Empires of Light

by Jill Jonnes

  What Franklin did not know as his kite bucked through the electrified heavens that warm late-summer afternoon was that his book Experiments and Observations on Electricity had been translated into French and portions read aloud earlier that spring at a Parisian scientific meeting. The many fractious French scientists, hearing these fascinating ideas for experiments with lightning rods and kites, promptly set off to try them. Three installed a forty-foot-tall lightning rod in a beauteous Gallic garden out in the countryside of Marly-le-roi. The pole, enshrined in a simple wooden structure, stood atop a three-legged stool set in three wine bottles. On May 10, 1752, a thunderclap was heard and an assistant rushed up with a Leyden jar just as a lightning storm began. He successfully drew off large sparks from the pole. As the heavens opened and hail pummeled down, a curious crowd ignored their ever wetter clothes to watch as the lightning was drawn off again and again into the jar. And so, much to Benjamin Franklin’s amazement, not long after he had flown his kite, he discovered that French electricians had beaten him to it! They had performed his proposed experiments from his book first.

  But their dramatic success and wild enthusiasm propelled Franklin to glittering fame and celebrity throughout the United States and Europe. The king of France, no less, applauded this astonished (but delighted) colonial tradesman for his scientific brilliance. Harvard and Yale bestowed honorary degrees, the prestigious Royal Society in London conferred the Sir Godfrey Copley gold medal and inducted the Philadelphian and fellow British subject into its exalted ranks. As one Italian scientist said, “Who would have ever imagined that Electricity would have learned cultivators in North America?”11 Word spread of these Promethean wonders, and Georg Richman, a Swedish scientist living in St. Petersburg in Russia, sought to replicate them. He held aloft a wire-tipped pole during a lightning storm and had the misfortune to attract a full hit of lightning. He was electrocuted on the spot, becoming in 1753 the first person to die during an electrical experiment, a martyr to the young science.

  Predictably, just as those seriously investigating electricity used it also to divert and amuse, so was it quickly hailed as a medical boon. As one Italian scientist said in 1746, “No thought could occur more readily than this, the moment people saw such light flashing from the body, limbs, and skin, and felt the stings, painful blows and sharp stimuli that penetrated almost into the bones when the lights appeared.”12 Real doctors (such as they were in those days) and itinerant quacks promoted electricity as the cure for constipation, nervous disorders, sexual maladies and infertility, sciatica, rheumatism, lacrimation, and herpes, to name a few ailments. In Italy, three medical schools opened devoted just to healing through electricity. Italy (then part of the Austrian empire) would also be the scene of one of the greatest modern advances in electricity, the consequence of a bitter scientific dispute between the quiet, retiring Luigi Galvani, esteemed physician and anatomist at the University of Bologna, and Alessandro Volta, respected professor of physics at the ancient University of Pavia. Like almost every other scientist of their age, each man was deeply fascinated by electricity, Galvani wondering about its possible role in the workings of the body’s nerves and muscles, Volta looking at the basic nature of electricity and its chemical interactions.

  This famous scientific feud had its origins in a series of experiments performed by Luigi Galvani, forty-four years old, handsome, clean-shaven, and coiffed in the era’s gentlemanly fashion—white peruke, fine lace jabot at his neck, and long dark coat and breeches. On January 26, 1781, Galvani was dissecting a pair of large frog’s legs with some assistants. Nearby, an electrostatic machine was being turned. Galvani’s assistant noticed with astonishment that when he touched the frog’s leg at a particular spot with a scalpel, the leg—unattached to any frog—jerked. Galvani wrote later, “I immediately repeated the experiment. I touched the other end of the crural nerve with the point of my scalpel, while my assistant drew sparks from the electrical machine. At each moment when sparks occurred the muscle was seized with convulsions.”13 Sensitized to this phenomenon of jerking frog’s legs, Galvani now noticed that prepared frogs suspended by brass hooks and hung on an iron trellis in his backyard also jerked when the brass hook was pushed against the trellis. Galvani became convinced that what he was seeing was “animal electricity” completing a circuit with these metallic instruments. “The idea grew that in the animal itself there was an indwelling electricity.”14 For the next decade, Galvani quietly worked on a variety of experiments with his frog’s legs and published a series of papers in Latin (the scientific language of the day), culminating in 1791 with “On the Effect of Electricity on the Motion of the Muscles.” Just as when Benjamin Franklin’s work became known, hundreds of dedicated electrical philosophers rushed to replicate Galvani’s “animal electricity” experiments.

