Boys' Second Book of Inventions

"I was always planning and contriving, and was never satisfied unless I was doing something difficult – something that had never been done before, if possible."

The grandfather built the first American locomotive; he was one of the most ardent supporters of Cyrus Field in the great project of an Atlantic cable, and he was for a score of years the president of a cable company. His was the curious, constructive mind. As a boy he built a washing machine to assist his overworked mother; later on he built the first lawnmower and invented a process for rolling iron, the first used in this country; he constructed a torpedo-boat to aid the Greeks in their revolt against Turkish tyranny in 1824. He dreamed of utilising the current of the East River for manufacturing power; he even experimented with flying machines, becoming so enthusiastic in this labour that he nearly lost the sight of an eye through an explosion which blew the apparatus to pieces.

It will be seen, therefore, that the grandson comes naturally by his inclinations. It was his grandfather who gave him his first chest of tools and taught him to work with his hands, and he has always had a fondness for contriving new machines and of working out difficult scientific problems. Until the last few years, however, he has never devoted his whole time to the work which best pleased him. For years he was connected with his father's extensive business enterprise, an active member, in fact, of the firm of Cooper, Hewitt & Co., and he has always been prominent in the social life of New York, a member of no fewer than eight prominent clubs. But never for a moment in his career – he is now forty-two years old, though he looks scarcely thirty-five – has he ceased to be interested in science and mechanics. As a student in Stevens Institute, and later in Columbia College, he gave particular attention to electricity, physics, chemistry, and mechanics. Later, when he went into business, his inventive mind turned naturally to the improvement of manufacturing methods, with the result that his name appears in the Patent Records as the inventor of many useful devices – a vacuum pan, a glue clarifier, a glue cutter and other glue machinery. He worked at many sorts of trades with his own hands – machine-shop practice, blacksmithing, steam-fitting, carpentry, jewelry work, and other work-a-day employments. He was employed in a jeweller's shop, learning how to make rings and to set stones; he managed a steam launch; he was for eight years in his grandfather's glue factory, where he had practical problems in mechanics constantly brought to his attention. And he was able to combine all this hard practical work with a fair amount of shooting, golfing, and automobiling.

Most of Mr. Hewitt's scientific work of recent years has been done after business hours – the long, slow, plodding toil of the experimenter. There is surely no royal road to success in invention, no matter how well a man may be equipped, no matter how favourably his means are fitted to his hands. Mr. Hewitt worked for seven years on the electrical investigations which resulted in his three great inventions; thousands of experiments were performed; thousands of failures paved the way for the first glimmer of success.

His laboratory during most of these years was hidden away in the tall tower of Madison Square Garden, overlooking Madison Square, with the roar of Broadway and Twenty-third Street coming up from the distance. Here he has worked, gradually expanding the scope of his experiments, increasing his force of assistants, until he now has an office and two workshops in Madison Square Garden and is building a more extensive laboratory elsewhere. Replying to the remark that he was fortunate in having the means to carry forward his experiments in his own way, he said:

"The fact is quite the contrary. I have had to make my laboratory pay as I went along."

Mr. Hewitt chose his problem deliberately, and he chose one of the most difficult in all the range of electrical science, but one which, if solved, promised the most flattering rewards.

"The essence of modern invention," he said, "is the saving of waste, the increase of efficiency in the various mechanical appliances."

This being so, he chose the most wasteful, the least efficient of all widely used electrical devices – the incandescent lamp. Of all the power used in producing the glowing filament in the Edison bulb, about ninety-seven per cent. is absolutely wasted, only three per cent. appearing in light. This three per cent. efficiency of the incandescent lamp compares very unfavourably, indeed, with the forty per cent. efficiency of the gasoline engine, the twenty-two per cent. efficiency of the marine engine, and the ninety per cent. efficiency of the dynamo.

Mr. Hewitt first stated his problem very accurately. The waste of power in the incandescent lamp is known to be due largely to the conversion of a considerable part of the electricity used into useless heat. An electric-lamp bulb feels hot to the hand. It was therefore necessary to produce a cool light; that is, a light in which the energy was converted wholly or largely into light rays and not into heat rays. This, indeed, has long been one of the chief goals of ambition among inventors. Mr. Hewitt turned his attention to the gases. Why could not some incandescent gas be made to yield the much desired light without heat?

This was the germ of the idea. Comparatively little was known of the action of electricity in passing through the various gases, though the problem involved had long been the subject of experiment, and Mr. Hewitt found himself at once in a maze of unsolved problems and difficulties.

"I tried many different gases," he said, "and found that some of them gave good results – nitrogen, for instance – but many of them produced too much heat and presented other difficulties."

