camp somewhat hastily across the stream. At 9 o'clock 

 it boiled up again, at times throwing out considerable water, so that it was nearly- 

 empty as far as we could see, looking far down into the crater. It rapidly filled, how- 

 ever, and a second outburst on a small scale took place. Two hours later a more vig- 

 orous display commenced, the hot water being thrown to a height of 100 feet, by a 

 series of successive irregular throbs, like the beats of a pump ; the heavy thumping 

 going on below in a startling manner. This irregular display, extremely interesting 

 and beautiful, yet nothing compared with what the Giantess is said to do, lasted for 

 one hour; the entire volume of water thrown out being very great. At length, with 

 a sudden burst, the steam drove up the water to a much greater height than before 

 seen, the noise and concussions accompanying the outburst being very violent. The 

 water was kept at its greatest height for two or three minutes, and for this time we 

 found the Giantess all that had been claimed for it. But the reservoir was almost ex- 

 hausted, and in a short time the only escape was a mass of steam, which rushed out 

 of the crater with a force which no words could describe. * » * This steam es- 

 cape lasted for an hour without any sensible diminution in violence, and we could not 

 helj) regretting that all the water had been ejected before the most powerful burst of 

 steam had begun, so that we might have had a full display of the power that was at 

 hand acting on the water. The conception offeree given by this great steam escape 

 was j)erhaps even greater than if it had taken merely the form of a fountain. Six 

 hours later the steam was still escaping, though with somewhat diminished energy, 

 and an occasional liquid jet seemed to show that a little water was draining into the 

 reservoir, only to be immediately ejected.* 



I can find no record of any spouting in 1876 or 1877. 



1878. — I reached the Upper Geyser Basin on the afternoon of August 

 27, and remained until the morning of September 2, and during this, 

 my first visit, the Giantess was quiet. We were camped immediately 

 opposite the mound, and had an eruption taken place during the night 

 we could scarcely have missed hearing it. In the morning before my 

 arrival an eruption was noted from a distance, but the notes were 

 meager. It began about 8.45 a. m., and was followed by a second spurt 

 at 10.48 a. m. The first lasted 9 minutes, and the second 13. On Sep- 

 tember 1 the surface temperature was 199° F., and at a depth of 12 

 feet 201° F. The water appeared to be in constant ebullition. Our 

 second visit was from the evening of September 8 until the afternoon of 

 September 11. During this visit no change was observed in the condi- 

 tion of the Giantess, and we left the Basin without having seen it in. 

 action. 



From the descriptions that have been given, it is evident that the 

 eruption of this geyser is divided into three distinct periods. Lang- 

 ford probably saw it after the first was ended, for he found the crater 

 or bowl empty, and Doane, speaking of the geyser, says : 



This grand geyser played three times in the afternoon, but appears to be irregular 

 in its periods, as we did not see it in eruption again while in the valley.t 



He does not give any idea as to the interval separating these erup- 

 tions. In the eruption witnessed by myself in 1872, the interval be- 

 tween the first and second periods was 47 minutes, and between the 

 second and third 1 hour and 5 minutes, the interval between the first 

 and third being 1 hour and 52 minutes, which is nearly that observed 

 by Grinnell and Dana, namely, 2 hours. They, however, do not give 

 the duration of the two preliminary periods, which, in the case of the 

 eruption noted in 1872, was 17 minutes for each. Dana and Grinuel 

 noticed preliminary attempts 2 J hours before the eruption and give the 

 leugth of the steam period following it as over 6 hours. 



As to the interval between the eruptions, the observations are too few 

 in number to determine much. It is, however, undoubtedly long. When 



* Eeport of a Eeconnaissance from Carroll, Mont., to Yellowstone National Park, &c., 

 1875, 1876, pp. 131, 132. 

 tEeport of Yellowstone Expedition of 1870, p. 32. 



