i-EALE.] GEYSER THEORIES. 421 



comes heated and evolves vapor also, as in o. After a time the ex- 

 pansion of the vapor in c is able to overcome the combined pressure 

 of the water and vapor in h and o, when the latter is forced out, followed 

 by a portion of the water in the reservoir d. The force thus expended, 

 a vacuum is produced in c by the receding of the column of water in d, 

 and the foregoing operations are indefinitely repeated." " The passage 

 b may be kept filled with water by means of the surplus which tails 

 back into the bowl." 



This idea of Professor Comstock supposes that an escape of vapor is 

 the first indication of an eruption, followed by a rising of the water so 

 as to fill the surface chamber of basin of the geyser. In most cases the 

 steam that comes from the geysers is the result of the violent boiling 

 of the water whose surface is a short distance below the bowl or basin. 

 In many geysers the first intimation of an eruption is the bulging and 

 boiling of the water at the surface, as in the Grand and Fountain 

 Geysers. In Old Faithful, spurts of water, due to abortive attempts at 

 eruption, are the precursors of eruptions. In the Union Geyser violent 

 boiling and spurts of some considerable height were constant for two 

 days preceding the eruptions. The steam period, instead of occurring 

 before the erux^tion, is characteristic in most cases of the close of the 

 eruption. 



Baring-Gould'' s theory. — S. Baring-Gould, who visited the Iceland gey- 

 sers in 1863, thinks that a bent tube is sufficient to explain the action 

 of the Great Geyser. He took an iron tube and bent it at angle 110°, 

 keeping one arm half the length of the other. He filled the tube with 

 water and placed the short arm in the fire. For a moment the sur- 

 face of the liquid remained quiet, and then the pipe began to quiver; 

 a slight overflow took place, without any sign of ebullition, and then 

 suddenly, with a throb, the whole column was forced high into the air. 

 With a tube, the long arm of which measured 2 feet, and the bore of 

 which was three-eighths of an inch, he sent a jet to the height of 18 

 feet. Steam is generated in the short arm and presses down the water, 

 causing an overflow until the steam bubble turns the angle, when it 

 forces out the column in the long arm with incredible violence. This is 

 an adaptation of McKenzie's theory. 



Of the theories that we have just enumerated, perhaps no one is ade- 

 quate to explain all the phenomena of geyser action. Bunsen's theory 

 comes nearest to it, and in the simplest kinds of geysers is a sufiicient 

 explanation. The variations and modifications in the geyser tubes and 

 subterranean water passages must undoubtedly be important factors 

 entering into any comiilete explanation of geyser action. Now, of 

 course, we can see what the conditions are at the surface, bur in our ex- 

 periments we can penetrate to a very inconsiderable distance. We have, 

 therefore, no data to i)resent on these points, and investigations of this 

 branch ot the subject will have to be carried on in an artificial manner; 

 that is, artificial geysers will have to be constructed, and various modi- 

 fications made in the tubes until results are reached analogous to those 

 seen in the natural geysers. If water in a glass tube be heated with 

 rapidity from the bottom, it will be expelled from the tube violently, 

 and if boiled in a kettle which has a lid and a spout, either the lid will 

 be blown off or the Water will be forced out tlirough the spout. Tlio 

 first case is an illustration, in part at least, of Bunsen's tbeory, and the 

 second exemplifies the theories which presuppose the existence of sub- 

 terranean cavities with tubes at or near the surface. According to the 

 former we must suppose that the layer of rock, extending 75 to 77 feet 



