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decisive: then your proposed solemn league and covenant will go better down, and perhaps most of our other strong measures be adopted.

I am always glad to hear from you, but I do not deserve your favours, being so bad a correspondent. My eyes wil now hardly serve me to write by night, and these short rlays have been all taken up by such varioiy of business that I seldum can sit down ten ninulos without interruption, God give you success!

I ain, with the greatest esteem,

Yours affectionately,

B. FRANKLIN

ON THE THEORY OF THE EARTH.

TO ABBE SOULIAVE.

Passy, September 22, 1782.

SIK, I RETOWN the papers with some corrections. I dici not find coal inines, under the calcareous rock in Derbyshire.-I only remarked, that at the lowest pari of that rocky mountain, which was in sigh, there were oyster shells mixed with the stone; and part of the high country of Derby being probably as much above the level of the sea, as the coal mines of Whitehaven were below, it seemed a proof that there had been a great bouieversement in the surface of that island, some part of it having been depressed under the sea, ard other parts, which had been under 'it, being raiseul above it. Such changes in the super ficial parts of the globe seemed to me unlikely to hap pen, if the earth were solid at the centre. I therm

fre imagined that the internal parts might be a fluid dvore dense, and of greater specific gravity than any (f the solids we are acquainted with; which there. 1ɔre might swim in or upon that iuid. Thus the sur face of the glove would be a shell, capable of being proken and disordered by the vicleni morements of fluid on which it resteri. And, as air has been compressed by art so as to be twice as dense as waler, 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 Aoa above and upon it; and, as we know not yet the de. gree 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 occu. pying 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. tral 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 thát air, and immersed in is, wouid recede from the centre, an, i rise till they arrire at that region of the air, which was of the saine specific gra. rity 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 after. wards the wxis should be changed, the dense internal fluid, by alrering its form, must burst the shell, and throw all e substance into the confusion in which w find it. A 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 bo.ame a particular magnet. In soft or hot iron the Juid 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 fuid 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 to 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 pola) 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 ed 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 become a perfect magnet, we are perliaps sato 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 Auid: 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, inpressing with the same force the fluid 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 roveries. 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 permitted myself to wander a little in the wilds of fancy. With great esteem, i have the 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 froin the other. It seems natural to conclude from this, that water and air were ingred.ents in their originel cornposition: for men cannot make new matter of any kind. In the same manner do we not suppose, that when we consume combustibles uf 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: Heot 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,

can conceive that, in the first assemblage of the particl«s of this earth is composed, each brought its portior of the loose heat that had been connected with i and the whole, when pressed ingether, produeed ine internal fire which still subsists.

LOOSE THOUGHTS ON THE UNIVER

SAL FLUID, &c.

Passy, June 25, 1784.

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

l'hig fluid may possibly be the same with thai which, being atiracted by and entering into other more solid inatter, dilates the substance, by separating the constituent particles, and so rendering 801116 solids fluid, and maintaining the Auidity of

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