11 ~ The break-through
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“The electric light has caused me the greatest amount of study and has required the most elaborate experiments,” Edison said in recollection; “I was never myself discouraged, or inclined to be hopeless of success. I cannot say the same for all my associates.”304
Thus, in 1905 he could review in unemphatic terms the years of storm through which he had passed a generation earlier. At the time, however, he was like a man possessed. After every reverse or disappointing trial, he worked on, day and night, compulsively. Was it pride that turned him into a demiurge? Was it some dim, long-buried sense of “guilt” that disposed him to endure any ordeal and made him toil while others slept?
One of Edison’s favorite books, since his youth, was Victor Hugo’s mythopoeic romance, Toilers of the Sea. Its hero Gilliatt, described by his neighbors as both “crafty” and laborious and believed by them to be in communication with supernatural powers, sets out alone to extricate a small steamship from a reef in the English Channel on which she has been stranded. In his long effort he must contend against the immeasurable forces of nature: the sea, the tides, the storm, to reach his goal. By his courage, his powers of endurance, and his mechanical skill, Gilliatt assumes for us the symbolic figure of homo faber; the steamship that he is bent on saving, of course, symbolizes Progress. So Edison too strove against the unknown elements of nature. Titanlike, he seemed in those days chained to his “cave” at Menlo Park, given over to superhuman exertions, so that in the end he might “steal the fire of the gods” with which to light the lamps of the world.
With characteristic optimism he had talked of completing this enterprise in “about six weeks.” To be sure, he was already distinguished among inventors for the “lightninglike rapidity with which he seized upon an idea elaborated by someone else and, foreseeing its application before others, improved and adapted it to use.” This time the weeks turned into months; a year passed, and he had not reached his goal.
Unfortunately, once he had made himself a favorite subject of the press his investigations could no longer be carried on behind closed doors; he was afflicted with the very publicity he had courted, for the world insisted on having bulletins periodically reporting his advances and retreats. After the favorable public interest first aroused by news of his electric light venture, a reaction of feeling prejudicial to his just fame set in during the spring of 1879. The influential gaslight interests undoubtedly inspired the publication of articles bitterly attacking him. It was said that
He incautiously raised expectations which he is anxious to fill, but which are taxing his energies... We hope that he will not drive on at this Herculean task, until, some day, despite... his extraordinary powers of endurance, he has sacrificed his health and broken down, on his work.305
In other articles it was charged that through want of education, and by his “feverish methods of research accompanied by propaganda,” he had placed himself before the world as a “charlatan”; his reputation as a scientist was “smirched.” One report had it that he lay almost at the point of death and that “a state of despair reigned at Menlo Park.”306
To his intimate associates he seemed nothing daunted by public criticisms or misrepresentations, but continued patiently on the general course he had marked out for himself. As Upton relates:
His greatness was always clearly to he seen when difficulties arose. They always made him cheerful, and started him thinking; and very soon would come a line of suggestions which would not end until the difficulty was met, or found insurmountable.307
After his first quick onset against this elusive opponent, the incandescent light, he saw that the combat would be long. Unlike his earlier telegraphic and sonic investigations, this would require a very broad knowledge of physical and chemical science. In this area there was ever so much that remained unmeasured, hidden to the eye. For example, only recently, since about 1875, had chemists begun working in high vacua — an unknown, miraculous world. He himself described as “peculiar and unsatisfactory” the conditions under which this investigation must be pursued:
Just consider this: we have an almost infinitesimal filament heated to a degree which it is difficult to comprehend, and it is in a vacuum under conditions of which we are wholly ignorant. You cannot use your eyes to help you, and you really know nothing of what is going on in that tiny bulb. I speak without exaggeration when I say that I have constructed 3,000 different theories in connection with the electric light, each of them reasonable and apparently likely to be true. Yet in two cases only did my experiments prove the truth of my theory.308
In the second stage of this work, after April, 1879, despite the failures of numerous trials, Edison directed his efforts on a much broader front of the area “under siege.” Added experience in this field made him more thorough in his methods. During the long train of incandescent-light experiments, it was observed that he seemed to become more “disciplined” and was “gradually converted into a scientific investigator.”309 In these researches he also employed instruments and means considered far beyond those possessed by most experimenters of his time.310 For it was not only a light he sought, as he realized now; he must try to create “a whole new industry with all its ramifications.”311
He now followed three main lines of investigation. First he worked out more thoroughly the scheme of electric current distribution he had conceived in 1878. The constant-amperage dynamo available then for arc lights must be adapted and redesigned, so that it was suitable for his new system requiring a constant-voltage current in a multiple circuit. Second, he directed a group of assistants in the key assignment of perfecting the pumping methods used in exhausting air from his lamp globes, so as to obtain a still higher vacuum. Third, another team, under his own watchful eye, carried out a long series of experiments in which about 1,600 different materials were tested for their worth as incandescent elements within his sealed vacuum globes.
His whole idea of the problem is shown (in his notebooks) to have changed in the course of seven or eight months. There are no more sketches of platinum lamps with thermostatic regulators; instead, his attention is devoted to the microscopic examination of materials tested under high heat, after the occluded gases in them were expelled.
To subdivide the electric current for numerous small lights in parallel, he would need a constant pressure dynamo, at an estimated 110 volts. Now the existing dynamos, of the Brush or Gramme type, were of too low efficiency and economy for his projected high-resistance lights. In 1877 a committee of scientists appointed by the Franklin Institute of Philadelphia had undertaken tests and measurements of several of the contemporary dynamo-electric machines. There existed then no precedent for a test of electrical machinery and the committee had to devise its own methods, which were carefully worked out. The Gramme type of dynamo was found to utilize from 38 to 41 per cent of the motive work produced, after deduction was made for friction and resistance of the air. The economy of the Brush dynamo was even lower, being estimated at 31 per cent; moreover these machines had strong induced eddy currents and often “ran wild.” Such losses did not matter in a circuit of big, low-resistance arc lights. But Edison concluded that he must devise a dynamo of lower internal resistance and capable of converting mechanical energy into electric current with much higher efficiency.