Finally, he took up experiments with mercury confined in a tube from which the air had been exhausted. The mercury arc, as it is called, had been experimented with years before, had even been used as a light, although at the time he began his investigations Mr. Hewitt knew nothing of these earlier investigations. He used ordinary glass vacuum tubes with a little mercury in the bottom which he had reduced to a gas or vapour under the influence of heat or by a strong current of electricity. He found it a rocky experimental road; he has called invention "systematic guessing."

"I had an equation with a large number of unknown quantities," he said. "About the only thing known for a certainty was the amount of current passing into the receptacle containing the gas, and its pressure. I had to assume values for these unknown quantities in every experiment, and you can understand what a great number of trials were necessary, using different combinations, before obtaining results. I presume thousands of experiments were made."

Many other investigators had been on the very edge of the discovery. They had tried sending strong currents through a vacuum tube containing mercury vapour, but had found it impossible to control the resistance. One day, however, in running a current into the tube Mr. Hewitt suddenly recognised certain flashes; a curious phenomenon. Always it is the unexpected thing, the thing unaccounted for, that the mind of the inventor leaps upon. For there, perhaps, is the key he is seeking. Mr. Hewitt continued his experiments and found that the mercury vapour was conducting. He next discovered that when once the high resistance of the cold mercury was overcome, a very much less powerful current found ready passage and produced a very brilliant light: the glow of the mercury vapour. This, Mr. Hewitt says, was the crucial point, the genesis of his three inventions, for all of them are applications of the mercury arc.

Thus, in short, he invented the new lamp. By the use of what is known to electricians as a "boosting coil," supplying for an instant a very powerful current, the initial resistance of the cold mercury in the tube is overcome, and then, the booster being automatically shut off, the current ordinarily used in incandescent lighting produces an illumination eight times as intense as the Edison bulb of the same candle-power. The mechanism is exceedingly simple and cheap; a button turns the light on or off; the remaining apparatus is not more complex than that of the ordinary incandescent light. The Hewitt lamp is best used in the form of a long horizontal tube suspended overhead in a room, the illumination filling all the space below with a radiance much like daylight, not glaring and sharp as with the Edison bulb. Mr. Hewitt has a large room hung with green material and thus illuminated, giving the visitor a very strange impression of a redless world. After a few moments spent here a glance out of the window shows a curiously red landscape, and red buildings, a red Madison Square, the red coming out more prominently by contrast with the blue-green of the light.

"For many purposes," said Mr. Hewitt, "the light in its present form is already easily adaptable. For shopwork, draughting, reading, and other work, where the eye is called on for continued strain, the absence of red is an advantage, for I have found light without the red much less tiring to the eye. I use it in my own laboratories, and my men prefer it to ordinary daylight."

In other respects, however, its colour is objectionable, and Mr. Hewitt has experimented with a view to obtaining the red rays, thereby producing a pure white light.

"Why not put a red globe around your lamp?" is a common question put to the inventor. This is an apparently easy solution of the difficulty until one is reminded that red glass does not change light waves, but simply suppresses all the rays that are not red. Since there are no red rays in the Hewitt lamp, the effect of the red globe would be to cut off all the light.

But Mr. Hewitt showed me a beautiful piece of pink silk, coloured with rhodimin, which, when thrown over the lamp, changes some of the orange rays into red, giving a better balanced illumination, although at some loss of brilliancy. Further experiments along this line are now in progress, investigations both with mercury vapour and with other gases.

Mr. Hewitt has found that the rays of his new lamp have a peculiar and stimulating effect on plant growth. A series of experiments, in which seeds of various plants were sown under exactly the same conditions, one set being exposed to daylight and one to the mercury gaslight, showed that the latter grew much more rapidly and luxuriantly. Without doubt, also, these new rays will have value in the curing of certain kinds of disease.

Further experimentation with the mercury arc led to the other two inventions, the converter and the interrupter. And first of the converter:

Hewitt's Electrical Converter.– The converter is simplicity itself. Here are two kinds of electrical currents – the alternating and the direct. Science has found it much cheaper and easier to produce and transmit the alternating current than the direct current. Unfortunately, however, only the direct currents are used for such practical purposes as driving an electric car or automobile, or running an elevator, or operating machine tools or the presses in a printing-office, and they are preferable for electric lighting. The power of Niagara Falls is changed into an alternating current which can be sent at high pressure (high voltage) over the wires for long distances, but before it can be used it must, for some purposes, be converted into a direct current. The apparatus now in use is cumbersome, expensive, and wasteful.

