Popular Books on Natural Science

In order to illustrate, how the velocity of the electric current can actually be measured, we must first introduce the following:

Whenever a wire is to be magnetized by an electric machine, at the moment it touches the machine, a bright spark is seen at the end of the wire. The same spark is seen also at the other end of the wire, if touching another apparatus. Let us call the first spark the "entrance-spark," the other the "exit-spark." If a wire, many miles in extent, is put up, and led back to where the beginning of the wire is, both sparks may be seen by the same observer.

Now it is evident, that the exit-spark appears after the entrance-spark just as much later, as the time it took the electric current to run from one end of the wire to the other end. But in spite of all efforts made, to see whether the exit-spark actually appears later, the human eye has not been able to detect the difference. The cause of this is partly owing to the long duration of the impression upon the retina, which leads us to the belief, that we see objects much longer than we really do; partly, the immense rapidity with which the exit-spark follows the entrance-spark. From these two causes, we are tempted to believe both sparks to appear at the same moment.

By an ingenious and excellent means, however, this defect in our eye has been greatly diminished. It is well worth the trouble to read a description of the experiment attentively. The truly remarkable way in which it was tried, will please all who read it.

In order to measure the velocity of the electric current, the ends of a very long wire are placed one above the other. If, now, one makes the observation with the naked eye, both sparks will be found to stand in a vertical line, one above the other, as the points of a colon, thus (:).

But he who wishes to measure the velocity of the electrical current does not look upon the sparks with the naked eye, but into a small mirror, which, by a clock-work, is made to revolve upon an upright axis with exceedingly great rapidity. Thus he can see both sparks in the mirror. If the apparatus be a good one, it will be observed that the sparks, as seen by the aid of the mirror, do not stand in a vertical line above one another, but obliquely, thus (.·).

Whence does this come?

The reason of it is, that after the appearance of the entrance-spark it takes a short time, before the exit-spark appears. During this short time the mirror moves, though but little, and in it the exit-spark is seen as if it had moved aside from the entrance-spark.

Hence, it is through the movement of the mirror that the time, which is necessary for electricity to go through the circuit of the wire, is ascertained. A little reflection will readily convince the reader, that the time may be precisely calculated, provided three things be known, viz.: the length of the wire, the velocity of rotation of the mirror, and the angular distance of the two sparks as seen in the mirror. Thus: Suppose the wire to be 1,000 miles long; and suppose the mirror is made to revolve 100,000 times in a second. Now, if the electrical current traversed these 1,000 miles of wire during one revolution of the mirror, then it follows, that the current must move 1,000 miles in the 1/100 part of a second; or, 100,000 miles in a second.[1 - Images of the original pages are available through Internet Archive/American Libraries. See http://www.archive.org/details/popularbooksonna00bernrich (http://www.archive.org/details/popularbooksonna00bernrich)]

It is found, however, that the mirror does not revolve an entire circle, or 360 degrees, while the current is passing over 1,000 miles of wire, but we find that the mirror turns through 144 degrees very nearly; therefore the electric current must travel more than 100,000 miles a second. How much more? Just as many times 100,000 miles, as 144 degrees are contained in 360 degrees (the entire circle), viz., two and a half times. Hence, the current travels 250,000 miles in a second.

PART III.

NUTRITION

CHAPTER I.

NOTHING BUT MILK

Conceive a man, gifted with the keenest intellect, but not knowing from experience, that sucklings grow and become men, and imagine what he would say, if you were to tell him this:

"Know, that the little being you see here, is a suckling, that is, a developing human being, who by and by will become thicker and taller. The bones of his body will become firmer and longer. The muscles that animate these bones will likewise increase in size. The same will happen with regard to his eyes, ears, nose, mouth; to his head, body, and feet; every component part of his small body will be developed further and further, until the child will become a perfect man."

There is no doubt, that he who does not know all this from experience, will shake his head at it.

