Benjamin Franklin: Enlightenment Archetype

by Roger Donway

This month's Achievers column begins to redeem the promise made on the inside back cover of the December 1999 Navigator. There, under the headline We're Celebrating Year 250, I wrote: At TOC's fall conference, both David Kelley and Robert Bidinotto remarked on the need to create, justify, and dramatize an ideal that will counter the pastoral ideal shared equally by our classical heritage and the Judaeo-Christian tradition. 'We must develop,' Kelley said, 'images, stories, and symbols that proclaim and celebrate the human creative power and the value of civilization.' In that connection, he noted, the Christians' Year 2000 can also be viewed as the 250th anniversary of the beginning of the Industrial Revolution, the historical event that finally proved the practical power of reason.

With this issue, Navigator begins its celebration of Year 250. Each month during this year, the newsletter will look at a person whose creative genius was at full flood 250 years ago. Beyond this year, we shall continue to give disproportionate emphasis to the spirit of the eighteenth century, a spirit that lives today in Objectivism's morality of rationality and independence.

Why Franklin?

Benjamin Franklin is the ideal person to lead off TOC's Year 250 celebration, for many reasons. First, Franklin was a man who lived wholly within the eighteenth-century Enlightenment, born in 1706 and dying in 1790. Then, too, Franklin was a child of America, the nation of the Enlightenment. Yet unlike many of America's Founders, Franklin was not a ruralist; he was a man of cities, spending his life in Boston, Philadelphia, London, and Paris. As a result, he had a much greater appreciation for the importance of civil society than did the plantation owners of Virginia, and he took an active part in creating local civic institutions. Franklin also had a much greater appreciation for the high achievements of European science than did many of the America's Founders (though Jefferson outranked him here). But, true to his country's practicality, Franklin founded a learned society called the American Philosophical Society for Useful Knowledge. Its first volume of Transactions stated:

Knowledge is of little use, when confined to mere speculation: But when speculative truths are reduced to practice, when theories grounded upon experiments, are applied to common purposes of life; and when, by these, agriculture is improved, trade enlarged, the arts of living made more easy and comfortable, and, of course, the increase and happiness of mankind promoted; knowledge then becomes really useful.

This is precisely the spirit of rational productiveness that our Year 250 celebration intends to honor. And to make the matter perfect, many of Franklin's scientific and technological discoveries regarding electricity were announced in the year 1750.

Franklin's Stature

Unfortunately, Franklin is not generally perceived as a scientist but as a tinkerer-the inventor of bifocals, an improved stove, and the lightning rod. But that misperception arises because the significance of the last-named gadget has not been properly appreciated. I.B. Cohen-America's first Ph.D. in the history of science and now a professor emeritus at Harvard University-put the invention of the lightning rod in historical perspective when he noted that Bacon and Descartes predicted that any basic scientific knowledge would lead to practical innovations of use to people everywhere, [but] by 1787 there had been only one spectacular example of disinterested or basic research in science that had led to an important invention. I refer here to the lightning rod. Obviously, science had been applied to achieve many striking results before 1787, from farming to warfare, but pure scientific investigation had not before yielded a previously unimagined invention of such dramatic magnitude as the lightning rod.

Franklin began his research because he wanted to learn about the operations of nature, and he had no idea where that research would lead. Well into the nineteenth century the lightning rod was cited as the premier example of the way in which fundamental scientific advances may produce practical inventions. (I.B. Cohen, Science and the Founding Fathers, [New York: W.W. Norton and Company, 1995] p. 242-43.)

Still, in two important senses, Franklin was a tinkerer. First, he was able to produce many of the devices that he required for his experiments. His rival in electrical studies, William Watson of London, wrote that Franklin had both a head to conceive and a hand to carry into execution whatever he thought might conduce to enlighten the subject-matter. Secondly, it was Franklin himself who envisioned and created the practical technology implied by his scientific discoveries, a distinct rarity in the history of invention but quite natural for the founder of the American Philosophical Society.