Mr. Hewitt's new converter is a mere bulb of glass or of steel, which a man can hold in his hand. The inventor found that the mercury bulb, when connected with wires carrying an alternating current, had the curious and wonderful property of permitting the passage of the positive half of the alternating wave when the current has started and maintained in that direction, and of suppressing the other half; in other words, of changing an alternating current into a direct current. In this process there was a loss, the same for currents of all potentials, of only 14 volts. A three-pound Hewitt converter will do the work of a seven-hundred-pound apparatus of the old type; it will cost dollars where the other costs hundreds; and it will save a large proportion of the electricity wasted in the old process. By this simple device, therefore, Mr. Hewitt has in a moment extended the entire range of electrical development. As alternating currents can be carried longer distances by using high pressure, and the pressure or voltage can be changed by the use of a simple transformer and then changed into a direct current by the converter at any convenient point along the line, therefore more waterfalls can be utilised, more of the power of coal can be utilised, more electricity saved after it is generated, rendering the operating of all industries requiring power so much cheaper. Every electric railroad, every lighting plant, every factory using electricity, is intimately concerned in Mr. Hewitt's device, for it will cheapen their power and thereby cheapen their products to you and to me.

Hewitt's Electrical Interrupter.– The third invention is in some respects the most wonderful of the three. Technically, it is called an electric interrupter or valve. "If a long list of present-day desiderata were drawn up," says the Electrical World and Engineer, "it would perhaps contain no item of more immediate importance than an interrupter which shall be … inexpensive and simple of application." This is the view of science; and therefore this device is one upon which a great many inventors, including Mr. Marconi, have recently been working; and Mr. Hewitt has been fortunate in producing the much-needed successful apparatus.

The chief demand for an interrupter has come from the scores of experimenters who are working with wireless telegraphy. In 1894 Mr. Marconi began communicating through space without wires, and it may be said that wireless telegraphy has ever since been the world's imminent invention. Who has not read with profound interest the news of Mr. Marconi's success, the gradual increases of his distances? Who has not sympathised with his effort to perfect his devices, to produce a tuning apparatus by means of which messages flying through space could be kept secret? And here at last has come the invention which science most needed to complete and vitalise Marconi's work. By means of Mr. Hewitt's interrupter, the simplicity of which is as astonishing as its efficiency, the whole problem has been suddenly and easily solved.

Mr. Hewitt's new interrupter may, indeed, be called the enacting clause of wireless telegraphy. By its use the transmission of powerful and persistent electrical waves is reduced to scientific accuracy. The apparatus is not only cheap, light, and simple, but it is also a great saver of electrical power.

The interrupter, also, is a simple device. As I have already shown, the mercury vapour opposes a high resistance to the passage of electricity until the current reaches a certain high potential, when it gives way suddenly, allowing a current of low potential to pass through. This property can be applied in breaking a high potential current, such as is used in wireless telegraphy, so that the waves set up are exactly the proper lengths, always accurate, always the same, for sending messages through space. By the present method an ordinary arc or spark gap – that is, a spark passing between two brass balls – is employed in sending messages across the Atlantic. Marconi uses a spark as large as a man's wrist, and the noise of its passage is so deafening that the operators are compelled to wear cotton in their ears, and often they must shield their eyes from the blinding brilliancy of the discharges. Moreover, this open-air arc is subject to variations, to great losses of current, the brass balls become eroded, and the accuracy of the transmission is much impaired. All this is obviated by the cheap, simple, noiseless, sparkless mercury bulb.

"What I have done," said Mr. Hewitt, "is to perfect a device by means of which messages can be sent rapidly and without the loss of current occasioned by the spark gap. In wireless telegraphy the trouble has been that it was difficult to keep the sending and the receiving instruments attuned. By the use of my interrupter this can be accomplished."

And the possibilities of the mercury tube – indeed, of incandescent gas tubes in general – have by no means been exhausted. A new door has been opened to investigators, and no one knows what science will find in the treasure-house – perhaps new and more wonderful inventions, perhaps the very secret of electricity itself. Mr. Hewitt is still busily engaged in experimenting along these lines, both in the realm of abstract science and in that of practical invention. He is too careful a scientist, however, to speak much of the future, but those who are most familiar with his methods of work predict that the three inventions he has already announced are only forerunners of many other discoveries.

The chief pursuit of science and invention in this day of wonders is the electrical conquest of the world, the introduction of the electrical age. The electric motor is driving out the steam locomotive, the electric light is superseding gas and kerosene, the waterfall must soon take the place of coal. But certain great problems stand like solid walls in the way of development, part of them problems of science, part of mechanical efficiency. The battle of science is, indeed, not unlike real war, charging its way over one battlement after another, until the very citadel of final secret is captured. Mr. Hewitt with his three inventions has led the way over some of the most serious present barriers in the progress of technical electricity, enabling the whole industry, in a hundred different phases of its progress, to go forward.

THE END

1

In the first "Boys' Book of Inventions," the author devoted a chapter entitled "Through the Air" to the interesting work of the inventors of flying machines who have experimented with aëroplanes; that is, soaring machines modelled after the wings of a bird. The work of Professor S. P. Langley with his marvellous Aërodrome, and that of Hiram Maxim and of Otto Lilienthal, were given especial consideration. In the present chapter attention is directed to an entirely different class of flying machines – the steerable balloons.