Benjamin Franklin

How to use this course

Most people meet Benjamin Franklin as a founder of the United States. Physicists meet him through two words he gave them, positive and negative, and through a sign convention that still makes the electron’s charge negative. Between 1746 and 1752 Franklin turned electricity from a parlour entertainment into a science with a conserved quantity, a working theory of the capacitor and a practical invention that saved lives. He then applied the same habits of measurement to ocean currents, storms, heat and thin films.

Each technical lesson opens with a paragraph for the general reader, then states Franklin’s results and their modern form, derives what can be derived, and ends with exercises whose solutions fold away. Franklin worked without mathematics, so the lessons pair his qualitative laws with the quantitative physics that later confirmed, corrected or extended them. Politics appears only briefly, in Part III.

Timeline

Boston, 1706–1723

Benjamin Franklin was born on Milk Street in Boston on 17 January 1706, by the calendar now in use. His father, Josiah Franklin, had emigrated from England in 1683 and made soap and candles. Josiah had seventeen children by two wives; Benjamin was the tenth and last son, and his mother was Abiah Folger of Nantucket. The Folger connection mattered decades later, when a Nantucket cousin explained the Gulf Stream to him (Lesson 08).

His schooling lasted about two years, first at the Boston Latin School and then at a writing and arithmetic school. He failed arithmetic at first and later taught himself from a book. At 12 he was apprenticed to his brother James, a printer. The print shop was his university. He read everything that passed through it, practised prose style by rewriting essays from the Spectator from memory, and argued about religion and philosophy with anyone who would listen.

In 1721 James founded the New-England Courant. The next year the sixteen-year-old Benjamin slipped a series of letters under the shop door, signed by an invented widow, Silence Dogood. James printed them before he knew who the author was. The brothers quarrelled, and in 1723 Benjamin broke his apprenticeship and left by sea, first for New York and then for Philadelphia, where he arrived at 17 with almost no money.

The printer of Philadelphia, 1723–1746

Franklin found work with the printer Samuel Keimer. Encouraged by the governor of Pennsylvania, William Keith, he sailed to London in late 1724 to buy equipment, only to find that Keith’s promised letters of credit did not exist. He spent eighteen months as a compositor in London printing houses, then returned to Philadelphia in 1726.

Over the next two decades he built a business and a civic network. He opened his own shop in 1728, took over the Pennsylvania Gazette in 1729 and began Poor Richard’s Almanack in 1732. In 1730 he formed a common-law marriage with Deborah Read; they had a son, Francis, who died of smallpox in 1736, and a daughter, Sarah. His elder son William, born around 1730 to an unknown mother, was raised in the household and helped him with the kite in 1752.

He was also an organizer. The Junto, founded in 1727, met weekly to debate questions of morals, politics and natural philosophy. Out of it came the Library Company (1731), a volunteer fire company (1736), the American Philosophical Society (1743) and the academy that became the University of Pennsylvania. Several of the men who later shared his electrical experiments, among them the silversmith Philip Syng and Thomas Hopkinson, came from this circle.

A first invention

In 1742 Franklin designed an iron fireplace that drew room air through a heated chamber before returning it to the room. His 1744 pamphlet on the “Pennsylvanian fire-places” is a small treatise on convection and draughts (Lesson 09). He declined a patent, a habit he kept for all his inventions.

The Philadelphia experiments, 1743–1752

In 1743, on a visit to Boston, Franklin saw the itinerant lecturer Archibald Spencer perform electrical tricks with glass tubes. The next year he advertised Spencer’s lectures in Philadelphia, and in 1746 he bought Spencer’s apparatus. Early in 1747 a gift arrived from Peter Collinson, a London cloth merchant and Fellow of the Royal Society who supplied the Library Company with books: a glass tube for rubbing, with notes on recent German experiments.

