Table of Contents
Title Page
Copyright Page
Chapter 1 - FIRST SPARKS
Chapter 6 - TESLA
Chapter 8 - OLD SPARKY
Chapter 12 - DC’S REVENGE
Further Readings in Electricity
The Author

Fig. 4.—Experiments in Killing Animals by the Alternating Current, as Conducted in the Edison Laboratory at Orange, N. J.


I’ve always had a healthy respect for electricity. Twice, it almost did me in.
The first time was serious. I was eleven years old, hanging out with my friend Mike in his basement. We had liberated some of his father’s tools from a chest and were happily drilling, hammering, and sawing away the afternoon. I picked up a staple gun, which I had never used before, and began firing wildly like a Wild West gunslinger. There was a powerful recoil every time you shot a staple, so it seemed like you were doing something significant when you squeezed the trigger.
Looking around, I noticed that some insulation in the ceiling was sagging a bit—nothing a dozen well-placed staples couldn’t fix. I dragged a metal chair under the spot, climbed on top, and with one arm stretched over my head Statue of Liberty style, began shooting staples into the insulation. It was difficult to aim while balancing on the chair, and one of the staples became embedded in a dark brown cord that ran along the edge of the ceiling. I’ll just pull that staple out with my hand, I thought.
The brown cord turned out to be a wire buzzing with 120 volts of electricity, the standard household current in the United States. When I touched the metal staple rooted in the wire, my body became part of the electrical circuit. The current raced into my hand, down my arm, across my chest, down my legs, through the metal chair and into the ground—all at nearly the speed of light.
The sensation of having electricity course through your body is hard to put into words. Benjamin Franklin, who was once badly shocked by electricity (though not while flying a kite), described the feeling in a letter to a friend: “I then felt what I know not how to describe,” Franklin wrote. “A universal blow throughout my whole body from head to foot, which seemed within as well as without.”
A blow that seemed “within as well as without”: yes. To me, the shock felt as though it was not simply running along the surface of my skin but was burrowing deep inside my body. The current felt like hot metal had been poured into my veins, a powerful surge that raced into the bones and down the marrow. The electricity was entering my body through my hand, but it didn’t feel like the current had any particular location. It was everywhere. It was me.
The electricity flowing through my body was encountering resistance, which in turn was converted to heat. When people talk about criminals being “fried” in the electric chair, it’s a fairly accurate description of what actually happens. I was slowly but steadily being cooked alive.
I’m not sure how long my hand clutched the electrified staple. Perhaps only a few seconds; maybe longer. Time seemed to have a different quality while in electricity’s grip. The burst of current contracted the muscles in my hand, causing me to grasp the staple even harder, a phenomenon noted by Italian physician Luigi Galvani in the late eighteenth century when he touched an exposed nerve of a dead frog with an electrostatically charged scalpel and saw the frog’s leg kick.
When a human touches a live wire, electricity often causes the muscles in the hand to contract involuntarily, an unlucky condition known among electrical workers as being “frozen on the circuit.” Victims frozen on the circuit often have to be forcibly removed from the wire since they’re unable to exercise control over their own muscles.
I was lucky. Just as my fingers were curling into a tight fist around the hot electrified staple, the sharp contraction of the muscles in my arm jerked my hand free. I immediately fell to the floor—pale, panting, and dazed, but otherwise uninjured. I had just felt the power of AC, or alternating current, the type of electricity found in every wall outlet in the home. In an AC circuit, the current alternates direction, flowing first one way and then the other, flipping back and forth through the wire dozens of times per second.
The 120 volts of electrical pressure that come out of an AC wall outlet are more than sufficient to kill a human being under the right circumstances. More than four hundred Americans are killed accidentally by electricity every year, and electric shock is the fifth leading cause of occupational death in the United States. And yet alternating current is utterly indispensable to modern life. The world as we know it simply couldn’t do without AC power. Every light bulb, television, desktop computer, traffic signal, toaster, cash register, refrigerator, and ATM is powered by alternating current. The Information Age is built squarely on a foundation of electricity; without electric power, bits can’t move, and information can’t flow. Even the bits themselves are tiny electrical charges; a computer processes information by turning small packets of electricity on and off.
