Brilliant: The Evolution of Artificial Light

by Jane Brox

  Some simply preferred the modest flame of the old light: "I boldly declare myself the friend of Argand lamps," stated one Parisian in comparing them to gas lamps; "these to tell the truth are content with shedding light and do not dazzle the eyes." Perhaps, for city dwellers, as the oil lamp began to take its place as part of the past—its notes diminishing as others sounded and strengthened—its intimacies seemed all the more desirable, and people instinctively clung to its lingering form, the ghost in the mist. "It seems there are dark corners in us that tolerate only a flickering light," wrote Gaston Bachelard. That flickering was a link to the light at the beginning of human time: the kerosene lamp was the apotheosis of the tallow cupped in limestone at Lascaux, the last self-tended flame.

  PART II

  You turn the thumbscrew and the light is there.

  —New York Times, September 5, 1882

  6. Life Electric

  HUMAN LIGHT HAS ITS SOUNDS—of a match struck and a candle flame muttering in a draft, of a stopcock turning and a gas jet hissing to life or hoarsely damping itself out. Now: the crackle and snap of electricity—for thousands of years a mystery and arriving as light only after ages of isolated experiments, speculation, observations, and discoveries. Light that required a new vocabulary—amps, volts, watts, joules, the galvanic cell. Light without fire, incandescently silent, its switch a "little click [that] says yes and no with the same voice." It was the harnessing of what has been marvelous at least since the ancient Greeks saw the way amber, when rubbed with a piece of wool, created sparks, so they could only conclude that it, too, had a soul, for "it seemed to live, and to exercise an attraction upon other things distant from it." Amber, which the Greeks believed were the tears of the Heliades, Phaëthon's sisters, who wept so long beside the river where he'd drowned that the gods in their pity turned them into poplars.

  The philosopher Thales, who lived around 600 B.C., was the first to mention the sparking of amber in his writings, though its electrostatic qualities were likely already well-known. The Greeks, it was said, treated gout by standing on electric eels, but whether they used amber for any practical or religious ends is only conjecture, as is the use of ancient batteries, dating to around 200 B.C., found in the vicinity of Baghdad. The five-inch-high clay vessels each contain an iron rod encased in a copper cylinder. One, if filled with vinegar, grape juice, or lemon juice, could have delivered a few volts of power. Archaeologists found needlelike objects near some of the batteries, so perhaps the current was used in acupuncture. Or the batteries may have been connected in series to produce a greater charge for electroplating. Or perhaps statues of idols were wired to them so that small shocks might inspire awe in supplicants.

  Electricity's modern path can be traced back to 1600 in London, where Dr. William Gilbert, surgeon to Queen Elizabeth I, noted in his De magnete that sparks flew not only from amber but also from glass and precious stones, resin, sulfur, sealing wax, and more than a dozen other substances. He called these substances "electrics," from the Latin word electrum, in turn derived from the Greek word for amber, elektron. Gilbert died only a few years after the publication of his work, though in succeeding years other scientists, knowing of his findings, extended the list of electrics—among them diamonds, white wax, and gypsum—which remained just a list until Otto von Guericke, mayor of Magdeburg (now in Germany) created an electrostatic machine: a small, solid sulfur globe about six inches in diameter, set in a wooden frame, which he turned with an attached handle. When he both rotated and quickly rubbed his machine, it not only glowed and sent sparks flying; it also attracted light objects.

  Guericke noted that electricity could repel things as well as attract them, and to the amusement of friends and visitors, he used his whirling globe to drive feathers across his drawing room, guiding them along until they rested on his guests' noses. For decades afterward, electricity—understood as a "virtue"—would remain largely an enigma that thrived as entertainment. An increased understanding of its properties only inched forward as a result of occasional observation of phenomena between amusements.

  In the early eighteenth century, Englishman Stephen Gray established the conductive properties of electricity, having found, after rubbing the bottom of a glass tube, that its cork stopper had become charged. Through his experiments, Gray also discovered the insulating properties of some substances:

  He suspended a long hempen line horizontally by loops of pack-thread, but failed to transmit through it the electric power. He then suspended it by loops of silk, and succeeded in sending the "attractive virtue" through seven hundred and sixty-five feet of thread. He at first thought that the silk was effectual because it was thin; but on replacing a broken silk loop by a still thinner wire, he obtained no action. Finally he came to the conclusion that his loops were effectual, not because they were thin, but because they were silk.

  With this knowledge, Gray developed his "dangling boy" experiment, which in succeeding years became popular in drawing rooms across England. He suspended a young boy—swathed in nonconducting clothes except for his head, hands, and a few toes—by thick silk ropes. The boy held a wand with a dangling ivory ball in one hand and stretched out his other hand freely. When Gray set an electrified glass tube against the child's bare toes, the boy's hair stood on end, and brass leaf that had been piled on the floor beneath him rose toward the ivory ball, his extended hand, and his face. Gray might then invite members of the audience to stand on some conductive material and touch the boy, whereupon they would receive shocks.

