of the comet would consist of granitic stones and dust such as constitutes clays.
The stones are reduced to a small size by the constant attrition:
"The stones of the 'till' are not of the largest; indeed, bowlders above four feet in diameter are comparatively seldom met with in the till."[2]
And this theory is corroborated by the fact that the eminent German geologist, Dr. Hahn, has recently discovered an entire series of organic remains in meteoric stones, of the class called chrondites, and which he identifies as belonging to classes of sponges, corals, and crinoids. Dr. Weinland, another distinguished German, corroborates these discoveries; and he has also found fragments in these stones very much like the youngest marine chalk in the Gulf of Mexico; and he thinks he sees, under the microscope, traces of vegetable growth. Francis Birgham says:
[1. "American Cyclopædia," article "Clay."
2. "The Great Ice Age," p. 10.]
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"This entire ex-terrestrial fauna hitherto discovered, which already comprises about fifty different species, and which originates from different meteoric falls, even from some during the last century, conveys the impression that it doubtlessly once formed part of a single ex-terrestrial-celestial body with a unique creation, which in by-gone ages seems to have been overtaken by a grand catastrophe, during which it was broken up into fragments."[1]
When we remember that meteors are now generally believed to be the droppings of comets, we come very near to proof of the supposition that comets are the débris of exploded planets; for only on planets can we suppose that life existed, for there was required, for the growth of these sponges, corals, and crinoids, rocks, earth, water, seas or lakes, atmosphere, sunshine, and a range of temperature between the degree of cold where life is frozen up and the degree of heat in which it is burned up: hence, these meteors must be fragments of bodies possessing earth-like conditions.
We know that the heavenly bodies are formed of the same materials as our globe.
Dana says:
"Meteoric stones exemplify the same chemical and crystallographic laws as the rocks of the earth, and have afforded no new element or principle of any kind."[2]
It may be presumed, therefore, that the granite crust of the exploded globe from which some comet was created was the source of the finely triturated material which we know as clay.
But the clays are of different colors--white, yellow, red, and blue.
[1. "Popular Science Monthly," November, 1881, p. 86.
2. "Manual of Geology," p. 3.]
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"The aluminous minerals contained in granite rocks are feldspar, mica, and hornblende. … Mica and hornblende generally contain considerable oxide of iron, while feldspar usually yields only a trace or none. Therefore clays which are derived from feldspar are light-colored or white, while those partially made up of decomposed mica or hornblende are dark, either bluish or red."[1]
The tail of the comet seems to be perpetually in motion. It is, says one writer, "continually changing and fluctuating as vaporous masses of cloud-like structure might be conceived to do, and in some instances there has been a strong appearance even of an undulating movement."[2]
The great comet of 1858, Donati's comet, which many now living will well remember, and which was of such size that when its head was near our horizon the extremity of the tail reached nearly to the zenith, illustrated this continual movement of the material of the tail; that appendage shrank and enlarged millions of miles in length.
Mr. Lockyer believed that he saw in Coggia's comet the evidences of a whirling motion--
"In which the regions of greatest brightness were caused by the different coils cutting, or appearing to cut, each other, and so in these parts leading to compression or condensation, and frequent collision of the luminous particles."
Olbers saw in a comet's tail--
"A sudden flash and pulsation of light which vibrated for several seconds through it, and the tail appeared during the continuance of the pulsations of light to be lengthened by several degrees and then again contracted."[1]
[1. "American Cyclopædia," article "Clay."
2. "Edinburgh Review," October, 1874, p. 208,
3, "Cosmos," vol. i, p. 143.]
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Now, in this perpetual motion, this conflict, these great thrills of movement, we are to find the source of the clays which cover a large part of our globe to a depth of hundreds of feet. Where are those exposures of granite on the face of the earth from which ice or water could have ground them? Granite, I repeat, comes to the surface only in limited areas. And it must be remembered that clay is the product exclusively of granite ground to powder. The clays are composed exclusively of the products of disintegrated granite. They contain but a trace of lime or magnesia or organic matters, and these can be supposed to have been infiltrated into them after their arrival on the face of the earth.[1] Other kinds of rock, ground up, form sand. Moreover, we have seen that neither glaciers nor ice-sheets now produce such clays.
We shall see, as we proceed, that the legends of mankind, in describing the comet that struck the earth, represent it as party-colored; it is "speckled" in one legend; spotted like a tiger in another; sometimes it is a white boar in the heavens; sometimes a blue snake; sometimes it is red with the blood of the millions that are to perish. Doubtless these separate formations, ground out of the granite, from the mica, hornblende, or feldspar, respectively, may, as I have said, under great laws, acted upon by magnetism or electricity, have arranged themselves in separate lines or sheets, in the tail of the comet, and hence we find that the clays of one region are of one color, while those of another are of a different hue. Again, we shall see that the legends represent the monster as "winding," undulating, writhing, twisting, fold over fold, precisely as the telescopes show us the comets do to-day.
[1. "American Cyclopædia," vol. iv, p. 650.]
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The very fact that these waves of motion run through the tail of the comet, and that it is capable of expanding and contracting on an immense scale, is conclusive proof that it is composed of small, adjustable particles. The writer from whom I have already quoted, speaking of the extraordinary comet of 1843, says:
"As the comet moves past the great luminary, it sweeps round its tail as a sword may be conceived to be held out at arm's-length, and then waved round the head, from one side to the opposite. But a sword with a blade one hundred and fifty millions of miles long must be a somewhat awkward weapon to brandish round after this fashion. Its point would have to sweep through a curve stretching out more than six hundred millions of miles; and, even with an allowance of two hours for the accomplishment of the movement, the flash of the weapon would be of such terrific velocity that it is not an easy task to conceive how any blade of connected material substance could bear the strain of the stroke. Even with a blade that possessed the coherence and tenacity of iron or steel, the case would be one that it would be difficult for molecular cohesion to deal with. But that difficulty is almost infinitely increased when it is a substance of much lower cohesive tenacity than either iron or steel that has to be subjected to the strain.
"There would be, at least, some mitigation of this difficulty if it were lawful to assume that the substance which is subjected to this strain was not amenable to the laws of ponderable existence; if there were room for the notion that comets and their tails, which have to be brandished in such a stupendous fashion, were sky-spectres, immaterial phantoms, unreal visions of that negative shadow-kind which has been alluded to. This, however, unfortunately, is not a permissible alternative in the circumstances of the case. The great underlying and indispensable fact that the comet comes rushing up toward the sun out of space, and then shoots round that great center of attraction by the force of its own acquired and ever-increasing impetuosity; the fact that it is obedient
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