// #28. The Yellowstone Park Geysers

THEIR ESSENTIAL FACTS AND CAUSES

I have been to school. Dame Nature is a most kind and skillful teacher. She first put me into the ABC class, and advanced me through conic sections. The first thing in the geyser line she showed me was a mound of rock, large as a small cock of hay, with a projection on top large as a shallow pint bowl turned upside down. In the center of this was a half-inch hole, and from it every two seconds, with a musical chuckle of steam, a handful of diamond drops of water was ejected to a height of from two to five feet. I sat down with it half an hour, compelled to continuous laughter by its own musical cachinnations. There were all the essentials of a geyser. There was a mound, not always existent, built up by deposits from the water supersaturated with mineral. It might be three feet high; it might be thirty. There was the jet of water ejected by subterranean forces. It might be half an inch in diameter; it might be three hundred feet, as in the case of the Excelsior geyser. It might rise six inches; it might rise two hundred and fifty feet. There was the interval between the jets. It might be two seconds; it might be weeks or years.


[Illustration: Formation of the Grotto Geyser.]

A subsequent lesson in my Progressive Geyser Reader was the "Economic." Here was a round basin ten feet in diameter, very shallow, with a hole in the middle about one foot across. The water was perfectly calm. But every six minutes a sudden spurt of water and steam would rise about thirty feet, for thirty seconds, and then settle economically, without waste of water, into the pool, sinking with pulsations as on an elastic cushion a foot below the bottom of the pool. One could stride the opening like a colossus for five and one half minutes without fear. He might be using the calm depth for a mirror. But stay a moment too long and he is scalded to death by the sudden outburst.

The next lesson required more patience and gave more abundant reward. I found a great raised platform on which stood a castellated rock, more than twenty feet square, that had been built up particle by particle into a perfect solid by deposits from the fiery flood. In the center was a brilliant orange-colored throat that went down into the bowels of the earth. That was not the geyser - it was only the trump through which the archangel was to blow. I had heard the preliminary tuning of the instrument.

The guide book said the grand play of this "Castle" geyser began from eight to thirty hours after a previous exhibition, and was preceded by jets of water fifteen to twenty feet high, and that these continued five or six hours before the grand eruption. I hovered near the grand stand till the full thirty hours and the six predictive hours were over, and then, as the thunder above roared threateningly and the rain fell suggestively, I took a rubber coat and camped on the trail of that famous spouter.

Geysers are more than a trifle freaky. "Old Faithful" is a notable exception. Every sixty-five minutes, with almost the regularity of star time, he throws his column of hissing water one hundred and fifty feet high. Others are irregular, sometimes playing every three hours for a few times, and then taking a rest for three or more days. This Castle geyser is not registered to be quiet more than thirty hours, nor to indulge in preparatory spouts for more than six hours. When I finally camped to watch it out all these premonitory symptoms had been duly exhibited. I first carefully noted the frequency and height of the spouts, that any change might foretell the grand finale. There were ten spouts to the minute, and an average height of twenty feet. Hours went by with no hint of a change: ten to the minute, twenty feet in height. People by the dozen came and asked when it would go off. I said, "Liable to go any minute; it is long past due now." Stage loads of tourists, scheduled to run on time, drove up, waited a few minutes, and drove on, as if the grand object of the trip was to make time - not to see the grandeur they had come a thousand miles to enjoy. A photographer set up his camera to catch a shadow of the great display. He stood, sometimes air-bulb in hand, an hour or two, then folded his camera tent and stole away. Five hours had passed and night was near. Everybody was gone. I lay down on the ground to convince myself that I was perfectly patient. I attained so nearly to Nirvana that a little ground squirrel came and ran over me, kissing my hand in a most friendly way.