Electricity was then a fashionable science. Machines with spinning glass globes produced sparks and shocks, and since 1745 the Leyden jar, discovered independently by Ewald von Kleist and by Pieter van Musschenbroek’s circle in Leiden, could store enough charge to knock a man down. The leading theorist, the Abbé Jean-Antoine Nollet in Paris, explained everything by two streams of electrical matter flowing in and out of bodies at once.

Franklin worked with Ebenezer Kinnersley, Philip Syng and Thomas Hopkinson. Syng built a machine that turned a glass sphere by a crank; Hopkinson noticed that points throw off electricity. In 1747 and 1748, after arranging for his business to run without him under David Hall, Franklin gave nearly all his time to the work. He reported it in a series of letters to Collinson, beginning on 25 May 1747. Collinson read them to the Royal Society and had them printed in 1751 as Experiments and Observations on Electricity, made at Philadelphia in America. Expanded editions followed in 1753, 1754, 1769 and 1774, and a French translation by Thomas-François Dalibard made Franklin famous on the Continent.

The letters are clear, modest and full of reversals. Franklin changed his mind in print when experiments went against him, and he built a vocabulary that is still in use: charge, battery, conductor, positive and negative, plus and minus. Part II takes the physics in the order he found it.

One fluid, plus and minus

For the general reader. When you rub a glass rod with silk, both become electrified. Before Franklin, people thought rubbing created electricity, and that there were two kinds. Franklin proposed that there is one electrical “fire” present in all matter. Rubbing does not create it; it only moves it from one body to another, so what one gains the other loses. This is the law of conservation of charge.

The experiment of the three people

Franklin’s letter of 25 May 1747 describes three people, A, B and C. A stands on wax, which insulates him from the floor, and rubs a glass tube. B, also on wax, draws off the fire from the tube with his knuckle. C stands on the floor. Each of A and B, if approached by C, gives a spark. If A and B touch each other, the spark between them is stronger, and afterwards neither is electrified at all.

Franklin’s reading: A, while rubbing, passes his own fire into the glass and is not resupplied, because the wax cuts him off from the floor. He is left with a deficit. B receives fire from the glass and holds a surplus. C, connected to the earth, has the normal amount, so he can give fire to A and take it from B. When A and B touch, B’s surplus exactly fills A’s deficit. He called B’s state plus or positive and A’s minus or negative.

Conservation of charge

Hypothesis 4 survived every later change in the theory of electricity. In modern form, with charge density \(\rho\) and current density \(\mathbf J\), it is the continuity equation

The charge in a region changes only by what flows through its boundary. In James Clerk Maxwell’s equations it is not an extra assumption: taking the divergence of the Ampère–Maxwell law \(\nabla\times\mathbf B=\mu_0\mathbf J+\mu_0\varepsilon_0\,\partial_t\mathbf E\) and using \(\nabla\cdot\mathbf E=\rho/\varepsilon_0\) gives it at once.

The sign convention

Franklin had to guess which body gains the fluid. He chose the glass. We now know that rubbing glass with silk moves electrons from the glass to the silk. Since electrons are what moves, Franklin’s fluid behaves like an absence of electrons, and the electron’s charge is negative. Conventional current, the flow of positive charge, runs opposite to the motion of electrons in a wire. This is the price of a coin tossed in 1747.

A flaw and its repair

The one-fluid theory explains attraction between a plus and a minus body and repulsion between two plus bodies, which both carry repelling fluid. It cannot explain why two minus bodies repel, since each has less fluid than normal. In his Tentamen theoriae electricitatis et magnetismi (1759), Franz Aepinus added a fourth force: particles of ordinary matter repel one another. With all forces of equal strength, neutral bodies feel no net force, and two minus bodies, each with uncompensated matter, repel. Aepinus also treated the forces mathematically, a step toward Charles-Augustin de Coulomb’s inverse-square law of 1785.