Upton, describing Edison’s independent mode of attack upon such problems, said long afterward:
I remember distinctly when Mr. Edison gave me the problem of placing a motor in circuit, in multiple arc, with a fixed resistance; and I... could find no prior solution. There was nothing I could find bearing on the counter-electromotive force of the armature... and the resistance of the armature on the work given out by the armature. It was a wonderful experience to have problems given me by him, based on enormous experience in practical work and applying to new lines of progress...312
Edison’s notebooks for December, 1878, show that he had made rough sketches for a new dynamo generating constant voltage almost at the beginning of his electric light project. At that period, however, there was the widespread and fallacious notion, held by most of the electrical savants, that the internal resistance of a dynamo “must” be equal to its external resistance (or that of the circuit). Through study of primary battery circuits they had “proved” that they could attain only a maximum efficiency of 50 per cent. Edison reasoned, however, that while this rule held true for a primary battery, it did not apply to a properly constructed dynamo. As Jehl recalls, he said that
he did not intend to build up a system of distribution in which the external resistance would be equal to the internal resistance. He said he was just about going to do the opposite; he wanted a large external resistance and a low internal resistance (in the dynamo). He said he wanted to sell the energy outside the station and not waste it in the dynamo and the conductors, where it brought no profits...313
Jehl, who was taught to carry out tests of resistances, remarks that the art of constructing dynamos was then as mysterious as air navigation. All electrical testing was in the embryonic stage. “There were no instruments for measuring volts and amperes directly; it was like a carpenter without his foot rule.”314
The problem of a constant voltage dynamo was attacked with the usual Edisonian élan. Seeking to visualize every possible structural innovation for his dynamo armature, he had his men lay out numerous wooden dummies of drum armatures on the floor and wind wire around them, spurring them on in their task by laying wagers as to who would finish first.
After Edison had decided upon the form of winding, the type of magnets to be used, and the direction of the current, Upton made drawings and tables after which the real armatures were wound and attached to the commutator. Edison eventually worked out an armature made of thin laminated cores of sheet iron that showed less eddy currents and so produced less heat than the solid armature cores then used. When the new cores were run in an excited field, it was Upton who made the mathematical calculations and drew the final blueprints.
The self-effacing Upton may therefore be given principal credit for interpreting Edison’s ideas and translating them into mathematical form. It was Edison, nevertheless, who had the ideas. Upton was frequently surprised by the accuracy of Edison’s “guesses” and never considered that he himself was given insufficient credit for his work. A careful student of contemporary electrical science, he seems to have been conversant with, and to have guided himself by, some of the important critical writing of Dr. John Hopkinson, of England, on the structure of the Siemens dynamo. As Upton admits, the design of the Edison-Upton dynamo, as we may call it, was not essentially different in principle from that of the Siemens. Edison’s main improvements seem to have been in dividing the formerly solid armature cores and the commutator into a far greater number of sections than had been formerly the practice. He also seems to have been the first to use mica in insulating the commutator sections from each other, a very effective method.
The new dynamo, though it was said to have incorporated a number of elementary mistakes, contained many admirable features for that period. With its great masses of iron and large, heavy wires, it stood in bold contrast to other dynamos having a more meager ferrous quantity. Its magnets seemed enormous in those pioneering days. When this machine was run at a certain constant speed, the voltage between its two armature brushes was approximately 110 and remained about constant, falling but slightly when increasing amounts of current were taken from the machine. The new dynamo’s bipolar form, owning to its two upright columns, led to its being nicknamed Edison’s “Long-waisted Mary Ann.”315
One of the “Long-waisted Mary Anns” built by Edison in 1879.
Pictures of the Edison dynamo drawn by artists for the illustrated magazines of 1879 show that the inventor and Upton had also contrived a ponderous dynamometer, set up in back of the Menlo Park engine house, with which they measured work output. Once Kruesi had completed the first going machine, Upton carefully checked the results. To his astonishment — and quite as Edison had “guessed” — the new dynamo, tested at full load, showed 90 per cent efficiency in converting mechanical energy (steam power) into electrical energy!
The machine shop at Menlo Park in the fall of 1879. The Edison dynamo (the “Long-waisted Mary Ann”) in the right foreground is attached by belts and pulleys to a dynamometer, also of Edison’s design, which measures the power produced by the steam engines in the room behind. Two field magnets lie beside the dynamo, and at the far left are several field electromagnet cores. (From a drawing by Edison’s draftsman Samuel D. Mott.)
The irrepressible inventor also had some fine engineering ideas for driving his new generator. Others commonly used belting. To the devil with belts, he said; they were wicked wasters of mechanical energy. He calculated, at first, upon using an intricate system of countershafts, then worked his way toward direct coupling, or the direct connection of dynamos with steam engines, which was the plan generally adopted by others after him. After trying slow-speed steam engines as his mechanical force, operating at about 66 to 100 revolutions per minute, he ordered a Porter-Allen steam engine designed to run as high as 600 revolutions per minute. This was delivered to Menlo Park toward the end of 1880, and was directly shafted to his dynamos — dynamo and engine thus forming a self-contained generating unit, mounted together on the same iron bedplate.
Then at last he could make his long-awaited test — for we anticipate the order of events by some months. “All right! Open ‘er up!” Edison yelled in his high voice. The engine clanked and shook, the steam pressure rose, and the dynamos revolved with a horrible din. The party watching the test at Menlo Park all thought it wise to retreat to the shelter of a brick wall adjacent to the engine house — when suddenly a steam pipe burst, and everything came to a stop. Now that, Edison remarked with philosophic calm, taught them something at any rate: the high-speed engine wouldn’t work, and therefore would need to be replaced with something allowing of more safety and economy. The next year, he would manage better with 120-horsepower steam engines running at only 350 r.p.m.
