Loe raamatut: «Boys' Second Book of Inventions», lehekülg 7
From a rude platform on top of the cylinder two men were working at the pumps to keep the water out. When the edge of the great iron rim heaved up with the waves, they pumped and shouted; and when it went down, they strangled and clung for their lives.
The builder saw the necessity of immediate assistance. Twelve men scrambled into a life-boat, and three waves later they were dashed against the rim of the cylinder. Here half of the number, clinging like cats to the iron plates, spread out a sail canvas and drew it over the windward half of the cylinder, while the other men pulled it down with their hands and teeth and lashed it firmly into place. In this way the cylinder shed most of the wash, although the larger waves still scuttled down within its iron sides. Half of the crew was now hurried down the rope-ladders inside the cylinder, where the water was nearly three feet deep and swashing about like a whirlpool. They all knew that one more than ordinarily large wave would send the whole structure to the bottom; but they dipped swiftly, and passed up the water without a word. It was nothing short of a battle for life. They must keep the water down, or drown like rats in a hole. They began work at sunset, and at sunrise the next morning, when the fury of the storm was somewhat abated, they were still at work, and the cylinder was saved.
The swells were now too high to think of planting the caisson, and the fleet ran into the mouth of the Great Wicomico River to await a more favourable opportunity. Here the builders lay for a week. To keep the men busy some of them were employed in mixing concrete, adding another course of iron to the cylinder, and in other tasks of preparation. The crew was composed largely of Americans and Irishmen, with a few Norwegians, the ordinary Italian or Bohemian labourer not taking kindly to the risks and terrors of such an expedition. Their number included carpenters, masons, iron-workers, bricklayers, caisson-men, sailors, and a host of common shovellers. The pay varied from twenty to fifty cents an hour for time actually worked, and the builders furnished meals of unlimited ham, bread, and coffee.
On April 17th, the weather being calmer, the fleet ventured out stealthily. A buoy marked the spot where the lighthouse was to stand. When the cylinder was exactly over the chosen site, the valves of two of the compartments into which it was divided were quickly opened, and the water poured in. The moment the lower edge of the caisson, borne downward by the weight of water, touched the shoal, the men began working with feverish haste. Large stones were rolled from the barges around the outside of the caisson to prevent the water from eating away the sand and tipping the structure over.
In the meantime a crew of twenty men had taken their places in the compartments of the cylinder still unfilled with water. A chute from the steamer vomited a steady stream of dusty concrete down upon their heads. A pump drenched them with an unceasing cataract of salt water. In this terrible hole they wallowed and struggled, shovelling the concrete mortar into place and ramming it down. Every man on the expedition, even the cooks and the stokers, was called upon at this supreme moment to take part in the work. Unless the structure could be sufficiently ballasted while the water was calm, the first wave would brush it over and pound it to pieces on the shoals.
After nearly two hours of this exhausting labour the captain of the steamer suddenly shouted the command to cast away.
The sky had turned black and the waves ran high. All of the cranes were whipped in, and up from the cylinder poured the shovellers, looking as if they had been freshly rolled in a mortar bed. There was a confused babel of voices and a wild flight for the steamer. In the midst of the excitement one of the barges snapped a hawser, and, being lightened of its load, it all but turned over in a trough of the sea. The men aboard her went down on their faces, clung fast, and shouted for help, and it was only with difficulty that they were rescued. One of the life-boats, venturing too near the iron cylinder, was crushed like an egg-shell, but a tug was ready to pick up the men who manned it.
So terrified were the workmen by the dangers and difficulties of the task that twelve of them ran away that night without asking for their pay.
On the following morning the builder was appalled to see that the cylinder was inclined more than four feet from the perpendicular. In spite of the stone piled around the caisson, the water had washed the sand from under one edge of it, and it had tipped part way over. Now was the pivotal point of the whole enterprise. A little lack of courage or skill, and the work was doomed.
The waves still ran high, and the freshet currents from the Potomac River poured past the shoals at the rate of six or seven miles an hour. And yet one of the tugs ran out daringly, dragging a barge-load of stone. It was made fast, and although it pitched up and down so that every wave threatened to swamp it and every man aboard was seasick, they managed to throw off 200 tons more of stone around the base of the caisson on the side toward which it was inclined. In this way further tipping in that direction was prevented, and the action of the water on the sand under the opposite side soon righted the structure.
Beginning on the morning of April 21st the entire crew worked steadily for forty-eight hours without sleeping or stopping for meals more than fifteen minutes at a time. When at last they were relieved, they came up out of the cylinder shouting and cheering because the foundation was at last secure.
The structure was now about thirty feet high, and filled nearly to the top with concrete. The next step was to force it down 15½ feet into the hard sand at the bottom of the bay, thus securing it for ever against the power of the waves and the tide. An air-lock, which is a strongly built steel chamber about the size of a hogshead, was placed on top of the air-shaft, the water in the big box-like caisson at the bottom of the cylinder was forced out with compressed air, and the men prepared to enter the caisson.
