Science Secrets Page 14
In 1753, Jacques de Romas in France reported his own successful attempts to collect airborne electricity with the twine of a large kite.15 (De Romas did not know whether Franklin or anyone else had conceived the same experiment.) Failing to collect electricity with a scarcely wet string, de Romas ran a thin copper wire along the hemp string. In daytime, he raised his kite to roughly 550 feet high (780 feet of string), and tied three and a half feet of silk at the bottom, anchored to a heavy stone pendulum. Near the silk, on the string, he tied a one-foot-long tin tube. De Romas then drew sparks by approaching a metal-tipped glass wand toward the hanging tube. He and several assistants and bystanders also used their fingers to draw sparks. The sparks ceased when the dark clouds overhead drifted away. When more clouds arrived, the witnesses used their fingers, keys, canes, and swords to feel the electricity, but then de Romas used a knuckle and received a painful shock—in his fingers, wrist, elbow, shoulder, abdomen, knees and ankles. After more experiments, the storm approached, growing violent, but no rain. So, fearing a deadly accident, de Romas then used only the glass-metal wand to draw sparks. Everyone took steps away. Straws on the ground stood upright and danced under the hanging tin tube. De Romas felt an electrical effect, like spider webs on his face. Then a long straw jumped from the ground to the tin tube and caused a terrifying explosion that cracked like thunder and caused a bright spark of electric “fire” roughly eight inches long. Crackling sounds happened, along with more sparks, and the string became luminous. The experiment ended because wind and rain made the kite fall; fortunately, nobody was injured.
Unlike Franklin, de Romas gave abundant detailed observations about various procedures, measurements, precautions, times, conditions, findings, observations, sounds, and even smells. Franklin had briefly described only one experiment, which was oddly cryptic and prescriptive, whereas de Romas described the execution of multiple specific experiments. Soon, some individuals wondered whether de Romas should well be credited as being the first to carry out the kite experiment and make the effect clearly visible.16 De Romas complained to the Paris Academy of Sciences that he was really the first to succeed and that aspects of Franklin's report seemed questionable. Nevertheless, scientists began to compare Franklin with Prometheus: “Among all the phenomena of electricity it is difficult to find one as marvelous as that which Mr. Franklin has discovered, if it is true that this new Prometheus managed to draw the fire from the Sky.”17
A committee of the academy concluded in 1764 that de Romas should indeed be regarded as having priority, unless Franklin or anyone provided evidence to the contrary. The committee included Franklin's scientific nemesis, Abbé Jean Nollet. The contentious Nollet had experience in criticizing and exposing electrical frauds and charlatans in France and Italy. But Franklin did not respond, just as he remained oddly quiet toward admirers who independently asked him about that particular experiment.18
Later, in 1767, Joseph Priestly published an account that added some details to Franklin's original brief article. Priestley wrote (presumably echoing Franklin) that Franklin had conducted the kite experiment in a field, under a shed, allegedly with one witness: his son. Priestley's account dated Franklin's experiment to June 1752—just a month after experimenters in Marly had already shown that lightning consists of electricity, but before Franklin had heard about it.19 Yet if this was the case, why did Franklin wait more than three months to first report his extraordinary and brave experiment in the August Gazette?
But why would we doubt Ben Franklin? Looking at Franklin's achievements prior to 1752, we find that he invented the lightning rod, he operated a newspaper, he founded a library and a volunteer firefighting company, he implemented techniques to prevent the counterfeiting of currency, he founded the Academy and College of Philadelphia, he worked to establish the Pennsylvania Hospital, he was elected to the Pennsylvania Assembly, and he served as a Justice of the Peace for Philadelphia.
