The last twist he found hard to accept. Edison was a compulsive, even fanatical recorder of every word, thought, and deed that he deemed to be of practical value. Like another deaf scribbler—Beethoven—he was at a loss without a pencil, and perpetually stuffed his pockets with notebooks and loose memoranda. Missing as much as he did of everyday conversation—gossip at Mary’s parties, banter among “the boys”—he drew a distinction between it and communication, which he felt to be his specialty as an inventor. Never far from his mind, as he delved deeper and deeper into the intangibles of acoustics, was the recording point of his motograph, the ink wheel of his automatic printer, and the stipple of his electric pen.
It followed that his first five patents at Menlo Park were all described as “telegraphs,” even though three of the designs were really telephonic, thrumming with multiple reeds, electromagnets, bulb and tube resonators, and sounder boxes, all tuned in pairs to different frequencies. He executed the last of them on 9 May, the day before the opening of Centennial in Philadelphia.120
His display there attracted less attention than it should have. He mounted it late, and rashly accepted an offer from William Orton to trade his own space for a share of Western Union’s. Orton did not want Thomas Edison to look too independent at a time when the company was financing most of his work. The electric pen and automatic telegraph, however, were exhibited separately, and both won prizes, as did the quadruplex. Sir William Thomson, the British mathematical physicist and chairman of the awards committee, praised the pen as “an invention of exquisite ingenuity.”121
But the quiet sensation of the show was Alexander Graham Bell’s demonstration on 25 June of his telephone to a private audience including Thomson, Elisha Gray, Josiah Reiff, and Edward Johnson. As the son of the creator of an instructional method for the speechless deaf, and a teacher of the deaf himself, Bell had an understanding of phonetics far more sophisticated than that of Edison, who was not present. He modestly described his membrane transmitter and linked, iron box receiver as “an invention in embryo.” It was just as well he did, because when he called Sir William in another room, Johnson saw that the judge, ear to the flapping lid of the iron box, was bewildered.*22 Gray applied his own ear and heard at first only “a very faint, ghostly ringing sort of a sound.” Eventually he caught the phrase “Aye, there’s the rub,” and was able to inform the rest of the party that Bell was quoting Shakespeare.122
REEDS, FORKS, BELLS, TAUT STRINGS, TIN TUBES
If Edison attended the Centennial, he did so unobtrusively. He was still so little known in Pennsylvania that a local paper referred to him as “an Englishman named Edison who has detected what is described as a new natural force.” A more sharply etched image was necessary if he was to imprint himself and his work on the public mind. Working in Newark and New York, he had at least been in the way of capturing press attention; as far removed as he now was, the best he could hope for was more respect from the trade. “I’m going to send something within next six weeks to patent ofs,” he scribbled in a note to an old operator buddy, “that will make the Teleghers [sic] eyes stick out a little.”123
This turned out to be a supersystem of acoustic transfer telegraphy, which he detailed in a lengthy caveat filed on 8 July. It required the synchronization of multiple stations in a frequency range “only limited to the amplitude of vibration which is practicable to give the reeds and the delicacy of the receiving instruments.” Edison’s novel idea was for acoustic signals of different length to swap intervals of wire time, so rapidly and smoothly that the flow of mainline current was never interrupted, nor would the messages themselves sound broken up at the ends of their respective branch lines. It was a concept of electrical time-sharing or, in future jargon, time-division multiple access.*23 He supplemented it with thirteen elaborate technical memoranda, entered and indexed in a set of notebooks he had initiated to keep track of experiments at Menlo Park. The record amounted to a retrospective survey of all his telegraph inventions, as well as a grounding for the specialized research he now undertook in the field of sound.124
While still working on multiple telegraph technology, he conducted a series of experiments in telephone transmission, sure he could improve on the weakness of Bell’s short-range signal. By speaking into a magnetized brass diaphragm held under pressure of a damp felt washer, he succeeded in getting a parchment receiver to say “How do you do.” But that nonsibilant phrase hardly matched the complexity of “Mr. Watson—come here—I want to see you,” a message Bell claimed to have sent coherently four months before. Edison proceeded to stick tiny tacks to diaphragms at various degrees of the curve to gauge where best he might cut in for particular pitches, and explore the acoustic potential of his electromotograph, which he found activated tuning forks as well as electromagnets. If this discovery was still more relevant to telegraphy than telephony, it at least taught him something about Helmholtz’s use of forks and magnets to study the mechanics of speech.125
Sometimes a thousand twangling instruments—reeds, forks, bells, taut strings, tin tubes—would hum about his ears:
and sometimes voices:
It was not always clear to him which discipline—acoustic telegraphy or telephonic transmission—he was exploring, or even if he was dimly envisaging another, not yet invented. Again and again cylinders and disks invaded his drawings. A cylinder might be an empty drum with a resonant base, or a hand-cranked harmonic receiver, or a roller duplicating lines of perforated print, or a spinning electromagnet,*24 or a telescopic tube that would enable him to gauge, precisely, the “column of air” necessary to send the “th sh ch s and other hissing sounds” so resistant to electrical dispatch. A disk might be stiff waxed paper revolving under the stylus of a “recorder-repeater,” taking a message in dots and dashes that spiraled inward from the perimeter, or an electrochemically coated plate turning in a telephone receiver, or a hard rubber button coated with carbon and touching the vibrant tinfoil face of another disk—a pairing he thought promising, but unaccountably delayed acting on.126
The most beautiful, and technologically pregnant, instrument to come out of all this speculation was the Edison translating embosser of 3 February 1877. Despite its name, it was not a linguistic device. It merely sped up the distribution, or “translation,” of enormous quantities of telegraphic text, such as presidential addresses, down long-distance wires.*25, 127 Nor was it acoustic in operation. But its design was so sleekly geometric, with twin turntables and twin recorder/reproducer arms tracking volute grooves, that it would look contemporary to audio engineers a century later.
