212 



EEPOET UNITED STATES GEOLOGICAL SURVEY. 



large cushion like masses of geyserite, somewhat like those in the crater 

 of the Turban. In these masses the orifice is 2 by 4 feet. It is situ- 

 ated near the Turban rather than in the center of the basin. There 

 is no marked raised riin to the latter, but there are shallow basins and 

 pools over the surrounding surface, the irregularity of which add to the 

 beauty of the general effect. This geyser was called the Comet by 

 Colonel Barlow, in 1871, but the same year we called it the Grand, 

 which name has been retained. I have given the name Comet to a 

 geyser in the White Pyramid Groui). The descriptions following will 

 give the best idea of the eruptions. 



1871. — The Grand Geyser was first seen in eruption in 1871, having 

 been unnoticed by the Washburn party in 1870. It spouted soon after 

 our arrival, on the evening of August 4. We had just camped on the 

 west side of the river, almost opposite the geyser, when a tremendous 

 rumbling was heard, accompanied by a shaking of the ground and a 

 huge escape of steam. It would be difficult to describe the feeling of 

 excitement with which we saw the immense column of steam and water 

 shoot from the crater to the height of 200 feet. The column was ver- 

 tical and accomi>anied by immense clouds of steam, and the water in 

 falling shook the ground. It was carried up in a succession of jets, the 

 main mass being large, and the highest jets appearing to be forced 

 through the latter. It w^as the first geyser of any power tliat we had 

 seen, and we called it the Grand Geyser. The display lasted altogether 

 about 20 minutes, and after it was over the water sank out of sight 

 in the tube. The next day its temperature was 188° F., the water having 

 again filled the basin. 



The first eruption took place at 5 p. m., August 4. A second oc- 

 curred at night on the. 5th, after an interval of about thirty-one hours. 

 A third one was noted by Colonel Barlow the last night of his stay, but 

 the time was not noted.* 



1872. — All the eruptions witnessed in 1872 occurred in the morning, 

 two of them so early that we obtained only the time of beginning and 

 time of ending. In order to get the height of the column, we kept guard 

 one night near the crater. It did not spout, however, until daylight, 

 when we succeeded in getting the height. The following are the erup- 

 tions noted: 



First eruption, August 18. — Eruption began 5.20 a. m.; duration, 15 

 minutes. 



Second eruption, August 19. — Eurption began 3.35 a. m.; duration, 37 

 minutes. 



Third eruption, August 20. — Eru]3tion began 6.33 a. m.j entire dura- 

 tion, 42 minutes. 



This eruption was in three distinct periods, as follows : 



Periods. 



Spouting 

 began. 



Duraiion. 



Interval of 

 quiet. 



Mean 

 height. 



Maximum 



height. 



First 



G.33a. m 



6.42 a. m 



6.56 a. m .... 







Feet. 

 79 

 149 

 53 



Feet. 

 122 

 173 

 84 



Second 



Third 



4 minutes . . . 

 9 minutes... 



6 minutes. .. 

 10 minutes.. 





This eruption did not appear to reach as great a height as the others. 

 The interval between the beginnings of first and second eruptions was 22 

 hours. The intervals between the beginnings of second and third erup- 



* Keconnaissance of the Yellowstone Eiver, p. 25. 