No toil can compare in its severity and danger with that of a caisson worker. He is first sent into the air-lock, and the air-pressure is gradually increased around him until it equals that of the caisson below; then he may descend. New men often shout and beg pitifully to be liberated from the torture. Frequently the effect of the compressed air is such that they bleed at the ears and nose, and for a time their heads throb as if about to burst open.
In a few minutes these pains pass away, the workers crawl down the long ladder of the air-shaft and begin to dig away the sand of the sea-bottom. It is heaped high around the bottom of a four-inch pipe which leads up the air-shaft and reaches out over the sea. A valve in the pipe is opened and the sand and stones are driven upward by the compressed air in the caisson and blown out into the water with tremendous force. As the sand is mined away, the great tower above it slowly sinks downward, while the subterranean toilers grow sallow-faced, yellow-eyed, become half deaf, and lose their appetites.
When Smith's Point Light was within two feet of being deep enough the workmen had a strange and terrible adventure.
Ten men were in the caisson at the time. They noticed that the candles stuck along the wall were burning a lambent green. Black streaks, that widened swiftly, formed along the white-painted walls. One man after another began staggering dizzily, with eyes blinded and a sharp burning in the throat. Orders were instantly given to ascend, and the crew, with the help of ropes, succeeded in escaping. All that night the men lay moaning and sleepless in their bunks. In the morning only a few of them could open their eyes, and all experienced the keenest torture in the presence of light. Bags were fitted over their heads, and they were led out to their meals.
That afternoon Major E. H. Ruffner, of Baltimore, the Government engineer for the district, appeared with two physicians. An examination of the caisson showed that the men had struck a vein of sulphuretted hydrogen gas.
Here was a new difficulty – a difficulty never before encountered in lighthouse construction. For three days the force lay idle. There seemed no way of completing the foundation. On the fourth day, after another flooding of the caisson, Mr. Flaherty called for volunteers to go down the air-shaft, agreeing to accompany them himself – all this in the face of the spectacle of thirty-five men moaning in their bunks, with their eyes burning and blinded and their throats raw. And yet fourteen men stepped forward and offered to "see the work through."
Upon reaching the bottom of the tower they found that the flow of gas was less rapid, and they worked with almost frantic energy, expecting every moment to feel the gas griping in their throats. In half an hour another shift came on, and before night the lighthouse was within an inch or two of its final resting-place.
The last shift was headed by an old caisson-man named Griffin, who bore the record of having stood seventy-five pounds of air-pressure in the famous Long Island gas tunnel. Just as the men were ready to leave the caisson the gas suddenly burst up again with something of explosive violence. Instantly the workmen threw down their tools and made a dash for the air-shaft. Here a terrible struggle followed. Only one man could go up the ladder at a time, and they scrambled and fought, pulling down by main force every man who succeeded in reaching the rounds. Then one after another they dropped in the sand, unconscious.
Griffin, remaining below, had signalled for a rope. When it came down, he groped for the nearest workman, fastened it around his body, and sent him aloft. Then he crawled around and pulled the unconscious workmen together under the air-shaft. One by one he sent them up. The last was a powerfully built Irishman named Howard. Griffin's eyes were blinded, and he was so dizzy that he reeled like a drunken man, but he managed to get the rope around Howard's body and start him up. At the eighteen-inch door of the lock the unconscious Irishman wedged fast, and those outside could not pull him through. Griffin climbed painfully up the thirty feet of ladder and pushed and pulled until Howard's limp body went through. Griffin tried to follow him, but his numbed fingers slipped on the steel rim, and he fell backward into the death-hole below. They dropped the rope again, but there was no response. One of the men called Griffin by name. The half-conscious caisson-man aroused himself and managed to tie the rope under his arms. Then he, too, was hoisted aloft, and when he was dragged from the caisson, more dead than alive, the half-blinded men on the steamer's deck set up a shout of applause – all the credit that he ever received.
Two of the men prostrated by the gas were sent to a hospital in New York, where they were months in recovering. Another went insane. Griffin was blind for three weeks. Four other caisson-men came out of the work with the painful malady known as "bends," which attacks those who work long under high air-pressure. A victim of the "bends" cannot straighten his back, and often his legs and arms are cramped and contorted. These terrible results will give a good idea of the heroism required of the sea-builder.
Having sunk the caisson deep enough the workmen filled it full of concrete and sealed the top of the air-shaft. Then they built the light-keeper's home, and the lantern was ready for lighting. Three days within the contract year the tower was formally turned over to the Government.
And thus the builders, besides providing a warning to the hundreds of vessels that yearly pass up the bay, erected a lasting monument to their own skill, courage, and perseverance. As long as the shoal remains the light will stand. In the course of half a century, perhaps less, the sea-water will gnaw away the iron of the cylinder, but there will still remain the core of concrete, as hard and solid as the day on which it was planted.
