Upton was a brilliant young man of mathematical and statistical bent, and because of those qualities, he was slow to comprehend the way Edison’s mind worked. To him, four months of failed experiments on one intractable thing meant that the thing was no good. To Edison, failure itself was good. It was the fascinating obverse of success. If studied long enough, like a tintype image tilted this way and that, it would eventually display a positive picture.
He almost blinded himself by peering through a microscope at the incandescence of platinum, iridium, and nickel burners, observing—as if he were still focusing on the sun’s corona—that they mysteriously cracked and popped just before melting. After seven hours his eyes began to throb “with the pains of hell,” but he was able to confirm the Russian physicist Alexander Lodygin’s discovery that certain gases, including oxygen, seeped out of fusible metals at white heat. This made the maintenance of any kind of vacuum in a lightbulb impossible after sealing.236
Edison understood from the start of his experiments that oxygen in any appreciable quantity decomposed a wire even as it incandesced. But having only a hand pump in the laboratory, he could never suck more than a token amount of air out of his experimental lamps. Gaseous occlusion at le moment critique tantalizingly shortened the lovely mellow glow he got from a platinum spiral. Around the same time he noticed that the finer the wire, and the tighter it was wound, the greater its luminosity. Or to put it another way, the higher the resistance of the filament, the more efficient the lamp. This phenomenon, simplified, led him to formulate Edison’s Electric Light Law: “The amount of heat lost by a body is in proportion to the radiating surface of that body.”237
This was a key insight—a tilt of the tintype—that stimulated another, just as radical. If his lamps as resistors increased the dissipation of energy as heat and light, they would commensurately decrease the size of the conductors needed to feed them with current. Edison thus reversed the consensus among illumination engineers that an extended network of subdivided lamps would offer as little resistance as possible to the circulation of current was ludicrously wrong, calling for prohibitive amounts of copper. He likened the flow of unresisted electrical power to that of city water rushing through overlarge pipes, losing pressure at the same time as it drained the reservoir upstate. The central station’s “reach” could be infinitely extended if only a minuscule amount of current was allowed to trickle into each burner in the circuit.
He further insisted that electrical conductors should be looped in multiple arc—not in series, like telegraph relays—so that if any number of lamps were switched off, the rest would continue to shine.*37, 238 Upton, his studies at the University of Heidelberg still rigidly in mind, could not adjust to these arguments when Edison first advanced them. They conflicted with orthodox opinion and must therefore be wrong. As he ruefully conceded in 1918, “The one great impression of my years in Menlo Park [was] how impenetrable the veil of the future seems to be when new problems are to be solved, and how simple the result often is when the darkness of ignorance is lighted by the genius of one man.”239
LINES OF FORCE
In April, Upton as mathematician, Batchelor as technician, and Edison as designer achieved a major breakthrough in dynamo design, obsolescing that of any other generator on the market. Having already tried two of William Wallace’s dynamos and found them wanting, Edison was convinced—again contrary to general belief—that those of Zénobe Gramme and Werner von Siemens did little more than consume their own energy. Over the course of the winter he had tested the European machines with dynamometers, bearing always in mind that they had to be powered with coal and steam before they could pass on any power of their own in the form of electricity. Batchelor drew many graceful graphs to plot the ideal curvature of armature windings, and Upton, probably the only man in Menlo Park who understood the theories of James Clerk Maxwell, translated the graphs into electromagnetic algebra and converted the energy output of each generator into foot-pounds. At basis was the team’s uncertainty whether the new dynamo should adopt the “ring” winding pattern favored by Gramme, with wires coiled in series around a revolving wheel, or the “drum” pattern of Siemens, which had a continuous wrap of wire encircling a fat cylinder. Edison decided on the latter configuration.
In a more seminal decision, guided by instinct rather than theory or even experimental evidence, he specified two unusually massive field electromagnets and an armature of extremely low resistance. The latter was designed to conserve as much energy as possible within the dynamo and maximize its efficiency—again, a notion counter to standard practice, which was to maximize output instead. When integrated into a phalanx of duplicate dynamos and connected to a complete illumination system (such as Edison intended to set up and exhibit in Menlo Park soon), the resultant strength of field would be regulated to supply only as much electricity as was called for in the mains—each machine sharing an equal amount of load, whatever the demand for power from outside.240
The prototype bipolar dynamo looked so lankily strange, as it stood on its armature like the bottom half of Paul Bunyan, as to evoke the hilarity of engineers more used to squat generators. John Tyndall, who had lavished such praise on Edison’s loudspeaker telephone, mocked it as “wholly new” and wholly misguided. Writing in the Journal of Gas Lighting, he harrumphed, “It is difficult adequately to express the ludicrous inefficiency of the arrangement; but one thing is abundantly certain, and that is that the person who seriously proposed it was wholly destitute of a scientific knowledge of either electricity or the science of energy.”241
All Edison knew in his American ignorance was that when he put the dynamo through its first paces, “it developed so much power that the coil on the bobbin [armature] was torn to pieces and I had to stop.” He made no apologies, then or later, for the slenderness, and minimal winding, of its four-foot iron poles. As far as he was concerned, their diameter was simply based on the resistance of the magnet, or the number of lines of force it could furnish, rather than the length or space through which the lines of force were propagated. He placed greater emphasis on their length, which governed how far the lines extended into space. It was that dimension, and the sheer intensity of the magnetic field around the armature, that had wrecked the spinning bobbin. “This fact seems never to have been brought out by any person in connection with dynamo machines but it is of the greatest importance. It explains the reason of my employing long magnets.”242
Countless small modifications were necessary before the machine’s performance was smoothed out, but its eccentric design made ultimate sense, and by July Upton could justifiably boast, “We have now the best generator of electricity ever made.”*38, 243
THE MOMENT WHEN
That summer, the last of the decade, brought a general relieved sense among Americans that the dragging depression of 1873 had at last run its course. Edison received a $24,500 advance royalty payment from the backers of his chalk telephone in Britain, and gave Mary a thousand to spend on herself.244 He splurged on five hundred books and periodicals for his brick library and hired some new assistants with a view to making a final, all-out blitz on light development in the fall. The young men were given quarters in a boardinghouse on Christie Street operated by “Aunt Sally” Jordan, Mary’s stepsister.
