Walter Isaacson Great Innovators e-book boxed set

by Walter Isaacson

  For centuries, the devastating scourge of lightning had generally been considered a supernatural phenomenon or expression of God’s will. At the approach of a storm, church bells were rung to ward off the bolts. “The tones of the consecrated metal repel the demon and avert storm and lightning,” declared St. Thomas Aquinas. But even the most religiously faithful were likely to have noticed this was not very effective. During one thirty-five-year period in Germany alone during the mid-1700s, 386 churches were struck and more than one hundred bell ringers killed. In Venice, some three thousand people were killed when tons of gunpowder stored in a church was hit. As Franklin later recalled to Harvard professor John Winthrop, “The lightning seems to strike steeples of choice and at the very time the bells are ringing; yet still they continue to bless the new bells and jangle the old ones whenever it thunders. One would think it was now time to try some other trick.”8

  Many scientists, including Newton, had noted the apparent connection between lightning and electricity. But no one had declared “Let the experiment be made,” nor laid out a methodical test, nor thought of the practicality of tying this all in with the power of pointed metal rods.

  Franklin first sketched out his theories about lightning in April 1749, just before his end-of-season turkey fry. The water vapors in a cloud can be electrically charged, he surmised, and the positive ones will separate from the negative ones. When such “electrified clouds pass over,” he added, “high trees, lofty towers, spires, masts of ships…draw the electrical fire and the whole cloud discharges.” It was not a bad guess, and it led to some practical advice: “Dangerous therefore it is to take shelter under a tree during a thunder gust.” It also led to the most famous of all his experiments.9

  Before he tried to conduct his proposed experiments himself, Franklin described them in two famous letters to Collinson in 1750, which were presented to the Royal Society in London and then widely published. The essential idea was to use a tall metal rod to draw some of the electrical charge from a cloud, just as he had used a needle to draw off the charge of an iron ball in his lab. He detailed his proposed 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…upright 20 or 30 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 the cloud. If any danger to the man 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 [i.e., insulating him from it]. So the sparks, if the rod is electrified, will strike from the rod to the wire and not affect him.

  Franklin’s one mistake was thinking that there would be no danger, as at least one European experimenter fatally discovered. His suggestion of using a wire held with an insulating wax handle was a smarter approach.

  If his suppositions held true, Franklin wrote in another letter to Collinson, then lightning rods could tame one of the greatest natural dangers people faced. “Houses, ships and even towns and churches may be effectually secured from the stroke of lightning by their means,” he predicted. “The electrical fire would, I think, be drawn out of a cloud silently.” He wasn’t certain, however. “This may seem whimsical, but let it pass for the present until I send the experiments at large.”10

  Franklin’s letters were excerpted in London by The Gentleman’s Magazine in 1750 and then published as an eighty-six-page booklet the following year. More significant, they were translated into French in early 1752 and became a sensation. King Louis XV asked that the lab tests be performed for him, which they were in February by three Frenchmen who had translated Franklin’s experiments, led by the naturalists Comte de Buffon and Thomas-François D’Alibard. The king was so excited that he encouraged the group to try Franklin’s proposed lightning rod experiment. As a letter to London’s Royal Society noted, “These applauses of his Majesty having excited in Messieurs de Buffon, D’Alibard and de Lor a desire of verifying the conjectures of Mr. Franklin upon the analogy of thunder and electricity, they prepared themselves for making the experiment.”

  In the village of Marly on the northern outskirts of Paris, the Frenchmen constructed a sentry box with a 40-foot iron rod and dragooned a retired soldier to play Prometheus. On May 10, 1752, just after 2 in the afternoon, a storm cloud passed over and the soldier was able to draw sparks as Franklin had predicted. An excited local prior grabbed the insulated wire and repeated the experiment six times, shocking himself once but surviving to celebrate the success. Within weeks it was replicated dozens of times across France. “M. Franklin’s idea has ceased to be a conjecture,” D’Alibard reported to the French Royal Academy. “Here it has become a reality.”

  Though he did not yet know it, Franklin had become an international sensation. An ecstatic Collinson wrote from London that “the Grand Monarch of France strictly commands” that his scientists convey “compliments in an express manner to Mr. Franklin of Philadelphia for the useful discoveries in electricity and application of the pointed rods to prevent the terrible effects of thunderstorms.”11

  The following month, before word of the French success reached America, Franklin came up with his own ingenious way to conduct the experiment, according to accounts later written by himself and his friend the scientist Joseph Priestley. He had been waiting for the steeple of Philadelphia’s Christ Church to be finished, so he could use its high vantage point. Impatient, he struck on the idea of using instead a kite, a toy he had enjoyed flying and experimenting with since his boyhood days in Boston. To do the experiment in some secrecy, he enlisted his son, William, to help fly the silk kite. A sharp wire protruded from its top and a key was attached near the base of the wet string, so that a wire could be brought near it in an effort to draw sparks.