The Leyden jar and the battery

For the general reader. A Leyden jar is a glass jar with metal on the inside and outside. Charged from a machine, it can give a violent shock. Nobody knew why. Franklin showed that the inside and outside always carry equal and opposite charges, and that the glass between them, which lets nothing through, is what holds the charge. He had found the principle of the capacitor.

Franklin’s analysis (1747–1749)

Franklin established, through a series of simple tests, that:

• when the inner coating gains fire, the outer coating loses exactly as much, which must pass to the earth through the hand or a wire;
• a jar standing on an insulator cannot be charged, because the outer coating cannot discharge;
• a cork ball hung between wires from the two coatings is attracted alternately to each until the jar is discharged;
• the shock comes from the restoration of balance between the two coatings through the body.

He then built a “dissectible” jar whose coatings could be lifted away after charging. The coatings, removed and handled, showed no charge, yet the glass, fitted with fresh coatings, gave a full shock. He concluded that the charge lives in the glass. In his letter of 29 April 1749 he described connecting panes of window glass, faced with lead foil, into what he called an electrical battery, borrowing the military word for guns fired together.

The modern capacitor

Derivation. By Gauss’s law the field between the plates is \(E=\sigma/(\varepsilon_0\varepsilon_r)\) with \(\sigma=Q/A\), and zero outside. Then \(V=Ed=Qd/(\varepsilon_0\varepsilon_rA)\). Moving charge \(dq\) against potential \(q/C\) costs \(dU=(q/C)\,dq\); integrating from 0 to \(Q\) gives \(U\). Equivalently, the energy sits in the field with density \(\tfrac12\varepsilon_0\varepsilon_rE^2\) over volume \(Ad\).

The equality of the charges on the two coatings, Franklin’s first finding, is a consequence of Gauss’s law: a closed surface drawn inside the conductors, enclosing the glass, has zero flux through it, so the total charge enclosed is zero.

The dissectible jar revisited

Franklin’s result is real but his explanation is incomplete. When the coatings are lifted off, the charge does not stay on the metal; small discharges in the air and the moisture film on the glass transfer most of it onto the glass surfaces, where it stays when the coatings are removed. The charge sits on the surfaces of the dielectric, not deep inside it. In 1756 Aepinus built a condenser with air between the plates, showing that glass is not essential.

Conductors and the power of points

For the general reader. Franklin noticed that a sharp needle silently draws electricity off a charged body from a distance, while a blunt object must come close and then gets a spark. He called this the power of points, and it became the basis of the lightning rod. The explanation is that charge piles up on the sharpest parts of a conductor, where the electric field becomes strong enough to tear air molecules apart.

Field at a curved surface

In equilibrium a conductor is at a single potential, its charge lies on its surface, and the field just outside is normal to the surface with magnitude \(E=\sigma/\varepsilon_0\). For an isolated sphere of radius \(r\) at potential \(V\), \(Q=4\pi\varepsilon_0rV\) and

A point is a conductor whose tip has a tiny radius of curvature. As a rough guide it behaves like a small sphere of the tip’s radius at the potential of the whole object. When the field reaches the breakdown strength of air, about \(3\times10^{6}\ \mathrm{V/m}\) at sea level, free electrons gain enough energy to ionize molecules and an avalanche starts. The result is a corona: a steady glow and a quiet current that drains the charge. Franklin saw that glow in the dark at the ends of needles.

The empty can

Franklin also noticed, in experiments he described in the mid-1750s, that a cork ball lowered into a charged silver can on an insulating stand was not attracted to the walls and came out uncharged. Joseph Priestley repeated this and, in his History and Present State of Electricity (1767), drew the inference that electrical attraction must follow the same law as gravity, by analogy with Isaac Newton’s theorem that a uniform shell exerts no force on a body inside it.

The first claim follows from Gauss’s law with a spherical surface inside the shell. The converse is what makes the null experiment a test of the law. Henry Cavendish ran a precise version in 1772–73 and found \(|\delta|\) below about \(1/50\); modern versions put \(|\delta|\) below \(10^{-16}\).