Electricity before Franklin

The full magnitude of Franklin's Baconian achievement cannot be appreciated The next step in the science of electricity illustrates the ways in which theory and technology reinforce each other. For the next step was to create a device capable of producing larger amounts of electricity for use in experimentation. This was the Leyden jar, so-called because it was invented (in 1746) by Pieter van Musschenbroek (1692-1761), who worked at the University of Leyden.

Before Franklin, the workings of the Leyden jar were not understood, only the result: its ability to accumulate far greater charges than in the past.

The demonstration of this device fascinated Europe in the 1740s. Birds and small animals were killed by the shocks produced from Leyden jars. Watson sent a pulse of electricity through a wire strung across the River Thames. More puckishly, the abbé Jean-Antoine Nollet, who popularized science in France, used a Leyden jar to send a current through a chain of 180 Royal Guardsmen. He also used iron wire to connect a line of Cathusian monks more than half a mile long; when the Leyden jar was discharged into the wire, it is said, the white-robed monks jumped in the air simultaneously.

Here is where matters stood when the subject of electricity came to the attention of Benjamin Franklin. (See box)

Franklin before the Experiments

Benjamin Franklin was born in Boston 1706. He had very little formal education and was apprenticed at age 12 to his brother James, who was a printer. For the next five years, he read continuously and taught himself to write well. When his brother got into trouble with the authorities, Benjamin found an opportunity to violate his indenture without being brought to law. After working briefly as a printer in Philadelphia and then London, Franklin returned to the former city and set up a successful printing partnership. In 1727, adopting a scheme begun by Cotton Mather in Massachusetts, Franklin organized the Leather Apron club, or Junto, to debate questions of morals, politics, and science. In 1729, he began The Pennsylvania Gazette, generally acknowledged to be the best of the colonial newspapers. In 1731, recognizing the Junto's need for books, he organized the Library Company of Philadelphia and had books sent from London by Peter Collinson, a Quaker merchant in London with friends in Philadelphia. In 1732, Franklin began Poor Richard's almanac. In 1735, he successfully promoted a fire company for Philadelphia. From 1736 until 1751, he was clerk of the Pennsylvania legislature, and from 1737 to 1753, he was postmaster of Philadelphia. In 1743, he launched the American Philosophical Society for Useful Knowledge by calling for constant correspondence of men with scientific interests throughout the colonies and by offering to serve as secretary of the APS.

Franklin's background in science is suggested by his 1744 report to the APS on the Pennsylvania fireplace (also known as the Franklin stove). Franklin enunciated the scientific principles on which the stove operated, described the method by which mechanics could construct it, listed fourteen advantages that it offered, and answered all the objections that had been raised against it. Along the way he provided citations to numerous scientific authorities, and from these we can glean some idea of his scientific education. For example, he cited Hermann Boerhaave (1668-1738), the great chemist, botanist, physician, and philosopher, who presided over the school of medicine at Leyden and who was one of Newton's staunchest allies when it came to an insistence on strict adherence to experimental results. Franklin himself knew well the major treatise on experimental physics of the age, Newton's Opticks. (I.B. Cohen, Franklin, Dictionary of Scientific Biography )

As regards electricity: Franklin may have heard about itinerant showmen who employed the new phenomenon, but he first encountered a demonstration of it in June 1743, while he was in Boston. Dr. Archibald Spencer (the name is variously given) presented a Course in Natural Philosophy, with some electrical experiments that, Franklin notes, were imperfectly performed, as he was not very expert. Nevertheless, when Spencer came to Philadelphia in April 1744 to repeat his lectures and experiments, Franklin bought his apparatus and then wrote to Collinson asking that more equipment be sent from London. Thus, Franklin tells us that in 1745 (or 1746) the Library Company received from Mr. Peter Collinson, F.R.S., of London a Present of a Glass Tube with some Account of the Use of it in making such electrical Experiments. Because he obtained his equipment through Collinson, Franklin fortunately made it a habit to report on his experiment to Collinson, and we therefore the progress of his work. Specifically, we know that he

eagerly seized the Opportunity of repeating what I had seen in Boston, and by much Practice acquir'd great Readiness in performing those also which we had an account of from England, adding a Number of new Ones.