My second encounter with electricity’s dark side wasn’t quite as serious, but still left its mark. I was in college trying to jump-start my car on a frigid day, and had just attached the jumper cables to the battery of another car. As I moved to clamp the other end of the cables onto the dead battery, I stumbled and inadvertently brought the two metal clamps together. Once again, I had completed an electrical circuit, and once more, I was caught in the middle of it. A brilliant yellow-blue spark leaped from the cables, accompanied by a loud “pop.” I immediately dropped the cables and discovered a black burn mark on my hand the size of a quarter, a battle scar from the electrical wars.
This time, I had been done in by DC, or direct current, the kind of current produced by batteries. Direct current moves in only one direction, from the positive to the negative terminal, but beside that, DC is the same “stuff” as AC: a flow of charged particles. A car battery produces about 12 volts of electrical pressure, only onetenth the power that comes out of an AC wall outlet, but that didn’t make my hand feel any better. Under the right conditions, direct current is every bit as deadly as alternating current.
And yet DC is also utterly essential to contemporary life. Every automobile on the road depends on DC to operate, along with every cell phone, laptop computer, camera, and portable music device. The same force that strikes people dead in lightning storms also saves lives. Cardiac defibrillators deliver a controlled burst of direct current to heart attack victims, forcing the heart muscles to contract and resume a regular rhythm.
Life and death, negative and positive. Electricity has many dualities, so it’s only fitting that the struggle to electrify the world would give birth to twins: AC and DC. Long before there was VHS versus Betamax, Windows versus Macintosh, or Blu-ray versus HD DVD formats, the first and nastiest standards war of them all was fought between AC and DC. The late-nineteenth-century battle over whether alternating or direct current would be the standard for transmitting electricity around the world changed the lives of billions of people, shaped the modern technological age, and set the stage for all standards wars to follow. The wizards of the Digital Age have taken the lesson of the original AC/DC war to heart: control an invention’s technical standard and you control the market.
The AC/DC showdown—which came to be known as “the war of the currents”—began as a rather straightforward conflict between technical standards, a battle of competing methods to deliver essentially the same product, electricity. But the skirmish soon metastasized into something bigger and darker.
In the AC/DC battle, the worst aspects of human nature somehow got caught up in the wires, a silent, deadly flow of arrogance, vanity, and cruelty. Following the path of least resistance, the war of the currents soon settled around that most primal of human emotions: fear. As a result, the AC/DC war serves as a cautionary tale for the Information Age, which produces ever more arcane disputes over technical standards. In a standards war, the appeal is always to fear, whether it’s the fear of being killed, as it was in the AC/DC battle, or the palpable dread of the computer age, the fear of being left behind.

The story of electricity begins with a bang, the biggest of them all. The unimaginably enormous event that created the universe nearly 14 billion years ago gave birth to matter, energy, and time itself. The Big Bang was not an explosion in space but of space itself, a cataclysm occurring everywhere at once. In the milliseconds following the Big Bang, matter was formed from elementary particles, some of which carried a positive or negative charge. Electricity was born the moment these charged particles took form.
All matter in the universe contains electricity, the opposing charges that bind atoms together. Even human beings are awash in it; the central nervous system is a vast neuroelectrical network that transmits electrical impulses across nerve endings to the body’s muscles and organs.
However, electricity, like the face of the Creator, is normally hidden from view. Most matter contains a balance of positive and negative charges, a stalemated tug-of-war that prevents electricity from manifesting itself. Only when these charges are out of balance do electrons move to restore the equilibrium, allowing electricity to show its face.
Electrical current is the flow of negatively charged electrons from one place to another in order to restore the natural balance of charge. It would take untold years and thousands of lives before humans learned to harness that flow and make those unseen charged particles do their bidding. Even then, electricity remained shrouded in mystery, an eccentric, invisible force with powers that seemed to come from another world.
Electricity first showed itself on earth as lightning, and as such, may have provided the original spark for life. Cosmologists believe that lightning may have provided some of the energy that transformed simple elements such as carbon, hydrogen, oxygen, and nitrogen into amino acids, the more complex molecular chains that are the building blocks of life.
Billions of years ago, the primordial surface of the earth was subjected to almost constant lightning strikes. Lightning is discharged when charged particles in the clouds separate; the lower portion of the cloud becomes negatively charged, producing an enormous electrical difference between it and the positively charged ground. The imbalance is discharged as a spark: lightning. A lightning bolt is a bundle of heat and energy, hotter than the surface of the sun and carrying an electrical force of more than a billion volts.