Lightning: sentry box, kite and rod

For the general reader. Many people had guessed that lightning was a giant electric spark. Franklin designed an experiment to prove it and an invention to use the answer. If a cloud is charged, a tall pointed rod should draw electricity from it, and a rod connected to the ground should lead a lightning strike harmlessly into the earth. In 1752 both ideas were confirmed, first in France and then by Franklin with a kite.

From analogy to experiment

In a 1749 notebook entry Franklin listed twelve ways in which lightning resembles electric sparks: light, colour, crooked path, swift motion, conduction by metals, noise, rending of bodies, killing animals, melting metals, setting fire, sulphurous smell. In 1750, in papers sent to Collinson, he turned the analogy into a test. On a high tower a man should stand in a sentry box on an insulating stand, holding a pointed iron rod 20 or 30 feet long. If clouds are electrified, the rod would draw sparks. The same papers proposed grounded pointed rods to protect buildings.

Philadelphia had no suitable tower. In France, Dalibard set up a 40-foot rod at Marly-la-Ville, north of Paris. On 10 May 1752, during a storm, a retired dragoon named Coiffier drew sparks from it. Delor repeated the result in Paris days later, and the experiment spread across Europe. In June 1752, before news from France reached him, Franklin flew a silk kite with a pointed wire on top, a hemp string and a key at the lower end, held by a silk ribbon kept dry under a shed. When the rain wet the string, loose fibres stood apart and he drew sparks from the key and charged a Leyden jar. He published a short account in the Pennsylvania Gazette on 19 October 1752; Priestley’s fuller account of 1767 adds that his son William helped.

The kite was not struck by lightning. The string and key took up the potential of the air around the kite, high in the field beneath the cloud. A direct strike would probably have killed him. In August 1753 Georg Wilhelm Richmann was killed in Saint Petersburg by a discharge from an insulated rod he was studying.

The sign of the cloud

In September 1752 Franklin led an insulated rod from his roof down into his house, where it rang a pair of bells when clouds passed. By comparing the rod’s charge with a jar of known sign, he found in 1753 that most thunderclouds are negatively charged at the base, though some are positive. This is still the standard picture: a typical thunderstorm has a negative charge region at a few kilometres altitude and a positive region above it, and most strikes to ground lower negative charge.

How a rod protects

A descending stepped leader from the cloud advances in jumps of tens of metres. When its tip comes within a critical striking distance of a grounded object, the field there is high enough to launch an upward streamer, and the two connect. A rod protects because it launches the connecting streamer first and offers a low-resistance path to earth. Lightning engineers turn this into a geometric rule, the rolling-sphere method: a sphere of radius equal to the striking distance \(r_s\) is rolled over the structure, and whatever it can touch is exposed. A common empirical formula is

Franklin believed a point would quietly drain a cloud and prevent strikes altogether. That part was wrong; a rod’s corona is negligible against a storm’s charge. His second claim, that a grounded rod carries a strike safely to earth, was right and is the basis of all lightning protection.

The Gulf Stream

For the general reader. Ships sailing from England to America found that some routes were weeks slower than others. Franklin learned from Nantucket whalers that a warm, fast current flows north-east along the American coast and out across the Atlantic. He had it drawn on a chart, named it the Gulf Stream, and showed that a thermometer dipped in the sea tells a captain when he is in it. Physics later explained why the strongest current in the Atlantic runs along its western edge.

History

Spanish pilots had known the current since Juan Ponce de León’s voyage of 1513 and used it to sail home from the Caribbean. In 1768, as deputy postmaster general for the colonies, Franklin heard complaints that the mail packets from Falmouth to New York took about two weeks longer than merchant ships sailing to Rhode Island. His cousin Timothy Folger, a Nantucket captain, explained that whalers hunted along the edges of the current and knew its boundaries by the colour of the water, the weed and the whales, while the packet captains sailed straight against it. Folger sketched the stream for him, and Franklin had the chart engraved and printed in London in 1769. British captains largely ignored it.

