150 



GEOLOGICAL SUEYEY OF THE TERRITOEIES. 



on top. The orifice of the geyser-tube is circular and 3 feet in diameter, 

 and its throat is lined with large globular masses, of an orange-color, and 

 beautifully beaded, as is seen so universally throughout bo«th geyser- 

 basins. An eruption is as follows : It commences with a succession of 

 jets of water, in number about twenty per minute, which rise to various 

 heights. These last about fifteen minutes and are succeeded by steam, 

 mingled with spray, which escapes with a sort of pulsating movement. 

 This soon changes to a steady escape. It seems as though the water 

 were exhausted and the steam was being forced out as rapidly as pos- 

 sible. This again changes, and the steam escapes in cloucl-like masses 

 with a roaring sound, like the escape of steam from some vast escape- 

 pipe, which in reality it is. This gradually dies away and the eruption 

 is ended, having lasted about an hour and twenty minutes. We wit- 

 nessed one fall eruption and parts of two others, as follows : 



First eruption, August 18. — Maximum height, 34 feet j mean height, 21 

 feet. 



Second eruption, August 19. — 10.3.0 a. m., commencement; 10.6.40 

 a. m., maximum of water-period, height 93 feet; 10.18 a. m., maxi- 

 mum of steam, height 115 feet; 11.25 a. m., end of eruption. 

 Mean height of water, 57 feet ; of steam, 81 feet. 

 Third eruption, Aiigust 20. — 7.24 a. m., eruption began; 7.40.20 a.m., 

 eruption ended. 



We did not see the beginning of the first eruption, and did not, there- 

 fore, wait until it was over. The angles for height were taken from the 

 end of a base-line of 100 feet, measured from the center of the orifice, 

 and the heights are above the end of the base-line. The third was wit- 

 nessed from a distance, and the height was not ascertained. At the 

 base of the Castle there is a spring, measuring 12 feet by 7 feet, 

 which babbles intermittently. The water was at the boilmg-poiut, 

 (199°;) air, 64^ F., at 11.35 a. m. Twelve feet from this there is a second 

 spring of the same character, measuring 6 feet by 3 feet and having a 

 temperature of 192° F. The bed of the stream flowing from these 

 springs is coated with bright-red oxide of iron. The water in these 

 springs rose and fell repeatedly during the eruption of the Castle. 

 While steam mingled with spray escaped from the Castle the water 

 Pig 27. ^^^ ^^^ ^^ sight in 



these springs, and 

 when steam alone es- 

 caped they were ac- 

 tive, spurting to the 

 height of 3 feet. The 

 principal spring near 

 the Castle is a large 

 blue spring, almost 

 circular in shape, 

 ^K measuring 19 by 21 

 ^ feet. It has a mosjt 

 ^ regular and beautiful 

 scalloped edge, and 

 looks as though it 

 were lined with white 

 marble. This white basin slopes to a large funnel-shaped orifice, which is 

 on the side next the Castle. This is 40 feet deep. The surface of the water 

 is placid and appears of a most intense blue, especially over the orifice. 

 The temperature of the water was 180° F. ; aii', 58° F., at 9.08 a. m. Fig. 

 37 is an illustration of one of the springs near the Castle, showing the ap- 



riil ABOUT A GE\Sb.r-TUBE, UPPER FIRE-HOLE 