The most important of these recruits was Ludwig Böhm, a glassblower trained in the celebrated Bonn workshop of Heinrich Geissler. He played the zither, sported the red student cap of an elite German university, and liked to recite his many social distinctions, humor not being one of them. As a result he was hazed so unmercifully that Edison took pity on him and let him stay in the attic of a little glass shop adjacent to the laboratory. When not puffing hundreds of globes and tubes for the lamp team, he would retire to his room and yodel Alpine songs until silenced by pebbles hurled against the pitched roof. The only person who liked him was six-year-old Marion, for whom he made many colored glass ani
mals.245
There was no question of his skill with a long pipe. He effortlessly blew flasks and tubes of flamingo-like delicacy, some of them, designed for mercury pumps, with an internal bore of only an eighth of an inch. They lightened the labor of Francis Jehl, a stocky eighteen-year-old who wanted to be an electrician but was assigned most of the time to the exhaustion of blank bulbs, exhausting himself in the process. Until the laboratory acquired its first Geissler and Sprengel evacuators, which operated automatically, Jehl had to bear down with both arms and shoulders on a stiff piston pump, seesawing it until the gauge told him he was within a few millimeters of a perfect vacuum. The difficulty of maintaining that state in a bulb, once the base burner unit was introduced, sealed, and wired up, was extreme. At first incandescence, the platinum curl would give off its occluded gases, lessening the vacuum unless they were at once pumped out. If any gas remained once the bulb was “necked off” with an oxyhydrogen flame, they would reenter the wire and weaken its structure.246
Edison’s infatuation with platinum, protracted by his delusion that somewhere in the world a vast lode of the precious metal could be found and mined to bring its cost down, lasted through the summer. He used an electric pen to duplicate fifteen hundred querulous letters to local authorities as far away as St. Petersburg, Russia—“Dear Sir: Would you be so kind as to inform me if the metal platinum occurs in your neighborhood?”—and sent a prospector all over Canada and the American West in the hope of striking lucky. Although the search yielded him nothing, he developed an interest in mining and mineralogy that would profoundly affect the future course of his life.*39, 247
By the end of August, when he went with Mary to Saratoga Springs to attend the annual meeting of the American Association for the Advancement of Science, Edison was persuaded that he at last had the makings of a workable electric light. He had several bipolar dynamos built or nearly finished, bulbs evacuating to a degree of 0.00001 atmospheres, and test filaments of various metals glowing for as long as four hours before they immolated themselves. In two days at the resort he wrote a triumphant paper, “On the Phenomenon of Heating Metals in Vacuo by Means of an Electric Current,” and got Upton to read it for him.*40 He claimed to have produced an unoccluded platinum that was the best of all elements for the production of domestic electric light—“a metal in a state hitherto unknown, a metal which is absolutely stable at [a] temperature where nearly all substances melt or are disintegrated, a metal which is as homogenous as glass, as hard as steel wire, in the form of a spiral…as springy and elastic when dazzling incandescent as when cold.”248
But on returning to light experiments in September, Edison had to acknowledge that platinum had other liabilities besides its cost. One was the tightness with which it had to be wound to produce the radiance, and resistance, he wanted. Some of Batchelor’s spirals were so fine they could be straightened to a length of thirty inches. What was more, a superfine coating of “pyro-insulator”was needed to prevent them from short-circuiting on the curl.249 This delicacy, plus an obstinate tendency to oxidize even in Jehl’s best vacuums, forced him to return, almost in despair, to carbon as a potential source of lux aeterna.
As with his invention of the phonograph two years before, the moment when he discovered his first viable filament (or when it discovered him) became myth so quickly that he could never be sure how and when the miracle happened. It must have been after Böhm blew together an amalgam of Geissler and Sprengel mercury pumps and permitted a bulb vacuum of nearly one million atmospheres, in the first week of October. It must have been after Charles Batchelor began to carbonize soft spirals of lampblack, scraped from the funnels of smoky oil lamps, in the second week of October. It could not have been when Edison had to deal with a crisis involving the chalk telephone in Britain, and his nephew Charley’s mysterious death in Paris,*41 in the third week of October.