On his voyages of 1775, 1776 and 1785 Franklin measured the water temperature several times a day. He found that the stream is markedly warmer than the water on either side and proposed the thermometer as a navigator’s instrument. His “Sundry Maritime Observations”, with an improved chart and the temperature records, appeared in the Transactions of the American Philosophical Society in 1786.

Geostrophic balance

On large scales away from the surface and the coast, the Coriolis force on moving water balances the horizontal pressure gradient. With \(f=2\Omega\sin\varphi\) the Coriolis parameter at latitude \(\varphi\), \(u,v\) the eastward and northward velocities and \(p\) the pressure,

At the surface \(p\) varies with the sea-surface height \(\eta\) as \(\partial p/\partial x=\rho g\,\partial\eta/\partial x\), so a northward current \(v\) requires the sea surface to rise eastward with slope \(\partial\eta/\partial x=fv/g\). The Gulf Stream is a ridge-edge: the sea surface is about a metre higher on the Sargasso Sea side than on the coastal side.

Sverdrup balance and western intensification

The trade winds blow westward in the tropics and the westerlies eastward at mid-latitudes, so the wind stress curl over the subtropical North Atlantic is negative and the interior flow is southward across the whole basin. That water must return north somewhere. Henry Stommel showed in 1948 that the return flow is forced into a narrow, fast boundary current on the western side, because only there can friction remove the vorticity the wind puts in. The Gulf Stream is that boundary current. Its transport is about 30 Sv (\(1\ \mathrm{Sv}=10^6\ \mathrm{m^3/s}\)) in the Florida Straits, rising to roughly 150 Sv off Newfoundland as it entrains recirculating water.

Heat: stoves, evaporation, colour

For the general reader. Franklin asked practical questions about heat. Why do most fireplaces waste their heat up the chimney? Why does wet skin feel cold in a wind? Why does a black coat feel hotter in the sun than a white one? Why does metal feel colder than wood at the same temperature? His answers, sketched in letters and pamphlets, correspond to the four ways heat moves: convection, latent heat, radiation and conduction.

Convection: the Pennsylvania fireplace

An open fireplace heats a room mainly by radiation from the fire, while its draught pulls large volumes of warmed room air up the chimney and draws cold air in through every crack. Franklin’s 1742 design placed a hollow iron box behind the fire. Cold room air entered at the bottom, was heated by the iron, and rose out of side vents into the room, while the smoke was led down behind the box and up the chimney so that it gave up more heat first. The buoyant flow through the box is free convection. The design drew poorly when the fire was low, and a later version by David Rittenhouse became the common “Franklin stove”.

Latent heat: cooling by evaporation

In 1758, in Cambridge, Franklin and the chemist John Hadley wetted the bulb of a thermometer repeatedly with ether and blew on it with bellows. On a warm day the thermometer fell to 7 °F (about −14 °C) and ice formed on the bulb. Franklin wrote up the experiment for the Charleston physician John Lining and linked it to sweating, to the coolness of wet clothes and to the cooling of water in porous jars.

Radiation: colour and absorption

In a 1761 letter to Mary Stevenson, Franklin described laying squares of cloth of different colours on snow in the sun: the black square sank deepest, the white hardly at all. He concluded that dark colours absorb more of the sun’s heat and recommended white clothing for hot climates. In modern terms a surface with solar absorptivity \(a\) in sunlight of flux \(S\) and thermal emissivity \(\varepsilon\) reaches radiative equilibrium when

with \(\sigma=5.67\times10^{-8}\ \mathrm{W\,m^{-2}K^{-4}}\) and \(h\) a convective coefficient.

