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been a supposition of mine, that the iron contained in the substance of the 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 diffused 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 and 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 present 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 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 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 uncovered that now are under water, and others covered that now are dry, the water rising and sinking in the different extremes near five leagues. Such an operation as this, possibly, occasioned much of Europe, and among the rest 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 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 occasioned by a wave in the internal ponderous fluid; 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 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 expressed myself so clearly, as not to get out of your sight in these reveries. If they occasion any new inquiries, and produce a better hypothesis, they will not be quite useless. You see I have given a loose to the 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 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 honour to be, Sir, &c.
BENJAMIN 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 original composition: For men cannot make new matter of any kind. In the same manner may we not suppose, that when we consume combustibles of all kinds, and produce heat or light, we do not create that heat or light; we only decompose a substance which received it originally as a part of its composition? Heat may thus be considered as originally in a fluid state ; but, attracted by organized bodies in their growth, becomes a part of the solid. Besides this, I can conceive that in the first assemblage of the particles of which this earth is composed, each brought its portion of the loose heat that had been connected with it, and the whole, when pressed together, produced the internal fire which still subsists.
LOOSE THOUGHTS ON AN UNIVERSAL FLUID, &c.
PASSY, JUNE 25, 1784. UNIVERSAL space, as far as we know of it, seems to be filled with a subtile fluid, whose motion, or vibration, is called Light, This fluid may possibly be the same with that which being attracted by, and entering into other more solid matter, dilates the substance, by separating the constituent particles, and so rendering some solids fluid, and maintaining the fluidity of others: of which fluid when our bodies 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 destroying the flesh, and is then called burning; and the fluid so entering and acting is called fire.
While organized bodies, animal or vegetable, are augmenting in growth, or are supplying their continual waste, is not this done by attracting and consolidating this fluid called fire, so as to form of it a part of their substance; and is it not a separation of the parts of such substance, which, dissolving its solid state, sets that subtile fluid at liberty, when it again makes its appearance as fire?
For the power of man relative to matter seems limited to the dividing it, or mixing the various kinds of it, or changing its form and appearance by different compositions of it; but does not extend 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 fluid when at liberty be capable of penetrating and entering into all bodies organized or not, quitting easily in totality those not organized; and quitting easily in part those which are; the part assumed and fixed remaining till the body is dissolved?
Is it not this fluid which keeps asunder the particles of air, permitting them to approach, or separating them more, 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 this fluid to mount with the matters to which it is at. fached, as smoke or vapour?
Does it not seem to have a great affinity with water, since it will quit a solid to unite with that fluid, and go off with it in va. pour, leaving the solid cold to the touch, and the degree measurable by the thermometer? The vapour
rises attached to this fluid, but at a certain height they separate, and the vapour descends in rain, retaining but little of it, in snow or hail less. What becomes of that fluid? Does it rise above our atmosphere, and mix equally with the universal mass of the same kind? Or does a spherical stratum of it, denser, or less mixed with air, attracted by this globe, and repelled or pushed up only to a certain height from its surface, by the greater weight of air, remain there surrounding the globe, and proceeding with it round the sun.
In such case, as there may be a continuity or communication of this fuid through the air quite down to the earth, is it not by the vibrations given to it by the sun that light appears to us; and may it not be, that every one of the infinitely small vibrations, striking common matter with a certain force, enter its substance, are held there by attraction, and augmented by succeeding vibrations, till the matter has received as much as their force can drive into it?
Is it not thus that the surface of this globe is continually heated by such repeated vibrations in the day, and cooled by the escape of the heat when those vibrations are discontinued in the night, or intercepted and reflected by clouds?
Is it not thus that fire is amassed, and makes the greatest part of the substance of combustible bodies?
Perhaps when this globe was first formed, and its original particles took their place at certain distances from the centre, in proportion to their greater or less gravity, the fluid fire, attracted towards that centre, might in great part be obliged, as lightest, to take place above the rest, and thus form the sphere of fire above supposed, which would afterwards be continually diminishing by the substance it afforded to organized bodies, and the quantity restored to it again by the burning or other separating of the parts of those bodies?
Is not the natural heat of animals thus produced, by separating in digestion the parts of food, and setting their fire at liberty?
Is it not this sphere of fire which kindles the wandering globes that sometimes pass through it in our course round the sun, have their surface kindled by it, and burst when their included air is greatly rarified by the heat on their burning surfaces?
IN the foregoing work, a paper is mentioned in which Dr. FRANKLIN, among his other conjectures and imaginations (as he modestly stiles them) supposes it possible, by attentive obser. vations made during the summer, to foretel the mildness or severity of the following winter.
“ When in summer (says he) the sun is high, and long every “ day above the horizon, his rays strike the earth more directly, “ and with longer continuance than in the winter: hence the “ surface is more heated and to a greater depth, by the effect « of these rays. When rain falls on the heated earth and sinks “ down into it, it carries down with it a great part of the heat « which by that means descends still deeper. The mass of “ earth, to the depth of perhaps 3 feet, being thus heated to a
ertain degree, continues to retain its heat for some time. “ Thus the first snows that fall in the beginning of winter, sel“ dom lie long on the surface. Afterwards, the winds that blow
over the country, on which the snows had fallen, are not ren“ dered so cold as they would have been, had these snows re“ mained; and thus the approach of the severity of the winter is retarded.
During several of the summer months of 1783, when the « efforts of the sun's rays to heat these northern regions would “ have been great, there existed a constant fog over all Europe, « and great part of North America. This fog was of a peculiar “ nature: it was dry, and the rays of the sun seemed to have “ little effect towards dissipating it, as they dissolve a moist fog “ arising from water. They were indeed rendered so faint in
passing through it, that when collected in the focus of a burn“ ing glass, they would scarce kindle brown paper. Of course “ their summer effect in heating the earth was exceedingly di“ minished: Hence the surface was early frozen: IIence the « first snows remained on it, and received continual additions : “ Hence the air was more chilled, and the winter more severely VOL. I.