I return the Papers with some Corrections, I did not find Coal Mines under the Calcareous Rock in Derby Shire. I only remark’d that in the lowest Part of that rocky Mountain which was in Sight, there were Oister Shells mix’d in 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, seem’d a Proof that there had been a great Boulversement in the Surface of that Island, some part of it having been depress’d under the Sea, and other Parts which had been under it, being rais’d above it. Such Changes in the superficial Parts of the Globe seem’d to me unlikely to happen if the Earth were solid to the Centre. I therefore imagin’d that the internal Part might be a fluid more dense and of greater specific Gravity than any of the Solids we are acquainted with, which therefore might swim in or upon that Fluid. Thus the Surface of the Globe would be a Shell, capable of being broken and disorder’d by any violent Movements of the Fluid on which it rested. And as Air has been compress’d by Art so as to be twice as dense as Water, in which case it such Air and Water could be contain’d in a strong Glass Vessil, the Air would be seen to take the lowest Place, and the Water to float above and upon it; and as we know not yet the Degree of Density to which Air may be compress’d; and M. Amontons calculated, that its Density increasing as it approach’d 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 compress’d. And as the Force of Expansion in dense Air when heated is in Proportion of its Density; this central Air might afford another Agent to move the Surface as well as be of use in keeping alive the central Fires; Tho’ as you observe the sudden Rarefaction of water coming into Contact with those Fires, may also be an Agent sufficiently strong for that Purpose, when acting between the incumbent Earth and the Fluid on which it rests. If one might indulge Imagination in supposing how such a Globe was formed, I should conceive, that all the Elements in separate Particles being originally mix’d in Confusion and occupying a great Space, they would as soon as the Almightly Fist ordain’d Gravity or the mutual Attraction of certain Parts, and the mutual Repulsion of other Parts, exist, all move towards their common Centre; the Air being a Fluid whose Parts repel each other; tho’ drawn to the common Centre, and rarer as more remote; consequently all Matters lighter than the central Part of that Air and immers’d in it, would recede from the Centre and rise till they arriv’d at the Region of the Air which was of the same specific Gravity with themselves, where they would rest; while other Matter mix’d with the lighter Air would descend, and the two meeting would form the Shell on the first Earth, leaving the upper atmosphere nearly clear. The original Movement of the Parts towards their common Centre, could naturally form a Whirl there; which would continue in the turning of the new form’d Globe upon its Axis, and the greatest Diameter of the Shell should be in its Equator. If by any Accident afterwards the Axis should be chang’d the dense internal Fluid by altering its Form must burst the Shell and throw all its Substance into the Confusion in which we 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 at our Theories, and at our Presumption in making them. I will just mention that your observation on the ferruginous Nature of the Lava which is thrown out from the Depths of our Volcanos, gave me great Pleasure. It has long been a Suppostion of mine that the Iron contain’d in the Substance of this Globe, has made it capable 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 universe as well as of this Globe, and that if it were possible for a Man to fly from Star to Star, he might govern his Course by the Compass. That it was by the Power of this general Magnetism this Globe became a particular Magnet. In soft or hot Iron the Fluid of Magnetism is naturally diffus’d equally, when within the Influence of a Magnet, it is drawn to one End of the Iron, made denser there, and rarer at the other, while the Iron continues soft or hot, it is only a temporary Magnet. If it cools or grows hard in that Situation, it becomes a permanent one, The Magnetic Fluid not easily resuming its Equilibrium. Perhaps it may be owing to the permanent Magnetism of this Globe, which it had not at first, that its Axis is at the present kept parallel to itself, and not liable to the Changes it formerly suffered, which occasion’d the Rupture of its shell, the Submersion and Emersions of its Lands and the Confusion of its Seasons. The present Polar and Equatorial Diameters differing from each other near ten Leagues; It is easy to conceive in case some Power should shift the Axis gradually, and place it in the present Equator and make the new Equator pass thro’ 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 different Extreams near five leagues. Such an operation as this, possibly, occasion’d much of Europe, and among the rest this Mountain of Passy on which I live, and which is compos’d of lime Stone Rock and Sea Shells, to be abandon’d by the Sea, and to change its ancient Climate, which seems to have been a hot one. The Globe being now become a permanent Magnet we are perhaps safe from any future Change of its Axis. But we are still subject to the Accidents on the Surface which are occasion’d by a Wave in the internal ponderous Fluid, and such a Wave is producible by the sudden violent Explosion you mention, happening from the Junction of Water and Fire under the Earth, which not only lifts the incumbent earth that is over the Explosion, but impressing 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 express’d myself so clearly as not to get out of your Sight in these Reveries. If they occasion any new Enquiries and produce a better Hypothesis, they will not be quite useless. You see I have given a loose to Imagination; but I approve much more your Method of philosophizing, which proceeds upon actual observation, makes a Collection of Facts and concludes no farther than those Facts will warrant. In my present Circumstances, that Mode of studying the Nature of this Globe is out of my Power, and therefore I have permitted myself to wonder a little in the Wilds of Fancy. with great Esteem, I have the honour to be, Sir, &c.