Conduction: why metal feels cold

In his letters on heat Franklin observed that metals feel colder than wood at the same temperature because they draw heat from the hand faster. When two semi-infinite bodies at temperatures \(T_1,T_2\) are pressed together, the contact temperature is

where \(e\) is the thermal effusivity. The skin senses \(T_c\), not the object’s temperature.

Oil on water and the atmosphere

For the general reader. Sailors said that oil poured on the sea calms the waves. Franklin tested it on a London pond and found that a single teaspoon spread over half an acre. Over a century later this observation gave one of the first estimates of the size of a molecule. Franklin also noticed that storms travel in a direction different from the wind, and that a volcanic haze could cool a whole summer.

The Clapham pond

In 1773, on a windy day on Clapham Common, Franklin poured no more than a teaspoon of oil onto the windward side of a pond. The film spread with surprising speed and stilled the ripples over perhaps half an acre, making that part of the pond look as smooth as glass. He reported the experiment in a letter of 7 November 1773 to William Brownrigg, published in the Philosophical Transactions in 1774. Franklin did not compute a thickness. In 1890 Lord Rayleigh measured oil films on water and estimated a thickness of about 1.6 nm; Agnes Pockels, working in her kitchen in Brunswick, developed the trough method that Irving Langmuir later made standard.

The oil damps waves because a surfactant film resists stretching and compression of the surface. Short capillary ripples, which the wind raises first and which give it grip on the water, are strongly damped. Without them the wind transfers less energy, and longer waves grow more slowly.

Storms that move against the wind

A lunar eclipse was due one evening in late October 1743 (Old Style; early November in the modern calendar), and a storm with north-east winds hid it from Philadelphia. Franklin later learned from Boston reports that there, to the north-east, the eclipse had been seen, and the storm arrived hours afterwards. He concluded that the storm itself travelled toward the north-east while its surface winds blew from the north-east. We now know this as the motion of an extratropical or coastal cyclone carried by the upper-level flow, while the low-level winds circulate around its centre.

The dry fog of 1783

During the summer of 1783 a persistent haze covered Europe; the sun at noon could be looked at directly. Franklin, then in Passy, noted that the sun’s rays seemed weakened and suggested that the haze reduced summer heating and contributed to the hard winter of 1783–84. He considered volcanic smoke from Iceland as one possible source. The cause was the Laki fissure eruption (June 1783 to February 1784), which released about 120 million tonnes of sulphur dioxide. His paper, “Meteorological Imaginations and Conjectures”, appeared in the Memoirs of the Manchester Literary and Philosophical Society in 1785, and is often cited as an early statement of volcanic climate forcing.

Fame, London and politics, 1753–1775

The confirmation at Marly-la-Ville made Franklin a celebrity. In 1753 the Royal Society gave him its Copley Medal, Harvard and Yale gave him honorary degrees, and he was appointed joint deputy postmaster general for the colonies. Nollet attacked him in print, defending his own two-stream theory and opposing grounded rods, but the younger generation of European electricians adopted Franklin’s framework. He was elected a Fellow of the Royal Society in 1756.

In 1757 the Pennsylvania Assembly sent him to London to argue its case against the proprietary Penn family. Apart from 1762–64, he spent most of the next eighteen years in England. There he became a central figure in a scientific network that included Collinson, John Pringle and Joseph Priestley, whom he encouraged to write his History and Present State of Electricity. He received honorary doctorates from St Andrews (1759) and Oxford (1762) and was known thereafter as Dr Franklin. In 1761 he designed the glass armonica, a set of nested glass bowls turned on a spindle and played with wet fingers, for which Mozart and Beethoven later wrote. The oil experiments, the Gulf Stream chart and the evaporation work all date from these years.

Lightning rods became a political matter too. In 1772 a Royal Society committee including Franklin recommended pointed rods for the powder magazines at Purfleet. After a strike there in 1777, Benjamin Wilson argued for blunt terminals, and George III ordered blunt ones for his palace, a choice later read as a snub to the American rebel. Field studies around 2000 suggested that moderately blunt tips are in fact struck at least as readily as sharp ones.