In midsummer of 1879, however, Edison was as jubilant as a small boy over the new dynamo. As was usual with him, the world was soon told all about his “Faradic Machine” — so named in honor of his favorite scientist. It was described and pictured in the Scientific American of October 18, 1879, in a lead article written by Upton, though unsigned. Once more there was a great scoffing and ridiculing of Tom Edison’s “absurd claims,” which were attributed to sheer ignorance by certain suspicious savants. Edward Weston, a well-known inventor and metallurgist of Newark, who also made dynamos, wrote at the time that the claims for such a generator made it seem “more or less like a perpetual-motion machine.”316
The hectoring of Edison by some of the leading American electrical experts, among them Dr. Henry Morton of Stevens Institute, now seems to us traceable to their own real ignorance of actual dynamo problems. Edison, on the other hand, as Francis Upton held, was opening up new paths. Reading Morton’s positive predictions of failure for his whole enterprise, Edison grimly promised himself that, once he had it all running “sure-fire,” he would erect at Menlo Park a little statue to his gloomy critic which would be eternally illuminated by an Edison lamp.
The engineering of an improved, constant-pressure dynamo during 1879 bore the same relation to the electric light system as the cheap production of gas from coal did to gaslighting. He had thus laid a firm foundation for his multiple circuit of small high-resistance lights — to which the most exhaustive studies were being devoted at the same time.
It must be remembered that, from the very outset of his work, Edison was guided by his overarching concept of a whole electric distribution system of which all the parts must be fitted into place. In contrast with other inventors, who searched only for some magical incandescing substance, he worked out all the supporting structure of his system: its power supply, conductors and circuit, and then came back to determine what kind of light would be demanded by it.
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The alleged “mechanic” who was said to lack education was to be found reading scientific journals and institutional proceedings at all hours of the day or night. It was thus that he had learned about Sir William Crookes’s achievements with high vacua, thanks to the Sprengel pump. The new opportunities to test the incandescent qualities of a broad variety of metals, rare earths, and carbons, under the hitherto unknown conditions of a vessel highly exhausted of oxygen, now allured Edison. (In England, Joseph Swan was also inspired by Crookes’s high vacua to resume his experiments with the incandescent light after 1877.) Edison had his boys pumping away for dear life, until by August, 1879, he had all but one one-hundred-thousandth of an atmosphere expelled from his glass globe.
The globe itself, incidentally, was much improved by the inventor’s own design, after he had brought to Menlo Park an artistic glass blower named Ludwig Boehm, who had been trained in the famous Geissler Works in Germany. Edison one day drew a sketch of a one-piece, all-glass globe, whose joint was completely sealed; and Boehm, late in April, 1879, working skillfully with hand and mouth, fashioned it in the small glass blower’s shed back of the laboratory.
“There never has been a vacuum produced in this country that approached anywhere near the vacuum which is necessary for me,” Edison wrote in his notebook. A hundred-thousandth part of an atmosphere was too much; the battle of the vacuum must go on unremittingly. Experience was gained during this constant struggle, and at last, after two months, he could say exultantly, “We succeeded in making a pump by which we obtained a vacuum of one-millionth part of an atmosphere.”317
With growing excitement he realized that a key position had been won in the late summer of 1879. In his mind’s eye he already saw what might be done with an extremely fine, yet highly resistant, incandescing substance under the conditions of such a high vacuum. His state of tension is reflected in the laboratory notebooks by some quite unscientific expletives, such as: “S————! Glass busted by Boehm!”318
In the later, much broader phases of his investigation we feel that Edison gradually converges upon the heart of the secret. He had his constant-voltage dynamo and a tight glass globe for his lamp with a high vacuum. All that remained for him, then, after his long coursing, was to discover an illuminant that would endure.
As we have seen, he had tormented himself over the platinum-wire burner until, as he himself admitted afterward, “It seemed as if it might make the search altogether vain.”319 But still, he had learned to raise the light of a slender platinum wire more than sixfold, as compared with its maximum light in open air, and within a globe that was still a poor vacuum. He had also discovered a way of expelling the occluded gases (or secreted oxygen) that still remained within the incandescing element and hastened its destruction. This had been done by keeping the burner aglow (with a charge of current) while the air was being pumped out. Tests then showed how greatly thereafter the platinum burner improved in hardness and candle power. Now he tried to solve his final problem — finding an illuminant that was superior to platinum — by using both his own interpretation of Ohm’s law of electrical resistance and also Upton’s mathematical tools.
It was in late August, or early September, after about a year’s search, that he turned back to experimenting with carbon again as his illuminant, and this time for good. Carbon had the highest melting point (6,233 degrees F., or about 3,500 C.) and the highest resistance. However, those slender reeds of carbon he had tried earlier had been impossible to handle, as he now understood, because carbon in its porous state has such a marked propensity for absorbing (that is, occluding) gases. But once he had his higher vacuum and his method of eliminating these injurious gases, he saw that he might work even better with burners of carbon reeds than of platinum.
He was of course extremely familiar with the properties of carbon. In a shed in back of the laboratory there was a line of kerosene lamps always burning, and a laborer engaged in scraping the lampblack off the glass chimneys to make carbon cake.
“Oh, Mr. Edison, the lamps are smoking,” visitors to Menlo Park sometimes warned him.
“Yes, I must remind them to turn the wicks down,” he would answer banteringly. But he did nothing of the sort. He had the cakes of carbon brought to him and kneaded them with his fingers into fine reeds.