Aside from his many positive contributions to science, politics, diplomacy, and printing, Ben Franklin was also good at hoaxes. In 1732, he began publishing a comic almanac that started with the hoax of a (fictional) editor who predicted the death of the real editor of a prominent almanac. In 1742, he wrote a “Plain Truth” essay pretending to be a Scottish Presbyterian trying to incite military actions. In 1747, he invented and published a story about a woman who was put on trial by Puritans for the sin of having many babies out of wedlock.20 The story gained much international attention, but twenty-two years later, Franklin admitted that it was entirely a prank. In other publications, he concocted plausible but fake messages from other characters: a Jesuit, the King of Prussia, and a Muslim who supposedly relished slavery. He also published a humorous letter stating that dead flies come back to life when submerged in wine. He published plenty of words that were simply not true.
Benjamin Franklin was not a Presbyterian, Jesuit, or Muslim; he was an active member of a secretive brotherhood: “that most ancient and Right Worshipful Fraternity,” the Freemasons. In 1734, when he served as Grand Master of their Pennsylvania Lodge, Franklin reprinted “The Constitutions of the Freemasons,” a treatise from 1723 that noted, among other things, that freemasonry, all of it—civil, military, and sacred—was based on the geometrical theorem authored by Pythagoras.21
Did Franklin really carry out the electric kite experiment? How can we fly a kite out of a window or doorway during a rainstorm? One would need to prevent the line from touching the window or door frame, so that the electric charge is not lost. How can the rain wet the line while keeping a silk ribbon tied to it dry? Tom Tucker, having researched the matter, even trying to fly kites out of a window and through a wooden frame, concluded, “He-really-didn't-do-this.”22
I used to agree with Tucker, but now I'm not sure. I had studied this topic in books, and I became convinced that a compelling argument against the story was that if Franklin were to fly a kite out of a building it would be terribly awkward to constantly try to prevent the line from touching or snagging against the sides of the window or doorway, as Tucker described. Therefore, one day, I went out to a field by El Morro castle, in Puerto Rico, and I flew a kite with my father from under the archway of an old structure, and also from under the entrance of another tall building with columns. The line was remarkably stable, it did not touch the sides of these entrances, not for dozens of minutes, not at all. So I no longer think that flying a kite from a building and keeping the line steady is a difficulty. Still, I did not fly the kite in a thunderstorm, and I did not fly it under a drizzle of rain. These factors in Franklin's account still make his story seem implausible: first, one would have to elevate the kite before the rain starts, then move to the covering provided by a building; then hopefully a drizzle would start, and finally, hopefully, the rain would not wet the portion of line beneath the silk ribbon. (Why not simply soak the string before elevating the kite?) Personally, I choose not to guess the past, I just don't know whether Franklin managed to do this.
Still, most writers and historians duly credit Franklin as having carried out the experiment. For example, in a classic article, I. B. Cohen accurately discussed much evidence, addressed various ambiguities, and he concluded that Franklin did fly the kite in June 1752. But at the end of his article, Cohen admitted that he had begun by assuming that what Franklin and Priestley had written was true, and subsequently had tried to interpret all the evidence in ways that would square with their account. Having overtly used a plethora of reasonable conjectures, he admitted that several more were implicit: “I am fully aware that many more statements in this article should contain such words as ‘very likely,’ ‘possibly,’ ‘probably,’ ‘may well have,’ etc.”23 By contrast, I have used no such speculative arguments, and therefore I have not reached the same conclusion as Cohen.
The television show MythBusters, in an episode aired in 2006, tried to replicate Franklin's experiment. The show's cast members constructed several kites, following Franklin's vague specifications, but they did not m
anage to get them to fly until they modified them. Instead of testing how a kite flying under a storm cloud can gather electricity, they tested the obvious myth that lightning struck the kite. Using a Van de Graaff generator, they transmitted an electrical discharge onto the wet string, which created a tiny spark from the key. A much greater discharge set it on fire. Next, they raised the generator to 480,000 volts and flew the kite—a spark of electricity jumped to the kite, down the wet string to the key, and onto the hand of a dummy made to look like Franklin. A heart monitor showed that this shock would have killed him.24
Meanwhile, in 2006, an electrician in Belize was flying a kite with a niece. But he wanted a longer line so, not having any more string, he added some long copper wire. Flying, the kite approached some high tension power lines. Reportedly, the kite broke loose and the copper wire fell onto the electrical lines which then electrocuted the man, knocked him down, and burned him severely; he died soon after.25 Following this incident, Belize Electricity Limited issued a press release giving several kite safety tips, saying that one should never use wire, and also: “Never fly kites in wet or stormy weather.”