  Among them was physicist Alessandro Volta of Pavia, forty-six, a stern-visaged, clean-shaven man with a thin fringe of dark hair. Professor Volta’s electrical accomplishments were already so stellar that he had been inducted into London’s prestigious Royal Society. Son of an impecunious nobleman, Volta had grown up on Lake Como and shown a precocious ability in science and mathematics. His major discovery up to this time was the highly sensitive “condensing electroscope” that measured electric charge. While Volta initially accepted Galvani’s striking discovery, applauding “the fine and grand discovery of an animal electricity, properly so called,” as he began to replicate the experiments on the frog’s legs he became more and more skeptical.15 Ultimately, he became convinced that the electricity was coming not from the frogs, but from the metal, and in 1794 he challenged Galvani to refute his, Volta’s, findings that the electricity was actually “metallic.” Galvani’s many supporters, led by his nephew Aldini, came back with a frog experiment that showed a distinct jerk even when no metal was involved. The always reserved Galvani himself was still mourning the loss in 1790 of his beloved wife, a learned woman who had worked on these experiments with him. The feud grew sufficiently bitter that Volta would write to one friend, “I know those gentlemen want me dead, but I’ll be damned if I’ll oblige them.”16 So the animal versus metallic electricity dispute dragged on, with each scientist and his followers throughout the Continent performing many subsequent experiments that often did little to illuminate the situation but seemed important or decisive at the time.

  Then in 1796 Napoleon Bonaparte swept over the Alps with the French army, and these Austrian citizens found themselves subjects of a new revolutionary Cisalpine Republic. Luigi Galvani loyally refused over the next two years to take an oath of allegiance to the new government, and in late April 1798 he was expelled from the University of Bologna, where he had happily practiced anatomy for thirty-five years. In early December, Luigi Galvani, sixty-one, died, politically ostracized and penniless. Professor Volta, after initial protests, reached some accommodation with the Napoleonic regime and continued on at the University of Pavia.

  As leader of the “metallic” electricity forces, Alessandro Volta had been methodically testing dissimilar metals and measuring their electric charge with his sensitive electroscope, determining if each was positive or negative. He also observed that the electrical charge was noticeably stronger when his finger touched the metals, which he deduced was the effect of saline moisture. On March 20, 1800, Volta wrote a letter in French to Sir Joseph Banks, president of London’s Royal Society, saying, “After a long silence, for which I shall offer no apology, I have the pleasure of communicating to you … some striking results I have obtained in pursuing my experiments on electricity excited by the mere mutual contact of different kinds of metal, and even by that of other conductors, also different from each other, either liquid or containing some liquid, to which they are properly indebted for their conducting power…. This apparatus to which I allude, and which will, no doubt, astonish you, is only the assemblage of a number of good conductors.”17

  Drawing on his carefully observed knowledge about which materials did and did not cond
uct electricity, Volta assembled atop one another inch-wide pairs of copper disks and zinc disks separated from other such disks by a cloth disk or pasteboard soaked with salt water. When these disks were all touching one another, the copper lost electrons to the saline-soaked cloth, while the zinc gained electrons from the same wet cloth. As the zinc dissolved, hydrogen gas was produced at the surface of the copper. The resulting electrical charges flowed out in a steady direct current along the wires. This electrochemical reaction produced the first steady generation of man-made current, flowing from the battery on two insulated wires, one on top and one on the bottom.