Six hours of waiting were nearly over when, without a single previous hint of change, one descending spout was met by an ascending one, and a vast column of hissing water rose, with a sound of continuous thunder, one hundred feet in air; and stood there like a pillar of cloud in the desert. The air throbbed as in a cannonade, and the sun brushed away all clouds as if he could not bear to miss a sight he had seen perhaps a million times. Then the top of this upward Niagara bent over like the calyx of a calla, and the downward Niagara covered all that elevated masonry with a rushing cascade. Shifting my position a little, I could see that the sun was thrilling the whole glorious outpour with rainbows. At such times one can neither measure nor express emotions by words. In the thunder which anyone can hear there is always, for all who can receive it, the ineffably sweet voice of the Father saying, "Thou art my beloved son, and all this grand display is for thy precious sake."

In sixteen minutes the flow of waters ceased, and a rush of saturated steam succeeded. At the same time the fierce swish of ascending waters and of descending cascades ceased, and a clear, definite note, as of a trumpet, exceeding long and loud, was blown. No archangel could have done better. As the steam rolled skyward it was condensed, and a very heavy rain fell on about an acre at the east as it was drifted by the air. It looked more like lines of water than separated drops. I found it thoroughly cooled by its flight in the upper air.

I climbed the huge natural masonry, and stood on the top. I could have put my hand into the hot rushing of measureless power. What a sight it was! There were the brilliant colors of the throat, open, three feet wide, and the dazzling whiteness of the steam. At thirty-two minutes from the beginning the steam suddenly became drier, like that close to the spout of a kettle, or close to the whistle of an engine. All pure steam is invisible. At the same time the note of the trumpet distinctly changed. The heavy rain at the east as suddenly stopped. The air could absorb the present amount of moisture. One could see farther down the terrible throat that seemed about to be rent asunder. The awful grandeur was becoming too much for human endurance. The contorted forms of rocks on the summit began to take the forms and heads of dragons, such as the Chinese carve on their monuments. The awful column began to change its effect from terror to fascination, and I knew how Empedocles felt when he flung himself into the burning Aetna. It was time to get down and stand further off.


[Illustration: Bee-Hive Geyser.]

The long waiting had been rewarded. "To patient faith the prize is sure." The grand tumult began to subside. It was beyond all my expectations. Nature never disappoints, for she is of God and in her He yet immanently abides. The next day the sky and all the air were full of falling rain. How could it be otherwise? It was the geyser returning to earth. I sought the place. The awful trumpet was silent, and the steam exhaled as gently as a sleeping baby's breath.

Only one more lesson will be recited at present. I had just arrived in camp when they told me that the Splendid geyser, after two days of quiet, was showing signs of uneasiness. I immediately went out to study my lesson. There was a little hill of very gentle slopes, a little pool at the top, three holes at the west side of it, with a dozen sputtering hot springs scattered about, while in a direct line at the east, within one hundred and forty feet, were the Comet, the Daisy, and another geyser. The Daisy was a beauty, playing forty feet high every two or four hours. All the slopes were constantly flowing with hot water. This general survey was no sooner taken than our glorious Splendid began to play. The roaring column, tinted with the sunset glories, gradually climbed to a height of two hundred feet, leaned a little to the southeast, and bent like a glorious arch of triumph to the earth, almost as solid on its descending as on its ascending side. No wonder it is named "Splendid."

Whoever has studied waterfalls of great height - I have seen nearly forty justly famous falls - has noticed that when a column or mass of water makes the fearful plunge smaller masses of water are constantly feathered off at the sides and delayed by the resistance of the air, while the central mass hurries downward by its concentrated weight. The general appearance is that of numerous spearheads with serrated edges, feathered with light, thrust from some celestial armory into the writhing pool of agonized waters below. In the geyser one gets this effect both in the ascending and in the descending flood. Four times that first night dear old Splendid lured me from my bed to watch her Titanic play in the full light of the moon. During all this time not a hot spring ceased its boiling, nor a smaller geyser its wondrous play, for this gigantic outburst of power that might well have absorbed every energy for a mile around. Obviously they have no connection. Then my beloved Splendid settled into a three-days' rest.

These are the essential facts of geyser display. There are very many variations of performance in every respect, I have seen over twenty geysers in almost jocular, and certainly in overwhelmingly magnificent, activity.

"To him who in the love of nature holds
Communion with her visible forms, she speaks
A various language."


WHAT ARE THE CAUSES?

