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- Curiosities of the Sky - 20/25 -


the latter. To appreciate this it is necessary to recall the way in which Moissan made his diamonds. It was by a combination of the effects of great heat, great pressure, and sudden or rapid superficial cooling on a mass of iron containing carbon. When he finally broke open his iron he found it a pudding stuffed with miniature black diamonds. When a fragment of the Canyon Diablo meteoric iron was polished in Philadelphia over fifteen years ago it cut the emery-wheel to pieces, and examination showed that the damage had been effected by microscopic diamonds peppered through the mass. How were those diamonds formed? If the sun or Sirius was the laboratory that prepared them, we can get a glimpse at the process of their formation. There is plenty of heat, plenty of pressure, and an abundance of vaporized iron in the sun and the stars. When a great solar eruption takes place, masses of iron which have absorbed carbon may be shot out with a velocity which forbids their return. Plunged into the frightful cold of space, their surfaces are quickly cooled, as Moissan cooled his prepared iron by throwing it into water, and thus the requisite stress is set up within, and, as the iron solidifies, the included carbon crystallizes into diamonds. Whether this explanation has a germ of truth in it or not, at any rate it is evident that iron meteorites were not created in the form in which they come to us; they must once have been parts of immeasurably more massive bodies than themselves.

The fall of meteorites offers an appreciable, though numerically insignificant, peril to the inhabitants of the earth. Historical records show perhaps three or four instances of people being killed by these bodies. But for the protection afforded by the atmosphere, which acts as a very effective shield, the danger would doubtless be very much greater. In the absence of an atmosphere not only would more meteorites reach the ground, but their striking force would be incomparably greater, since, as we have seen, the larger part of their original velocity is destroyed by the resistance of the air. A meteorite weighing many tons and striking the earth with a velocity of twenty or thirty miles per second, would probably cause frightful havoc.

It is a singular fact that recent investigations seem to have proved that an event of this kind actually happened in North America -- perhaps not longer than a thousand or two thousand years ago. The scene of the supposed catastrophe is in northern central Arizona, at Coon Butte, where there is a nearly circular crater in the middle of a circular elevation or small mountain. The crater is somewhat over four thousand feet in diameter, and the surrounding rim, formed of upturned strata and ejected rock fragments, rises at its highest point one hundred and sixty feet above the plain. The crater is about six hundred feet in depth -- that is, from the rim to the visible floor or bottom of the crater. There is no evidence that volcanic action has ever taken place in the immediate neighborhood of Coon Butte. The rock in which the crater has been made is composed of horizontal sandstone and limestone strata. Between three hundred and four hundred million tons of rock fragments have been detached, and a large portion hurled by some cause out of the crater. These fragments lie concentrically distributed around the crater, and in large measure form the elevation known as Coon Butte. The region has been famous for nearly twenty years on account of the masses of meteoric iron found scattered about and known as the ``Canyon Diablo'' meteorites. It was one of these masses, which consist of nickel-iron containing a small quantity of platinum, and of which in all some ten tons have been recovered for sale to the various collectors throughout the world, that as before mentioned destroyed the grinding-tool at Philadelphia through the cutting power of its embedded diamonds. These meteoric irons are scattered about the crater-hill, in concentric distribution, to a maximum distance of about five miles. When the suggestion was first made in 1896 that a monster meteorite might have created by its fall this singular lone crater in stratified rocks, it was greeted with incredulous smiles; but since then the matter has assumed a different aspect. The Standard Iron Company, formed by Messrs. D. M. Barringer, B. C. Tilghman, E. J. Bennitt, and S. J. Holsinger, having become, in 1903, the owner of this freak of nature, sunk shafts and bored holes to a great depth in the interior of the crater, and also trenched the slopes of the mountain, and the result of their investigations has proved that the meteoric hypothesis of origin is correct. (See the papers published in the Proceedings of the Academy of Natural Sciences of Philadelphia, December, 1905, wherein it is proved that the United States Geological Survey was wrong in believing this crater to have been due to a steam explosion. Since that date there has been discovered a great amount of additional confirmatory proof). Material of unmistakably meteoric origin was found by means of the drills, mixed with crushed rock, to a depth of six hundred to seven hundred feet below the floor of the crater, and a great deal of it has been found admixed with the ejected rock fragments on the outer slopes of the mountain, absolutely proving synchronism between the two events, the formation of this great crater and the falling of the meteoric iron out of the sky. The drill located in the bottom of the crater was sent, in a number of cases, much deeper (over one thousand feet) into unaltered horizontal red sandstone strata, but no meteoric material was found below this depth (seven hundred feet, or between eleven and twelve hundred feet below the level of the surrounding plain), which has been assumed as being about the limit of penetration. It is not possible to sink a shaft at present, owing to the water which has drained into the crater, and which forms, with the finely pulverized sandstone, a very troublesome quicksand encountered at about two hundred feet below the visible floor of the crater. As soon as this water is removed by pumping it will be easy to explore the depths of the crater by means of shafts and drifts. The rock strata (sandstone and limestone) of which the walls consist present every appearance of having been violently upturned by a huge body penetrating the earth like a cannon-ball. The general aspect of the crater strikingly resembles the impression made by a steel projectile shot into an armor-plate. Mr Tilghman has estimated that a meteorite about five hundred feet in diameter and moving with a velocity of about five miles per second would have made just such a perforation upon striking rocks of the character of those found at this place. There was some fusion of the colliding masses, and the heat produced some steam from the small amount of water in the rocks. As a result there has been found at depth a considerable amount of fused quartz (original sandstone), and with it innumerable particles or sparks of fused nickel-iron (original meteorite). A projectile of that size penetrating eleven to twelve hundred feet into the rocky shell of the globe must have produced a shock which was perceptible several hundred miles away.