Lightning may have not only sparked organic life but also preserved plant life during crucial evolutionary choke points when fuel supplies ran low. During the Archaean age two billion years ago, carbon dioxide levels fell dramatically, drying up the supply of nitrates, which are essential for plant growth. Lightning is believed to have helped produce additional nitrates in the atmosphere, allowing plants to survive through this period. When plants began to flourish again, more oxygen was produced, making the earth increasingly suitable for animals, and later, humans. In many ways, we are the products of lightning, the sons and daughters of electricity.
The first humans knew nothing of lightning’s creative power, only its terrible capacity for destruction. A jagged bolt from the heavens could incinerate someone in midstride, instantly turning a human being into a charred corpse. It was not the sort of power to be taken lightly. It would take millennia for humans to learn how to shield themselves from lightning, and longer still to learn its lifegiving power. Lightning strikes sparked fires, which in time were controlled and put to use to cook food, provide warmth, and ward off dangerous animals.
The first creatures to put electricity to work were Homo habilis, or “Handy Man,” the Stone Age humans that inhabited Africa about 1.8 million years ago. Handy Man, it turns out, wasn’t all that handy. He hadn’t yet worked out how to make fire; instead he waited for lightning to strike a bush or tree, and then carefully tended the flame. When it was time for the tribe to move to another location, Handy Man took lit branches along to start a new fire, or simply waited for lightning to strike again somewhere else.
For Homo sapiens, lightning and electricity would likewise be a luminous mystery. Around 600 B.C., the Greeks discovered that amber, a soft golden gem formed from fossilized tree sap, behaved oddly when rubbed by a piece of fur: the stone attracted pieces of straw or hair. Sometimes, the amber would even emit a spark, a miniature lightning bolt. The science behind this strange effect would remain a mystery for more than two thousand years, but the Greeks had discovered static electricity. As we now know, the fur transferred negatively charged electrons to the amber, giving it an imbalanced charge, which in turn attracted the straw. The phenomenon would later give electricity its name: elecktron is the Greek word for amber.
Even as humans struggled to understand electricity, the subject continued to be clouded by superstition. Thales of Miletus, an early Greek philosopher and mathematician, interpreted the curious properties of amber as evidence that objects were alive and possessed immortal souls. Greek mythology explained electricity by associating lightning with Zeus, the supreme god, who threw bolts of lightning down from the heavens to vent his anger at enemies below. Virgil’s Aeneid recounts the tale of Ajax, who, boasting of his own power, defied lightning to strike him down. Such a dare amounted to nothing less than shaking his fist in the face of the gods, and led to a predictably unhappy ending. In short order, Ajax was felled by an expertly aimed lightning bolt from the sky.
Lightning was so fearsome that many cultures sought to ascribe meaning to what seemed like a wantonly destructive power. The Etruscans and Romans believed that lightning was not simply a weapon of the gods but a message from them. The Etruscans were particularly keen observers of lightning, dividing the sky into sixteen sections in order to determine the significance of a bolt. Lightning moving from west to north was considered disastrous, while lightning to the left hand of the observer was thought to be fortunate. The Etruscans even compiled a sacred book about the art of interpreting lightning strikes, and laid out their towns in accordance with signs gleaned from the heavens.
In Roman times, objects or places struck by lightning were considered holy. Roman temples often were erected at these sites, where the gods were worshipped in an attempt to appease them. A man struck by lightning who lived to tell the tale was considered someone especially favored by the gods. In most cases, however, lightning was utterly destructive. A thunderbolt, the Roman poet Lucretius wrote, “can split towers asunder, overturn houses, tear out beams and rafters, move monuments of men, struck down and shattered, rob human beings of life, and slaughter cattle.”
Lightning mythology readily spread to other cultures—the phenomenon was clearly something that demanded explanation. The Vikings believed lightning was caused by Thor striking a hammer on an anvil as he rode his chariot across the sky. In Africa, Bantu tribesmen worshipped the bird-god Umpundulo, who directed lightning. Medicine men were sent into storms to bid Umpundulo to strike far away from a village, a practice that continues to this day in parts of Africa. The Book of Job places lightning in the hands of a wrathful God: “He fills his hands with lightning and commands it to strike its mark.” The Koran states that lightning, which is directed by Allah, can be a force for both creation and destruction: “He it is who shows you the lightning causing fear and hope.”