What is the power that can throw a stream of water two by six feet over the tops of the highest skyscrapers of Chicago? It is heat manifested in the expansive power of steam. Scientists have theorized long and experimented patiently to read the open book of this tremendous manifestation of uncontrollable energy. At first the form and action of a teakettle was supposed to be explanatory. Everyone knows that when steam accumulates under the lid it forces a gentle stream of water from the higher nozzle. This fact was made the basis of a theory to account for geysers by Sir George Mackenzie in 1811. But to suppose that nature has gone into the teakettle manufacturing business to the extent of thirty such kettles in a space of four square miles was seen to be preposterous. So the construction theory was given up.

But suppose a tube (how it is made will be explained later), large or small, regular or irregular, to extend far into the earth, near or through any great source of heat resulting from condensation, combustion, chemical action, or central fire. Now suppose this tube to be filled with water from surface or subterranean sources. Heat converts water, under the pressure of one atmosphere, or fifteen pounds to the square inch, into steam at a temperature of two hundred and twelve degrees. But under greater pressure more heat is required to make steam. The water never leaps and bubbles in an engine boiler. The awful pressure compels it to be quiet. A cubic inch of water will make a cubic foot - one thousand seven hundred and twenty-eight times as much - of steam under the pressure of one atmosphere. But under the pressure of a column of water one thousand feet high, giving a pressure of four hundred and thirty-two pounds to the square inch at the bottom, water becomes steam, if at all, only by great heat. Every engineer knows that the pressure exerted by steam increases by great geometrical ratios as the heat increases by small arithmetical ratios. Steam made by two hundred and twelve degrees exerts a pressure, as we have said, of fifteen pounds.

To simply double the two hundred and twelve degrees of heat increases the steam pressure twenty-three times.

Now suppose the subterranean tube or lake of Old Faithful to be freshly filled with its million gallons of water. Sufficient heat makes steam under any pressure. It rises up the tube and is condensed to water again by the colder water above. Hence no commotion. But the whole volume of water grows hotter for an hour. When it is too hot to absorb the steam, and the tube is too narrow to let the amount made bubble up through the water, it lifts the whole mass with a sudden jerk. The instant the pressure of the water is taken off in any degree, the water below, that was kept water by the pressure, breaks into steam most voluminously, and the measureless power floods the earth and sky with water and steam.

It is also known that superheated steam suddenly takes on such great power that no boiler can hold it. Once let the water in a boiler get very low and no boiler can hold the force of the resultant superheated steam. The same heat that, applied to water, gives perfect safety, applied to steam gives utter destruction. Hence the amazing force of the vast jets of the geyser that follow the first spurts.

As soon as the steam is blown off the subterranean waterworks fill the tube and the process is repeated.

This modus operandi was first proposed as a theory by Bunsen in 1846, and later was demonstrated by the artificial geyser of Professor J. H. J. Muller, of Freiburg.


[Illustration: Pulpit Terrace and Bunsen Peak.]


MOUNTS OF MINERAL DEPOSITS

I have the extremely difficult task of representing emotions by words - glories of color and form seen by the eye by symbols meant to be addressed to the ear. Before seeking to describe the diverse colors made largely by one substance, let us remember that while silica, the principal part of these water-built mounds, is one of the three parts of granite, namely, the white crystal quartz, it is also the substance of the beautifully variegated jasper, the lapis lazuli, the green malachite, and the opal, with its cloudy milk-whiteness through which flashes its heart of fire. Silica and alumina combine to make common clay, but alumina forms itself into the red ruby, the golden-tinted topaz, the violet oriental amethyst, the red, white, yellow, and violet sapphire, and the beautiful green emerald. With substances of such rare capabilities we may expect rich results in color and form.

We turn now to deposits from water of these two substances, especially the first. About the Old Faithful geyser is a mound about one hundred and forty-five feet broad at the base, twelve feet high, jeweled over with pools of beauty of every shape, beaded and fretted with glories of color never seen before except in the sky. How were they made?