  Clouds passed over to no effect. Franklin began to despair when he suddenly saw some of the strands of the string stiffen. Putting his knuckle to the key, he was able to draw sparks (and, notably, to survive). He proceeded to collect some of the charge in a Leyden jar and found it had the same qualities as electricity produced in a lab. “Thereby the sameness of electrical matter with that of lightning,” he reported in a letter the following October, was “completely demonstrated.”

  Franklin and his kite were destined to be celebrated not just in the annals of science but also in popular lore. Benjamin West’s famous 1805 painting, Franklin Drawing Electricity from the Sky, mistakenly shows him as a wrinkled sage rather than a lively 46-year-old, and an equally famous nineteenth-century Currier and Ives print shows William as a little boy rather than a man of about 21.

  Even among scientific historians, there is some mystery about Franklin’s celebrated kite flying. Although it supposedly took place in June 1752, before word had reached him of the French tests a few weeks earlier, Franklin made no public declaration of it for months. He did not mention it in the letters he wrote Collinson that summer, and he apparently did not tell his friend Ebenezer Kinnersley, who was lecturing on electricity in Philadelphia at the time. Nor did he publicly report his kite experiment even when word reached him, probably in late July or August, of the French success. His Pennsylvania Gazette for August 27, 1752, reprinted a letter about the French experiments, but it made no mention that Franklin and his son had already privately confirmed the results.

  The first public report came in October, four months after the fact, in a letter Franklin wrote to Collinson and printed in his Pennsylvania Gazette. “As frequent mention is made in the public papers from Europe of the success of the Philadelphia Experiment for drawing the electric fire from the clouds,” he wrote, “it may be agreeable to the curious to be informed that the same experiment has succeeded in Philadelphia, though made in a different and more easy manner.” He went on to describe the det
ails of constructing the kite and other apparatus, but in an oddly impersonal way, never using the first person to say explicitly that he and his son had carried it out themselves. He ended by expressing pleasure that the success of his experiments in France had prompted the installation of lightning rods there, and he made a point of noting that “we had before placed them upon our academy and state house spires.” The same issue of the paper advertised the new edition of Poor Richard’s Almanack, with an account of “how to secure houses, etc., from lightning.”

  A more colorful and personal account of the kite flying, including the details about William’s involvement, appeared in Joseph Priestley’s The History and Present State of Electricity, first published in 1767. “It occurred to him that, by means of a common kite, he could have a readier and better access to the regions of thunder than by any spire whatever,” Priestley wrote of Franklin, and “he took the opportunity of the first approaching thunder storm to take a walk into a field, in which there was a shed convenient for his purpose.” Priestley, a noted English scientist, based his account on information directly from Franklin, whom he first met in London in 1766. Franklin supplied Priestley with scientific material and vetted the manuscript, which ends with the flat declaration: “This happened in June 1752, a month after the electricians in France had verified the same theory, but before he had heard of anything they had done.”12

  The delay by Franklin in reporting his kite experiment has led some historians to wonder if he truly did it that summer, and one recent book even charges that his claim was a “hoax.” Once again, the meticulous I. Bernard Cohen has done an exhaustive job of historical sleuthing. Drawing on letters, reports, and the fact that lightning rods were erected in Philadelphia that summer, he concludes after forty pages of analysis that “there is no reason to doubt that Franklin had conceived and executed the kite experiment before hearing the news of the French performance.” He goes on to say that it was performed “not only by Franklin but by others,” and he adds that “we may with confidence conclude that Franklin performed the lightning kite experiment in June 1752, and that soon after, in late June or July 1752, it was in Philadelphia that the first lightning rods ever to be erected were put in service.”13

  Indeed, it is unreasonable, I think, to believe that Franklin fabricated the June date or other facts of his kite experiment. There is no case of his ever embellishing his scientific achievements, and his description and the account by Priestley contain enough specific color and detail to be convincing. Had he wanted to embellish, Franklin could have claimed that he flew his kite before the French scientists carried out their version of his experiment; instead, he generously admitted that the French scientists were the first to prove his theory. And Franklin’s son, with whom he later had a vicious falling-out, never contradicted the well-told tale of the kite.

  So why did he delay reporting what may be his most famous scientific feat? There are many explanations. Franklin almost never printed immediate accounts of his experiments in his newspaper, or elsewhere. He usually waited, as he likely did in this case, to prepare a full account rather than a quick announcement. These often took him a while to write out and then recopy; he did not publicly report his 1748 experiments, for example, until his letter to Collinson in April 1749, and there was a similar delay in conveying his results for the following year.

  He also may have feared being ridiculed if his initial findings turned out to be wrong. Priestley, in his history of electricity, cited such worries as being the reason Franklin flew his kite secretly. Indeed, even as the experiments were being carried out that summer, many scientists and commentators, including the Abbé Nollet, were calling them foolish. He thus may have been waiting, as Cohen speculates, to repeat and perfect the experiments. Another possibility, suggested by Van Doren, is that he wanted the revelation to coincide with the publication of the article about lightning rods in his new almanac edition that October.14

  Whatever his reason for delaying the report of his experiment, Franklin was prompted that summer to convince the citizens of Philadelphia to erect at least two grounded lightning rods on high buildings, which were apparently the first in the world to be used for protection. That September, he also erected a rod on his own house with an ingenious device to warn of the approaching of a storm. The rod, which he described in a letter to Collinson, was grounded by a wire connected to the pump of a well, but he left a six-inch gap in the wire as it passed by his bedroom door. In the gap were a ball and two bells that would ring when a storm cloud electrified the rod. It was a typical combination of amusement, research, and practicality. He used it to draw charges for his experiments, but the gap was small enough to allow the safe discharge if lightning actually struck. Deborah, however, was less amused. Years later, when Franklin was living in London, he responded to her complaint by instructing her, “if the ringing frightens you,” to close the bell gap with a metal wire so the rod would protect the house silently.

