Boys' Second Book of Inventions

Indeed, so hot is the core that there is really no accurate means of measuring its temperature, although science has been enabled by various curious devices to form a fairly correct estimate. The furnace has a provoking way of burning up all of the thermometers and heat-measuring devices which are applied to it. A number of years ago a clever German, named Segar, invented a series of little cones composed of various infusible earths like clay and feldspar. He so fashioned them that one in the series would melt at 1,620 degrees Fahrenheit, another at 1,800 degrees, and so on up. If the cones are placed in a pottery kiln, the potter can tell just what degree of temperature he has reached by the melting of the cones one after another. But in Mr. Acheson's electrical furnaces all the cones would burn up and disappear in two minutes. The method employed for coming at the heat of the electrical furnace, in some measure, is this: a thin filament of platinum is heated red hot – 1,800 degrees Fahrenheit – by a certain current of electricity. A delicate thermometer is set three feet away, and the reading is taken. Then, by a stronger current, the filament is made white hot – 3,400 degrees Fahrenheit – and the thermometer moved away until it reads the same as it read before. Two points in a distance-scale are thus obtained as a basis of calculation. The thermometer is then tried by an electrical furnace. To be kept at the same marking it must be placed much farther away than in either of the other instances. A simple computation of the comparative distances with relation to the two well-ascertained temperatures gives approximately, at least, the temperature of the electrical furnace. Some other methods are also employed. None is regarded as perfectly exact; but they are near enough to have yielded some very interesting and valuable statistics regarding the power of various temperatures. For instance, it has been found that aluminium becomes a limpid liquid at from 4,050 to 4,320 degrees Fahrenheit, and that lime melts at from 4,940 to 5,400 degrees, and magnesia at 4,680 degrees.

There are two kinds of electrical furnaces, as there are two kinds of electric lights – arc and incandescent. Moissan has used the arc furnace in all of his experiments, but Mr. Acheson's furnaces follow rather the principle of the incandescent lamp. "The incandescent light," said Mr. Fitzgerald, "is produced by the resistance of a platinum wire or a carbon filament to the passage of a current of electricity. Both light and heat are given off. In our furnace, the heat is produced by the resistance of a solid cylinder or core of pulverised coke to the passage of a strong current of electricity. When the core becomes white hot it causes the materials surrounding it to unite chemically, producing the carborundum crystals."

The materials used are of the commonest – pure white sand, coke, sawdust, and salt. The sand and coke are mixed in the proportions of sixty to forty, the sawdust is added to keep the mixture loose and open, and the salt to assist the chemical combination of the ingredients. The furnace is half filled with this mixture, and then the core of coke, twenty-one inches in diameter, is carefully moulded in place. This core is sixteen feet long, reaching the length of the furnace, and connecting at each end with an immense carbon terminal, consisting of no fewer than twenty-five rods of carbon, each four inches square and nearly three feet long. These terminals carry the current into the core from huge insulated copper bars connected from above. When the core is complete, more of the carborundum mixture is shovelled in and tramped down until the furnace is heaping full.

Everything is now ready for the electric current. The wires from the Niagara Falls power-plant come through an adjoining building, where one is confronted, upon entering, with this suggestive sign:

DANGER

2,200 Volts

Tesla produces immensely higher voltages than this for laboratory experiments, but there are few more powerful currents in use in this country for practical purposes. Only about 2,000 volts are required for executing criminals under the electric method employed in New York; 400 volts will run a trolley-car. It is hardly comfortable to know that a single touch of one of the wires or switches in this room means almost certain death. Mr. Fitzgerald gave me a vivid demonstration of the terrific destructive force of the Niagara Falls current. He showed me how the circuit was broken. For ordinary currents, the breaking of a circuit simply means a twist of the wrist and the opening of a brass switch. Here, however, the current is carried into a huge iron tank full of salt water. The attendant, pulling on a rope, lifts an iron plate from the tank. The moment it leaves the water, there follow a rumbling crash like a thunder-clap, a blinding burst of flame, and thick clouds of steam and spray. The sight and sound of it make you feel delicate about interfering with a 2,200-volt current.

This current is, indeed, too strong in voltage for the furnaces, and it is cut down, by means of what were until recently the largest transformers in the world, to about 100 volts, or one-fourth the pressure used on the average trolley line. It is now, however, a current of great intensity – 7,500 ampères, as compared with the one-half ampère used in an incandescent lamp; and it requires eight square inches of copper and 400 square inches of carbon to carry it.

