Stories of Useful Inventions Part 2

We may begin the story with an odd but interesting kind of lamp. The firefly or lightning-bug which we see so often in the summer nights was in the earliest time brought into service and made to shed its light for man. Fireflies were imprisoned in a rude box--in the sh.e.l.l of a cocoanut, perhaps, or in a gourd--and the light of their bodies was allowed to shoot out through the numerous holes made in the box. We must not despise the light given out by these tiny creatures. "In the mountains of Tijuca," says a traveler, "I have read the finest print by the light of one of these natural lamps (fireflies) placed under a common gla.s.s tumbler (Fig. 1), and with distinctness I could tell the hour of the night and discern the very small figures which marked the seconds of a little Swiss watch."

[Ill.u.s.tration: FIG. 1.--A FIREFLY LAMP.]

[Ill.u.s.tration: FIG. 2.--A BURNING STICK WAS THE FIRST LAMP.]

Although fireflies have been used here and there by primitive folk, they could hardly have been the first lamp. Man's battle with darkness really began with the _torch_, which was lighted at the fire in the cave or in the wigwam and kept burning for purposes of illumination. A burning stick was the first lamp (Fig. 2). The first improvement in the torch was made when slivers or splinters of resinous or oily wood were tied together and burned. We may regard this as a lamp which is all wick.

This invention resulted in a fuller and clearer light, and one that would burn longer than the single stick. A further improvement came when a long piece of wax or fatty substance was wrapped about with leaves.

This was something like a candle, only the wick (the leaves) was outside, and the oily substance which fed the wick was in the center.

In the course of time it was discovered that it was better to smear the grease on the _outside_ of the stick, or on the outside of whatever was to be burned; that is, that it was better to have the wick _inside_.

Torches were then made of rope coated with resin or fat, or of sticks or splinters smeared with grease; here the stick resembled the wick of the candle as we know it to-day, and the coating of fat corresponded to the tallow or paraffin. Rude candles made of oiled rope or of sticks smeared with fat were invented in primitive times, and they continued to be used for thousands of years after men were civilized. In the dark ages--and they were dark in more senses than one--torch-makers began to wrap the central stick first with flax or hemp and then place around this a thick layer of fat. This torch gave a very good light, but about the time of Alfred the Great (900 A.D.) another step was taken: the central stick was left out altogether, and the thick layer of fat or wax was placed directly around the wick of twisted cotton. All that was left of the original torch--the stick of wood--was gone. The torch had developed into the _candle_ (Fig. 3). The candles of to-day are made of better material than those of the olden time, and they are much cheaper; yet in principle they do not differ from the candles of a thousand years ago.

[Ill.u.s.tration: FIG. 3.--THE CANDLE.]

[Ill.u.s.tration: FIG. 4.--A Sh.e.l.l FILLED WITH OIL AND USED AS A LAMP.]

I have given the development of the candle first because its forerunner, the torch, was first used for lighting. But it must not be forgotten that along with the torch there was used, almost from the beginning, another kind of lamp. Almost as soon as men discovered that the melted fat of animals would burn easily--and that was certainly very long ago--they invented in a rude form the _lamp_ from which the lamp of to-day has been evolved. The cavity of a sh.e.l.l (Fig. 4) or of a stone, or of the skull of an animal, was filled with melted fat or oil, and a wick of flax or other fibrous material was laid upon the edge of the vessel. The oil or grease pa.s.sed up the wick by capillary action,[6] and when the end of the wick was lighted it continued to burn as long as there were both oil and wick. This was the earliest lamp. As man became more civilized, instead of a hollow stone or a skull, an earthen saucer or bowl was used. Around the edge of the bowl a gutter or spout was made for holding the wick. In the lamp of the ancient Greeks and Romans the reservoir which held the oil was closed, although in the center there was a hole through which the oil might be poured. Sometimes one of these lamps would have several spouts or nozzles. The more wicks a lamp had, of course, the more light it would give. There is in the museum at Cortona, in Italy, an ancient lamp which has sixteen nozzles. This interesting relic (Fig. 5) was used in a pagan temple in Etruria more than twenty-five hundred years ago.

[Ill.u.s.tration: FIG. 5.--AN ETRUSCAN LAMP 2500 YEARS OLD.]

[Ill.u.s.tration: FIG. 6.--AN ANCIENT LAMP.]

Lamps such as have just been described were used among the civilized peoples of the ancient world, and continued to be used through the Middle Ages far into modern times. They were sometimes very costly and beautiful (Fig. 6), but they never gave a good light. They sent out an unpleasant odor, and they were so smoky that they covered the walls and furniture with soot. The candle was in every way better than the ancient lamp, and after the invention of wax tapers--candles made of wax--in the thirteenth century, lamps were no longer used by those who could afford to buy tapers. For ordinary purposes and ordinary people, however, the lamp continued to do service, but it was not improved. The eighteenth century had nearly pa.s.sed, and the lamp was still the unsatisfactory, disagreeable thing it had always been.

[Ill.u.s.tration: FIG. 7.--AN ARGAND LAMP.]

