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TO JAMES BOWDOIN.
Queries and Conjectures relating to Magnetism and the Theory of the Earth.
READ AT A MEETING OF THE AMERICAN PHILOSOPHICAL
SOCIETY, JANUARY 15TH, 1790.
Philadelphia, 31 May, 1788.
I received your favors by Messrs. Gore, Hilliard, and Lee, with whose conversation I was much pleased, and wished for more of it; but their stay with us was too short. Whenever you recommend any of to me, you oblige me.
I want to know whether your Philosophical Society* received the second volume of our Transactions. I sent it, but never heard of its arriving. If it miscarried, I will send another. Has your Society among its books the French work Sur les Arts et les Métiers? It is voluminous, well executed, and may be useful in our country. I have bequeathed it them in my will; but if they have it already, I will substitute something else.
Our ancient correspondence used to have something philosophical in it. As you are now more free from public cares, and I expect to be so in a few months, why may we not resume that kind of correspondence? Our much regretted friend Winthrop once made me the compliment, that I was good at starting game for philosophers; let me try if I can start a little for you.
Has the question, how came the earth by its magnetism, ever been considered?
Is it likely that iron ore immediately existed when this globe was first formed; or may it not rather be supposed a gradual production of time?
* The American Academy of Arts and Sciences. — EDITOR.
If the earth is at present magnetical in virtue of the masses of iron ore contained in it, might not some ages pass before it had magnetic polarity?
Since iron ore may exist without that polarity, and by being placed in certain circumstances may obtain it from an external cause, is it not possible that the earth received its magnetism from some such cause?
In short, may not a magnetic power exist throughout our system, perhaps through all systems, so that if men could make a voyage in the starry regions, a compass might be of use? And may not such universal magnetism, with its uniform direction, be serviceable in keeping the diurnal revolution of a planet more steady to the same axis?
Lastly, as the poles of magnets may be changed by the presence of stronger magnets, might not, in ancient times, the near passing of some large comet, of greater magnetic power than this globe of ours, have been a means of changing its poles, and thereby wrecking and deranging its surface, placing in different regions the effect of centrifugal force, so as to raise the waters of the sea in some, while they were depressed in others?
Let me add another question or two, not relating indeed to magnetism, but, however, to the theory of the earth.
Is not the finding of great quantities of shells and bones of animals (natural to hot climates) in the cold ones of our present world, some proof that its poles have been changed? Is not the supposition, that the poles have been changed, the easiest way of accounting for the deluge, by getting rid of the old difficulty how to dispose of its waters after it was over? Since, if the poles were again to be changed, and placed in the present equator, the sea would fall there about fifteen miles in height, and rise as much in the present polar
regions; and the effect would be proportionable, if the new poles were placed anywhere between the present and the equator.
Does not the apparent wreck of the surface of this globe, thrown up into long ridges of mountains, with strata in various positions, make it probable, that its internal mass is a fluid; but a fluid so dense as to float the heaviest of our substances? Do we know the limit of condensation air is capable of? Supposing it to grow denser within the surface, in the same proportion nearly as it does without, at what depth may it be equal in density with gold?
Can we easily conceive how the strata of the earth could have been so deranged, if it had not been a mere shell supported by a heavier fluid? Would not such a supposed internal fluid globe be immediately sensible of a change in the situation of the earth's axis, alter its form, and thereby burst the shell, and throw up parts of it above the rest? As, if we would alter the position of the fluid contained in the shell of an egg, and place its longest diameter where the shortest now is, the shell must break; but would be much harder to break, if the whole internal substance were as solid and hard as the shell.
Might not a wave, by any means raised in this supposed internal ocean of extremely dense fluid, raise in some degree, as it passes, the present shell of incumbent earth, and break it in some places, as in earthquakes? And may not the progress of such wave, and the disorders it occasions among the solids of the shell, account for the rumbling sound being first heard at a distance, augmenting as it approaches, and gradually dying away as it proceeds? A circumstance observed by the inhabitants of South America in their last great earthquake, that noise coming from a place
some degrees north of Lima, and being traced by inquiry quite down to Buenos Ayres, proceeded regularly from north to south at the rate of leagues per minute, as I was informed by a very ingenious Peruvian whom I met with at Paris.
Description of the Process to be observed in making large Sheets of Paper in the Chinese Manner, with one smooth Surface.
IN Europe, to have a large surface of paper connected together, and smooth on one side, the following operations are performed.
1. A number of small sheets are to be made separately.
2. These are to be couched, one by one, between blankets.
3. When a heap is formed it must be put under a strong press, to force out the water.
4. Then the blankets are to be taken away, one by one, and the sheets hung up to dry.
5. When dry, they are to be again pressed, or, if to be sized, they must be dipped into size made of warm water, in which glue and alum are dissolved.
6. They must then be pressed again to force out the superfluous size.
7. They must then be hung up a second time to dry, which, if the air happens to be damp, requires some days. 8. They must then be taken down, laid together, and again pressed.
9. They must be pasted together at their edges. 10. The whole must be glazed by labor, with a flint. In China, if they would make sheets, suppose of four and a half ells long and one and a half ells wide, they
have two large vats, each five ells long and two ells wide, made of brick, lined with a plaster that holds water. In these the stuff is mixed ready to work.
Between these vats is built a kiln or stove, with two inclining sides; each side something larger than the sheet of paper; they are covered with a fine stucco that takes a polish, and are so contrived as to be well neated by a small fire circulating in the walls.
The mould is made with thin but deep sides, that It may be both light and stiff; it is suspended at each end with cords that pass over pulleys fastened to the ceiling, their ends connected with a counterpoise nearly equal the weight of the mould.
Two men, one at each end of the mould, lifting it out of the water by the help of the counterpoise, turn it and apply it with the stuff to the smooth surface of the stove, against which they press it, to force out great part of the water through the wires. The heat of the wall soon evaporates the rest, and a boy takes off the dried sheet by rolling it up. The side next the stove receives the even polish of the stucco, and is thereby better fitted to receive the impression of fine prints. If a degree of sizing is required, a decoction of rice is mixed with the stuff in the vat.
Thus the great sheet is obtained, smooth and sized, and a number of the European operations saved.
As the stove has two polished sides, and there are two vats, the same operation is at the same time performed by two other men at the other vat; and one fire serves.
END OF VOL. VI.