Within the furnace, when the current is turned on, a thousand horse-power of energy is continuously transformed into heat. Think of it! Is it any wonder that the temperature goes up? And this is continued for thirty-six hours steadily, until 36,000 "horse-power hours" are used up and 7,000 pounds of the crystals have been formed. Remembering that 36,000 horse-power hours, when converted into heat, will raise 72,000 gallons of water to the boiling point, or will bring 350 tons of iron up to a red heat, one can at least have a sort of idea of the heat evolved in a carborundum furnace.

When the coke core glows white, chemical action begins in the mixture around it. The top of the furnace now slowly settles, and cracks in long, irregular fissures, sending out a pungent gas which, when lighted, burns lambent blue. This gas is carbon monoxide, and during the process nearly six tons of it are thrown off and wasted. It seems, indeed, a somewhat extravagant process, for fifty-six pounds of gas are produced for every forty of carborundum.

"It is very distinctly a geological condition," said Mr. Fitzgerald; "crystals are not only formed exactly as they are in the earth, but we have our own little earthquakes and volcanoes." Not infrequently gas collects, forming a miniature mountain, with a crater at its summit, and blowing a magnificent fountain of flame, lava, and dense white vapour high into the air, and roaring all the while in a most terrifying manner. The workmen call it "blowing off."

At the end of thirty-six hours the current is cut off, and the furnace is allowed to cool, the workmen pulling down the brick as rapidly as they dare. At the centre of the furnace, surrounding the core, there remains a solid mass of carborundum as large in diameter as a hogshead. Portions of this mass are sometimes found to be composed of pure, beautifully crystalline graphite. This in itself is a surprising and significant product, and it has opened the way directly to graphite-making on a large scale. An important and interesting feature of the new graphite industry is the utilisation it has effected of a product from the coke regions of Pennsylvania which was formerly absolute waste.

To return to carborundum: when the furnace has been cooled and the walls torn away, the core of carborundum is broken open, and the beautiful purple and blue crystals are laid bare, still hot. The sand and the coke have united in a compound nearly as hard as the diamond and even more indestructible, being less inflammable and wholly indissoluble in even the strongest acids. After being taken out, the crystals are crushed to powder and combined in various forms convenient for the various uses for which it is designed.

I asked Mr. Acheson if he could make diamonds in his furnaces. "Possibly," he answered, "with certain modifications." Diamonds, as he explained, are formed by great heat and great pressure. The great heat is now easily obtained, but science has not yet learned nature's secret of great pressure. Moissan's method of making diamonds is to dissolve coke dust in molten iron, using a carbon crucible into which the electrodes are inserted. When the whole mass is fluid, the crucible and its contents are suddenly dashed into cold water or melted lead. This instantaneous cooling of the iron produces enormous pressure, so that the carbon is crystallised in the form of diamond.

But whatever it may or may not yet be able to do in the matter of diamond-making, there can be no doubt that the possibilities of the electrical furnace are beyond all present conjecture. With American inventors busy in its further development, and with electricity as cheap as the mighty power of Niagara can make it, there is no telling what new and wonderful products, now perhaps wholly unthought-of by the human race, it may become possible to manufacture, and manufacture cheaply.

CHAPTER V

HARNESSING THE SUN

The Solar Motor

It seems daring and wonderful enough, the idea of setting the sun itself to the heavy work of men, producing the power which will help to turn the wheels of this age of machinery.

At Los Angeles, Cal., I went out to see the sun at work pumping water. The solar motor, as it is called, was set up at one end of a great enclosure where ostriches are raised. I don't know which interested me more at first, the sight of these tall birds striding with dignity about their roomy pens or sitting on their big yellow eggs – just as we imagine them wild in the desert – or the huge, strange creation of man by which the sun is made to toil. I do not believe I could have guessed the purpose of this unique invention if I had not known what to expect. I might have hazarded the opinion that it was some new and monstrous searchlight: beyond that I think my imagination would have failed me. It resembled a huge inverted lamp-shade, or possibly a tremendous iron-ribbed colander, bottomless, set on its edge and supported by a steel framework. Near by there was a little wooden building which served as a shop or engine-house. A trough full of running water led away on one side, and from within came the steady chug-chug, chug-chug of machinery, apparently a pump. So this was the sun-subduer! A little closer inspection, with an audience of ostriches, very sober, looking over the fence behind me and wondering, I suppose, if I had a cracker in my pocket, I made out some other very interesting particulars in regard to this strange invention. The colander-like device was in reality, I discovered, made up of hundreds and hundreds (nearly 1,800 in all) of small mirrors, the reflecting side turned inward, set in rows on the strong steel framework which composed the body of the great colander. By looking up through the hole in the bottom of the colander I was astonished by the sight of an object of such brightness that it dazzled my eyes. It looked, indeed, like a miniature sun, or at least like a huge arc light or a white-hot column of metal. And, indeed, it was white hot, glowing, burning hot – a slim cylinder of copper set in the exact centre of the colander. At the top there was a jet of white steam like a plume, for this was the boiler of this extraordinary engine.