The machine held blanks of oiled paper (Edison found that lard lubricated best) under its circular clamps, pressing them flat against the grooved platen of each turntable. Incoming electromagnetic pulsations caused a lightly sprung embossing point to indent the paper of the first turntable, rotated by an electric motor, while the recording arm, wormed to the platen’s degree of spiral, made sure the point stayed on track. A hidden double lever started the second turntable the moment the first was full. Repetition (to use the current term for reproduction) was a simple process of letting the sprung point ride again at high speed over its own indentations, sending the recorded signals on to as many subsidiary stations as could be connected to a sounder in the embosser’s circuitry.128
MOLECULAR MUSIC
In that same February that saw Edison turn thirty and show his first streaks of silver hair, he and Batchelor began a new series of experiments on what they called, variously, the “telephonic telegraph,” the “speaking telegraph,” and the “talking telephone.” This confusion of names was common in the communications industry, and would last as long as Americans took to adjust to the startling notion that an electrically transmitted message did not necessarily have to be transcribed. It was beyond even Bell’s imagination that people might one day use his invention just to chat. As far as Edison was concerned, the telephone was a dev
ice to speed up the process of turning words into pulsations of current, then turning the pulsations back into words at the other end—words intended to be heard only by a receiving operator, who would then (as Edison had done thousands of times as a youth) copy out the message for delivery. Hence the instrument really was, for all its crackly noise, telegraphic in function.
Edison’s embossing recorder-repeater, February 1877.
Audibility was key, and he had failed so far in his efforts to improve on the wretched Bell magneto transmitter. He thought he might achieve full vocability through the principle of variable resistance within a closed circuit, which he held essential to the electrification of speech.129 Working often through the night, he and Batchelor made transmitters out of membranes that shifted rollers or pins along graphite tracks in circuit, but when they tried to speak clearly through them, got only “a mumbling sound.” Not until they returned to Edison’s old idea of a wired button held against a diaphragm, and molded it out of crushed black lead instead of rubber, did they achieve a dramatic increase in clarity. “With this apparatus,” Batchelor recorded on 12 February, “we have already been able to distinguish clearly (known) sentences well between New York and Menlo Park.”130
The excitability of pure carbon under pressure was a major discovery—or rather, rediscovery. Four years before, while constructing a tubular rheostat, Edison had found that the electrical resistance of packed, powdered graphite shot up and down, like a rogue barometer, “with every noise, jar or sound.” Eerily, when a carbon button was framed in an iron ring and warmed with the heat of his hand, it gave off creaky, harmonic tones that he called “molecular music.”