Water is a general solvent. It can take into its substance several similar bulks of other substances without greatly increasing its own, some actually diminishing it. Hot alkaline water will dissolve even silica rock. When water is saturated with sugar, salt, or other substance, if a little or much water is evaporated some of the saturating substance must be deposited as a solid. All crystals, as quartz or diamonds, have been made by deposits from water. Hot water can hold in solution much more of a solid than cold water. Therefore, when hot water comes out of the earth and is cooled, some of the saturating substance must be deposited as a solid. It is done in various ways, especially two.

Suppose a little pool with perpendicular sides, say twenty feet across. It leaps and boils two feet high. It deposits nothing till the water comes to the cooling edge. Then it builds up a wall where it overflows, and wherever it flows it builds. The result is that you walk up the gentle slopes of a broad flat cone, and find the little lakelet in a gorgeous setting, perfectly full at every point of the circumference. If there is but little overflow, the result may be to deposit all the matter where it first cools, and make a perpendicular wall around the cup two or ten feet high. If the overflow is too much to be cooled at once, the deposit may still be made fifty or one hundred feet from the point of issue. If the overflow is sufficient, it may be building up every inch of a vast cone at once, every foot being wet.


[Illustration: The Punch Bowl, Yellowstone Geysers.]

Many minerals are held in solution and are deposited at various stages of evaporation. Let us suppose the lake to have the bottom sloping toward the abysmal center; the different minerals will be assorted as if with a sieve. At the Sunlight Basin the edge is as flaming red as one ever sees in the sunlit sky. And every color ever seen in a sunset flames almost as brilliantly in the varying depths. Suppose a low cone to be flooded only occasionally, as in the case of the Old Faithful geyser. The cooled water falling from the upper air builds up, under the terrible drench of the cataract, walls three or four inches high, making pools of every conceivable shape, a few inches deep, in which are the most exquisite and varied colors ever seen by mortal eye. You walk about on these dividing walls and gaze into the beaded and impearled pools of a hundred shades of different colors, never equaled except by that perpetual glory of the sunset.

Consider the case of a pool that does not overflow. Just as lakes that have no outlet must grow more and more salt till some have become solid salt beds, so must this pool, tossing its hot waves two or three feet high, evaporate its water and deposit its solids. Where? First, against the cooler sides of the rock under the water, tending to reduce the opening to a mere throat. Second, each wavelet tossed in air is cooled, and deposits on the edge, solid as quartz, a crust that overhangs the pool and tends to close it over as with hot ice. It may build thus a mound fifteen feet high with an open throat in the middle. Thus the pool has constructed an intermittent geyser. If the water supply continues, it also destroys itself. The throat closes up by its own deposits. It is a case of geyseral membranous croup.

I exceedingly longed to try vivisection on a geyser, or at least take one of half a hundred, drain it off, and make a post-mortem examination. On my very last day I found opportunity. I found a dead geyser, though not by any means yet cold. It was still so hot that people had given it an infernal name. I squeezed myself down through its hot throat, which seemed a veritable open sepulcher, and found a cave about twenty-five feet deep, twelve feet wide, and about sixty feet long. It was elliptical in form, the sides coming together at a sharp angle at the ends, bottom, and top. The way down to the fiery heart of the earth had simply grown up by deposits of silex on the sides and at the bottom. The water had evaporated by the intense heat, and I was in the hot hollow that had once held an earthquake and volcano. When I squeezed up to the blessed upper air I was glad there was no help from below.

I could tell of mounds that grew so fast as to inclose the limbs of a tree, making the firmest kind of a ladder by which I climbed to the top; of floods that overflowed acres of forest, leaving every tree firmly planted in solid rock; of mounds hundreds of feet high, covering twenty acres with forms of indescribable beauty - but I despair. The half has not been told. It cannot be. Great and marvelous are all Your works, Lord God Almighty! In wisdom have You made them all.

Emerson says: "Whilst common sense looks at things or visible nature as real and final facts, poetry, or the imagination which dictates it, is a second sight, looking through these, and using them as types or words for thoughts which they signify." Using these faculties and not mere eyesight, one must surely say: "Since this world, in power, fineness, finish, beauty, and adaptations not only surpasses our accomplishment, but also is past our finding out to its perfection, it must have been made by One stronger, finer, and wiser than we are."