Native American tribes were particularly attuned to lightning’s dual nature, its power to kill and to give birth. Native tribes saw with remarkable clarity the inherent duality of electricity centuries before Western science would describe electrical current as a flow between negative and positive poles. One legend has Black Elk, an Oglala Sioux, testifying: “When a vision comes from the thunder beings of the West, it comes with terror like a thunder storm; but when the storm of vision has passed, the world is greener and happier; for wherever the truth of vision comes upon the world, it is like a rain. The world, you see, is happier after the terror of the storm.... You have noticed that truth comes into this world with two faces. One is sad with suffering, and the other laughs; but it is the same face, laughing or weeping.”
Negative and positive, plus and minus, good and evil, life and death. The Chinese Taoists termed the pair of opposites found in nature yin and yang, and the concept is well suited to electricity. Yin and yang are not opposites in conflict; they are simply different aspects of the same system. One depends on the other for its existence. As one aspect overcomes the other, the seeds of a reversal are sown.
Likewise, the negative and positive poles in electricity represent an ever-changing polarity—the dominance of a negative charge contains the inception of a rise of a positive charge. The famous yin-yang symbol expresses the concept with elegant simplicity: the blackest part of the symbol contains a tiny white dot, and the whitest part a black dot, the seeds of the inevitable opposite about to give birth.
Not until the end of the Middle Ages would philosophers begin to look at electricity scientifically. The first truly scientific study of electricity and magnetism was taken up by William Gilbert, an English physician to Queen Elizabeth I. Gilbert’s book De Magnete (On the Magnet), published in Latin in 1600, introduced the term electricity to describe the attractive force of rubbed amber.
Gilbert spent seventeen years experimenting with magnetism and electricity, attempting to strip away the myths that had shadowed electricity since the dawn of time. Gilbert was the first to describe a relationship between electricity and magnetism, as well as being the originator of the terms electric force, magnetic pole, and electric attraction. Gilbert divided objects into “electrics” (such as amber) and “non-electrics” (such as glass). He attributed the electrification of an object to the removal of a fluid, or “humour,” which then left an “effluvium,” or atmosphere, around the body. Gilbert actually wasn’t far off the mark. His “electrics” would later be known as conductors, while the “non-electrics” would be called insulators. The “humour” that was stripped off objects would be known as a “charge” and the “effluvium” that was created became an “electric field.”
Before long, experimenters developed machines that could produce large amounts of static electricity on demand. In 1660, German experimenter Otto von Guericke made the first electrostatic generator out of a ball of sulfur and some cloth. The sulfur ball was mounted on a shaft placed inside a glass globe. A crank rotated the ball against the cloth, and a static electric spark was produced. To von Guericke, the sulfur ball symbolized the earth, which shed part of its electric “soul” when rubbed—not exactly a scientific explanation. But the machine worked, letting experimenters produce electric sparks whenever they wanted.
In 1745, Pieter van Musschenbroek, a physicist and mathematician in Leiden, Holland, was one of several experimenters to fashion a device that would become known as the Leyden jar. Van Musschenbroek’s Leyden jar consisted of a glass vial partially filled with water. A beaded metal chain dangled in the water, held by a wire that ran through a cork stopper and out the top of the jar, terminating in a metal knob. Van Musschenbroek held the jar in one hand and touched the knob to a spark generator. When nothing happened, van Musschenbroek touched the knob with his other hand, and at that instant, got the shock of his life:
“My right hand was struck with such force that my whole body quivered just like someone hit by lightning,” van Musschenbroek wrote. “Generally the blow does not break the glass, no matter how thin it is, nor does it knock the hand away, but the arm and the entire body are affected so terribly I can’t describe it. I thought I was done for.”
Van Musschenbroek couldn’t figure out what had caused the shock—after all, the jar was no longer connected to the static generator when he got zapped. He later told an associate he would never try such an experiment again, but others weren’t so cautious. Leyden jar experimenters soon reported everything from nosebleeds, convulsions, and prolonged dizziness to temporary paralysis when they unleashed the charge with their hand.
The Leyden jar was electricity in a bottle, an ingenious way to store a static electric charge and release it at will. When a charge was applied to the inside surface of the Leyden jar, it meant that the outside surface (which was insulated from the inside) had an equal but opposite charge. When the inside and outside surfaces were connected by a conductor—in this case, a human hand—the circuit was completed, and the charge was released with a dramatic spark. The Leyden jar was the forerunner of what today is known as a capacitor. Capacitors are found in a camera’s electronic flash, for example, used to store a charge and then release it instantly when a picture is snapped.