  The sulfur globes, and the glass ones that succeeded them, could only produce electricity; the first record of its successful storage dates from 1745. In Camin, Germany, Ewald von Kleist wrote of an experiment in a letter to a friend:

  When a nail or piece of brass wire is put into a small apothecaries' phial and electrified, remarkable effects follow; but the phial must be very dry and warm. I commonly rub it over beforehand with a finger on which I put some powdered chalk. If a little mercury or a few drops of spirits of wine be put into it, the experiment succeeds the better. As soon as the phial and nail are removed from the electrifying glass, or the prime conductor to which it hath been exposed is taken away, it throws out a pencil of flame so long that with this burning machine in my hand I have taken about sixty steps.... I can take it into another room, and then fire spirits of wine with it. If while it is electrifying I put my finger or a piece of gold which I hold in my hand to the nail, I receive a shock which stuns my arms and shoulders.

  Scientists in Leiden (or Leyden), Holland, refined von Kleist's machine, and thereafter it was known as a Leyden jar. The most elaborate of the jars consisted of a water-filled glass container with an outer and inner coating of metal foil and metal filings at the bottom of the jar. It was capped with a cork or a wooden lid, from which a conductor—a metal rod, usually brass, topped with a metal ball—protruded. A metal chain hung into the jar from the lid. Experimenters could transfer the electric charge from a whirling globe to the protruding ball; the charge traveled down the rod and chain to the water and foil. A Leyden jar could retain its charge for several days, which, as historian Philip Dray notes, allowed experimenters "to move electricity about as part of a graduated process, not merely to see it as the sudden flash that occurred between objects in a friction experiment."

  One of the first experimenters in Leiden found that the jar contained enough power to make his whole body quiver. "I advise you never to try [it] yourself," he wrote to a colleague, "nor would I, who have experienced it and survived by the Grace of God, do it again for all the kingdom of France." But many others across Europe and in America did try it in the succeeding decades. Men administered shocks to small animals and birds, to themselves and their wives; they suffered nosebleeds and fevers, convulsions and weakness. Still they experimented. Abbé Jean-Antoine Nollet, at the court of Louis XV at Versailles, in an effort to see how far a shock could travel, sent a charge through 180 soldiers who'd joined hands. He was satisfied to see t
hat they all jumped in unison, and then he tried the experiment on 750 Carthusian monks, who, holding wires between them, formed a line 5,400 feet long. As the abbé sent the current through, they, too, all jumped at the same moment.

  Experimenters made bells ring, set rum on fire, and sent sparks shooting around gilded picture frames. They generated "electric kisses" by suspending a young woman in the same way Gray had suspended his "dangling boy." They then invited men from the audience to kiss her on the cheek, and sometimes the charge was significant enough to crack teeth. Still, electricity remained "a vast country, of which we know only some bordering provinces," and its experimenters were thought to be dabbling in a toy science, for no one had yet found a practical application for its power.

  Benjamin Franklin, one of the eighteenth century's most tireless "electricians"—a phrase he coined and by which electrical experimenters were then known—was "chagrined a little that we have been hitherto able to produce nothing in this way of use to mankind." He knew electricity's true power only too well, having received at least one considerable jolt. "I have lately made an experiment in electricity that I desire never to repeat," he explained in a letter to a friend in Boston.

  Two nights ago, being about to kill a turkey by the shock from two large glass jars, containing as much electrical fire as forty common phials, I inadvertently took the whole through my own arms and body.... The company present ... say that the flash was very great, and the crack as loud as a pistol; yet, my senses being instantly gone, I neither saw the one nor heard the other; nor did I feel the stroke on my hand, though afterwards found it raised a round swelling where the fire entered, as big as half a pistol-bullet, by which you may judge the quickness of the electrical fire, which by the instance seems to be greater than that of sound, light, or animal sensation.

  Franklin advanced the understanding of electricity with countless experiments and considerable writings on the subject, and he clarified some of its mystery. Philip Dray notes that Franklin "was the first to discover that the [Leyden] jar's stored charge was not in the water, as others had believed, but in the glass. The glass was a dielectric, meaning it stored and allowed the passage of electricity but did not conduct it." Perhaps most significantly, Franklin—like Stephen Gray and Abbé Nollet—suspected that lightning and the electrical charges they'd created in their experiments were one and the same substance. The common belief at the time, however, held that lightning—heavenly fire—was its own distinct phenomenon and a manifestation of the will of God, a belief that may have been reinforced by the fact that churches and monasteries, with their high steeples and bell towers, were often struck during storms. "There was scarce a great abbey in England which was not burnt down with lightning from heaven," notes a church history of Britain. Many thought such destruction could be warded off by the sounding of church bells during electrical storms, though the practice only served to hasten the deaths of countless bell ringers.

  Franklin suggested a new way to ward off such destruction. "There is something ... in the experiments of points, sending off or drawing on the electrical fire," he wrote. "For the doctrine of points is very curious, and the effects of them truly wonderful.... I am of the opinion that houses, ships, and even towers and churches may be effectually secured from the strokes of lightning by their means." When he began to promote the use of lightning rods on buildings, he encountered considerable resistance from church leaders, who claimed the rods were blasphemous and warned that drawing lightning from the sky would cause earthquakes. He was undeterred, however, and his observations of the workings of lightning rods led to his most renowned experiment, which proved that the charges in the heavens and those in Leyden jars were one and the same.