// #28. The Yellowstone Park Geysers

THEIR ESSENTIAL FACTS AND CAUSES

I have been to school. Dame Nature is a most kind and skillful teacher. She first put me into the ABC class, and advanced me through conic sections. The first thing in the geyser line she showed me was a mound of rock, large as a small cock of hay, with a projection on top large as a shallow pint bowl turned upside down. In the center of this was a half-inch hole, and from it every two seconds, with a musical chuckle of steam, a handful of diamond drops of water was ejected to a height of from two to five feet. I sat down with it half an hour, compelled to continuous laughter by its own musical cachinnations. There were all the essentials of a geyser. There was a mound, not always existent, built up by deposits from the water supersaturated with mineral. It might be three feet high; it might be thirty. There was the jet of water ejected by subterranean forces. It might be half an inch in diameter; it might be three hundred feet, as in the case of the Excelsior geyser. It might rise six inches; it might rise two hundred and fifty feet. There was the interval between the jets. It might be two seconds; it might be weeks or years.


[Illustration: Formation of the Grotto Geyser.]

A subsequent lesson in my Progressive Geyser Reader was the "Economic." Here was a round basin ten feet in diameter, very shallow, with a hole in the middle about one foot across. The water was perfectly calm. But every six minutes a sudden spurt of water and steam would rise about thirty feet, for thirty seconds, and then settle economically, without waste of water, into the pool, sinking with pulsations as on an elastic cushion a foot below the bottom of the pool. One could stride the opening like a colossus for five and one half minutes without fear. He might be using the calm depth for a mirror. But stay a moment too long and he is scalded to death by the sudden outburst.

The next lesson required more patience and gave more abundant reward. I found a great raised platform on which stood a castellated rock, more than twenty feet square, that had been built up particle by particle into a perfect solid by deposits from the fiery flood. In the center was a brilliant orange-colored throat that went down into the bowels of the earth. That was not the geyser - it was only the trump through which the archangel was to blow. I had heard the preliminary tuning of the instrument.

The guide book said the grand play of this "Castle" geyser began from eight to thirty hours after a previous exhibition, and was preceded by jets of water fifteen to twenty feet high, and that these continued five or six hours before the grand eruption. I hovered near the grand stand till the full thirty hours and the six predictive hours were over, and then, as the thunder above roared threateningly and the rain fell suggestively, I took a rubber coat and camped on the trail of that famous spouter.

Geysers are more than a trifle freaky. "Old Faithful" is a notable exception. Every sixty-five minutes, with almost the regularity of star time, he throws his column of hissing water one hundred and fifty feet high. Others are irregular, sometimes playing every three hours for a few times, and then taking a rest for three or more days. This Castle geyser is not registered to be quiet more than thirty hours, nor to indulge in preparatory spouts for more than six hours. When I finally camped to watch it out all these premonitory symptoms had been duly exhibited. I first carefully noted the frequency and height of the spouts, that any change might foretell the grand finale. There were ten spouts to the minute, and an average height of twenty feet. Hours went by with no hint of a change: ten to the minute, twenty feet in height. People by the dozen came and asked when it would go off. I said, "Liable to go any minute; it is long past due now." Stage loads of tourists, scheduled to run on time, drove up, waited a few minutes, and drove on, as if the grand object of the trip was to make time - not to see the grandeur they had come a thousand miles to enjoy. A photographer set up his camera to catch a shadow of the great display. He stood, sometimes air-bulb in hand, an hour or two, then folded his camera tent and stole away. Five hours had passed and night was near. Everybody was gone. I lay down on the ground to convince myself that I was perfectly patient. I attained so nearly to Nirvana that a little ground squirrel came and ran over me, kissing my hand in a most friendly way.