If so oversensitive then, surely carbon could not be too much so now, when he was looking for a relay that would accommodate the infinite gradations of the human voice—even to the nonvocal breaths, sighs, coughs, and hesitations that punctuated speech?131
The question was how compressed the texture of his button should be, or how loose, to give the widest resistance range.*26 Carbon came in an infinite variety of forms, from softest lampblack to rocklike anthracite. He would have to compound and test most of them for resilience and porosity, with the aural help of Batchelor and Adams. “I am so deaf that I am debarred from hearing all the finer articulations & have to depend on the judgment of others.”132
UTTERANCES
That May Edison was in the midst of sketching some devices for the capture of sibilants when Rep. Benjamin Butler of Massachusetts challenged him to invent a telephone recorder that would convert sound into text. Edison brooded for a day or two, then came up with the opposite idea.133 He drew what looked like a xylophone floating in space and scrawled:
Keyboard Talking Telgh,
I propose to have a long shaft with wheels on having breaks (ie electrical) so arranged with a Key board that by depressing say the letters T H I S simultaneously that contact springs will one after another send the proper vibrations over the wire to cause the Emg*27 & diaphragm to speak plainly the word this….No difficulty will be had in obtaining the hissing consonants and as the break wheels & contact springs may be arranged in any form and as many as required used the overtones harmonics of the parts of speech can easily be obtained Turn this over in your mind Mr E & hoop it up.134
The xylophone bars turned out to be lettered keys, each ending in a tiny metal wheel serrated to make or break signals in the high frequencies. Edison apparently thought he could play the keys—one for each unit of the alphabet—in such legato combinations that T would blend into H, then into the vowel I, which would sharpen into a hiss as the last key was depressed. It was hardly the text recorder Butler had suggested, nor was it workable. Edison soon realized that letters had little to do with phonetics. Instead, he had dreamed up something truly radical: the notion of text transformed digitally into sound.*28, 135
Impractical as it was, the keyboard talking telegraph—which he believed could be made to print as well as speak—marked a significant advance in his acoustic understanding. It featured, at least in theory, “tonewheels” rolling out the shapes of sound waves, an acknowledgment that speech consisted of overtones as well as volumes of air pressure,136 and the double embrace in one instrument of recording and reproducing functions.137
Sibilants continued to elude Edison through June. Until he could get a diaphragm to articulate such a word as scythe, he felt he could not realize the full potential of his carbon rheostat. In its current experimental form, it took the form of a granular graphite disk about the width of a dime, sometimes sheathed in silk. When laid on the cupped poles of an electromagnet, then compressed beneath a battery-connected armature, the buttons were put in local circuit with them and a sounder. An inflow of main line current lightened the magnetic “weight” of the armature, reducing the resistance of the carbon to a mere few ohms; withdrawal of the current had the reverse effect, increasing resistance to several hundred ohms and again activating the sounder. In an article headed “Edison’s Pressure Relay,” the Journal of the Telegraph remarked, “It is probably the only device yet invented which will allow of the translation of signals of variable strengths, from one circuit into another, by the use of batteries in the ordinary manner.”138
Despite the ongoing problem of high-frequency registration, Edison was able by midmonth to construct a combination telephone transmitter-receiver that tested “far plainer and better than Bell’s.” The normally phlegmatic Batchelor was so pleased with it that he boasted to his brother, “We have just got our ‘speaking telegraph’ perfected.” That turned out not to be the case, and the pace of around-the-clock sonic experiments increased to the point that the Operator reported, “T. A. Edison is gray as a badger, and rapidly growing old.”139
If so, Edison was not lacking in vitality. He was flush with contractual money from Gold & Stock and Western Union and enjoying the first of the “insomnia” blitzes that would characterize his life as an inventor. Not until 16 July did he feel he had a telephone worth patenting. The application he signed that day specified multiple tympani that “reproduced” vocal inflections and a sibilant-sensitive diaphragm with a layer of platina foil interposed between it and the contact point. But a laboratory visitor (spying for Alexander Graham Bell) found the instrument more powerful than clear, with the word schism sounding more like kim: “If Edison gets the articulation more perfect, which he is now working at, he can talk in thunder tones any distance.”140
“We have had terrible hard work on the Speaking telegraph,” Batchelor complained to Ezra Gilliland. “This last 5 or six weeks frequently working 2 nights together until we all had to knock off from want of sleep.”141
Edison’s gray look may well have come from the rub-off of carbon dust, platinum black, hyperoxide of lead, graphite, and other sooty conductors that besmirched him as the summer progressed. After one of these adjournments Mary entered the spare bedroom of her house and found an apparent chimney sweep lying dead to the world “on my nice white counterpanes and pillow shams.”142
VOICES
“Just tried experiment with a diaphragm having an embossing point & held against parafin paper moving rapidly,” Edison wrote on 18 July. “The spkg vibrations are indented nicely & theres no doubt that I shall be able to store up and reproduce automatically at any future time the human voice perfectly.”143
When exactly, that summer, did the sum total of all Edison’s past work on the sending and reception of sound coalesce into his greatest invention? As a discovery, it was so sensational that legends began to accrete around it almost at once, and his own memories of the moment swam confusedly. Perhaps it was when, listening to the hum of his elegant translating embosser—not an acoustic instrument, yet strangely melodious when its disks whirled at high speed—he thought he heard voices, “apparently talking in a language which could not be understood.” Again, it was the faint sound of his own voice reciting the alphabet, when h
e retraced some diagrammatic scratches he had made on a strip of paraffined paper. Again, it was when he shouted “Halloo! Halloo!” into the mouthpiece and, pulling the paper through a second time, heard as from the far side of a valley, “Halloo! Halloo!” Yet again, it might have been the behavior of a voice-activated toy he made of a little man sawing wood to the loud recitation of any nursery rhyme. Or it was the sight, rather than the sound, of a needle attached to a live diaphragm, punching out oscillations as he said into it, “A—A—A.” It may even have been when, absent-mindedly caressing such a needle as it vibrated, he felt a prick on his thumb—a sonic wave inscribing itself in his own flesh.*29, 144
“Kruesi—make this,” he recalled saying to his master machinist, giving him a drawing of a mounted, foil-wrapped cylinder, with a handle on one side to turn it, and a vibrant mouthpiece projecting a stylus that just touched the surface of the wrap.
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