According to a romanticized account of this culminating experiment, given by a contemporary in 1879, he discovered the carbon filament by “chance”:
Sitting one night in his laboratory... Edison began abstractedly rolling between his fingers a piece of compressed lampblack mixed with tar for use in his telephone. For several minutes his thoughts continued far away, his fingers in the meantime mechanically rolling over the little piece of tarred lampblack until it had become a slender filament. Happening to glance at it the idea occurred to him that it might give good results as a burner if made incandescent. A few minutes later the experiment was tried and, to the inventor’s gratification, satisfactory, if not surprising, results were obtained. Further experiments were made with altered forms and compositions of the [carbon], each demonstrating that at last he was on the right track.320
A more rational, a more satisfying account of his process of discovery, an account supported by the documentary evidence of his own laboratory notebooks, indicates that Edison proceeded here according to the true methods of science. By a number of very intelligent choices, he had begun working for a higher vacuum instead of using an inert gas; then he had gone on to plan for a multiple circuit, a high-resistance burner, and the right generator for it. In the laboratory notebooks are recorded Upton’s extended mathematical calculations of the nature of the voltage, current, and conductors that would be most effective with a multiple circuit system of distribution; they show also the determinations of how much resistance (ohms) the small light must provide, and how small an amount of current (amperage) it could suffice with. Thus Edison and Upton arrived at the conclusion that, given a 100-volt multiple circuit system, the resistance of his new lamps must be raised to about 200 ohms.321
The idea of reversing the contemporary practice of making incandescent lamps of low resistance (one or two ohms) was embodied in Edison’s patent application of April, 1879, for his improved (second) high-resistance platinum light.
Not only must the illuminant be equal to this high resistance, but (in accordance with Edison’s usage of Ohm’s law) it must have a very small cross section, or radiating surface. “After considerable calculation,” according to an engineer who served under Edison in early days, “Edison estimated that the carbon should be not over one sixty-fourth (or 15.6 thousandths) of an inch in diameter! He also estimated that the carbon filament should be about six inches long.”322
It was a bold undertaking: raising the resistance of their illuminant about a hundredfold above that which contemporary technique used, and reducing it to the thinness of ordinary heavy sewing thread. Would so slender a reed of carbon bear rough usage and support those high temperatures, where thick rods had melted? By grace of the improved vacuum, and the new method of expelling gases secreted in the carbon, they hoped to succeed.
The quantitative calculations by Edison and his assistants on the precise structure of the filament and the lamp were “of outstanding merit,” in the opinion of an English historian of modern invention who examined the work of the leading British competitor, Joseph W. Swan. By reducing the diameter of his filament by one half, say from one thirty-second to one sixty-fourth of an inch, Edison could make it incandescent with eight times less current.323 Swan had an unsatisfactory lamp with its carbon “rod” about one sixth of an inch in diameter, or 10 2/3 times as thick as Edison’s; that meant a world of difference.
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Through the summer months Edison and his staff worked at the tantalizing job of making some fine reeds of carbon lampblack mixed with tar behave properly in an incandescent lamp. His assistants kept kneading away at this puttylike substance for hours and hours. It seemed impossible to make fine threads of it, for the stuff crumbled, as an assistant complained one day.
“How long did you knead it?” Edison asked.
“More than an hour.”
“Well just keep on for a few hours more and it will come out all right,” said Edison.324
Before long they were able to make threadlike filaments as thin as seven one-thousandths of an inch. They then tested them. Systematically Edison investigated the relations between electrical resistance, shape, and heat radiation of these filaments, tests that required infinite pains and were time-consuming.
On October 7, 1879, he enters into his notebooks the report of twenty-four hours of testing: “A spiral made of burnt lampblack was even better than the Wallace (soft carbon) mixture.”325 This was indeed promising; the threads lasted an hour or two before they burned out. But it was not yet good enough.
In the later stages of this long campaign, as he felt himself approaching the goal, Edison drove his co-workers harder than ever; they held watches over current tests round the clock, one man taking a sleep of a few hours while another remained awake. Under the inspiration of the master, one of the laboratory assistants invented what was called a “corpse-reviver”; it was a sort of noise machine which would be set going with horrible effect to waken a comrade who had overslept.
Francis Upton said that Edison “could never understand the limitations of the strength of other men because his own mental and physical endurance seemed to be without limit.”326
At this stage of his life Edison worked with minimum rest periods of three or four hours a day, his enormous recuperative powers helping to sustain him. He would doze off for a cat nap on a bench, or even under a table, with a resistance box for his pillow, but his assistants had orders to waken him if anything occurred that required his attention. When they did arouse him from his brief slumbers, he would be wide awake on the instant, ready to answer any questions. In response to a query he might refer his interlocutor to the exact page of some scientific lexicon, such as the Dictionary of Solubilities. His long memory for miscellaneous facts continued undiminished as the years went on.
To the original “Menlo Park team,” the group of technicians and mechanics who knew him so well and worked with him so well, much credit must also be given for loyalty to Edison as well as for their varied skills and patient endurance. An egoist the inventor might well be, but his old associates came to love him as men who had shared dangers, fatigues, and triumphs together. He continued to behave much like the captain of some jolly pirate ship, who knew how to inspire his sea dogs to the utmost exertions. For one thing he was “always on deck” when the going was rough. Above all, he tried to keep his men on the alert and played on their emotions of pride and loyalty or set them to competing with one another to win bonuses for unusual effort.327
After they had suffered some heartbreaking failures and felt downcast, Edison would raise their spirits by starting the next morning on a new round of similar trials with the undimmed hope and joy of a guileless child. His irrepressible enthusiasm was infectious. At such moments he would say proudly, “The trouble with other inventors is that they try a few things and quit. I never quit until I get what I want!”328
On the other hand, when things were going badly and the old-timers saw by small signs that the Old Man was seriously troubled — showing himself choleric or extremely distracted — they would creep away as if overcome with emotions of guilt or fear, and set to work as if the devil were after them.