Six hours of waiting were nearly over when, without a single previous hint of change, one descending spout was met by an ascending one, and a vast column of hissing water rose, with a sound of continuous thunder, one hundred feet in air; and stood there like a pillar of cloud in the desert. The air throbbed as in a cannonade, and the sun brushed away all clouds as if he could not bear to miss a sight he had seen perhaps a million times. Then the top of this upward Niagara bent over like the calyx of a calla, and the downward Niagara covered all that elevated masonry with a rushing cascade. Shifting my position a little, I could see that the sun was thrilling the whole glorious outpour with rainbows. At such times one can neither measure nor express emotions by words. In the thunder which anyone can hear there is always, for all who can receive it, the ineffably sweet voice of the Father saying, "Thou art my beloved son, and all this grand display is for thy precious sake."

In sixteen minutes the flow of waters ceased, and a rush of saturated steam succeeded. At the same time the fierce swish of ascending waters and of descending cascades ceased, and a clear, definite note, as of a trumpet, exceeding long and loud, was blown. No archangel could have done better. As the steam rolled skyward it was condensed, and a very heavy rain fell on about an acre at the east as it was drifted by the air. It looked more like lines of water than separated drops. I found it thoroughly cooled by its flight in the upper air.

I climbed the huge natural masonry, and stood on the top. I could have put my hand into the hot rushing of measureless power. What a sight it was! There were the brilliant colors of the throat, open, three feet wide, and the dazzling whiteness of the steam. At thirty-two minutes from the beginning the steam suddenly became drier, like that close to the spout of a kettle, or close to the whistle of an engine. All pure steam is invisible. At the same time the note of the trumpet distinctly changed. The heavy rain at the east as suddenly stopped. The air could absorb the present amount of moisture. One could see farther down the terrible throat that seemed about to be rent asunder. The awful grandeur was becoming too much for human endurance. The contorted forms of rocks on the summit began to take the forms and heads of dragons, such as the Chinese carve on their monuments. The awful column began to change its effect from terror to fascination, and I knew how Empedocles felt when he flung himself into the burning Aetna. It was time to get down and stand further off.


[Illustration: Bee-Hive Geyser.]

The long waiting had been rewarded. "To patient faith the prize is sure." The grand tumult began to subside. It was beyond all my expectations. Nature never disappoints, for she is of God and in her He yet immanently abides. The next day the sky and all the air were full of falling rain. How could it be otherwise? It was the geyser returning to earth. I sought the place. The awful trumpet was silent, and the steam exhaled as gently as a sleeping baby's breath.

Only one more lesson will be recited at present. I had just arrived in camp when they told me that the Splendid geyser, after two days of quiet, was showing signs of uneasiness. I immediately went out to study my lesson. There was a little hill of very gentle slopes, a little pool at the top, three holes at the west side of it, with a dozen sputtering hot springs scattered about, while in a direct line at the east, within one hundred and forty feet, were the Comet, the Daisy, and another geyser. The Daisy was a beauty, playing forty feet high every two or four hours. All the slopes were constantly flowing with hot water. This general survey was no sooner taken than our glorious Splendid began to play. The roaring column, tinted with the sunset glories, gradually climbed to a height of two hundred feet, leaned a little to the southeast, and bent like a glorious arch of triumph to the earth, almost as solid on its descending as on its ascending side. No wonder it is named "Splendid."

Whoever has studied waterfalls of great height - I have seen nearly forty justly famous falls - has noticed that when a column or mass of water makes the fearful plunge smaller masses of water are constantly feathered off at the sides and delayed by the resistance of the air, while the central mass hurries downward by its concentrated weight. The general appearance is that of numerous spearheads with serrated edges, feathered with light, thrust from some celestial armory into the writhing pool of agonized waters below. In the geyser one gets this effect both in the ascending and in the descending flood. Four times that first night dear old Splendid lured me from my bed to watch her Titanic play in the full light of the moon. During all this time not a hot spring ceased its boiling, nor a smaller geyser its wondrous play, for this gigantic outburst of power that might well have absorbed every energy for a mile around. Obviously they have no connection. Then my beloved Splendid settled into a three-days' rest.

These are the essential facts of geyser display. There are very many variations of performance in every respect, I have seen over twenty geysers in almost jocular, and certainly in overwhelmingly magnificent, activity.

"To him who in the love of nature holds
Communion with her visible forms, she speaks
A various language."


WHAT ARE THE CAUSES?

