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fre imagined that the internal parts might be a fluid More dense, and of greater specific gravity than any of the solids we are acquainted with; which thereföre might swim in or upon that fluid. Thus the sur face of the globe would be a shell, capable of being proken and disordered by the vicleni morements of fluid on which it rester. And, as air has been compressed by art so as to be twice as dense as water, in which case, if such air and water could be contained in a strong glass vessel, the air would be seen to take the lowest place, and the water to loa above and upon it; and, as we know not yet the degree of density to which air may be compressed, and M. Amontons calculated, that, its density increasing as it approached the centre in the same proportion as above the surface, it would at the depth of leagues, be heavier than gold, possibly the dense fluid occupying the internal parts of the globe might be air compressed. And as the force of expansion in dense air when heated, is in proportion to its density : this central air might afford another agent to move the surface, as weil as be of use in keeping alive the cen. tra) fires; though, as you observe, the sudden rare. faction of water, coming into contact with those fires, may be an agent sufficiently strong for that purpose, when acting between the incumbent and the fluid on which it rests.

If one night indulge imagination in supposing how such a globe was formed, I should conceive, that all the elements in separate particles, being originally mixed in confusion, and occupying a great space, they would as soon (as soon as the Almighty fiat ordained gravity, or the mutual attraction of cer ain parts, and the inutual repulsion of other parts, to xist) all move towards their common centre: tha the air being a Auid whose parts repel each other though drawn to the common centre by their gravity, would be densest towards the centre, and rarer as more remote; consequently, all bodies, lighter than the central parts of that air, and immersed in it, wouid recede from the centre, an í rise till they arrire at that region of the air, which was of the saine specific gra. vity with themselves, where they would rest; while

other matter mixed with the lighter air, woula descend, and the two, meeting, would form the shell of the first earth, leaving the upper atmosphere nearly clear. The original movement of the parts towards their common centre would form a whirl there; which would continue in the turning of the new-formed globe upon its axis, and the greatest diameter of the shell would be in its equator. If by any accident afterwards the wis should be changed, the dense internal fluid, by alrering its form, must burst the shell, and throw all no substance into the confusion in which w find it. I will not trouble you at present with my fancies concerning the manner of forming the rest of our system. Superior beings smile on our theories, and at our presumption in making them. I will just mention that your observation of the ferruginous nature of the lava, which is throrin out from the depths of our volcanoes, gave me great pleasure. It has long been a supposition of mine, that the iron contained in the substance of the globe has made it capa. ble of becoming, as it is, a great magnet; that the fluid of magnetism exists perhaps in all space; so that there is a magnetical North and South of the uni. verse, as well as of this globe; and tha: if it were possible for a man to fly from star to stu, he might govern his course by the coinpass; that it was by the power of this general magnetism this glote be ame a particular magnet. In soft or hot iron the fuid of magnetism is naturally diffused equally; when with. in the influence of a magnet, it is drawn to ow end of the iron, made denser there and rarer at tho other. While the iron continues soft and hot, it is only a temporary magnet: if it cools or grows hard in than situation, it becomes a permanent one, the inagnetio duid not easily resuming its equilibrium. Perhap it may be owing to the permanent magnetism of this globe, which it had not at first, that its axis is at pre sent kept parallel to itself, and not liable tc the changes it formerly suffered, which occasioned the rupture of its shell, the submersions and emersions of its lands and the confusion of its seasons. The present polas and equatorial diameters differing froni each other near ten leagues, it is easy to conceive, in case soms power should shift the axis gradually, and place it in the present equator, and make the new equator pass through the present poles, what a sinking of the waters would happen in the present equatorial regions, and what a rising in the present polar regions; so that vast tracts would be discovered that now are under water, and others covered that now are dry, the water rising and sinking in the differet extremes near tive leagues ! Such an operation as this possibly occasion