The First Experiments

Franklin had the help of three other men: Philip Syng, a skilled silversmith and a member of the Junto; Thomas Hopkinson, president of the American Philosophical Society; and Ebenezer Kinnersley, a Baptist minister without a church, who became a major spokesman for the quartet's discoveries.

To generate electric charge, they set up a crank-turned sphere like Guericke's, and in 1747, only one year after the Leyden jar's invention, they acquired or built such a device to collect the charge. Consequently, throughout 1747, Franklin was able to report a number of discoveries to Collinson. The first of these involved the shape of conductors. He found that a blunt conductor, when grounded, could draw off a charge from a distance of about an inch, and then only through a spark. A pointed conductor, however, could draw off a charge from a distance of six to eight inches, with no spark. (This first discovery, though not interesting in itself, became important in the invention of the lightning rod.)

Franklin's first major hypothesis was that electrical fire is a real element, or species of matter, not created by friction, but collected only. Thus, all electrification was to be explained by the transfer of electrical fire. To electrise plus or minus, no more needs to be known than this, that the parts of the tube or sphere that is rubbed, do, in the instant of friction, attract the electrical fire, and therefore take it from the thing rubbing. The hypothesis implied that, when a given body accumulated electrical fire in a certain quantity, other bodies lost it in an exactly equal amount. This principle, known today as the conservation of charge, is one os physics' most important laws. A further implication of Franklin's hypothesis was that one need no longer assume the existence of two types of electricity-vitreous and resinous. The existence of bodies electrified in different ways could be explained more simply as the abundance and deficit of a single substance.

Understanding Electricity.

On July 29, 1750, Franklin sent to Collinson a summary of his Opinions and Conjectures, concerning the Properties and Effects of the Electrical Matter, Arising from Experiments and Observations, Made at Philadelphia, 1749. If we consider ten points made in this paper, in light of our current knowledge regarding the primary role that electrons play in the phenomena of electricity, we may get a better idea of just how much Franklin had discovered. Though the electron was not actually identified until 1897, Franklin's hypotheses taken together seem in retrospect to delineate so many fundamental properties of the particle that Robert Millikan (who won the Nobel Prize in Physics for his work with electrons and for verification of Einstein's photoelectric effect.) declared Franklin to be the electron's true discoverer.

Apart from thus delineating the fundamental nature of electricity, the greatest theoretical contribution that Franklin made was the discovery of induced charge. Says I.B. Cohen, Franklin explained clearly-for what was, so far as I know, the first time-the mechanism of induced charges, the phenomenon of a positive charge being induced on a grounded conductor when a negative charged is brought near it.

Thus, only Franklin and his followers could explain such phenomena as the following. Let an uncharged metal conductor be set on an insulator and a negatively charged object be brought near to it. Let the metal be briefly and temporarily grounded before the negatively charged object is withdrawn. After it is withdrawn, the metal will be positvely charged, the positive charge having been induced by the presence of the negative charge. (The force from the first object's excess of electrons pushed the electrons from the metal and into the earth while it was temporarily grounded object; the insulator prevented them from returning.) Or, again: let an uncharged metal conductor be set on an insulator and a negatively charged object be brought near to it. The end of the metal nearest the negatively charged object will be positively charged and the end furthest will be negatively charged. When the negatively charged object is removed, the metal will return to an electrically neutral state. (The force from the first object's excess of electrons pushed the electrons in the metal to the point furthest away from it. When the charged object was removed, the electrons returned.)

In the eighteenth century, Cohen writes, many scientists adduced this feature of the Franklinian theory (its ability to predict exactly the outcome of such experiments) as its major asset. With this understanding of induced charge, it followed that one could not negatively charge the inside of a Leyden jar to any great extent unless negative charge already present on the opposite side of the glass could be pushed off into the earth through the body of an experimenter. Franklin also predicted, and proved by experiment, that the Leyden jar would work in reverse: by charging the outside of the glass and grounding the inner wire.