What is the power that can throw a stream of water two by six feet over the tops of the highest skyscrapers of Chicago? It is heat manifested in the expansive power of steam. Scientists have theorized long and experimented patiently to read the open book of this tremendous manifestation of uncontrollable energy. At first the form and action of a teakettle was supposed to be explanatory. Everyone knows that when steam accumulates under the lid it forces a gentle stream of water from the higher nozzle. This fact was made the basis of a theory to account for geysers by Sir George Mackenzie in 1811. But to suppose that nature has gone into the teakettle manufacturing business to the extent of thirty such kettles in a space of four square miles was seen to be preposterous. So the construction theory was given up.

But suppose a tube (how it is made will be explained later), large or small, regular or irregular, to extend far into the earth, near or through any great source of heat resulting from condensation, combustion, chemical action, or central fire. Now suppose this tube to be filled with water from surface or subterranean sources. Heat converts water, under the pressure of one atmosphere, or fifteen pounds to the square inch, into steam at a temperature of two hundred and twelve degrees. But under greater pressure more heat is required to make steam. The water never leaps and bubbles in an engine boiler. The awful pressure compels it to be quiet. A cubic inch of water will make a cubic foot - one thousand seven hundred and twenty-eight times as much - of steam under the pressure of one atmosphere. But under the pressure of a column of water one thousand feet high, giving a pressure of four hundred and thirty-two pounds to the square inch at the bottom, water becomes steam, if at all, only by great heat. Every engineer knows that the pressure exerted by steam increases by great geometrical ratios as the heat increases by small arithmetical ratios. Steam made by two hundred and twelve degrees exerts a pressure, as we have said, of fifteen pounds.

To simply double the two hundred and twelve degrees of heat increases the steam pressure twenty-three times.

Now suppose the subterranean tube or lake of Old Faithful to be freshly filled with its million gallons of water. Sufficient heat makes steam under any pressure. It rises up the tube and is condensed to water again by the colder water above. Hence no commotion. But the whole volume of water grows hotter for an hour. When it is too hot to absorb the steam, and the tube is too narrow to let the amount made bubble up through the water, it lifts the whole mass with a sudden jerk. The instant the pressure of the water is taken off in any degree, the water below, that was kept water by the pressure, breaks into steam most voluminously, and the measureless power floods the earth and sky with water and steam.

It is also known that superheated steam suddenly takes on such great power that no boiler can hold it. Once let the water in a boiler get very low and no boiler can hold the force of the resultant superheated steam. The same heat that, applied to water, gives perfect safety, applied to steam gives utter destruction. Hence the amazing force of the vast jets of the geyser that follow the first spurts.

As soon as the steam is blown off the subterranean waterworks fill the tube and the process is repeated.

This modus operandi was first proposed as a theory by Bunsen in 1846, and later was demonstrated by the artificial geyser of Professor J. H. J. Muller, of Freiburg.


[Illustration: Pulpit Terrace and Bunsen Peak.]


MOUNTS OF MINERAL DEPOSITS

I have the extremely difficult task of representing emotions by words - glories of color and form seen by the eye by symbols meant to be addressed to the ear. Before seeking to describe the diverse colors made largely by one substance, let us remember that while silica, the principal part of these water-built mounds, is one of the three parts of granite, namely, the white crystal quartz, it is also the substance of the beautifully variegated jasper, the lapis lazuli, the green malachite, and the opal, with its cloudy milk-whiteness through which flashes its heart of fire. Silica and alumina combine to make common clay, but alumina forms itself into the red ruby, the golden-tinted topaz, the violet oriental amethyst, the red, white, yellow, and violet sapphire, and the beautiful green emerald. With substances of such rare capabilities we may expect rich results in color and form.

We turn now to deposits from water of these two substances, especially the first. About the Old Faithful geyser is a mound about one hundred and forty-five feet broad at the base, twelve feet high, jeweled over with pools of beauty of every shape, beaded and fretted with glories of color never seen before except in the sky. How were they made?