d much of Europe, and, among the rest, of this mountain of Passy, on which I live, and which is composed of limestone, rock and sea shells, to be abandoned by the sea, and to change its ancient clie mate, which seems to have been a hot one. The globe being now bccome a perfect magnet, we are perliaps safe from any future change of its axis. But we are still subject to the accidents on the surface, which are occasioned by a wave in the interna: ponderous duid: and such a wave is produced by the sudden violent explosion you mention, happening from the junction of water and fire under the earth, which not only lifts the incunibent earth thai is over the explosion, but, linpressing with the same force the duid under it, creates a wave that may run a thousand leagues, lifting, and thereby shaking successively, all the countries under which it passes. I know not whether I have expressed myself so cleariy, as not to get ont of your sight in these reveries. If they occasion any new inquiries, and produce a better hypothesis, they will not be quite useless. You set I have given a loose to imagination, but I approve much more you method of philosophising, whicb proceeds upon actual observation, makes a collection of facts, and concludes no farther than ihose facts wil warrant. In iny present circumstances, that mod of studying the nature of the globe is out of my power and therefore I have permitied myself to wander a little in the wilds of fancy. With great esteem, i have the nonour to be,

Sir, &c. .. R. FRANKLIN

P. S. I have heard that chemists can by their art decompose stone and wood, extracting a considerable quantity of water from the one, and air from the other. It seems natural to conclude from this, that water and air were ingredients in their originel coroposition: for men cannot make new matter of any kind. In the same manner do we not suppose, that when we consume combustibles of ail kinds, and produce heat or light, we do not create the hea or light, we only decompose a subs.ance which re ceived it originally as a part of its composition. Heat may thus be considered as originally in a puid etate; but, attracted by organized bodies in their growin, becomes a part of the solid. Besides this, I can conceive that, in the first assemblage of the particles of this earth is composed, each brought its pcrtior of the loose heat that had been connected with i and the whole, when pressed together, produeed ine internal fire which still subsists.



Passy, June 25, 1784.'

UNIVERSAL space, as far as we know of it, seems t be filled with a subtle fluid, whose motion, or vibrao ion, is called liglit.

I'his fuid may possibly be the same with that which, being atiracted by and entering into other, more solid inatter, dilates the substance, by separating the constituent particles, and so rendering Bonne solids fluid, and maintaining the Buidity of

others : of which fluid when our bodárs are totally deprived, they are said to be frozen; when they have a proper quantity, they are in health, and fit to perform all their functions; it is then called natural heat: when too much, it is called fever; and when forced into the body in too great a quantity from without, it gives pain by separating and des troying the fesh, and is then called burning; and th Quid so entering and acting is called fire.

While organized bodies, animal or vegetable, ar augmenting in growth, os are supplying their con tinual waste, is not this done by attracting and con solidating this fluid called fire, so as to form of it a part of their substance and it is not a separation of the parts of such substance, whicli, dissolving its solid state, sets that subtle fuic at liberty, when it again makes its appearance as fire ?

For the power of a man relative to matter seems limited to the dividing it, or mixing the various kinde of it, or changing its form and appearance by differ. ing compositions of it; but does not estend to the making or creating of new matter, or annihilating the old : thus, if fire be an original element, or kind of matter, its quantity is fixed and permanent in the world. We cannot destroy any part of it, or make addition to it; we can only separate it from that which confines it, and so set it at liberty, as when we put wood in a situation to be burnt; or transfer it from one solid to another, as when we make lime by burning stone, a part of the fire dislodged from the wood being left in the stone. May not this fuid, when at liberty, be capable of penetrating and enter ing into all bodies, organized or not; quitting easily a totally those not organized ; and quitting easily is art those which are; the part assumed and fixed remaining till the body is dissolved ?

Is it 19t this fluid which keeps asunder the particles of air, permitting them to approach, or separat. ing them morc, in proportion as its quantity is diminished or augmented ? Is it not the greater gravity of the) particles of air, which forces the particles of

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