Eventually, the Leyden jar was refined so that the electric charge could be released without having to shock the user, a boon for further experimentation. Leyden jars quickly became as much a novelty item as a scientific instrument. Scores of enterprising experimenters drew rapt crowds all over Europe demonstrating electricity with the jars. They killed birds and small animals with a burst of stored electric charge and sent electrostatic sparks through long wires over rivers and lakes. In 1746, Jean-Antoine Nollet, a French clergyman and physicist, discharged a Leyden jar in the presence of King Louis XV, sending a current of static electricity rushing through a chain of 180 Royal Guards who were holding hands. In another demonstration, Nollet connected a row of Carthusian monks with a metal wire. A Leyden jar was used to send a charge through the wire, and the white-robed monks were said to have leapt simultaneously into the air, goosed by a jolt of electricity.
One of the electric showmen of the day was Dr. Archibald Spencer, a physician from Scotland who came to Boston in 1743 to demonstrate “electric magic” to an audience. Spencer’s demonstrations were high on theatrics—in one display, he drew sparks from the feet of a boy hanging from the ceiling by silk cords. The audience was astonished, never having seen such wonders performed. One audience member was particularly fascinated by the demonstration, a visiting postmaster from Philadelphia named Ben Franklin.

Ben Franklin flying a kite in a thunderstorm: It’s an image burned in the brain of every American schoolchild, an icon as durable as Paul Revere galloping through the countryside or George Washington blithely chopping down a cherry tree. There stands Ben, usually in full colonial dress, tugging on the string of a kite that’s being struck by a jagged bolt of lightning. A key tied to the end of the string gives off a faint but unmistakable glow. Franklin’s face is curiously impassive, particularly for a man who’s come within inches of several million volts of electricity.
Like many of history’s most familiar scenes, the Franklin kite story is a blend of fact and fiction, what a modern-day movie advertisement might describe as being based on a true story. Franklin did indeed fly a kite in a thunderstorm to see whether lightning was a form of electricity, but he wasn’t the first to test this theory, nor was his experiment a very smart approach—Franklin came perilously close to being incinerated on the spot. As it turns out, the kite demonstration was only the most celebrated of Franklin’s many experiments with electricity during his lifetime. Had Ben never flown the kite, his contribution to the electrical arts would have been no less important.
Unlike almost every experimenter who would follow him, Franklin was only a part-time player in the field of electricity. Nearly all of Franklin’s discoveries in electricity took place within a six-year period culminating with his kite experiment sometime in June 1752. Such was the expansiveness of Franklin’s genius that he managed to squeeze groundbreaking electricity research into such a brief period, leaving time for him to be a publisher, writer, postmaster, statesman, raconteur, political philosopher, insurrectionist, and inventor (of the Franklin stove, bifocals, the flexible medical catheter, and swim fins).
Franklin caught the electricity bug after attending Archibald Spencer’s demonstrations in Boston, a show that included drawing long sparks from a Leyden jar as well as from statically charged volunteers. “Being on a subject quite new to me, they equally surprised and pleased me,” Franklin later wrote of Spencer’s stunts. Franklin’s only complaint was that Spencer wasn’t much of a showman; the doctor’s electrical tricks “were imperfectly performed, as he was not very expert.”
Franklin’s insatiable curiosity and theatrical flair made him a natural to take on the mysteries of electricity. Franklin also happened to have free time on his hands. He was in the process of selling his printing shop in Philadelphia and retiring from business in order to devote his time to what Franklin called “philosophical studies and amusements.” After seeing Spencer’s show, Franklin went out and purchased all the electrical equipment he could find, including a Leyden jar. Franklin also obtained a long glass tube for generating static charges, a gift from Peter Collinson, a botanist and fellow of the Royal Society of London. Collinson would quickly become Franklin’s most trusted correspondent in matters relating to electricity, a sounding board for emerging theories. The two men exchanged dozens of letters, and Franklin’s folksy, clear-headed descriptions of his experiments, which were later published, would demystify electricity for thousands.