But if you were to tell him: "This development and growth have their source in the baby's sucking at the mother's breast a white juice called milk, and out of this milk all the constituent parts of the child are manufactured within himself," – certainly your hearer would laugh in your face, and perhaps call you a credulous fool.

"What!" he would exclaim, "do you mean to say that milk contains flesh? Or can you make bones out of milk, or hair? Can you make nails and teeth out of milk? Do you wish to persuade me, that milk may be changed into eyes? that from milk may be manufactured feet, hands, cheeks, eyelids, and the various other parts of the human body?"

And if, in answer to this, you were to reply: "Yes, it is so. Within this little creature is a factory, that not only makes all you have mentioned, but much more. In this establishment, bones, hair, teeth, nails, flesh, blood, veins, nerves, skin, juices, and water are manufactured; all this is made from milk, and during the first months of the child's life from nothing but milk," – then your hearer, though he may have the understanding of the most judicious of men, would be dumbfounded, and would beseech you to tell him more about this factory.

You may be certain, he would like to know, how many boilers, cylinders, valves, wires, ladles, oars, pumps, hooks, pins, spokes, and knobs there may be in this factory; more especially would he wish to know, whether the engine of this wonderful establishment be made of steel, wood, cast-iron, silver or gold, or of diamonds.

Now, if you were to tell him, "It contains nothing of the kind. Of all the factories you have seen in your life, there is none that bears any resemblance to this one. And I will tell you furthermore, that it is not even a complete factory, but it is continually developing; it becomes larger and heavier like the child's body itself; moreover, the factory does not consist of iron or steel, nor of gold or diamonds, but it reproduces itself at every moment; it does so merely from the milk that the child drinks," – then, to be sure, your hearer would begin to doubt his own senses; he would exclaim: "What is the intellect of the intelligent, the judgment of the judicious, what is the wisdom of the wise, when compared to a little of the mother's milk?"

And yet, you are well aware, my friendly reader, that mother's milk is, after all, nothing but milk; and that milk, again, is nothing but a means of nutrition; and nutrition, in its turn, is nothing but a part of the action of the human body.

May I hope that you will favor me with your attention, while, in a few articles, I speak to you about the nutrition of the human body?

CHAPTER II.

MAN THE TRANSFORMED FOOD

Before speaking of the process of nutrition in the human body, we must first obtain a correct idea of what is meant by nutrition.

Why are we obliged to eat?

Of course we know that hunger forces us to do so. But every one is aware also, that above all we must ask, whence hunger arises; that we must first get better acquainted with hunger itself, in order to understand nutrition.

To explain this, however, it is necessary to turn our attention to another thing, no less a miracle than nutrition itself, viz., what in scientific language is called "Exchange of Matter." To all of you it is a well-known fact, that nothing in the human body remains even for a moment in the same state; but that in every part of the body a continued exchange takes place. Air is breathed in and exhaled again; but the air exhaled is different from the air inhaled. By this process an exchange of matter has taken place; new matter has entered the body and waste matter has been thrown out.

This exchange of matter – we shall speak more about it at another opportunity – is a principal necessity for the body and its functions; it consists in the main of an incessant change, by which our body is forced to cast out matter that formed parts of it, and is therefore obliged, in order to compensate for the loss, to take in new matter. Hence there is no exaggeration in the expression, "Man is continually renewing himself;" we indeed lose and receive particles of our body at every moment. People have gone so far as to calculate that it takes seven years for the renewal of the whole body of man, and that after this space, there is not even an atom left of the man as he was seven years before.

The regular exchange of matter, as we have seen, supposes the body to be a barter-place, where people take in at the same ratio they pay out. Since, however, man often pays out involuntarily and suffers so many losses – by the mere process of breathing he ejects matter which he must replace afterwards – this exchange of matter is the cause of the body's possessing the feeling of want. The body has paid out and receives nothing in return; this feeling of want is what we call "Hunger." It forces us to absorb as much as we have paid out.