During the great hunt for the electric light, Edison’s chief mechanical assistant, Charles Batchelor, particularly distinguished himself for his manual skill. After working for many hours to mount a tiny filament (according to Upton’s account) he would keep his hand “as steady and his patience as unyielding at the end of those many hours as it was at the beginning... The control of his fingers was marvelous, and his eyesight was sharp.” Kruesi was equally able in his field — overseeing the production of machines or models by hand — and as tireless. Edison recognized the services of these two key workers, and those of Upton, by rewarding them with fractional shares of his own winnings, in cash or securities.
Tension among the laboratory force increased during the late summer days of 1879, as the several components of Edison’s incandescent-lighting system were being perfected. But the “chief mucker” also knew how to divert their minds by serving some food and light wine after they had been working late at night, or by sitting down to swap stories with his men, or listen to music they made up for the squeaky tin-foil phonograph. One of the assistants on one occasion regaled his companions by improvising a parody of Gilbert and Sullivan’s H.M.S. Pinafore in Edison’s honor:
For I am the Wizard of the Electric Light,
And a wide-awake Wizard too...329
Boehm, the glass blower, who loved to perform on a zither, would be called in from his shed to play German ditties or lullabies, or sad beer-hall melodies such as Edison was fond of — “The Heart Bowed Down,” and “My Heart Is Sad with Dreaming.”
Early in 1878, after the invention of the phonograph, a handsome organ had been installed in back of the laboratory’s upper floor. It was presented to the inventor by Hilborne Roosevelt, a cousin of Theodore Roosevelt and a famous designer of such instruments. Sometimes Edison, deaf though he was, and without knowledge of music, would go to the organ and play chords or improvise melodies for himself.
Out of the period of the long hunt for the incandescent light many stories have come down to us illustrating what may be regarded either as Edison’s unfailing sense of humor or his irrepressible vice of practical joking. For example, cranks used to force their way into the laboratory occasionally. One of this type, a man with bent back and snow-white hair, walked in softly one day with a sizable package under his arm and insisted on showing it to Edison. Laying it out on a bench, he disclosed a square contraption with some wooden cogwheels. Edison raised his large brows expressively, while everyone stopped and looked on.
“Mr. Edison, I have a machine here, which I should like you to look at; I have been working over it a good many years,” the man said in a sad and gentle voice.
“What is it?”
“It is a perpetual-motion machine.”
Edison’s face was impassive. “Does it work?” he asked blandly.
“Well, it almost works,” said the owner. “There is just one little point where it seems to stick... I thought perhaps you might be able to tell me what to do.”
“Yes,” replied Edison firmly, “I can tell you what to do.” The man’s face brightened. “What you want to do is to provide the machine with a stomach. Then feed it good beefsteak and potatoes, and it will generate the energy it needs to make it work!”
The man gave a weak smile, repacked his machine and without a word left the room as softly as he had entered it.330
When it seemed, at certain dark moments, that the electric light would never be made to work, Edison would entertain his helpers with tales of new inventions to come; these were his “other irons in the fire” (some of them nonexistent) that would win fortune for all of them. Thus he had the thought of making a thermopile, which “Honest John” Kruesi was instructed to prepare for him in the form of metal bars to be subjected to heat. One of these alloys, as it chanced, was polished so brightly that it shone like gold. Studying it, Edison had a brilliant idea. Looking at Kruesi with an air of triumph (while winking to the other men nearby), he declared with great emphasis: “We have it this time, our troubles are over!” They could close up shop now, he added.
“What on earth has happened?” Kruesi asked in perplexity.
Edison remained silent, beaming. Then at length he exclaimed: “Why you never thought what you had in your hands, Kruesi; why, it’s solid gold!”
“Gold!” cried the bewildered Kruesi.
“Yes,” Edison said. He had had Dr. Haid, the chemist, give it the acid test and also determine its specific gravity. Kruesi could rest assured, it was “pure gold,” and they could now “make it by the ton. Our worries are over,” he cried, “and now we don’t need the electric light.”
Edison swore Kruesi to secrecy until he had had time to execute a patent for this “invention.” Everyone of the other assistants listening tried to keep a straight face as long as possible, until one of them suddenly went off into convulsive laughter, and the joke was over.331
One day when the artistic glass blower Boehm was discouraged, after a series of mishaps with his pumps, someone remarked: “Could we not put the lamps in a balloon and send them up high enough to fill them with vacuum and then seal them up there?”
“Good idea,” said Edison heartily; then he added with professional caution, “We’ll have to take a patent on that, sure.”
“But how could we seal them off, if there was no air to use in the blow pipe?” somebody else asked.
“That’s always the way,” said Edison with a long-drawn sigh; “that’s always the way — no sooner does a man bring out a brilliant and practical idea, but some ignoramus must interfere and try to show some reason why the scheme is impractical. There’s no chance for a real bright inventor nowadays!”332
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The impersonal records of the laboratory notebooks for October, 1879, show Edison’s mood of anticipation pervading the whole staff at this stage. He had been pushing on with hundreds of trials of extremely fine lamp filaments, so attenuated that no one could conceive of how they would stand up under terrific heat. The culminating experiments, verified by Upton, and published in December of the same year, are described in a contemporary account:
A spool of cotton thread lay on the table in the laboratory. [It was no accident, to be sure!] The inventor cut off a small piece, put it in a groove between two clamps of iron and placed the latter in the furnace. The satisfactory light obtained from the tarred lampblack had convinced him that filaments of carbon of a texture not previously used... were the hidden agents to make a thorough success of incandescent lighting, and it was with this view he sought to test the carbon remains of a cotton thread.333
He had tried various methods for treating the threads before carbonizing them, but they would break. Finally he had packed them with powdered carbon in horseshoe form in an earthenware crucible which was then sealed with fire clay and heated at high temperatures. At last he had a firm, unbroken carbonized thread, or a filament, as the inventor himself called it. It was, however, very hard to handle, being then fastened by delicate clamps to the end of platinum lead-in wires. It was actually the ninth of a series of very fine incandescent filaments Edison had carefully constructed. The memorandum in the notebooks reads:
Oct. 21 — No. 9 ordinary thread Coats Co. cord No. 29, came up to one-half candle and was put on 18 cells battery permanently at 1:30 a.m.