"It is all very simple when you come to see it," the manager was saying to me. "Every boy has tried the experiment of flashing the sunshine into his chum's window with a mirror. Well, we simply utilise that principle. By means of these hundreds of mirrors we reflect the light and heat of the sun on a single point at the centre of what you have described as a colander. Here we have the cylinder of steel containing the water which we wish heated for steam. This cylinder is thirteen and one-half feet long and will hold one hundred gallons of water. If you could see it cold, instead of glowing with heat, you would find it jet black, for we cover it with a peculiar heat-absorbing substance made partly of lampblack, for if we left it shiny it would re-reflect some of the heat which comes from the mirrors. The cold water runs in at one end through this flexible metallic hose, and the steam goes out at the other through a similar hose to the engine in the house."

Though this colander, or "reflector," as it is called, is thirty-three and one-half feet in diameter at the outer edge and weighs over four tons, it is yet balanced perfectly on its tall standards. It is, indeed, mounted very much like a telescope, in meridian, and a common little clock in the engine-room operates it so that it always faces the sun, like a sunflower, looking east in the morning and west in the evening, gathering up the burning rays of the sun and throwing them upon the boiler at the centre. In the engine-house I found a pump at work, chug-chugging like any pump run by steam-power, and the water raised by sun-power flowing merrily away. The manager told me that he could easily get ten horse-power; that, if the sun was shining brightly, he could heat cold water in an hour to produce 150 pounds of steam.

The wind sometimes blows a gale in Southern California, and I asked the manager what provision had been made for keeping this huge reflector from blowing away.

"Provision is made for varying wind-pressures," he said, "so that the machine is always locked in any position, and may only be moved by the operating mechanism, unless, indeed, the whole structure should be carried away. It is designed to withstand a wind-pressure of 100 miles an hour. It went through the high gales of the November storm without a particle of damage. One of the peculiar characteristics of its construction is that it avoids wind-pressure as much as possible."

The operation of the motor is so simple that it requires very little human labour. When power is desired, the reflector must be swung into focus – that is, pointed exactly toward the sun – which is done by turning a crank. This is not beyond the power of a good-sized boy. There is an indicator which readily shows when a true focus is obtained. This done, the reflector follows the sun closely all day. In about an hour the engine can be started by a turn of the throttle-valve. As the engine is automatic and self-oiling, it runs without further attention. The supply of water to the boiler is also automatic, and is maintained at a constant height without any danger of either too much or too little water. Steam-pressure is controlled by means of a safety-valve, so that it may never reach a dangerous point. The steam passes from the engine to the condenser and thence to the boiler, and the process is repeated indefinitely.

Having now the solar motor, let us see what it is good for, what is expected of it. Of course when the sun does not shine the motor does not work, so that its usefulness would be much curtailed in a very cloudy country like England, for instance; but here in Southern California and in all the desert region of the United States and Mexico, to say nothing of the Sahara in Africa, where the sun shines almost continuously, the solar motor has its greatest sphere of usefulness, and, indeed, its greatest need; for these lands of long sunshine, the deserts, are also the lands of parched fruitlessness, of little water, so that the invention of a motor which will utilise the abundant sunshine for pumping the much-needed water has a peculiar value here.

The solar motor is expected to operate at all seasons of the year, regardless of all climatic conditions, with the single exception of cloudy skies. Cold makes no difference whatever. The best results from the first model used in experimental work at Denver were obtained at a time when the pond from which the water was pumped was covered with a thick coating of ice. But, of course, the length of the solar day is longer in the summer, giving more heat and more power. The motor may be depended upon for work from about one hour and a half after sunrise to within half an hour of sunset. In the summer time this would mean about twelve hours' constant pumping.

Think what such an invention means, if practically successful, to the vast stretches of our arid Western land, valueless without water. Spread all over this country of Arizona, New Mexico, Southern California, and other States are thousands of miles of canals to bring in water from the rivers for irrigating the deserts, and there are untold numbers of wind-mills, steam and gasoline pumps which accomplish the same purpose more laboriously. Think what a new source of cheap power will do – making valuable hundreds of acres of desert land, providing homes for thousands of busy Americans. Indeed, a practical solar motor might make habitable even the Sahara Desert. And it can be used in many other ways besides for pumping water. Threshing machines might be run by this power, and, converted into electricity and saved up in storage batteries, it might be used for lighting houses, even for cooking dinners, or in fact for any purpose requiring power.