  In some circles, especially religious ones, Franklin’s findings stirred controversy. The Abbé Nollet, jealous, continued to denigrate his ideas and claimed that the lightning rod was an offense to God. “He speaks as if he thought it presumption in man to propose guarding himself against the thunders of Heaven!” Franklin wrote a friend. “Surely the thunder of Heaven is no more supernatural than the rain, hail or sunshine of Heaven, against the inconvenience of which we guard by roofs and shades without scruple.”

  Most of the world soon agreed, and lightning rods began sprouting across Europe and the colonies. Franklin was suddenly a famous man. Harvard and Yale gave him honorary degrees in the summer of 1753, and London’s Royal Society made him the first person living outside of Britain to receive its prestigious gold Copley Medal. His reply to the Society was typically witty: “I know not whether any of your learned body have attained the ancient boasted art of multiplying gold; but you have certainly found the art of making it infinitely more valuable.”15

  A Place in the Pantheon

  In describing to Collinson how metal points draw off electrical charges, Franklin ventured some theories on the underlying physics. But he admitted that he had “some doubts” about these conjectures, and he added his opinion that learning how nature acted was more important than knowing the theoretical reasons why: “Nor is it much importance to us to know the manner in which nature executes her laws; it is enough if we know the laws themselves. It is of real use to know that china left in the air unsupported will fall and break; but how it comes to fall and why it breaks are matters of speculation. It is a pleasure indeed to know them, but we can preserve our china without it.”

  This attitude, and his lack of grounding in theoretical math and physics, is why Franklin, ingenious as he was, was no Galileo or Newton. He was a practical experimenter more than a systematic theorist. As with his moral and religious philosophy, Franklin’s scientific work was distinguished less for its abstract theoretical sophistication than for its focus on finding out facts and putting them to use.

  Still, we should not minimize the theoretical importance of his discoveries. He was one of the foremost scientists of his age, and he conceived and proved one of the most fundamental concepts about nature: that electricity is a single fluid. “The service which the one-fluid theory has rendered to the science of electricity,” wrote the great nineteenth-century British physicist J. J. Thompson, who discovered the electron 150 years after Franklin’s experiments, “can hardly be overestimated.” He also came up with the distinction between insulators and conductors, the idea of electrical grounding, and the concepts of capacitors and batteries. As Van Doren notes, “He found electricity a curiosity and left it a science.”

  Nor should we underestimate the practical significance of proving that lightning, once a deadly mystery, was a form of electricity that could be tamed. Few scientific discoveries have been of such immediate service to humanity. The great German philosopher Immanuel Kant called him the “new Prometheus” for stealing the fire of h
eaven. He quickly became not only the most celebrated scientist in America and Europe, but also a popular hero. In solving one of the universe’s greatest mysteries, he had conquered one of nature’s most terrifying dangers.

  But as much as he loved his scientific pursuits, Franklin felt that they were no more worthy than endeavors in the field of public affairs. Around this time, his friend the politician and naturalist Cadwallader Colden also retired and declared his intention to devote himself full time to “philosophical amusements,” the term used in the eighteenth century for scientific experiments. “Let not your love of philosophical amusements have more than its due weight with you,” Franklin urged in response. “Had Newton been pilot but of a single common ship, the finest of his discoveries would scarce have excused or atoned for his abandoning the helm one hour in time of danger; how much less if she had carried the fate of the Commonwealth.”

  So Franklin would soon apply his scientific style of reasoning—experimental, pragmatic—not only to nature but also to public affairs. These political pursuits would be enhanced by the fame he had gained as a scientist. The scientist and statesman would henceforth be interwoven, each strand reinforcing the other, until it could be said of him, in the two-part epigram that the French statesman Turgot composed, “He snatched lightning from the sky and the scepter from tyrants.”16

  Chapter Seven

  Politician

  Philadelphia, 1749–1756

  The Academy and the Hospital

  The ingenious lad who did not get to go to Harvard, who skewered that college’s pretensions with ill-disguised envy as a teenage essayist, and whose thirst for knowledge had made him the best self-taught writer and scientist of his times had for years nurtured the dream of starting a college of his own. He had discussed the idea in his Junto back in 1743, and after his retirement he became further motivated by the joy he found in science and reading. So in 1749 he published a pamphlet on “Proposals Relating to the Education of Youth in Pennsylvania” that described, with his usual indulgence in detail, why an academy was needed, what it should teach, and how the funds might be raised.