Afterward, Edison related, it was necessary to take it to the glass blower’s house in order to seal it within a globe.
With the utmost precaution Batchelor took up the precious carbon, and I marched after him, as if guarding a mighty treasure. To our consternation, just as we reached the glass-blower’s bench the wretched carbon broke. We turned back to the main laboratory and set to work again. It was late in the afternoon before we produced another carbon, which was broken by a jeweler’s screw driver falling against it. But we turned back again and before nightfall the carbon was completed and inserted in the lamp. The bulb was exhausted of air and sealed, the current turned on, and the sight we had so long desired to see met our eyes.334
The trial of the No. 9 model of carbonized cotton filament was put on late during the night of October 21. The men looking on were thoroughly used to these things fizzling out. But the notebook entries for that night convey all the drama and the sense of triumphant resolution that the results meant for them:
No. 9 on from 1:30 a.m. till 3 p.m. — 13 1/2 hours and was then raised to 3 gas jets for one hour then cracked glass and busted.
That night there was no sleeping. The next day’s entries for the performance of another No. 9 lamp tell us:
October 22: we made some very interesting experiments on straight carbon from cotton threads, so. We took a piece of 6 cord thread, #24, which is about 13 thousandths of an inch thickness, and, after fastening to platinum (lead-in wire) we carbonized in a closed chamber. We put it in a bulb and in vacuo; it had resistance of 113 ohms start and afterward went up to 140 ohms.335
The tales that were woven about that day of triumph (October 21-22), certainly a big day for all electrical science, featured a “death watch” of “forty hours” maintained by Edison and five of his associates; one of them, Upton, who felt ill, went home for a short nap and on returning at dawn found the others still awake; to his amazement the lamp was still glowing! The evidence of the records speaks only of an incandescent lamp that burned for more than half a day, that is, 13 1/2 hours; but there is frequent mention of a lamp having burned forty hours — very possibly they wrote down no notes of this, in the excitement of the moment.
Replica of the first successful electric incandescent light, made October 21, 1879, with a filament of carbonized cotton thread. This model was made by Edison at the Festival of Light at Dearborn, October 21, 1929.
Contemporary accounts of this historic event, appearing soon afterward, told of how the inventor, after having been long misled, at last through “the happy discovery of the uses of a bit of cotton thread, had in a moment turned the whole current of the story into a fortunate channel... The whole affair seemed like one of those little romances of science with which the road to great invention is strewn...”
Edison was described as turning on the current for the perfected lamp:
Presto! a beautiful light greeted his eyes. He turns on more current, expecting the fragile filament to fuse; but no, the only change is a more brilliant light. He turns on more current and still more, but the delicate thread remains entire. [Edison said, “We sat and watched with anxiety growing into elation.”] Then with characteristic impetuosity and, wondering and marveling at the strength of the little filament, he turns on the full power of his machine... For a minute or more the tender thread seems to struggle with the intense heat — that would melt diamond itself — then at last it succumbs and all is darkness. The powerful current had broken it in twain, but not before it had emitted a light of several gas jets.336
As it went out the weary men waiting there jumped from their chairs and shouted and cheered with joy. Edison, one of them recalled, remained quiet, then said, “If it can burn that number of hours I know I can make it burn a hundred.” Yet none seemed so completely astounded as were Edison, Batchelor, Kruesi, Upton, and the other workers at Menlo Park. They had become accustomed to labor without hope. “They never dreamed that their long months and years of hard work could be ended thus abruptly, and almost by accident. The suddenness of it takes their breath away.”337
He took up the broken filament and examined it under the microscope, noting how hard it had become and how its very structure had changed. He knew at last that the high-resistance element he wanted must be tenacious, fibrous in structure, some form of cellulose. He would look for still better materials than cotton thread, which broke too readily.
We know that it was no accident that he turned to carbonizing that cotton thread and so reducing his burner to a filament, but that he arrived at this solution only after he and Upton had calculated the cross section and radiating surface they wanted for his high-resistance lights, connected in multiple circuit. Herein lay his boldness and originality. Now, he was at the crest, and on the right track; the rest of the going from here would be downhill.
The October 21, 1879, lamp gave but a feeble, reddish glow. (Turning one of the old models on again in a dark attic of the Smithsonian Institution, the writer could not but exclaim, “What a beautiful thing to have invented!”) It was the best and most practical incandescent light contrived in more than fifty years of inventive effort, the future light of the world.
5
For once he tried to be discreet and keep his momentous discoveries a secret until he had improved upon his lamp filament. He wanted a more serviceable illuminant, and, since the cotton thread was a vegetable fiber, reasoned that some other vegetable substance of tenacious and fibrous character would provide the answer. His laboratory staff was then hurriedly put to work testing a long list of similar materials, among them bagging, baywood, boxwood, cedar shavings, celluloid, fishline, flax, cocoanut shell, hickory, plumbago, punk, twine. And what else might they try?
