o say:

"Of the theories that we have just enumerated, perhaps no one is
adequate to explain all the phenomena of geyser action. Bunsen's theory
comes nearest to it, and in the simplest kinds of geysers is a
sufficient explanation. The variations and modifications in the geyser
tubes and subterranean water passages must undoubtedly be important
factors entering into any complete explanation of geyser action. Now, of
course, we can see what the conditions are at the surface, but in our
experiments we can penetrate to a very inconsiderable distance. We have,
therefore, no data to present on these points, and investigations of
this branch of the subject will have to be carried on in an artificial
manner; that is artificial geysers will have to be constructed, and
various modifications made in the tubes until results are reached
analogous to those seen in 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 through the
spout. The first case is an illustration, in part at least, of Bunsen's
theory, and the second exemplifies the theories which presuppose the
existence of subterranean cavities with tubes at or near the surface.
According to the former we must suppose that the layer of rock,
extending seventy-five to seventy-seven feet below the surface, contains
sufficient heat to account for geyseric phenomena; or else that the
geyser tube has some opening, either at the bottom or on the sides, by
which steam and superheated water have access to it from a considerably
greater depth where the temperature is very high. At these depths
caverns probably exist." * * * *

"That such cavities exist is more than probable. On page 405 I have
indicated my belief, that all geysers are originally due to a violent
outburst of steam and water, and under such conditions, irregular
cavities and passages are more likely to be formed than regular
tubes." * *

"In view of what we have just written, Bunsen's conclusion (No. 2)
would have to be modified somewhat. His conclusion was that at no point
in the tube did the water attain the temperature of ebullition which it
should have under the pressure to which it is subjected. As far as this
relates to the straight tube in which his temperatures were taken, it
may be so; but if he could have taken tempe