Nutrition, consequently, is the continual replacing of continual losses. It is the wonderful transformation of food into the materials composing the human body.

When looking at our fellow-men, however, we must not think, that they are merely beings that have eaten food; but rather that they themselves, viz., their skin, hair, bones, brain, flesh, blood, nails, and teeth, are nothing but their own food, consumed and transformed.

CHAPTER III.

WHAT STRANGE FOOD WE EAT

Man, according to what has preceded, is nothing but transformed food.

This idea may frighten us; it may be terrible to our hearts; but let us frankly confess, it is a true one! Man consists only of such substances as he has consumed; he is, in fact, nothing but the food he has eaten; he is food in the shape of a living being.

A child is said to live on his mother's milk; but what else does this mean than: "It is mother's milk, that has become alive by having been changed into head, body, hands, feet, etc., etc."

Indeed, it may sound strange, yet it is quite correct: This mother's milk in the shape of a human being consumes again new mother's milk, and, by respiration, by evaporation and secretion of matter, casts out the used-up milk.

This being so, it will now appear evident to every one, that by a profound chemical knowledge of our daily food, we may readily learn to know the chemical components of man, and vice versâ; knowing the substances of which man is made, it is easy for us to determine, what kind of food he must take, in order to continually renew his body.

Since the mother's milk is the simplest and most natural food for the child, let us consider it according to its importance. We shall then have a stepping-stone towards the knowledge of the food of adults and its effects. The mother's milk contains all the elements, with which the human body can renew itself; should there be but one of those elements wanting in it, the child would inevitably perish.

If, for example, milk did not contain calcareous earth, the consequence would be, that the bones of the child would, soon after its birth, neither grow nor increase in number, but they would fast diminish, and the child would die in consequence of this. The attempt was once made to feed animals on articles without calcareous parts, when, strange to behold, they all grew fat, but very weak in their bones, and finally broke down.

If milk contained no phosphorus, not only would the bones and teeth suffer from the want of it, but even the completion of the child's brain could not properly take place, and the child could not replace the quantity of brain which it emits and loses every moment by breathing.

If there were no iron in the mother's milk, the child would die from the green-sickness, a malady which, by the way, is dangerous also for grown people, and which is cured by medicines containing plenty of iron.

If there were no sulphur in it, the child's bile could not develop; the bile, as every one knows, has an important function in the human body.

These are but accessory elements of the mother's milk, elements which usually are not looked upon as articles of food; for who is aware that he must eat, and actually does eat daily, phosphorus, iron, calcareous earth, and sulphur? And not only these; there are a great many other articles, such as magnesia, chlorine, and fluor, that we eat without being aware of it; moreover, our proper food consists also of three gases: nitrogen, oxygen, and hydrogen; and of a solid substance called "carbon," which is no less and no more than pure coal.

All these, my friendly readers, are contained in milk – all these are the elements which in truth constitute the human body. Perhaps some persons believe that there is nothing easier than to procure proper food. It would only be necessary to take a certain quantity of carbon, hydrogen, oxygen, and nitrogen; a little bit of potassium, natron, calcium, and magnesia; to mix a small piece of iron, sulphur, phosphorus, chlorine, and fluor, and take this mixture by the spoon at regular intervals, in order to give the body the necessary aliments. This, however, would be a mistake, for which the perpetrator would pay with his life.

Although it is true that these substances form the proper and most important constituents of our daily food; yet, in order to enjoy the desired result, we must not partake of them in their primary forms; they can actually feed our body only when they are combined together in a peculiar, wondrous manner.

In the next chapter it may be seen how nature first must combine these substances before they are presented to us as proper food; and it will also be seen, that we receive them sometimes in altogether different forms and combinations; for example, in the mother's milk, when we eat the above-named elements in the forms of caseine (cheese), butyrine (butter), sugar of milk, salt, and water.