The Lightning Rod

In late 1749, as he came to understand the nature of electricity, Franklin began to theorize about the electrical nature of lightning. He drew up a list of twelve characteristics on which lightning and electrical sparks were similar. Recurring then to his earliest discovery, he wrote: The electric fluid is attracted by points [pointed conductors]. We do not know whether this property is in lightning. But since they agree in all particulars wherein we can already compare them, is it not probable they agree likewise in this? Let the experiment be made.

In May 1750, Franklin wrote a letter to Collinson that came back to the topic. The doctrine of points is very curious, and the effects of them truly wonderful; and, from what I have observed in experiments, I am of the opinion that houses, ships, and even towers and churches may be effectually secured from the strokes of lightning by their means.

In the July 1750 paper that he sent to Collinson, Franklin elaborated a possible experiment-known as the sentry box experiment-by which his ideas could be tested.

To determine the question whether the clouds that contain lightning are electrified or not, I would propose an experiment to be tried where it may be done conveniently. 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 [an insulator to prevent grounding]. 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 it to him from a cloud.

Clearly, Franklin had no conception of the electrical force contained in lightning.

In 1751, Peter Collinson assembled and had published a ninety-page book of Franklin's writings concerning electricity. The renowned French scientist Buffon came across the work and had it translated by Thomas Francois D'Alibard. A year later the two men undertook the sentry box experiment.

Buffon and D'Alibard set up a forty-foot iron rod pointed with brass. Having no resin with which to insulate it, they set it upon a plank-with three wine bottles for legs. On the tenth of May, a former dragoon named Coiffier, left to watch the experiment, heard a single clap of thunder and sent a child for the local prior, who was already on the way to the sentry box. As the villagers stood well back, watching the rod throw off sparks and hearing it crackle, the prior drew off all the electricity and then wrote to D'Alibard, who on May 13 made a report to the Académie Royal des Sciences: In following the path that Mr. Franklin has traced for us, I have obtained complete satisfaction. Franklin's conjecture was proven. On May 18, the experiment was repeated in Paris and the king sent Franklin his congratulations through Collinson. Throughout the summer of 1752, the experiment was repeated many times throughout Europe, and Franklin became internationally famous.

But before Franklin could hear of the French success, he undertook his own experiment, with very different equipment. He had been waiting for the construction of a particular church spire, but in June 1753 he suddenly realized that he could carry out the test using a simple kite, whereby he could obtain better access to the regions of thunder than by any spire whatever. The kite was made of silk, because silk was better able [than paper] to bear the wet and wind of a thunder-gust without tearing. To the top of the upright stick was fixed a very sharp pointed wire, rising a foot or more above the wood. To the end of the twine, next the hand, is to be tied a silk ribbon [for insulation], and where the silk and twine join, a key may be fastened.

Joseph Priestley, who presumably had the story directly from Franklin, recounted the story as follows:

Just as he was beginning to despair of his contrivance, he observed some loose threads of the hempen string to stand erect, and to avoid one another, just as if they have been suspended from a common conductor. Struck with this promising appearance, he immediately presented his knuckle to the key, and (let the reader judge of the exquisite pleasure he must have felt at that moment) the discovery was complete. He perceived a very evident electric spark.

Franklin, too, had been lucky. A year later, the Swedish physicist G.W. Richmann was killed while performing the lightning experiment.

In September, Franklin finally heard of the experiments conducted in Europe, but, oddly, he had not yet announced his own successful trial, and this epilogue casts an interesting light on Franklin's complicated attitude toward theoretical and practical science. Franklin withheld news of his experiment for four months so that he could simultaneously announce its success (in the Pennsylvania Gazette) and the availability of lightning rods (in Poor Richard's Almanack). Yet this was not for gain or glory. He announcements failed to mention that he had performed the experiment and he had invented the lightning rod. Nor had he patented the rods. Thus, it appears that he coordinated his announcement of the experiment with his announcement regarding lightning rods simply because he wished to be an effective publicist for an invention that he earnestly considered a boon to mankind.

The End of the Adventure

In the course of ten years, Benjamin Franklin had encountered the phenomenon of electricity, become the leading experimental and theoretical scientist in the field, conceived a headline-grabbing demonstration that made him famous throughout Europe, and, lastly, derived from his discoveries the first completely original technology to come out of pure scientific research.

