186 GEOLOGICAL SURVEY OF THE TEEEITOEIES. 



camp, on the left bank of the river, and spouted with great regularity 

 every ten minutes, throwing the water up 10 feet, resembling very much 

 a soda-fountain, wheuce its name. The Grotto Geyser was situated 

 about 500 yards northwest from our camj). It consists of a mass of 

 sinter 12 feet in diameter and 5 feet high, full of large sinuous orifices, 

 from which the water is projected during an eruption. Four hundred 

 feet southeast of the Grotto is the Giant. The crater of this geyser is 

 very rough and rises about 10 feet above the surrounding level. It is 8 

 feet in diameter at its base and 5 or 6 at the top. One side is somewhat 

 broken down, allowing one to see the boiling water in it. It i)rojects a 

 column of water of about 5 feet in diameter to the height of 125 feet, 

 the erui^tions each lasting about two hours. Xear the Grand Geyser, 

 which was immediately opposite our camp, there was a small one, whicli 

 we named the Saw Mill Geyser. It threw a small stream to the height 

 of 10 or 15 feet almost uninterruptedly. Still farther up the river, and 

 on the opposite side, is the Castle, the most beautiful of them all. It is 

 situated in the center of a large, gently sloping mound of sinter, above 

 which its crater rises about 20 feet. It is about 50 feet in length, and 

 beautifully incrusted with bead-like formations. The whole mass 

 resembles some old castle that has been subjected to a bombardment. 

 It has an eruption every few hours. Between the Castle and the river 

 is one of the large springs or cisterns so numerous throughout the 

 region. It corresponds to the Langs of Iceland, which some time in the 

 past have been geysers. This one is about 20 feet in diameter, and is 

 funnel-shaped. The edge is lined with a series of beautifully regular 

 scallops. The water in this white siliceous basin is an exquisite tint, 

 resembling the turquois blue. This intense blue, however, is not peculiar 

 to this region. It is noticed as well in Xew Zealand and in Iceland. 

 The temperature of the water was 172^ F. At the head of the valley 

 stands Old Faithful, so named for the regularity of its spouting, which 

 takes place every lifty minutes, lasting about ten minutes, the water 

 reaching the height of 125 to 150 feet. Its crater is conical, and G feet 

 high, year it there are four geyser-cones, which are now extinct 

 geysers. On the opposite side of the river from Old Faithful are the 

 Giantess and Bee Hive, neither of which were seen in operation by us. 



Bunsens theory of the geyser is the simplest and probably the most 

 correct. It can be verified by ex])eriment, and the facts observed by us 

 sustain it. Briefly stated, it is this : The water deposits nothing except 

 by evaporation, which takes place rapidly at the edges ; here, then, the 

 silica which is held in solution is deposited and builds up the beautiful 

 tube and basin of the geyser. Bunsen succeeded in determining the tem- 

 perature of the geyser-tube, from top to bottom, a few moments before 

 eruption, and found that at no part of the tube was it at the boiling-point. 

 How, then, does the eruption take place ? It is always noticed that before 

 an eruption the water rises in the tube. The higher we "o in the tube 

 the lower is the i^oint at which the water boils. Suppose the column 

 of water is elevated by the entrance of steam through ducts at the bot- 

 tom of the tube. The water, which at a certain point was near the 

 boiling-point, is elevated to a part of the tube where the boiling-point 

 is lower than the temperattire it has ; there is therefore an excess of 

 heat. This excess of heat is used in generating steam ; the water is 

 elevated higher, more steam is formed, and suddenly the water above 

 is thrown into the air, mingled with clouds of steam, and we have the 

 geyser in action. The water has to be very near the builiug-])oint before 

 an eruption can take place. 



In the Fire-Hole geysers we noticed that just before an eruption the 



