192 



EEPOET UNITED STATES GEOLOGICAL SURVEY. 



1873. — Professor Comstock describes one eruption as follows: 



We witnessed but one eruption, which began at 2.17 p. m., August 25, continuing 

 tininterruj)tedly till 3.03 p. m., when it ceased altogether. The water was ejected with 

 much force in two irregularly-alternating columns, proceeding from the two large, 

 conical chimneys of which the mound is made up and from several intermediate open- 

 ings of small size. The volume of water and vapor was large, and a good-sized stream 

 was formed by the surplus, Which ran off down the hill to the river.* The maximum 

 height Avas nearly 25 feet. 



1875. — Captain Ludlow sayst the Grotto played whenever he was 

 near it, and gives the height as 20 or 25 feet. Griunell and Dana, in the 

 same report, say the Grotto was almost continuously active during their 

 stay. 



1877. — General Sherman says that durins: their stay, in 1877, the Grotto 

 was repeatedly in agitation, but tliejets did not exceed 20 feet. 



1878. — I witnessed only two eruptions on the afternoon of September 

 11. They were separated by an interval of 2 hours 26J minutes. The 

 duration was not ascertained nor was the height ascertained, but it was 

 not over about 20 feet in each case. A very smaL ^■^T^tion of the time 

 we were in the Upper Basin was devoted to the Gr„.uc-^, and we did not, 

 therefore, obtain any data as to its periods. The following temjDera- 

 tures were taken : Cone ISTo. 1, 198^ F. ; cone No. 2, 193° ¥. 



The duration of the three eruptions that have been noted above are : 

 38 minutes, 2 hours 33 minutes, 46 minutes, which are so different that 

 very little can be determined from them. It is i^robable that the Grotto 

 has a double set of eruptions. 



Springs 3 and 4 are east of the Grotto at a little lower level. 



Nos. 6, 7, and 8 are in one basin and at times evidently connect, prob- 

 ably when the overflow from the Grotto is large, as the channel leadiug 

 from the geyser carries the water directly into No. 7. The basin is of 

 hard, grayish geyserite. The three bowls are ^ciently described in 

 the table. The temperatures are low, indicating that the springs are to 

 a certain extent reservoirs. 



No. 17. This is really a series of bowls or bpsins f^r.r>nected by chan- 

 nels, the rim being continuous around the culix^ ua^n., which has a 

 total length of about 181 feet, a is a quiet s '""^ Hiat is now probably 

 nearly extinct. It is lined Avith tuft-like m-. ^ x^oRiug masses, e is a 

 beautiful blue cavern- like spring of great depth, and was named by one 

 of the members of the party, who called it " the bottomless pit." The 

 following is the comparison of the temperatures in this spring, taken in 

 1871 and in 1878: 



^ Basin. 



1871. 



1878. 



a . . 



°F. 

 'l68 

 150 

 Not taken. 

 166 

 150 



°F. 

 ■ 120 

 150 

 153 

 165 

 184 



6 



c 



d 







From this table it is probable that e has periods of activity which 

 increase the temperature, a appears to have decreased in temperature 

 since 1871, which the character of the basin also indicates. The other 

 two springs, b and d, remain about the same. 



The rest of the springs on the west side of the river do not '' 



* Eeconnaissance of N. W. Wyoming by Capt. W. A. Jones, in 1873, -p-p. 251-252. 

 t Reconnaissance from Carroll, M. T., to Yellowstone National Park, a^ returi , Ir. 

 1875, p. 25. 