Water is a general solvent. It can take into its substance several similar bulks of other substances without greatly increasing its own, some actually diminishing it. Hot alkaline water will dissolve even silica rock. When water is saturated with sugar, salt, or other substance, if a little or much water is evaporated some of the saturating substance must be deposited as a solid. All crystals, as quartz or diamonds, have been made by deposits from water. Hot water can hold in solution much more of a solid than cold water. Therefore, when hot water comes out of the earth and is cooled, some of the saturating substance must be deposited as a solid. It is done in various ways, especially two.

Suppose a little pool with perpendicular sides, say twenty feet across. It leaps and boils two feet high. It deposits nothing till the water comes to the cooling edge. Then it builds up a wall where it overflows, and wherever it flows it builds. The result is that you walk up the gentle slopes of a broad flat cone, and find the little lakelet in a gorgeous setting, perfectly full at every point of the circumference. If there is but little overflow, the result may be to deposit all the matter where it first cools, and make a perpendicular wall around the cup two or ten feet high. If the overflow is too much to be cooled at once, the deposit may still be made fifty or one hundred feet from the point of issue. If the overflow is sufficient, it may be building up every inch of a vast cone at once, every foot being wet.


[Illustration: The Punch Bowl, Yellowstone Geysers.]

Many minerals are held in solution and are deposited at various stages of evaporation. Let us suppose the lake to have the bottom sloping toward the abysmal center; the different minerals will be assorted as if with a sieve. At the Sunlight Basin the edge is as flaming red as one ever sees in the sunlit sky. And every color ever seen in a sunset flames almost as brilliantly in the varying depths. Suppose a low cone to be flooded only occasionally, as in the case of the Old Faithful geyser. The cooled water falling from the upper air builds up, under the terrible drench of the cataract, walls three or four inches high, making pools of every conceivable shape, a few inches deep, in which are the most exquisite and varied colors ever seen by mortal eye. You walk about on these dividing walls and gaze into the beaded and impearled pools of a hundred shades of different colors, never equaled except by that perpetual glory of the sunset.

Consider the case of a pool that does not overflow. Just as lakes that have no outlet must grow more and more salt till some have become solid salt beds, so must this pool, tossing its hot waves two or three feet high, evaporate its water and deposit its solids. Where? First, against the cooler sides of the rock under the water, tending to reduce the opening to a mere throat. Second, each wavelet tossed in air is cooled, and deposits on the edge, solid as quartz, a crust that overhangs the pool and tends to close it over as with hot ice. It may build thus a mound fifteen feet high with an open throat in the middle. Thus the pool has constructed an intermittent geyser. If the water supply continues, it also destroys itself. The throat closes up by its own deposits. It is a case of geyseral membranous croup.

I exceedingly longed to try vivisection on a geyser, or at least take one of half a hundred, drain it off, and make a post-mortem examination. On my very last day I found opportunity. I found a dead geyser, though not by any means yet cold. It was still so hot that people had given it an infernal name. I squeezed myself down through its hot throat, which seemed a veritable open sepulcher, and found a cave about twenty-five feet deep, twelve feet wide, and about sixty feet long. It was elliptical in form, the sides coming together at a sharp angle at the ends, bottom, and top. The way down to the fiery heart of the earth had simply grown up by deposits of silex on the sides and at the bottom. The water had evaporated by the intense heat, and I was in the hot hollow that had once held an earthquake and volcano. When I squeezed up to the blessed upper air I was glad there was no help from below.

I could tell of mounds that grew so fast as to inclose the limbs of a tree, making the firmest kind of a ladder by which I climbed to the top; of floods that overflowed acres of forest, leaving every tree firmly planted in solid rock; of mounds hundreds of feet high, covering twenty acres with forms of indescribable beauty - but I despair. The half has not been told. It cannot be. Great and marvelous are all Your works, Lord God Almighty! In wisdom have You made them all.

Emerson says: "Whilst common sense looks at things or visible nature as real and final facts, poetry, or the imagination which dictates it, is a second sight, looking through these, and using them as types or words for thoughts which they signify." Using these faculties and not mere eyesight, one must surely say: "Since this world, in power, fineness, finish, beauty, and adaptations not only surpasses our accomplishment, but also is past our finding out to its perfection, it must have been made by One stronger, finer, and wiser than we are."