Stories of Useful Inventions. Forman Samuel Eagle
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Название: Stories of Useful Inventions
Автор: Forman Samuel Eagle
Издательство: Public Domain
Жанр: Зарубежная классика
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Soon after Argand invented his lamp, William Murdock, a Scottish inventor, showed the world a new way of lighting a house. It had long been known that fat or coal, when heated, gives off a vapor or gas which burns with a bright light. Indeed, it is always a gas that burns, and not a hard substance. In the candle or in the lamp the flame heats the oil which comes up to it through the wick and thus causes the oil to give off a gas. It is this gas that burns and gives the light. Now Murdock, in 1797, put this principle to a good use. He heated coal in a large vessel, and allowed the gas which was driven off to pass through mains and tubes to different parts of his house. Wherever he wanted a light he let the gas escape at the end of the tube (Fig. 8) in a small jet and lighted it. Here was a lamp without a wick. Murdock soon extended his gas-pipes to his factories, and lighted them with gas. As soon as it was learned how to make gas cheaply, and conduct it safely from house to house, whole cities were rescued from darkness by the new illuminant. A considerable part of London was lighted by gas in 1815. Baltimore was the first city in the United States to be lighted by gas. This was in 1821.
FIG. 8. – THE GAS JET.
FIG. 9. – AN EARLY ARC LAMP.
The gas-light proved to be so much better than even the best of lamps, that in towns and cities almost everybody who could afford to do so laid aside the old wick-lamp and burned gas. About 1876, however, a new kind of light began to appear. This was the electric light. The powerful arc light (Fig. 9), made by the passage of a current of electricity between two carbon points, was the first to be invented. This gave as much light as a hundred gas-jets or several hundred lamps. Such a light was excellent for lighting streets, but its painful glare and its sputtering rendered it unfit for use within doors. It was not long, however, before an electric light was invented which could be used anywhere. This was the famous Edison's incandescent or glow lamp (Fig. 10), which we see on every hand. Edison's invention is only a few years old, yet there are already more than thirty million incandescent lamps in use in the United States alone.
FIG. 10. – AN INCANDESCENT ELECTRIC LIGHT.
The torch, the candle, the lamp, the gas-light, the electric light, – these are the steps of the development of the lamp. And how marvelous a growth it is! How great the triumph over darkness! In the beginning a piece of wood burns with a dull flame, and fills the dingy wigwam or cave with soot and smoke; now, at the pressure of a button, the house is filled with a light that rivals the light of day, with not a particle of smoke or soot or harmful gas. Are there to be further triumphs in the art of lighting? Are we to have a light that shall drive out the electric light? Only time can tell.
THE FORGE
After men had learned how to use fire for cooking and heating and lighting they slowly learned how to use it when working with metals. In the earliest times metals were not used. For long ages stone was the only material that man could fashion and shape to his use. During this period, sometimes called the "stone age," weapons were made of stone; dishes and cooking utensils were made of stone; and even the poor, rude tools of the age were made of stone (Fig. 1).
FIG. 1. – IMPLEMENTS OF THE STONE AGE.
FIG. 2. – IMPLEMENTS OF THE BRONZE AGE.
In the course of time man learned how to make his implements and weapons of metals as well as of stone. It is generally thought that bronze was the first metal to be used and that the "stone age" was followed directly by the "bronze age," a period when all utensils, weapons, and tools were made of bronze (Fig. 2). It is easy to believe that bronze was used before iron, for bronze is made of a mixture of tin and copper and these two metals are often found in their pure or natural state. Whenever primitive man, therefore, found pieces of pure copper and tin, he could take the two metals and by melting them could easily mix them and make bronze of them. This bronze he could fashion to his use. There is no doubt that he did this at a very early age. In nearly all parts of the world there are proofs that in primitive times, many articles were made of bronze.
If primitive man were slow to learn the use of iron it was not because this metal was scarce, for iron is everywhere. "Wherever, as we go up and down, we see a red-colored surface, or a reddish tint upon the solid substances of the earth, we see iron – the bank of red clay, the red brick, the red paint upon the house wall, the complexion of rosy youth, or my lady's ribbon. Even the rosy apple derives its tint from iron which it contains."8 But although iron is so abundant it is seldom found in its pure or natural state. It is nearly always mixed with other substances, the mixture being known as iron ore. Primitive man could find copper and tin in their pure state but the only pure iron he could find was the little which fell from heaven in the form of meteors, and even this was not perfectly pure for meteoric iron is also mixed slightly with other metals.
The iron which lay about primitive man in such abundance was buried and locked tightly in an ore. To separate the iron from the other substances of the ore was by no means an easy thing to do. Iron can best be extracted from the ore by putting the ore in a fire and melting out the iron. Place some iron ore in a fire and if the fire is hot enough – and it must be very hot indeed – the iron will leave the ore and will gather into a lump at the bottom of the fire. To separate the iron from its ore in this way is to make iron. When and where man first learned the secret of making iron is of course unknown. A camp-fire in some part of the world may have shown to man the first lump of iron, or a forest fire sweeping along and melting ores in its path may have given the first hint for the manufacture of iron.
Iron making at first doubtless consisted in simply melting the ore in an open heap of burning wood or charcoal, for charcoal is an excellent fuel for smelting (melting) ores. But this open-fire method was wasteful and tedious and at a very early date the smelting of the ore was done in a rude sort of a furnace. A hole ten or twelve feet deep was dug in the side of a hill. In the hole were placed charcoal and iron ore, first a layer of charcoal, then a layer of the ore. At the top of the mass there was an opening and at the bottom there were several openings. When the mass was set on fire the openings produced a good strong draft, the charcoal was consumed, and the ore was smelted. The product was a lump of wrought iron, known as the bloom.
FIG. 3. – THE PRIMITIVE FORGE.
FIG. 4. – BELLOWS WORKED BY THE FEET.
FIG. 5. – THE WOODEN BELLOWS.
The hillside furnace worked well enough when the wind was favorable, but when the wind was unfavorable there was no draft and no iron could be made. So ironmakers found a way by which the air could be driven into the furnace by artificial means. They invented the bellows, a blowing apparatus (Fig. 3) which was usually made of goat skins sewed together and which was operated either by the hands or by the feet (Fig. 4). Sometimes the bellows consisted of a hollow log in which a piston was worked up and down (Fig. 5). After the invention of the bellows, ironmakers could make their iron whenever and wherever they pleased, for they could force air into their furnaces at any time and at any place. This rude bellows forcing a draft of air into a half-closed furnace filled with a burning mass of charcoal and iron ore was the first form of the forge, one of the greatest of all inventions.
With СКАЧАТЬ
J. R. Smith, "The Story of Iron and Steel," p. 3.