  Here was the first primitive battery able to deliver a continual, steady electrical charge, in contrast with the electrostatic machines or the Leyden jar, which delivered their electricity in high-voltage static bursts or jolts. His pile, said Volta, operated “without ceasing, and its charge re-establishes itself after each explosion. It operates, in a word, by an indestructible charge, by a perpetual action or impulse in the electric fluid.” Actually, the Volta battery pile would stop generating electricity once the saline liquid dried up or the metal was all dissolved. For while Volta believed it was solely the contact of dissimilar metals that powered his battery, it was in fact the electrochemical interactions between these metals and the liquids. The longer the battery ran, the more these materials diminished. Volta also designed an alternate version of his battery, which he called his “crown of cups,” that featured brine-filled cups connected by alternate strips of zinc and silver and metal wire.

  With France and England at war, Volta’s communication took some time to reach London and was not read before the Royal Society until June 26, 1800. Volta’s brilliant and pathbreaking work was hailed throughout Europe and America. A contemporary declared the battery “the most wonderful apparatus that has ever come from the hand of man, not excluding even the telescope or the steam engine.” Other scientists quickly replicated Volta’s “electrical pile,” building larger and larger versions. Ironically, the steady current of electricity generated by Volta’s battery—steady direct current—came to be known as Galvanic, thus verbally immortalizing his electrical foe. Volta, in turn, was linguistically enshrined by the term volt, which measures the electrical force of a current. In the immediate aftermath of his epochal electrical triumph, Volta was much honored and richly rewarded, becoming a count in the Napoleonic government. Newly married, famous, and wealthy, he then played little role in further advancing his battery or electrical philosophy.

  Other scientists scrambled to construct ever bigger, more powerful Voltaic batteries to generate more powerful, longer-lasting Galvanic currents. Over in London at the new Royal Institution on Albemarle Street, already “the world’s greatest showplace for the popularization of science,” the dashing young chemist Humphry Davy arranged to have constructed progressively larger batteries in the institution’s basement laboratory. In the first decade of the nineteenth century, Davy applied these big batteries to his pathbreaking work establishing that electrochemical reactions were the basis of electricity. The Royal Institution was opened in 1799 to advance and apply science “to the common purposes of life,” and its initial patrons were the distinguished English grandee Sir Joseph Banks, president of the Royal Society, and the controversial inventor-statesman Count Rumsford, an American-born “opportunist, womaniser, philanthropist, egotistical bore, soldier of fortune, military and technical adviser.”18 It was Count Rumsford who hired Davy, a handsome and charismatic young chemist who was beginning his swift rise to scientific and intellectual glory. Davy’s public lectures at the Royal Institution combined such erudite pyrotechnics and dazzling showmanship, hundreds of well-dressed personages soon flocked into the amphitheater to watch and listen as this effervescent Cornishman with his tumbling locks brought to life the abstruse mysteries of electricity or chemistry. The poet Samuel Taylor Coleridge, friend and admirer, attended these crowded scientific affairs and claimed in awe that if Davy had not been “the first chemist of the age, he would have been the first poet.”

  From the start, Davy believed that the electricity produced by Alessandro Volta’s battery came from electrochemical interactions. Moreover, once Davy had constructed a sufficiently powerful battery in October 1807, he demonstrated that the converse was true—chemical compounds could be decomposed into their basic elements by electricity. Davy decomposed alkalies into potash and soda ash with electricity, then further extracted entirely new elements, potassium and sodium. Davy, this son of a humble wood-carver, had by now burnished his innate nobility by marrying a wealthy heiress. Fortune was soon followed by public honors, including a knighthood. He became Sir Humphry Davy. Sir Humphry’s passion, panache, and accomplishment allowed him to travel in the highest social circles, whether among dukes and lords at their great country estates or among the era’s most brilliant artists and thinkers, immortals like the poet William Wordsworth and the incomparable painter of landscapes and light Joseph Turner. In 1808, Davy, by now director of the Royal Institution, had constructed a gigantic battery of two thousand pairs of plates in the basement laboratory. Applying the intense electrical energy produced by this massive battery to alkaline earth, Davy extracted more new elements—magnesium, calcium, barium, and strontium.