Most probably—even certainly, according to the compulsion of all concerned to fix a momentous event in time—it was at the beginning of the fourth week and on the night of Tuesday 21 October blending into the small hours of Wednesday, that a length of carbonized thread, or a twist of carbonized paper, or a carbonized fishing line, or some other carbonized fiber began to glow in vacuo with a light that would not go out. The delight of watching that one filament shine and shine was so great that Edison could be excused for saying, later on, that it incandesced for “over forty hours.”250
According to Batchelor’s contemporary notes, the light lasted no longer than thirteen and a half hours, but that was more than enough to signal that the Old Man was destined, in spite of all doubts, to make it shine as long as he chose.
BRIGHTENING OF THE HUMAN OWL
On the eve of New Year’s Eve, when all the excitement was over, and Edison’s “Eureka” moment (he actually wrote the word in his laboratory logbook) had been headlined around the world, and fifty-nine reliable lamps were strung up around Menlo Park, ready for the grand public exhibition he had so long promised, “the boys” gathered in the laboratory for an anticipatory celebration. Edwin Fox of The New York Herald was there to record the occasion.251
At first, he wrote in his account of the evening, Edison was nowhere to be seen. Batchelor prevailed upon Ludwig Böhm to bring up his zither from the glass shop. “Play us something with those shake notes in it. They go right down my back.” Böhm obliged with an exquisite melody.252
Charles Batchelor in the Menlo Park laboratory. The first photograph ever taken by incandescent light, 22 December 1879.
During the playing a man with a crumpled felt hat, a white silk handkerchief at his throat, his coat hanging carelessly and his vest half buttoned, came silently in, and, with his hand to his ear, sat close by the glass blower, who, wrapped up in his music, was back perhaps in his native Thuringia again.
“That’s nice,” said he, looking around. It was Edison.
The glassblower played on, and the scene was curious. Standing by a blazing gas furnace he had lighted, Van Cleve,*42 with bare folded arms, listened or else shifted the hot irons [of the filament furnace] with his pincers, but he did it gently. Edison sat bent forward. The others who had taken up one tool or another moved them slowly. Far back through the half-darkened shop young Jehl might be seen lifting the heavy bottles of gleaming quicksilver at the vacuum pumps, and the soft music was delicately thrilling through it all. It was the wedding of spirit and matter, and impressed me strangely.
“Can you play The Heart Bowed Down?” said Edison, suddenly.
“No, I cannot.”
“Here—whistle it, some of you.”253
Five or six obeyed, but Böhm shook his head. Edison lost interest in the music. He took a pad and pencil out of his pocket, sketched a glass implement, and held it out to Böhm.
“Can you blow that?”
“Yes,” said the youth, and hurried back to his shop. It was ten-thirty P.M., and Edison was clearly ready to begin one of his nocturnal workbench sessions.
During the hours that followed, Fox was struck by the acuteness and force of Edison’s remarks as he attacked theoretical scientists. “Take a whole pile of them that I can name and you will find uncertainty if not imposition in half of what they state as scientific truth….Say, Van Cleve, bring me the Dictionary of Solubilities.”254
He scornfully pointed out an entry stating that platinum was infusible, except in the heat of an oxy-hydrogen flame. “Come here; I’ll melt some in that gas jet….Look in here now. You see along the magnified wire a number of little globules? That is where the platinum has fused.”
Next he turned to the subject of electrical illumination. “The peculiar moonlight color in the voltaic arc light is due to the impurities in the carbon, magnesium among the rest. What’s the matter with you, Francis?”255
JEHL: I’m hungry.
EDISON: Where’s the lunch?
JEHL (Despondently): There was none ordered. We didn’t think you were coming back to work all night, and now we’re here and there’s nothing.
EDISON: Get something to eat. (To FOX) You see, the carbon used is made out of a powder, held together by various substances….George, get me a stick of carbon and a filament.256
He proceeded to demonstrate, explain, and propound some of his discoveries, reeling off chemical and metallurgical names with what Fox described as “the peculiar nocturnal brightening of the human owl.” Midnight came and went. Unstoppably garrulous, Edison reverted to his idée fixe about the superiority of the empirical over the academic scientist. “Professor This or That will controvert you out of the books, and prove out of the books that it can’t be so, though you have it right in the hollow of your hand and could break his spectacles with it.”257
Edison’s “New Year’s Eve Lamp,” 1879.
When, at length, “lunch” arrived, all Jehl had managed to buy at the depot was a brown paper bag of smoked herring, and another of crackers. Van Cleve found some lager to wash the repast down, but Edison chose a tin mug of water.
By the time he stopped talking it was four A.M., and everybody but the reporter had fallen asleep (Jehl with his head on the Dictionary of Solubilities). Only then did Edison take off his coat and look around for a bench to nap on. Fox went out into the night feeling both inspired and bilious. “I shall place those smoked herrings, biscuit and cold water on a high shelf, a very high shelf, in my memory; my stomach may never forget them.”258
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