I don't know whether Franklin flew the kite, but even if he didn't, the story still works. That one of America's founding fathers crowned his real contributions to science with a captivating bluff, that the mere idea of his experiment was extraordinarily influential. The rags-to-riches commoner who boldly used a child's toy to draw down the awesome power of lightning from the sky—this image insinuates equality: that self-educated, lone amateurs can contribute to science just as much as the intellectual elite. Even if Franklin did not actually carry out the experiment, some brave individuals managed to pull it off with various contraptions and safety precautions. Besides, there are other experiments in the history of electricity that were similarly extraordinary and clearly did happen. Whereas in the kite experiment we may well be fearful and hesitant to test its truth by carrying it out, there are other perplexing experiments that we can well try.
7
Coulomb's Impossible Experiment?
IN many schoolbooks, electricity shows up as just another dry, boring, difficult, and monotonous subject. But it wasn't always that boring. Electricity seemed to hold the secret of life after death. In 1802, an Italian experimenter, Giovanni Aldini, performed demonstrations before French scientists, using dead animals and prongs to transmit electrical currents. Witnesses reported: “Aldini, after having cut off the head of a dog, passed the current of a strong battery: the mere contact triggers truly frightful convulsions. The mouth opens, teeth rattle, eyes roll in their sockets; and if reason did not deter the agitated imagination, one would almost believe that the animal is again suffering and alive.”1
Aldini also had the nerve to conduct this kind of experiment on human bodies, publicly. And audiences had the courage to witness the results. Back then, punishment for criminals did not always end at death. In London, for example, a man could be sentenced to death followed by a public dissection. Bodies were cut and flayed and organs were pulled out for the edification and education of the masses, and also as a continuation of penal torture. On 18 January 1803, George Foster was executed by hanging at Newgate Prison, London, for murdering his wife and child by drowning them. His lukewarm corpse was then taken to a house where Professor Giovanni Aldini would “galvanize” it. The proceedings were reported in the Newgate Calendar: The Malefactor's Bloody Register.2 In front of a medical audience, Aldini applied an electrical rod to the cadaver's mouth and another to an ear, whereupon the face grimaced horribly, his jaw quivered, and an eye opened. Aldini also applied the electrical rods to the corpse's rear end, causing the entire body, legs and arms, to convulse.3 Some spectators feared that murderer George Foster was coming back to life. One old official of the Surgeons' Company was so alarmed that soon after he left he died of fright.4 The Bloody Register noted that if a convict were revived, he would have been killed by hanging again.
Electricity was a high-stakes field in the early 1800s: Aldini's ultimate aim was to learn to “command the vital powers,” and disturbed by the implications of electrical experiments, Mary Shelley wrote the horror novel Frankenstein. Electricity seemed to hold not only the power of life and death, but also of sanity, as Aldini reportedly cured mentally ill patients by inflicting electric shock. Even decades earlier, in the 1740s, when experimenters had found a way to store electrical fluid in a so-called Leyden jar, electricity was used to amuse and perplex, by administering it even to dozens of men in a chain, all of whom would then scream and contort. Moreover, electricity could be used to really do the presumably impossible—to move things without touching them.
Since ancient times, people had seen that when certain materials are rubbed, especially amber, small things such as hair move toward them. Amber could pick up small bits of stuff from the ground. According to Diogenes Laertius, the ancient philosopher Thales of Miletus believed that there was soul or life in inanimate objects such as amber.5 This precious yellow substance is the fossilized resin of extinct coniferous trees, and since it was yellow, the Greeks called it elektron, as it resembled the pale gold metal that had the same name. That metal, electrum, is a natural alloy of silver and gold, and its root word, elektor, meant “beaming sun.”
