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small a depth comparatively that we can penetrate, we can by no means say that the body of the earth is of any solid material—though some have asserted that it must
to account for its bulk. ANNE.--I do not understand this.
Mrs. L.—Bulk, in the language of Natural Philosopby, is not size, but quantity—the quantity of matter contained in any body.
MATILDA.-But how can the quantity of matter in the earth be ascertained ?
MRS. L.-Only by its perceived influence on other bodies, estimated according to the laws of gravitation. It does not appear to me that this is sufficiently certain : and some have supposed the interior of the earth to be water, others that it is fire, or something at least in an igneous state.
ANNE.Is either of these conjectures probable ?
Mrs. L.-Neither is impossible--and both one system and the other have been made to explain many phænomena difficult to explain without them. I can but repeat to you what has been conjectured, without giving an opinion. It is evident that much of what now is solid on the surface of the earth, has been sometime in a state of fluidity, held in solution, dissolved, or, as we call it in common language when applied to metals, melted. Water and fire are the great solvent principles with which we are acquainted, and to the agency of one or the other, much of the present appearance of the globe must be attributed—probably to both : of this we shall have occasion to speak again, in mentioning the changes that have taken place on the earth since its first formation. Every thing indicates that the waters have sometime covered the whole surface of the globe-at the flood we know they did so temporarily; and the Mosaic account of the Creation leads us to think they did so till the third day of the Creation, when it is said, “ Let the waters be gathered together in one place and let the dry land appear.” The poet of Israel celebrates
this retreating of the waters: “ The waters stood above the mountains. At thy rebuke they fled; at the voice of thy thunders they hasted away; they went over the mountains, they went down by the valleys unto the place which thou didst assign them. Thou didst set a bound which they should not pass over.” We know that at the flood, these bounds were broken-He who had inclosed the waters in their place again set them free-besides the rains that fell forty days upon the earth, we are told that the fountains of the great deep were broken
But at the same time that these records lead us to think there may be a concentration of waters beneath the surface of the earth, they do not prove it so—the place to which the Creator confined them might be no other than the beds of the ocean, deepened at the time to receive them.
MAT.-And what can have led Geologists to suppose there may be fire there.
. Mrs. L.—I will give you an extract on the subject from the Geology of Messrs. Conybeare and Phillips but you must observe that it occurs there merely as a conjecture of things possible, not as an assertion of fact, Speaking of those disruptions of the surface, which we shall notice hereafter, it is said —"The only agent with which we are acquainted, whose operation bears any analogy to the effects specified, is the volcanic energy, which still occasionally forms new islands and elevates new mountains. Although these effects are indeed now partial and limited, yet there is certain proof that volcanic agency has formerly been much more active; the extinct volcanoes of the Rhine, Hungary, and Auvergne, as well as those which occupy so large a portion of Italy, where one only now remains in activity, concur in proving that we now experience only the expiring efforts, as it were, of those gigantic powers which had once ravaged the face of nature. The question will undoubtedly present itself, what is the source of volcanic action; and sufficient proof exists that this source is deeply seated beneath the lowest rocks with which our examination of the earth's surface makes us acquainted; for in Auvergne the Lavas have evidently been erupted from beneath the primitive rocks. The important recent discoveries with regard to the increased temperature noticed in descending deep mines, &c., by Messrs Fourier and Fox, will, if confirmed by further examination, prove that some great source of heat exists beneath the earth's crust. On this supposition (that of the crust of the earth resting on a heated Nucleus) we should at once perceive why the effects of the volcanic force may have been much more violent in earlier periods, while the mass of deposits which now covers the supposed volcanic Nucleus was only gradually forming over it, than at present; and we shall also find a reason for the higher temperature which many of the remains both of animal and vegetable kingdoms, found in the strata of countries now too cold for their existence, appear to indicate as having formerly prevailed.” Thus you see, does the enquiring mind of man amuse itself in conjecturing what in áll probability it will never know. Let us leave to its uncertainty this hidden Nucleus, and return to what
you will now perhaps allow me to call the surface of the earth.
ANNE.—Most willingly—but you must not go on too fast, for I feel in danger of getting puzzled at every step-Nucleus—that is the Latin for kernel or heart, I suppose--but then you said something about CRYSTALS, MINERALS, and Fossils-is it too soon to have these terms explained?
Mrs. L.-The best time to explain, is when you are getting puzzled, as you call it. MINERALS, as separate from' rocks, “are distinguished by their never forming large masses. They are either constituent parts of rocks, or occur irregularly dispersed through them.” The description of these substances belongs more properly to the mineralogist, but I intend to notice and describe them when they occur in our present subject.
MINERALS frequently assume regular forms, which are called their respective CRYSTALS. By what process nature produces these beautiful conformations, we cannot tell- we can take her work to pieces and find of what the brilliant diamond is composed, but we cannoi put it together again, or so concrete the substance as to form the like. There is a great variety of mineral substances that will crystallize before our eyes—for this purpose you need but to dissolve a little salt in water, and pour it on a plate—as the water evaporates, you may observe with the naked eye, and yet better with a glass, the particles of the salt assembling themselves into the form of crystals. In a similar manner you have amused yourself with making ornaments, by dissolving alum in water, and as the water cooled, allowing it to fix itself in crystals upon a basket placed in the liquid to receive it. So the substance called Copperas is made -the oxyde of which it is composed forms itself upon what seems a bed of useless earth, whence it is washed by the rain into a cistern prepared to receive it. Large sticks or branches are placed in the liquid, on which the Copperas forms itself in the most beautiful green crystals, and is the article so useful in many of our manufactures. How far the process of crystalization in nature resembles that which passes before our eyes, we are left to conjecture. But we know that under circumstances unknown to us, a mineral will pass into a form as regular as our finest instruments could cut it, different in different minerals, but in the same mineral always the same-except that some minerals have more than one crystal appropriated to them—thus lead, a substance to which in our common knowledge of it, we do not attach the idea of form, becomes in its crystalized state a cube-Plate 2. Fig.1. The Garnet, which we rank among the precious stones, is several common earths crystallized together, and is found in the form of a rhomboidal dodecahedron. Fig. 2. Common Quartz, a substance that presents itself to us