The great velocity ascribed to the supposed meteorite at the moment of striking could be accounted for by the fact that it probably plunged nearly vertically downward, for it formed a circular crater in the rocky crust of the earth. In that case it would have been less retarded by the resistance of the atmosphere than are meteorites which enter the air at a lower angle and shoot ahead hundreds of miles until friction has nearly destroyed their original motion when they drop upon the earth. Some meteoric masses of great size, such as Peary's iron meteorite found at Cape York, Greenland, and the almost equally large mass discovered at Bacubirito, Mexico, appear to have penetrated but slightly on striking the earth. This may be explained by supposing that they pursued a long, horizontal course through the air before falling. The result would be that, their original velocity having been practically destroyed, they would drop to the ground with a velocity nearly corresponding to that which gravity would impart within the perpendicular distance of their final fall. A six-hundred-and-sixty-pound meteorite, which fell at Knyahinya, Hungary, striking at an angle of 27 from the vertical, penetrated the ground to a depth of eleven feet.

It has been remarked that the Coon Butte meteorite may have fallen not longer ago than a few thousand years. This is based upon the fact that the geological indications favor the supposition that the event did not occur more than five thousand years ago, while on the other hand the rings of growth in the cedar-trees growing on the slopes of the crater show that they have existed there about seven hundred years. Prof. William H. Pickering has recently correlated this with an ancient chronicle which states that at Cairo, Egypt, in the year 1029, ``many stars passed with a great noise.'' He remarks that Cairo is about 100, by great circle, from Coon Butte, so that if the meteorite that made the crater was a member of a flock of similar bodies which encountered the earth moving in parallel lines, some of them might have traversed the sky tangent to the earth's surface at Cairo. That the spectacle spoken of in the chronicle was caused by meteorites he deems exceedingly probable because of what is said about ``a great noise;'' meteorites are the only celestial phenomena attended with perceptible sounds. Professor Pickering conjectures that this supposed flock of great meteorites may have formed the nucleus of a comet which struck the earth, and he finds confirmation of the idea in the fact that out of the ten largest meteorites known, no less than seven were found within nine hundred miles of Coon Butte. It would be interesting if we could trace back the history of that comet, and find out what malicious planet caught it up in its innocent wanderings and hurled it with so true an aim at the earth! This remarkable crater is one of the most interesting places in the world, for there is absolutely no record of such a mass, possibly an iron-headed comet, from outer space having come into collision with our earth. The results of the future exploration of the depths of the crater will be awaited with much interest.

The Wrecking of the Moon

There are sympathetic moods under whose influence one gazes with a certain poignant tenderness at the worn face of the moon; that little ``fossil world'' (the child of our mother earth, too) bears such terrible scars of its brief convulsive life that a sense of pity is awakened by the sight. The moon is the wonder-land of the telescope. Those towering mountains, whose ``proud aspiring peaks'' cast silhouettes of shadow that seem drawn with india-ink; those vast plains, enchained with gentle winding hills and bordered with giant ranges; those oval ``oceans,'' where one looks expectant for the flash of wind-whipped waves; those enchanting ``bays'' and recesses at the seaward feet of the Alps; those broad straits passing between guardian heights incomparably mightier than Gibraltar; those locket-like valleys as secluded among their mountains as the Vale of Cashmere; those colossal craters that make us smile at the pretensions of Vesuvius, Etna, and Cotopaxi; those strange white ways which pass with the unconcern of Roman roads across mountain, gorge, and valley -- all these give the beholder an irresistible impression that it is truly a world into which he is looking, a world akin to ours, and yet no more like our world than Pompeii is like Naples. Its air, its waters, its clouds, its life are gone, and only a skeleton remains -- a mute but eloquent witness to a cosmical tragedy without parallel in the range of human knowledge.

One cannot but regret that the moon, if it ever was the seat of intelligent life, has not remained so until our time. Think what the consequences would have been if this other world at our very door had been found to be both habitable and inhabited! We talk rather airily of communicating with Mars by signals; but Mars never approaches nearer than 35,000,000 miles, while the moon when nearest is only a little more than 220,000 miles away. Given an effective magnifying power of five thousand diameters, which will perhaps be possible at the mountain observatories as telescopes improve, and we should be able to bring the moon within an apparent distance of about forty miles, while the corresponding distance for Mars would be more than seven thousand miles. But even with existing telescopic powers we can see details on the moon no larger than some artificial constructions


Curiosities of the Sky - 20/25

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