In 1753, the Royal Society of England presented Franklin with its highest award, and in 1756 it made him a Fellow. He received honorary degrees from Harvard and Yale in 1753, and from William and Mary in 1756.

But that was the end of Franklin's adventure with electricity. In 1753, Franklin became deputy postmaster general for the colonies, a post he would hold for nineteen years. From 1757 to 1762, he was in England as the agent for Pennsylvania, returning to America for a brief two years, and then going back to England, where he remained until March 1775. During the enforced quiet of his voyage home, Franklin took temperature measurements of the Gulf Stream. But he arrived to find that war had broken out at Lexington and Concord.

In 1776, Franklin attended the Second Continental Congress and, following the declaration of independence, accepted a commission to Paris where he had so recently been elected to the Royal Academy of Sciences. In 1781, he was one of three commissioners sent to England to negotiate the peace treaty. In 1785, Franklin returned to America, participated in the Constitutional Convention of 1787, and died in 1790.

Because of his double role as scientist-inventor and bourgeois revolutionary, the Baron de Turgot had, in 1778, had written an immortal epigram about Franklin: Eripuit caelo fulmen sceptrumque tyrannis. He seized the lightning from the sky and the scepter from tyrants. No saying better sums up the alliance of the Enlightenment and the Industrial Revolution.

But Franklin, unlike some of his overly sanguine friends, could see that these two children of the Age of Reason were following quite paths. The rapid progress true science makes occasions my regretting sometimes that I was born too soon, he wrote.. . . . O that moral science were in as fair a way of improvement, that men would cease to be wolves to one another.

The prescience of Franklin's insight into the disparate futures of science and technology on the one hand, and philosophy and culture on the other, cannot be better summed up than by a 1783 incident involving his own invention. When the people of St. Omer passed a law prohibiting the use of lightning rods, and then tore down those erected by M. de Vissery de Bois-Valé, the matter went to the Council of Artois. There the brief for Franklin's invention happened to fall to a young lawyer, who took it on as his first case. Despite his inexperience, the lawyer argued eloquently-and successfully-for the cause of reason, science, and progress. As a result, the young man won considerable fame and so was enabled to launch himself into public life. His name was Robespierre.

Franklin Explains the Leyden Jar

The Leyden jar is variously called a condenser or capacitor, and the reasons for those two names become obvious when one understands the logic of its operation. The earliest Leyden jars of the mid-eighteenth century consisted of a glass bottle fitted with a cork and filled with water. A copper wire, which was immersed in the water, ran through the cork and was held to a machine generating (let us say) negative charge. Today, we know that this means the generator is sending electrons flowing through the wire and the water, creating a negative charge on the inside of the glass. If the bottle were insulated from the earth, one would soon reach a point at which no more negative charge or electrons could be absorbed by the jar. But with an experimenter holding the outside of the bottle, the results were quite different. Since like charges repel, the force of the negative charges on the inside of the bottle would push electrons out from the experimenter's palm and the adjacent glass and ultimately into the earth. The positive charge remaining on the experimenter's hand and adjacent glass would pull on the electrons inside the glass, packing them together more tightly and making room for still more electrons and a greater negative charge. Because the Leyden jar worked by squeezing the electrons or negative charge more closely together, this type of device later came to be called a condenser. (The term seems to have originated with Alessandro Volta in approximately 1780). Because the result of the process was an increase in the jar's capacity to absorb charge, the more modern term for such a device is a capacitor

But even without understanding how
the Leyden jar worked, several improvements were made to it. Rather than using the glass itself as both the bearer of charge and the insulator between the two types of charge, William Watson lined the glass jar inside and out with metal foil; the glass then served principally as an insulator. The copper wire through which charge was entering was attached directly to the foil by a metal wire rather than by water.