Once Franklin committed himself to learning everything he could about electricity, he could barely contain his excitement. “For my own part, I never was before engaged in any study that so engrossed my attention and my time as this has lately done,” Franklin wrote to Collinson. The fanciful tricks demonstrated by Dr. Spencer had appealed to Franklin’s roguish nature, and he was soon entertaining friends with his own electrical stunts. Franklin applied an electrical charge to an iron fence surrounding his Philadelphia house so that the fence gave off a harmless but dramatic spark when it was touched. He fashioned a fake spider out of metal and then put a charge to it, making it scurry across the ground. He rigged a portrait of King George II so that anyone touching the king’s crown received “a high-treason shock.” He charged drinking glasses filled with wine so that unsuspecting guests were treated to a spark as they imbibed. He also participated in a parlor game called “the electric kiss,” in which participants passed a charge around a circle with their lips.
In the summer of 1749, Franklin threw a “party of pleasure” on the banks of the Schuylkill River for his friends, with electricity as the featured attraction. Franklin described the affair: “A turkey is to be killed for our dinners by the electrical shock, and roasted by the electrical jack, before a fire kindled by the electrical bottle; while the healths of all the famous electricians in England, Holland, France, and Germany are to be drank in electrified bumpers, under the discharge of guns from the electrical battery.” The electrified turkey, to the surprise of guests, proved to be quite tasty. “The birds killed in this manner eat uncommonly tender,” Franklin wrote.
Franklin delighted in such antics, presenting his latest electrical trick to friends with a mischievous twinkle in his eye. Still, Franklin took the subject of electricity seriously. In his studies, he was guided by one of his favorite aphorisms: “The noblest question in the world is: ‘What good can I do in it?’” Franklin wasn’t so much interested in acquiring knowledge about electricity for its own sake; the goal was always to use the information for the good of all.
Franklin sought to understand electricity through rigorous experimentation, a somewhat novel approach at the time. He performed dozens of experiments with electrical charges drawn from a Leyden jar (“that wonderful bottle,” Franklin called it) and soon began compiling a list of the peculiar properties of electricity. “Electric fire loves water, is strongly attracted by it,” noted Franklin after seeing how water, and even dampness, was a particularly good conductor of electricity. Franklin also discovered—the hard way—that electricity doesn’t merely travel along the surface of an object, but rather passes entirely through it. “If anyone should doubt whether the electric matter passes through the substance of bodies, or only over and along their surfaces, a shock from an electrified large glass jar, taken through his body, will probably convince him,” Franklin wrote.
Experimenting with electricity was dangerous work, and Franklin received his share of unexpected shocks. One jolt was particularly harrowing. A few days before Christmas 1750, Franklin strung together two large Leyden jars, intending to kill a turkey with electricity for his holiday feast. Franklin inadvertently grasped the charged metal chain of one of the Leyden jars, thus completing the circuit. There was a brilliant flash of light and “a crack as loud as a pistol” as the jar discharged, sending a large burst of electrical charge through Franklin’s body.
“The first thing I took notice of was a violent, quick shaking of my body, which gradually remitting, my sense was gradually returned,” Franklin wrote. “That part of my hand and fingers which held the chain was left white, as though the blood had been driven out, and remained so eight or ten minutes after, feeling like dead flesh; and I had a numbness in my arms and the back of my neck, which continued to the next morning.”
Despite producing some painful lessons, Franklin’s experiments began to bear fruit. At the time, it was widely believed that electricity involved two kinds of fluids, known as vitreous and resinous, which operated independently of one another. These two types of fluid were meant to explain why some electrified objects attracted other substances, while others repelled them. Franklin’s own experiments convinced him that electricity was instead a single fluid that manifested itself as two different charged states. As Franklin explained in a letter to Collinson, “Hence have arisen some new terms among us: we say B (and bodies like circumstanced) is electrized positively; A negatively. Or rather, B is electrized plus; A minus.” Franklin apologized for the new terminology, adding, “These terms we may use until your philosophers give us better.”
As it turned out, Franklin’s terms—negative and positive—would stand the test of time, and persist to this day. Franklin’s only mistake was stating that electricity flowed from positive—the terminal with an “excess” of charge—to negative, the terminal with a “shortage” of charge, when in fact it’s the other way around. It would be nearly 150 years until the electron was discovered, the negatively charged particle whose movement is the basis of current flow. By that time, Franklin’s original sense of positive and negative had been in use for so long that his terminology was retained. Even today, electrical circuits are drawn showing the electricity flowing from positive to negative, even though the electron flow is actually in the opposite direction.