It is fitting that work which has drawn so largely upon the highest intellectual and moral endowments of the engineer and the builder should not serve the selfish interests of any one man, nor of any single corporation, nor even of the Government which provided the means, but that it should be a gift to the world at large. Other nations, even Great Britain, which has more at stake upon the seas than any other country, impose regular lighthouse taxes upon vessels entering their harbours; but the lights erected by the United States flash a free warning to any ship of any land.
CHAPTER IX
THE NEWEST ELECTRIC LIGHT
Peter Cooper Hewitt and His Three Great Inventions – The Mercury Arc Light – The New Electrical Converter – The Hewitt Interrupter
It is indeed a great moment when an inventor comes to the announcement of a new and epoch-making achievement. He has been working for years, perhaps, in his laboratory, struggling along unknown, unheard of, often poor, failing a hundred times for every achieved success, but finally, all in a moment, surprising the secret which nature has guarded so long and so faithfully. He has discovered a new principle that no one has known before, he has made a wonderful new machine – and it works! What he has done in his laboratory for himself now becomes of interest to all the world. He has a great message to give. His patience and perseverance through years of hard work have produced something that will make life easier and happier for millions of people, that will open great new avenues for human effort and human achievement, build up new fortunes; often, indeed, change the whole course of business affairs in the world, if not the very channels of human thought. Think what the steam-engine has done, and the telegraph, and the sewing-machine! All this wonder lies to-day in the brain of the inventor; to-morrow it is a part of the world's treasure.
Such a moment came on an evening in January, 1902, when Peter Cooper Hewitt, of New York City – then wholly unknown to the greater world – made the announcement of an invention of such importance that Lord Kelvin, the greatest of living electricians, afterward said that of all the things he saw in America the work of Mr. Hewitt attracted him most.
On that evening in January, 1902, a curious crowd was gathered about the entrance of the Engineers' Club in New York City. Over the doorway a narrow glass tube gleamed with a strange blue-green light of such intensity that print was easily readable across the street, and yet so softly radiant that one could look directly at it without the sensation of blinding discomfort which accompanies nearly all brilliant artificial lights. The hall within, where Mr. Hewitt was making the first public announcement of his discovery, was also illuminated by the wonderful new tubes. The light was different from anything ever seen before, grateful to the eyes, much like daylight, only giving the face a curious, pale-green, unearthly appearance. The cause of this phenomenon was soon evident; the tubes were seen to give forth all the rays except red – orange, yellow, green, blue, violet – so that under its illumination the room and the street without, the faces of the spectators, the clothing of the women lost all their shades of red; indeed, changing the very face of the world to a pale green-blue. It was a redless light. The extraordinary appearance of this lamp and its profound significance as a scientific discovery at once awakened a wide public interest, especially among electricians who best understood its importance. Here was an entirely new sort of electric light. The familiar incandescent lamp, the invention of Thomas A. Edison, though the best of all methods of illumination, is also the most expensive. Mr. Hewitt's lamp, though not yet adapted to all the purposes served by the Edison lamp, on account of its peculiar colour, produces eight times as much light with the same amount of power. It is also practically indestructible, there being no filament to burn out; and it requires no special wiring. By means of this invention electricity, instead of being the most costly means of illumination, becomes the cheapest – cheaper even than kerosene. No further explanation than this is necessary to show the enormous importance of this invention.
Mr. Hewitt's announcement at once awakened the interest of the entire scientific world and made the inventor famous, and yet it was only the forerunner of two other inventions equally important. Once discover a master-key and it often unlocks many doors. Tracing out the principles involved in his new lamp, Mr. Hewitt invented:
A new, cheap, and simple method of converting alternating electrical currents into direct currents.
An electrical interrupter or valve, in many respects the most wonderful of the three inventions.
Before entering upon an explanation of these discoveries, which, though seemingly difficult and technical, are really simple and easily understandable, it will be interesting to know something of Mr. Hewitt and his methods of work and the genesis of the inventions.
Mr. Hewitt's achievements possess a peculiar interest for the people of this country. The inventor is an American of Americans. Born to wealth, the grandson of the famous philanthropist, Peter Cooper, the son of Abram S. Hewitt, one of the foremost citizens and statesmen of New York, Mr. Hewitt might have led a life of leisure and ease, but he has preferred to win his successes in the American way, by unflagging industry and perseverance, and has come to his new fortune also like the American, suddenly and brilliantly. As a people we like to see a man deserve his success! The same qualities which made Peter Cooper one of the first of American millionaires, and Abram S. Hewitt one of the foremost of the world's steel merchants, Mayor of New York, and one of its most trusted citizens, have placed Mr. Peter Cooper Hewitt among the greatest of American inventors and scientists. Indeed, Peter Cooper and Abram S. Hewitt were both inventors; that is, they had the imaginative inventive mind. Peter Cooper once said:
"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.
