Among the Forces - Henry White Warren (books for 8th graders TXT) 📗

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.

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.


MOUNDS 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.

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