Professor Comstock’s idea of the tube having a double curve.  The double curve is, or was, conspicuous in both the caves.  Unfortunately, its perfection in Wind Cave was necessarily partially sacrificed to make the passage traversable for visitors; but in describing the enormous labor of opening up the cave, Mr. McDonald showed how an arching “crawl” had been worked down by blasting, and the depression beyond filled to raise it to the desired level for securing the present easy passage at the bottom of the main tube, which is the entrance passage.  This double curve in the tube is simply the rough original of the S trap of sanitary plumbing.  In both caves it is somewhat irregular and deformed, but the familiar “trap” is easily recognized.  The destruction of one of the Yellowstone geysers was, no doubt, due to the breaking of the S. One of the many reasons for establishing military control over the Park is said to have been the disastrous results following the introduction of a large quantity of soap into the geyser to cause a premature eruption.  The impatience of the party was rewarded by an eruption accompanied by explosions that shook the earth for a great distance, and the geyser has not been seen in action since.

Dr. Peal finds the theories advanced for the generation of steam unsatisfactory and insufficient, especially in the class of geysers having a long steam period.  He says:  (page 423)

“The Castle Geyser differs from Old Faithful and the Bee Hive mainly in the fact that it has a long steam period, during which the steam pours out or is pushed from the geyser throat with great violence and a terrific noise.  There appear to be only two possible explanations of this difference, viz., either an accumulation of immense volumes of steam in the Castle, or an instantaneous formation of steam throughout the length of the geyser tube.  The former, to our mind, is untenable, because it seems impossible that the water, which is exhausted in fifteen minutes, should exert enough power to keep down the immense amount of steam that escapes for more than an hour.  According to Bunsen’s theory, it can be readily explained.  The relief afforded by the first part of the eruptions allows the superheated water to rise rapidly, and before it can reach the top or orifice of the tube it is all converted into steam from the top downward with inconceivable rapidity, and must be forced out with the terrific violence which is noted in the case of the Castle.  On page 208 we have expressed the opinion that it is the oldest geyser in the region, and it seems to us that a greater length in the tube, with a consequent greater supply of water, will account for the difference between the Castle and Old Faithful, the latter of which we consider one of the youngest geysers in the Upper Geyser Basin.”