  In July 1750, Franklin proposed that a sentry box, large enough to house a man and with a pointed rod rising from it, be built. It would contain an electrical stand which, if it

  be kept clean and dry, a man standing on it when such clouds are passing low might be electrified and afford sparks, the rod drawing fire to him from a cloud. If any danger to the man should be apprehended (though I think there would be none), let him stand on the floor of his box, and now and then bring near to the rod the loop of a wire that has one end fastened to the leads, he holding it by a wax handle; so the sparks, if the rod is electrified, will strike from the rod to the wire and not affect him.

  In May 1752, before he could conduct his experiment, a French physicist successfully followed his suggestion. The following month, Franklin, knowing nothing of the events in France, carried out a similar experiment with a silk kite, a hemp rope, and a key, which he later detailed:

  As soon as any of the thunder-clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite, with all the twine, will be electrified, and the loose filaments of the twine will stand out every way, and be attracted by an approaching finger. And when the rain has wetted the kite and twine, so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key the phial may be charged; and from electric fire thus obtained spirits may be kindled, and all the other electric experiments be performed which are usually done by the help of a rubbed glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated.

  To connect heavenly forces to the "virtue" that humans had puzzled over since the first sparks were rubbed from amber elevated electricity above the realm of toy science and entertainment. As Philip Dray notes, "Franklin's conclusions demanded that electricity join gravity, light, heat, and meteorology in any account philosophers offered for the majestic workings of nature." Still, half a century after Franklin's kite experiment, at the end of the eighteenth century, in a world illuminated at best by the Argand lamp, the understanding of electricity had hardly advanced any further, hampered in part by the limits of the Leyden jar, which could only bring experimenters so far, since it stored limited energy.

  In the late eighteenth century, in Italy, Alessandro Volta challenged Luigi Galvani's conclusion that convulsions in frogs, which Galvani had hung from brass hooks upon an iron trellis, were caused by innate electricity within the animals themselves. Volta argued that the convulsions were caused simply by the contact between the brass and the iron, and he proved his theory by creating the first modern battery, which he described in a letter to the Royal Society in London in 1800:

  I obtain several dozen small round plates or disks of copper, brass, or better of silver, an inch in diameter, more or less; for example coins, and an equal number of plates of tin, or, what is still better, of zinc, of the same shape and size approximately.... I prepare besides a sufficiently great number of disks of cardboard, or cloth ... capable of imbibing and retaining considerable water.... I place, generally horizontally, on a table or other base, one of the metallic plates, for example, one of silver; on this first, I then place a second of zinc; on this second, I place a moistened disk; then another plate of silver, followed immediately by another of zinc, to which I can make succeed a moistened disk. I then continue ... always in the same direction.... I continue, I say, to form by many of these sets a column sufficiently high that it may be able to stand upright.

  The charge would last for as long as the electrochemical interactions between the liquids and various metals lasted. Volta had created a sustained, continuous flow of electricity. As Park Benjamin, writing in the nineteenth century, noted, Volta's invention "made electricity manageable. He reduced the infinite rapidity of the lightning stroke to the comparatively slow but enormously powerful current, which in the future was destined to carry men's words from one end of the world to the other, and to produce the dazzling light inferior only to the solar ray."

  Volta's "pile" immediately intrigued scientists across Europe and America, none more so than Sir Humphry Davy—creator of one of the first miners' safety lamps—who, at the beginning of the nineteenth century, held a post as chemist at the Royal Institut
ion in London. Davy worked at refining Volta's pile and eventually had large batteries built in the basement of the institution's laboratory. He carried out a series of experiments with them, including demonstrations of the first electric lights. In 1802 he succeeded in making a platinum filament glow, if only momentarily, by infusing it with electric current. Then in 1809, with the aid of the largest battery yet—consisting of two thousand pairs of plates—he demonstrated the first lasting electric light, the voltaic arc. He passed a current through a charcoal stick, which served as a conductor of electricity; then he touched another charcoal stick to the first, and a spark jumped from the first to the second. As he pulled them apart, an arc of brilliant blue-white light leapt across the heated air between them. But light wasn't created by the arc alone; the carbons glowed incandescently.

  Davy never took the voltaic arc beyond the demonstration stage—an enduring, practical electric light was still many decades away, for considerable problems had to be overcome. Not only did Davy's charcoal electrodes burn quickly and unevenly, but as the carbons burned down and the gap between them widened, the light sputtered, then failed. Scientists had to develop electrodes that would burn slowly and steadily, at a constant distance from each other. The greater challenge, however, lay in producing a more enduring power system than the batteries of the day, and widespread arc lighting would depend on a reliable electric generator, or dynamo, as it was commonly called. That would not arrive until well after 1831, the year Michael Faraday established the principle of electromagnetic induction.