Franklin may have gotten the direction of the flow wrong, but he was correct in viewing electricity as a flow of charge that moves in an effort to reach a state of equilibrium. As Franklin noted, when the top of a Leyden jar was charged positively, the bottom was charged negatively in exact proportion. Franklin’s discovery of this phenomenon, known as conservation of charge, was an important breakthrough. Electricity, far from being some magical, capricious force, acted with the predictability of an accountant, always seeking to balance nature’s ledger book of charge.
As Franklin began to piece together the laws that governed electricity, he never lost sight of searching for practical applications of his knowledge. Franklin found one area of inquiry particularly promising: “the wonderful effect of pointed bodies, both drawing off and throwing off the electrical fire,” he wrote in another letter to Collinson.
“Points have a property, by which they draw on, as well as throw off the electrical fluid, at greater distances than blunt objects can,” Franklin wrote. “Thus a pin held by the head, and the point presented to an electrified body, will draw off its atmosphere at a foot distance; where, if the head were presented instead of the point, no such effect would follow.”
Franklin didn’t understand exactly why pointed objects drew sparks better than blunt ones and, ever the pragmatist, didn’t really care. “To know this power of points may possibly be of some use to mankind, though we should never be able to explain it,” Franklin wrote. The power of pointed objects excited Franklin because he saw a useful way to exploit the phenomenon: as a way to draw lightning away from buildings. He noted that lightning, like the electricity in his experiments, seemed to be attracted to tall pointed objects: tall trees, the masts of ships, the spires of churches, and chimneys. Taking note of a sea captain’s account of lightning striking his ship’s mast, Franklin found it significant that the mast gave off sparks shortly before the bolt of lightning actually struck. The metal mast was drawing off a charge from the cloud just as Franklin had drawn off sparks with the pointed end of a pin in his laboratory.
Perhaps lightning was nothing more than a gigantic spark; an oversized version of the small sparks Franklin had discharged in his experiments hundreds of times. Franklin compiled a list of a dozen properties shared by electricity and lightning, including the color of the light emitted; its swift, crooked motion; its ability to be conducted by metals; its crack or noise in exploding; and its sulfurous smell. “Electrical fluid is attracted by points,” Franklin wrote. “We do not know whether this property is in lightning. But since they all agree in particulars wherein we can already compare them, is it not probable they agree likewise in this?” To this question Franklin appended a brief declaration that would become a kind of battle cry for researchers to follow: “Let the experiment be made!”
To determine whether clouds that contain lightning are electrified or not, Franklin proposed a novel experiment: “On the top of some high tower or steeple, place a kind of sentry-box, big enough to contain a man and an electrical stand. From the middle of the stand let an iron rod rise and pass bending out of the door, and then upright twenty or thirty feet, pointed very sharp at the end. If the electrical stand 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.”
Franklin wasn’t the first person to suggest that lightning was a form of electricity; he was, however, the first to propose a scientific method of proving the theory. Franklin never performed the experiment exactly as he proposed it, but the suggestion and the theory behind it attracted worldwide attention after his letters to Collinson were included in a 1751 pamphlet, Experiments and Observations on Electricity, which soon was translated into French, German, and Italian. The booklet caused a sensation in Europe, turning Franklin into an international celebrity, and sparking a surge of amateur experimenting with electricity. The most important of these put Franklin’s proposed lightning experiment to the test.
On May 10, 1752, in the village of Marly-la-Ville just north of Paris, French experimenters constructed a sentry box according to Franklin’s specifications, topped by a pointed iron bar, forty feet high. At twenty minutes past two in the afternoon, a storm cloud passed over the sentry box, and suddenly, the iron bar began attracting sparks of fire. No lightning had struck the iron bar; the metal was drawing off a charge from the storm cloud, just as Franklin had predicted. The experiment was soon replicated in several other locations throughout Europe, though not always with happy results. Georg Wilhelm Richmann, a Swedish physicist working in Russia, was killed by lightning while attempting to replicate the Franklin experiment. Richmann was found dead on the ground with a red spot on his forehead and two holes in his shoes, the entry and exit points of the electrical flow.
News traveled slowly in eighteenth-century America, and Franklin was unaware that the French already had performed his lightning experiment when, about a month later, he decided to try it himself. Thus, while the conventional tale has Franklin’s experiment “proving” his theories about lightning, Franklin’s concepts actually were confirmed experimentally a month before he picked up his kite.