  But most visually spectacular of Sir Humphry’s electrical researches was the arc light. In 1809, he gave one of his most literally dazzling lectures. He stood before his usual large enthralled audience and held up two thin charcoal sticks, which served as conductors of electricity. One stick was then connected to a powerful Voltaic pile. When the electricity began to flow through the first stick, Sir Humphry touched it to the top of the second stick. A brilliant spark appeared where the two met. What amazed those present was that as Sir Humphry pulled the two sticks slightly apart, the spark grew larger and the electricity traveled in a dazzling arc of light between the two slender carbon rods. This almost painfully bright blue white light would burn until either the carbons or the electricity ran out. Sir Humphry’s thrilling demonstration set off determined efforts to produce a commercial arc light, but properly calibrating the carbons created many troubles and no battery could economically run bright lights for the many hours needed to be practical.

  And there the art of electricity would linger, as frustrated scientists and philosophers tried year after year to unlock and decipher electricity’s multitude of remaining secrets, especially what many suspected was its relationship to magnetism. The early days of dedicated individual philosophers working on electricity in their homes—men like Benjamin Franklin, Otto von Guericke, and Stephen Gray—were slowly giving way now to the modern era of university-trained scientists operating out of university laboratories or special institutes. Mastering the growing mass of specialized knowledge was time-consuming, while few individuals could afford to construct the ever more complex equipment needed to study electricity, especially the gigantic Voltaic piles. Moreover, national leaders were well convinced of the vital importance of science and technology to national wealth and well-being. So it was not surprising that the next great electrical breakthrough came out of a European university.

  In the spring of 1820, Hans Christian Oersted, forty-three, physics professor at the University of Copenhagen, was giving a private lecture on electricity to a group of advanced students. The professor, a tall, sturdy man with dark curls and thick sideburns, was dressed in a long black coat, vest, and high-collared white shirt and cravat. Before him on his wooden laboratory table, Professor Oersted had set up a small Voltaic battery. In his hand, he held a charged electrical wire, intending to make a point about heating platinum wire using electrical current. But as he prepared to apply the wire, the professor noticed the wildly swinging magnetic needle on his large desk compass. When he moved the wire above and around the compass, the needle responded strongly—as if to a magnet—and in very specific ways to the electric current.

  Oersted, like Sir Humphry Davy, was a self-made scientist, a country boy of little me
ans whose love for learning and intellectual prowess had earned him scholarships and finally a university appointment. Fluent in several languages, Oersted was trained in pharmacy (thereby having access to many chemicals), had traveled widely to meet other scientists, and was also among the many striving to establish the relationship between magnetism and electricity. In an 1813 book, he had written, “An attempt should be made to see if electricity in its latent stage, has any action on a magnet as such.”19 Now here, seven years later, by his astute observation of the swinging compass needle, Professor Oersted had stumbled across the long-sought clue. In subsequent experiments, Oersted found that the compass needle swung about and took up a position at right angles to the charged wire. If he reversed the flow of electricity, the needle deflected in the opposite direction. In short, electric current produced its own magnetic field and, by means of that field, a force.

  On July 21, 1820, Han Christian Oersted announced his discovery of electromagnetism in a four-page paper written in Latin, whose (translated) title was “Experiments on the Effect of an Electric Current on the Magnetic Needle.” He sent copies of his monograph to every important university, learned society, and electrical scholar in Europe. Oersted wanted full credit for making this historic discovery, which unraveled further the mysteries of this invisible but potent force, electricity. As word of his great breakthrough slowly spread in this era before telegraph, telephone, or train—Sir Humphry learned of it only in October—Han Christian Oersted was hailed and feted as an electrical genius, as had been Benjamin Franklin and Alessandro Volta before him. Oersted was awarded the Royal Society’s Copley gold medal and inducted into many scientific societies.