Edison racked his memory, then suddenly stared at the tough red beard of his old friend and mentor of Mt. Clemens, Michigan, J. U. Mackenzie, who had recently joined his staff as laboratory assistant. There, perhaps, was the answer to their prayers. They must, on the instant, cut off some hairs of Mackenzie’s beard, carbonize them and raise them to incandescence! That tested out well enough, for a bit of elaborate horseplay. But in the end it was paper, in the form of tough, Bristol cardboard, that proved most enduring and infusible when carbonized and reduced to a hairlike filament. Edison was exultant when this filament burned for 170 hours, and swore that he would perfect his lamp so that it would withstand 400 to 1,000 hours of incandescence, before any news of it was to be published.
Edison carbonizing a paper lamp filament, which is enclosed in a metal mold to keep it from oxidizing in the furnace.
On November 1, 1879, he executed a patent application for a carbon filament lamp, which was quickly granted (January 27, 1880) as U.S. Patent No. 223,898. Its most significant passage was the declaration:
I have discovered that even a cotton thread, properly carbonized and placed in sealed glass bulbs, exhausted to one-millionth of an atmosphere, offers from one hundred to five hundred ohms’ resistance to the passage of the current and that it is absolutely stable at a very high temperature.
The other specifications called for a distinctive one-piece, all-glass container with the conducting, or lead-in wires of platinum passing through the glass base and being clamped to the carbon filament, all the joints being sealed by fusing the glass. (Not long afterward the costly platinum lead-in wires were replaced with a metal alloy which, like platinum, had the same coefficient of expansion as glass.)
Here were the essential features of the basic Edison carbon filament lamp, in the form that was to be known to all the world during the next half century, and whose patents were to be sustained in all the courts. It was not the “first” electric light, nor even the first incandescent electric lamp. It was the first practical and economical electric light for universal domestic use. Excellent exploratory work in this field had been done before him by Americans and Europeans, including assorted Russian inventors. Swan (whom the English still consider the “prior inventor” in this case) had an operable incandescent lamp and a perfected vacuum; but his thick carbon rod was of the low-resistance type, using a hundred times more current than Edison’s filament. In England only St. George Lane-Fox had experimented with a high-resistance burner, though his lamp functioned poorly. What Edison had accomplished was “a combination of old elements which produced a new thing.” It opened the way to the electrification of men’s dwellings throughout the world, and introduced the large-scale production and sale of electric power itself.338
It was early in November, 1879, that the worried capitalists who had supported Edison’s venture learned the secret of his success. Two of J. P. Morgan’s partners, Eggisto Fabbri (a man of musical tastes who greatly admired the phonograph) and Hood Wright, paid a quiet visit to Menlo Park a short time later, and found that Upton’s house and Edison’s were brilliantly illuminated by the new lamps.339
During the first thirteen months Edison had expended $42,869.21 on experimental work, not counting legal, patent, and other expenses, most of which had been met by the Edison Electric Light Company. Now he raised the question of further money advances for experimental and development work, so that he might complete a pilot light-and-power station at Menlo Park. Edison pointed out that he had spent out of pocket more money than he had been given and pleaded for continued support. But the directors were stony. They were uncertain, as yet, about the future of his invention. Was it “only a laboratory toy,” as one of them charged? Would it not need a great deal more work before it became marketable?
As before, Grosvenor Lowrey defended his protégé like a lion. To the doubters he boldly declared that this invention would be of “enormous value,” exclaiming before the board of directors, “Edison is giving us the greatest return for capital that was ever offered — his talent, his knowledge, his health — while plenty of others [give] only capital.”340
The future electric light and power industry, now aching to be born, would be valued, for its American section alone, at roundly 15 billion dollars at the time of the inventor’s death. Yet there was prolonged haggling before another comparatively small sum was advanced to Edison, early in 1880, through loans by the original stockholders. And this was only obtained after Lowrey, prematurely, and over Edison’s objections, made the secret of the electric lamp invention public. The lawyer foresaw that the news would startle the world, and that his fellow capitalists would be the more disposed to loosen their purse strings.
Rumors had been spreading about the ill-kept secret for several weeks. New Jersey neighbors told of brilliant lights blazing all night at Menlo Park; and railroad passengers between New York and Philadelphia also saw the bright lights, with astonishment, from their train windows. In Wall Street there was a flurry of speculation in Edison Electric stock, only a few shares of which were available as yet; the price rose, for a brief period, to a level of $3,500 a share — on the mere hopes or prospects of Edison’s success.
Then came the front-page story in the New York Herald, on Sunday, December 21, 1879:
EDISON’S LIGHT
THE GREAT INVENTOR’S TRIUMPH
IN ELECTRICAL ILLUMINATION
---
A SCRAP OF PAPER
---
IT MAKES A LIGHT WITHOUT GAS
OR FLAME, CHEAPER THAN OIL
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SUCCESS IN A COTTON THREAD
The exclusive story of the inventor’s struggles for fourteen months, in a (more or less) secluded laboratory, was now told to the world con amore by Marshall Fox, who had written much of Edison before and won his confidence. For the daily press of the United States the detailed treatment of such an adventure in applied science as a feature story was something of an innovation — more than one member of the newspaper’s own staff feared it might be a hoax! Its relative accuracy of detail was owing to the help furnished by Batchelor and Upton, whose drawings of dynamo and lamps illustrated the Herald’s Sunday supplement on Edison’s light. The writer did his best to explain how this light was produced from a “tiny strip of paper that a breath would blow away”; why the paper filament did not burn up but became hard as granite; and how the light-without-flame could be ignited — without a match — when an electric current passed through it, giving “a bright, beautiful light, like the mellow sunset of an Italian autumn.”
Acclaim for Edison (still mixed with some expression of incredulity) reverberated again on both sides of the Atlantic. The news “shook the scientific world to its foundations.”341 Scarcely two years before, thanks to his phonograph, Edison had gained international celebrity. Now his fame spread to the remotest corners of the earth. Menlo Park was again to be invaded by thousands of scientific pilgrims and plain curiosity seekers. But the new invasion was more troublesome than before due to a premature announcement that the inventor would have all the region of Menlo Park illuminated for New Year’s Eve, 1880. Every Tom, Dick, and Harry wanted to see it; and Edison wasn’t ready.