These solar motors can be built at no great expense. I was told that ten-horse-power plants would cost about $200 per horse-power, and one-hundred-horse-power plants about $100 per horse-power. This would include the entire plant, with engine and pump complete. When it is considered that the annual rental of electric power is frequently $50 per horse-power, whether it is used or not, it will be seen that the solar motor means a great deal, especially in connection with irrigation enterprises.

And the time is coming – long-headed inventors saw it many years ago – when some device for the direct utilisation of the sun's heat will be a necessity. The world is now using its coal at a very rapid rate; its wood, for fuel purposes, has already nearly disappeared, so that, within a century or two, new ways of furnishing heat and power must be devised or the human race will perish of cold and hunger. Fortunately there are other sources of power at hand; the waterfalls, the Niagaras, which, converted into electricity, may yet heat our sitting-rooms and cook our dinners. There is also wind-power, now used to a limited extent by means of wind-mills. But greater than either of these sources is the unlimited potentiality of the tides of the sea, which men have sought in vain to harness, and the direct heat of the sun itself. Some time in the future these will be subdued to the purpose of men, perhaps our main dependence for heat and power.

When we come to think of it, the harnessing of the sun is not so very strange. In fact, we have had the sun harnessed since the dawn of man on the earth, only indirectly. Without the sun there would be nothing here – no men, no life. Coal is nothing but stored-up, bottled sunshine. The sunlight of a million years ago produced forests, which, falling, were buried in the earth and changed into coal. So when we put coal in the cook-stove we may truthfully say that we are boiling the kettle with million-year-old sunshine. Similarly there would be no waterfalls for us to chain and convert into electricity, as we have chained Niagara, if the sun did not evaporate the waters of the sea, take it up in clouds, and afterward empty the clouds in rain on the mountain-tops from whence the water tumbles down again to the sea. So no wind would blow without the sun to work changes in the air.

In short, therefore, we have been using the sunlight all these years, hardly knowing it, but not directly. And think of the tremendous amount of heat which comes to the earth from the sun. Every boy has tried using a burning-glass, which, focusing a few inches of the sun's rays, will set fire to paper or cloth.

Professor Langley says that "the heat which the sun, when near the zenith, radiates upon the deck of a steamship would suffice, could it be turned into work without loss, to drive her at a fair rate of speed."

The knowledge of this enormous power going to waste daily and hourly has inspired many inventors to work on the problem of the solar motor. Among the greatest of these was the famous Swedish engineer, John Ericsson, who invented the iron-clad Monitor. He constructed a really workable solar motor, different in construction but similar in principle to the one in California which I have described. In 1876 Ericsson said:

"Upon one square mile, using only one-half of the surface and devoting the rest to buildings, roads, etc., we can drive 64,800 steam-engines, each of 100 horse-power, simply by the heat radiating from the sun. Archimedes, having completed his calculation of the force of a lever, said that he could move the earth. I affirm that the concentration of the heat radiated by the sun would produce a force capable of stopping the earth in its course."

A firm believer in the truth of his theories, he devoted the last fifteen years of his life and $100,000 to experimental work on his solar engine. For various reasons Ericsson's invention was not a practical success; but now that modern inventors, with their advancing knowledge of mechanics, have turned their attention to the problem, and now that the need of the solar motor is greater than ever before, especially in the world's deserts, we may look to see a practical and successful machine. Perhaps the California motor may prove the solution of the problem; perhaps it will need improvements, which use and experience will indicate; perhaps it may be left for a reader of these words to discover the great secret and make his fortune.

CHAPTER VI

THE INVENTOR AND THE FOOD PROBLEM

Fixing of Nitrogen – Experiments of Professor Nobbe

No lad of to-day, ambitious to become a scientist or inventor, reading of all the wonderful and revolutionising discoveries and inventions of recent years, need fear for plenty of new problems to solve in the future. No, the great problems have not all been solved. We have the steam-engine, the electric motor, the telegraph, the telephone, the air-ship, but not one of them is perfect, not one that does not bring to the attention of inventors scores of entirely new problems for solution. The further we advance in science and mechanics the further we see into the marvels of our wonderful earth and of our life, and the more there is for us to do.