In a letter of April 1748, Franklin described some new experiments showing that a charged Leyden jar always has charges of opposite signs on the two conductors and that the charges are of the same magnitude. (I.B. Cohen, Franklin, The Dictionary of Scientific Biography, p. 131) In that sense, Franklin said, experimenters did not charge and discharge the Leyden jar. It contained a certain amount of electrical fluid before charging and an equal amount afterward. Charging the jar simply meant redistributing the fluid, and discharging was required because the original equilibrium could not be restored by having electrical fluid pass through the bottle (nor, practically speaking, over the lip of the bottle). It could be restored only through a conducting connection between the outside and inside.

Using an early type of Leyden jar, without foil lining, Franklin then announced the most surprising discovery of all. The whole force of the bottle, and power of giving a shock, is in the GLASS ITSELF. Franklin proved this by eliminating all the other candidates.

First, he set his Leyden jar on a glass insulator. After he had carefully removed the cork and wire, the jar could still be discharged by having the experimenter touch the outside and the water. Next, he carefully poured off the water from a charged Leyden jar into an empty uncharged jar resting on glass. This jar gave no indication of having received a power to shock. He then refilled the empty Leyden jar with an equal amount of pure water, and discovered that the jar retained the power to shock. Clearly, the glass itself must be implicated.

For a final experiment with Leyden jars, Franklin asked whether the charge on the jar was influenced by shape. This was not so absurd as it may seem. Franklin's first discovery, remember, had been that the shape of conductors had an effect on their ability to discharge an electrified body. So the question about the shape of the jar was hardly silly. To answer the question, Franklin constructed a condensor consisting of two lead plates separated by a flat sheet of glass. It produced the same effect as Leyden jar. Franklin then made a series of eleven such flat condensers and linked up the lead plates with a wire, creating what he was the first to called an electrical-battery.

Franklin's Ten Basic Hypotheses

1. Electrical matter consists of extremely small particles. (True. Electrons are particles and are smaller than can be measured.)

2. Electrical matter is a single fluid, not two. (True, if one considers that the phenomena observed in the electrostatic experiments of the eighteenth century involved only the movement of electrons, not the movement of positively charged ions.)

3. In light of Point 2, opposite electrical charges are to be explained by an excess and defect of electrical matter. (True, if one thinks of electricity as consisting only of electrons. Unfortunately, Franklin [as he understood] had no way to determine which of the two electrical states represented an excess of electrical particles and which a deficiency. He made a fifty-fifty bet-and lost. The state he dubbed negative [thinking it had a deficienc of electrical fluid] is in fact the state that has an excess of electrons. To preserve his language, it has been necessary to establish the convention that the electron has a negative charge and the proton a positive charge.)

4. Electrical matter can be accumulated and discharged but not destroyed. (True. The conservation of charge still stands as an important principle of physics.)

5. The difference between particles of common matter and particles of electrical matter is that the former attract each other (as Newton showed) and the latter repel. (Effectively true-if one thinks of electrical particles as electrons only. Of course, electrons are part of common matter and possess gravitational attraction for each other. But the electrical repulsion between two electrons is 4 x 1042 times stronger than the gravitational attraction between them. So, the latter can be ignored.)

6. Generally, common matter contains as much electrical matter as it can hold; if one attempts to add more electrical matter, it accumulates on the surface of the common matter to form an electrical atmosphere. In that case, the common matter is said to be electrified. (Effectively true. Atoms are, in general, electrically neutral. But an atom's outer electrons can be stripped away from it and added to the outer shell of other atoms.)

7. A body that has lost some of its normal quantity of electrical matter attracts the electrical matter in the electric atmosphere of a positively charged body, drawing the two bodies together. (Effectively true. Matter stripped of electrons will tend to attract matter with an abundance of electrons.)

8. Two electrified bodies repel each other because they both have electrical atmospheres made up of particles that repel each other. (A major flaw. Even on Franklin's own terms, this hypothesis would explain only why two positively charged bodies repel each other. It could not explain why two negatively charged bodies repel each other. The defect in Franklin's theory had to be corrected by Franz Aepinus [1724-1802].)

9. All bodies do not retain electric matter equally; glass and other nonconductors hold it more strongly than metals and other conductors. (True.)

10. Electrical matter is nonetheless present in all matter, because we can always pump some out. (Effectively true. Electrons are present in all neutral atoms.)



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