In the week following Christmas, 1879, hundreds upon hundreds of visitors made their way to the world-famous New Jersey hamlet from all over the northeastern part of the country, by train, carriage, or on foot. Edison hurried with his preparations as well as he could, but was forced to use his whole staff of sixty persons to handle the crowds. He could do no more than put on an improvised exhibition, with only one dynamo and a few dozen lights.
There were only two light globes attached to the entrance of the small library-and-office building by the gate; eight more were set out on wooden poles in the grounds outside the laboratory and along the road; while in the main laboratory building a miniature central station supplied a circuit of thirty lights connected in parallel.
Throngs of people, of all classes and every degree of scientific ignorance, had come to see “the light of the future” and to pay homage to its good “Wizard.” The closing nights of the year 1879 actually turned into a sort of spontaneous mass festival, which reached its climax on New Year’s Eve, when a mob of 3,000 sight-seers flooded the place. The crowds never seemed to tire of turning those lights on and off, as they moved slowly through the rooms of the laboratory. Nearly all who came acknowledged that they were satisfied that they had seen “progress on the march.”342
They had also come to see Thomas A. Edison. The cry would go up, “There’s Edison,” and a rush would start toward him. As usual, he appeared in his working clothes, which were almost of a deliberate negligence, a white handkerchief at his throat in place of a cravat, and his vest half buttoned. He was by now well accustomed to appearing before admiring crowds in the guise of a modest, hard-working inventor. Among the visitors were bankers, manufacturers, scientists, journalists, artists making sketches, and farm hands whose questions ran from “How you got the red-hot hairpin into that bottle?” to inquiries about the cost of such lamps and their economy of operation, in terms of coal and horsepower.
What they saw here was but a token of what was in store for them in the near future, as the inventor promised the great throng of merry well-wishers who came on New Year’s Eve. He was waiting for the completion of his new generator, he said, and intended to illuminate all the surroundings of Menlo Park, for a square mile, with 800 lights. After that he would light up the darkness of the neighboring towns, and even the cities of Newark and New York! His lamp would be sold for twenty-five cents, he predicted, and would cost but a few pennies a day to run. At the moment, the lamps were very costly to produce, for it took two men six hours to pump a high vacuum for his globes, and only a few score lamps were on hand.
In the crush a few minor accidents occurred. Several persons who ventured into the dynamo room, despite warnings not to do so, had their pocket watches magnetized. A well-dressed lady, who bent down to examine something on the floor near one of the generators, found all the hairpins leaving her head.
Not all who came were well-wishers; after the party was over, it was found that a vacuum pump had been smashed and that eight of the still rare electric lamps had been stolen. Then there were the representatives of the gaslight “monopoly” (as Edison called them) who after leaving, aired “a general feeling of disappointment,” declaring that Edison had gulled the public by showing them only forty burners, none of which gave more light than an ordinary gas jet. There was also one disagreeable visitor, said to have been the rival electrical inventor, William E. Sawyer, who seemed wildly “inebriated,” and who, while moving through the crowd, gave vent to his bitter disappointment, yelling that it was all a trick and shouting imprecations at Edison — until the crowd hushed him up. Edison also said in recollection:
I remember the visit of one expert, a well-known electrician, then representing a Baltimore gas company. Sixty of the men employed at the laboratory were used as watchers, each to keep an eye on a certain section of the exhibition and see there was no monkeying with it. This man had a length of insulated No. 10 wire around his sleeve and back, so that his hands would conceal the ends, and no one would know he had it. His idea, of course, was to put this across the ends of the supplying circuit and short-circuit the whole thing — put it all out of business without being detected. Then he could report how easily the electric light went out and a false impression would be conveyed to the public. He did not know that we had already worked out the safety fuse and that every little group of lights was protected independently. He slyly put this jumper in contact with the wires — and just four lamps went out in the section he tampered with. The watchers saw him do it, however, and got hold of him, and just led him out of the place with language that made the recording angels jump to their typewriters.343
The world’s praise showering upon him seems to have been thoroughly enjoyed, for the moment, by Edison in his relaxed mood. One useful result of the wave of publicity at Christmastime was that the directors of the Edison Company now willingly “coughed up” another $57,568 for his proposed development work in the next twelve months. A less pleasing side effect was the hasty entrance of quite a number of imitators and “pirates” into the electric lighting field with merchandise very similar to his own, when he was still unready to market his product. Hiram Maxim, for example, with such patent applications as he could muster, began to offer incandescent lights of some sort for buildings early in 1880. Also upon the publication of Edison’s second carbon filament patent, January 9, 1880, using carbonized paper, his inveterate adversary, William E. Sawyer — “that despicable puppy,” Edison called him — entered a petition of interference at the United States Patent Office, claiming that he, Sawyer, had first used carbonized paper as an incandescing element and patented it a year earlier.344
In the face of this litigation, another filament material, in lieu of carbonized paper (which Edison considered not satisfactory enough) had to be quickly improvised.
He had won a great battle on October 21, 1879, yet the campaign was far from ended. The future commercial value of the incandescent light, he held, was now established beyond question; but it remained for him to put a complete central-station lighting system in operation on a large scale. This would mean facing many more problems, inventing numerous electrical appliances then unknown, and in fact developing a whole new art. In such development work Edison would be driven to efforts even more original than the work on the lamp itself. He was still at sea, so far as concerned the actual working-out of such a large-area light-and-power-distributing system. “Remember, nothing that’s good works by itself, just to please you,” he used to say; “you’ve got to make the damn thing work.”