Late in the eighteenth century the improvement came. In 1783 a man named Argand, a Swiss physician residing in London, invented a lamp that was far better than any that had ever been made before. What did Argand do for the lamp? Examine an ordinary lamp in which coal-oil is burned.

The _chimney_ protects the flame from sudden gusts of wind and also creates a draft of air,[7] just as the fire-chimney creates a draft.

Argand's lamp (Fig. 7) was the first to have a chimney. Look below the chimney and you will see open pa.s.sages through which air may pa.s.s upward and find its way to the wick. Notice further that as this draft of air pa.s.ses upward it is so directed that, when the lamp is burning, an extra quant.i.ty of air plays directly upon the wick. Before Argand, the wick received no supply of air. Now notice--and this is very important--that the wick of our modern lamp is flat or circular, but _thin_. The air in abundance plays upon both sides of the thin wick, and burns it without making smoke. Smoke is simply half-burned particles (soot) of a burning substance. The particles pa.s.s off half-burned because enough air has not been supplied. Now Argand, by making the wick thin and by causing plenty of air to rush into the flame, caused all the wick to be burned and thereby caused it to burn with a white flame.

After the invention of Argand, the art of lamp-making improved by leaps and by bounds. More progress was made in twenty years after 1783 than had been made in twenty centuries before. New burners were invented, new and better oils were used, and better wicks made. But all the new kinds of lamps were patterned after the Argand. The lamp you use at home may not be a real Argand, but it is doubtless made according to the principles of the lamp invented by the Swiss physician in 1783.

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 pa.s.s 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.

[Ill.u.s.tration: FIG. 8.--THE GAS JET.]

[Ill.u.s.tration: 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 pa.s.sage 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.

[Ill.u.s.tration: 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 b.u.t.ton, 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.

FOOTNOTES:

[6] Hold the end of a dry towel in a basin of water and watch the water rise in the towel. It rises by capillary action.

[7] Light a short piece of candle and place it in a tumbler, and cover the top of the tumbler. The experiment teaches that a flame must have a constant supply of fresh air and will go out if the air is shut off.

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 fas.h.i.+on 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).

[Ill.u.s.tration: FIG. 1.--IMPLEMENTS OF THE STONE AGE.]

[Ill.u.s.tration: 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 fas.h.i.+on 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.

[Ill.u.s.tration: FIG. 3.--THE PRIMITIVE FORGE.]

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 ma.s.s there was an opening and at the bottom there were several openings. When the ma.s.s 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_.

[Ill.u.s.tration: FIG. 4.--BELLOWS WORKED BY THE FEET.]

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 ma.s.s of charcoal and iron ore was the first form of the forge, one of the greatest of all inventions.

[Ill.u.s.tration: FIG. 5.--THE WOODEN BELLOWS.]

With the invention of the forge the stone age gradually pa.s.sed away and the iron age was ushered in. Tools and weapons could now be made of iron. And great was the difference between iron tools and stone tools.

To cut down a tree with a flint hatchet required the labor of a man for a month, while to clear a forest with such an implement was an impossible task. But the forge gave to man iron for the sharp cutting tools, for the ax and knife and chisel and saw. With these he became the master of wood and he could now easily cut down trees and build houses and make furniture and wagons and boats.

As time went on and man advanced in civilization, iron was found to be the most useful of metals. Iron can be shaped into many forms. It can be drawn into wire of any desired length or fineness, it may be bent in any direction, it may be sharpened, or hardened, or softened, at pleasure.

"Iron accommodates itself to all our wants and desires and even to our caprices. It is equally serviceable to the arts, the sciences, to agriculture and war; the same ore furnishes the sword, the plowshare, the scythe, the pruning-hook, the needle, the spring of a watch or of a carriage, the chisel, the chain, the anchor, the compa.s.s and the bomb.

It is a medicine of much virtue and the only metal friendly to the human frame."[9]

A metal that was so useful was needed in large quant.i.ties, yet the primitive forge could turn out only small quant.i.ties of iron. A day's labor at the bellows would produce a lump weighing only fifteen or twenty pounds. As a result of this slowness in manufacture there was always in primitive and ancient times a scarcity of iron. Indeed in some countries iron was a precious metal, almost as precious as silver or gold. In many countries, it is true, there were thousands of forges at work, but in no country was the supply of iron equal to the demand. The old forge could not supply the demand, yet centuries pa.s.sed before any great improvement was made in the progress of iron making.

[Ill.u.s.tration: FIG. 6.--A BLAST FURNACE OF THE MIDDLE AGES.]

Near the close of the Middle Ages improvements upon the primitive forge began to be made. In the sixteenth century ironmakers in Germany began to smelt ore in closed furnaces and to build their furnaces higher and to make them larger (Fig. 6). Sometimes they built their furnaces to a height of twenty or thirty feet. About this time also a better and a stronger blast was invented. Water-power instead of hand-power began to be used for operating the bellows. In some cases wooden bellows--great wooden pistons working in tubs--were subst.i.tuted for the old bellows of leather. By the end of the sixteenth century so many improvements had been made upon the primitive forge that it no longer resembled the forge of ancient times. So the new forge received a new name and was called a _blast furnace_.[10] You should observe, however, that the blast furnace was simply the old forge built with a large closed furnace and provided with a more powerful blast.