As population increases and people become more intelligent there is a constant demand for new things, new machinery which will enable the human race to move more rapidly and crowd more work and more pleasure into our short human life. One man working to-day with machinery can accomplish as much as many men of a hundred years ago; he can live in a house that would then have been a palace; enjoy advantages of education, amusement, luxury, that would then have been possible only to kings and princes.

And the very greatest of all the problems which the inventors and scientists of coming generations must solve is the question – seemingly commonplace – of food.

We who live in this age of plenty can hardly realise that food could ever be a problem. But far-sighted scientists have already begun to look forward to the time when there will be so many people on the earth that the farms and fields will not supply food for every one. It is a well-known fact that the population of the world is increasing enormously. Think how America has been expanding; a whole continent overrun and settled almost within a century and a half! Nearly all the land that can be successfully farmed has already been taken up, and the land in some of the older settled localities, like Virginia and the New England States, has been so steadily cropped that it is failing in fertility, so that it will not raise as much as it would years ago. In Europe no crop at all can be raised without quantities of fertiliser.

While there was yet new country to open up, while America and Australia were yet virgin soil, there was no immediate cause for alarm; but, as no less an authority than Sir William Crookes pointed out a few years ago in a lecture before the British Association, the new land has now for the most part been opened and tamed to the plough or utilised for grazing purposes. And already we are hearing of worn-out land in Dakota – the paradise of the wheat producer. The problem, therefore, is simple enough: the world is reaching the limits of its capacity for food production, while the population continues to increase enormously: how soon will starvation begin? Sir William Crookes has prophesied, I believe, that the acute stage of the problem will be reached within the next fifty years, a time when the call of the world for food cannot be supplied. If it were not for our coming inventors and scientists it would certainly be a gloomy outlook for the human race.

But science has already foreseen this problem. When Sir William Crookes gave his address he based his arguments on modern agricultural methods; he did not look forward into the future, he did not show any faith in the scientists and inventors who are to come, who are now boys, perhaps. He did not even take cognisance of the work that had already been done. For inventors and scientists are already grappling with this problem of food.

In a nutshell, the question of food production is a question of nitrogen.

This must be explained. A crop of wheat, for instance, takes from the soil certain elements to help make up the wheat berry, the straw, the roots. And the most important of all the elements it takes is nitrogen. When we eat bread we take this nitrogen that the wheat has gathered from the soil into our own bodies to build up our bones, muscles, brains. Each wheat crop takes more nitrogen from the soil, and finally, if this nitrogen is not given back to the earth in some way, wheat will no longer grow in the fields. In other words, we say the farm is "worn out," "cropped to death." The soil is there, but the precious life-giving nitrogen is gone. And so it becomes necessary every year to put back the nitrogen and the other elements which the crop takes from the soil. This purpose is accomplished by the use of fertilisers. Manure, ground bone, nitrates, guano, are put in fields to restore the nitrogen and other plant foods. In short, we are compelled to feed the soil that the soil may feed the wheat, that the wheat may feed us. You will see that it is a complete circle – like all life.

Now, the trouble, the great problem, lies right here: in the difficulty of obtaining a sufficient amount of fertiliser – in other words, in getting food enough to keep the soil from nitrogen starvation. Already we ship guano – the droppings of sea-birds – from South America and the far islands of the sea to put on our lands, and we mine nitrates (which contain nitrogen) at large expense and in great quantities for the same purpose. And while we go to such lengths to get nitrogen we are wasting it every year in enormous quantities. Gunpowder and explosives are most made up of nitrogen – saltpetre and nitro-glycerin – so that every war wastes vast quantities of this precious substance. Every discharge of a 13-inch gun liberates enough nitrogen to raise many bushels of wheat. Thus we see another reason for the disarmament of the nations.

A prediction has been made that barely thirty years hence the wheat required to feed the world will be 3,260,000,000 bushels annually, and that to raise this about 12,000,000 tons of nitrate of soda yearly for the area under cultivation will be needed over and above the 1,250,000 tons now used by mankind. But the nitrates now in sight and available are estimated good for only another fifty years, even at the present low rate of consumption. Hence, even if famine does not immediately impend, the food problem is far more serious than is generally supposed.

Now nitrogen, it will be seen, is one of the most precious and necessary of all substances to human life, and it is one of the most common. If the world ever starves for the lack of nitrogen it will starve in a very world of nitrogen. For there is not one of the elements more common than nitrogen, not one present around us in larger quantities. Four-fifths of every breath of air we breathe is pure nitrogen – four-fifths of all the earth's atmosphere is nitrogen.