By the late 1700s, numerous devices harnessed the divine powers of electricity. It became increasingly important to understand electricity. How does it work? Could it be understood in terms of natural laws? If anyone could find a mathematical order in electrical effects, then electricity would be understood not as an occult wonder, but as a natural phenomenon. A solution to this problem was advanced, some fifteen years prior to Aldini's works, by a retired French engineer: Charles Augustin Coulomb.
What Coulomb claimed to find amounted to saying that electricity obeys the following algebraic law:
It states that two electrical charges (q1 and q2) attract or repel one another with a force that increases as the square of the distance (d) between them decreases. The remarkable thing about this equation is that it is formally identical to Newton's law of gravity:
That is, the force of gravity between masses varies with the square of the distance in the same proportion. Newton's law seemed to meet the reputedly Pythagorean ambition to understand phenomena numerically. And likewise, Coulomb's law exhibited the same form, submitting the mysterious phenomena of electricity to the harmonious rule of numbers.6
Why did the two laws have the same form? Gravitational effects seemed quite different from electrical effects. For example, gravity seemed to be universal; according to Newton all bodies have gravity, whereas not every object seemed to have electrical charge. And charge flows in and out of bodies such that one object can have a lot of charge at one moment and apparently none at another, whereas gravity never seems to vary in any one object. Moreover, electrically charged objects can attract or repel one another, whereas gravity only attracts. So why would such different forces follow the same mathematical equation?
One might imagine that electrostatic attraction is weaker than gravity, because we usually see it in minor things such as hair and sweaters, whereas the sun's gravity holds the immense planet Jupiter in orbit, millions of miles away. Actually, electrical force is stronger than gravity. By contrast, the gravity on a comb is much too weak to attract anything as large as a flake of dandruff. Electrical force is billions of times stronger. Roughly put, electrical force is 1039 times stronger than gravity. It does not instantly kill us because we live in a mostly delicately balanced, nearly neutral electrical environment. But lightning kills. So, scientists struggled to figure out how electricity operates.
Following Newton's successful account of the dynamics of the heavens, people in Europe tried to replicate his mathematical method in various fields. The members of the Paris Academy of Sciences, for example, were convinced that reason aided by mathematics could comprehend the most puzzling physical phenomena. Charles Coulomb was a member of the Paris Academy, and he worked to analyze the elect
rical force. In 1785, he announced to the academy that he had proven that electrical forces behave mathematically like Newton's gravity. Whereas the academy had cast doubt on Franklin's brief and vague report, they accepted and praised Coulomb's experiment. How did Coulomb do it?
First, let's look at the inverse square equation. Until we have made some experimental tests, it is only a conceivable theoretical account. So, to test the equation, one might find some of its numerical consequences and check to see if such numerical values, or others, actually show up in some experiments.
One simple property of the equation is that it entails that if the distance between two bodies decreases by half then the force between them should become four times greater. This might not be obvious to everyone, so it may be explained as follows. Consider two electrically charged bodies, q1 and q2, separated by a distance d. If the electrostatic repulsion between them really can be described by an inverse square law, then we expect that their force of repulsion is:
Now, if these two bodies, while keeping their charges, are brought closer together, so that their separation is now half as large, then we may express their force of repulsion as:
Again, only the force and distance have changed. This equation may be rewritten as:
which together with the equation for F1 yields:
This means that at half the distance, there is four times the force between the two bodies. (As with the alleged finding of the Pythagoreans: the same tension upon a string half as long acts four times more.) Coulomb devised a way to test this simple relation. If electrical repulsion really acted as the equations suggest, then wherever the distance between two charged bodies is reduced by half, the force between them should quadruple.