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Charles. Can matter indeed be infinitely divided, for I suppose that this is what is meant by a division without end?

Father. Difficult as this may at first appear, yet I think it very capable of proof. Can you conceive of a particle of matter so small as not to have an upper and under surface?

Charles. Certainly, every portion of matter, however minute, must have two surfaces at least, and then I see, that it follows of course that it is divisible.

Father. Your conclusion is just, and though there may be particles of matter too small for us actually to divide, yet this arises from the imperfection of our instruments; they must nevertheless, in their nature, be divisible.

Emma. But you were to give us some remarkable instances of the minute division of matter.

Father. A few years ago a lady spun a single pound of wool into a thread 168,000 yards long. And Mr. Boyle mentions that two grains and a half of silk was spun into a thread 300 yards in length. If a pound of silver, which, you know, contains 5760 grains, and a single grain of gold be melted together, the gold will be equally diffused through the whole silver, insomuch that if one grain of the mass be dissolved in a liquid called Aqua Fortis, which is diluted nitric acid, the gold will fall to the bottom. By this experiment it is evident that a grain may be divided into 5761 visible parts, for only the 5761st part

of the gold is contained in a single grain of the

mass.

The gold-beaters, whom you have seen at work in the shops in Long-Acre, can spread a grain of gold into a leaf containing fifty square inches, and this leaf may be readily divided into 500,000 parts, each of which is visible to the naked eye: and by the help of a microscope which magnifies the area or surface of the body 100 times, 100th part of each of these becomes visible, that is, the 50 millionth part of a grain of gold will be visible, or a single grain of that metal may be divided into fifty million of visible parts. But the gold which covers the silver wire used in making what is called gold lace, is spread over a much larger surface, yet it preserves, even if examined by a microscope, an uniform appearance. It has been calculated that one grain of gold under these circumstances would cover a surface of nearly thirty square yards.

The natural divisions of matter are still more surprising. In odoriferous bodies, such as camphor, musk, and asafoetida, a wonderful subtilty of parts is perceived, for though they are perpetually filling a considerable space with odoriferous particles, yet these bodies lose but a very small part of their weight in a great length of time.

Again, it is said by those who have examined the subject with the best glasses, and whose

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accuracy may be relied on, that there are more animals in the milt of a single cod-fish, than there are men on the whole earth, and that a single grain of sand is larger than four millions of these animals. Now if it be admitted that these little animals are possessed of organized parts, such as a heart, stomach, muscles, veins, arteries, &c. and that they are possessed of a complete system of circulating fluids, similar to what is found in larger animals, we seem to approach to an idea of the infinite divisibility of matter. It has indeed been calculated that a particle of blood of one of these animalcula is as much smaller than a globe one-tenth of an inch in diameter, as that globe is smaller than the whole earth. Nevertheless, if these particles be compared with the particles of light, it is probable, that they would be found to exceed them in bulk as much as mountains do single grains of sand:

In thousand species of the insect kind!
Lost to the naked eye, so wondrous small

Were millions join'd, one grain of sand would cover all,
Yet each within its little bulk, contains

A heart which drives the torrent through its veins;
Muscles to move its limbs aright; a brain

And nerves disposed for pleasure and for pain ;
Eyes to distinguish; sense whereby to know
What's good or bad; is, or is not its foe.

BAKER.

I might enumerate many other instances of the same kind, but these, I doubt not, will be

you

sufficient to convince into what very minute parts matter is capable of being divided: and with these we will put an end to our present conversation.

མས་

CONVERSATION III.

Of the Attraction of Cohesion.

Father. Well, my children, have you reflected upon what we last conversed about? Do you comprehend the several instances which I enumerated as examples of the minute division of matter?

Emma. Indeed the examples which you gave us very much excited my wonder and admiration, and yet from the thinness of some leaf-gold which I once had, I can readily credit all you have said on that part of the subject. But I know not how to conceive of such small animals as you described; and I am still more at a loss how to imagine that animals so minute, should possess all the properties of the larger ones, such as a heart, veins, blood, &c.

Father. I can, the next bright morning, by the

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help of my solar microscope, show you very distinctly, the circulation of the blood in a flea, which you may get from your little dog; and with better glasses than those of which I am possessed, the same appearance might be seen in animals still smaller than the flea, perhaps, even in those which are themselves invisible to the naked eye. But we shall converse more at large on this matter, when we come to consider the subject of optics, and the construction and uses of the solar microscope. At present we will turn our thoughts to that principle in nature, which philosophers have agreed to call gravity or attraction.

Charles. If there be no more difficulties in philosophy than we met with in our last lecture, I do not fear but that we shall, in general, be able to understand it. Are there not, papa, several kinds of gravity?

Father. Yes, there are; two of which it will be sufficient for our present purpose to describe; the one is the attraction of cohesion; the other that of gravitation. The attraction of cohesion is that power which keeps the parts of bodies together when they touch, and prevents them from separating, or which inclines the parts of bodies to unite, when they are placed sufficiently near to each other.

Charles. Is it then by the attraction of cohesion that the parts of this table, or of the penknife, are kept together?

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