Franklin helped secure repeal of the Stamp Act in 1766. As relations with Britain collapsed, he was humiliated before the Privy Council in 1774, and he sailed home in March 1775. He measured water temperatures across the Gulf Stream on the way.

France, death and legacy, 1776–1790

In 1776 Franklin served on the committee that drafted the Declaration of Independence, and in October he sailed for France as one of the American commissioners. He was already famous there as the man who had disarmed lightning; the economist Turgot wrote a Latin epigram saying that he had snatched lightning from the sky and the sceptre from tyrants. From his house in Passy he negotiated the 1778 alliance with France and in 1783 signed the Treaty of Paris that ended the war.

He kept up his science. He watched the first balloon ascents in Paris in 1783, noted the dry fog of that summer, and in 1784 sat with Antoine Lavoisier, Jean Sylvain Bailly and others on the royal commission that investigated Franz Anton Mesmer’s “animal magnetism”. The commissioners used blind trials, in which subjects did not know whether they were being “magnetized”, and attributed the effects to imagination: an early controlled experiment. In a 1785 letter he described his “double spectacles”, the bifocals he had worn for years.

He sailed home in 1785, measuring sea temperatures on the way and writing his maritime observations. He served three years as President of Pennsylvania, was a delegate to the Constitutional Convention of 1787, and in his last years was president of the Pennsylvania Abolition Society. He died at home in Philadelphia on 17 April 1790, aged 84, and was buried in Christ Church Burial Ground.

Legacy

• Electricity: conservation of charge, the signs of charge, the theory of the capacitor, the power of points, and a vocabulary (battery, charge, conductor, positive, negative) still in daily use. The CGS unit of charge, the statcoulomb, is also called the franklin.
• Lightning protection: the grounded rod, essentially in the form he proposed, protects buildings worldwide.
• Oceanography and meteorology: the first printed chart of the Gulf Stream, the thermometer as a navigational tool, travelling storms, and an early link between volcanic haze and climate.
• Method: simple apparatus, careful reporting and a readiness to revise. His letters were a model for later experimenters, including Michael Faraday, who also worked without mathematics and wrote for a broad public.

Connections

People linked to Benjamin Franklin across this collection. A name without a link has no page here yet. See Benjamin Franklin in the network of all 337 lives →

Influenced by

• Isaac Newton

Influenced

• Alessandro Volta
• Charles-Augustin de Coulomb
• Luigi Galvani
• Franz Aepinus

Colleagues and collaborators

• Antoine Lavoisier 1784
• Henry Cavendish 1772
• Ebenezer Kinnersley 1746-1752
• Philip Syng 1747
• Thomas Hopkinson 1747
• Thomas-François Dalibard 1752

Rivals

• Jean-Antoine Nollet 1752-1770

Friends

• Joseph Priestley
• Peter Collinson 1747-1768

Family

• Norbert Wiener
• Timothy Folger 1768
• William Franklin

Also mentioned in this life

• André-Marie Ampère
• Gaspard-Gustave Coriolis
• Richard Courant
• Michael Faraday
• Carl Friedrich Gauss
• Johann Heinrich Lambert
• James Clerk Maxwell
• Lord Rayleigh
• James Watt

Fields

• electricity 5 lives
• heat 3 lives

Sources and further reading

Biography

1. Benjamin Franklin, Wikipedia (with extensive references).
2. Benjamin Franklin, MacTutor History of Mathematics.
3. The Papers of Benjamin Franklin, Founders Online, National Archives.
4. B. Franklin, Autobiography (written 1771–1790).
5. W. Isaacson, Benjamin Franklin: An American Life, Simon & Schuster, 2003.
6. J. Chaplin, The First Scientific American: Benjamin Franklin and the Pursuit of Genius, Basic Books, 2006.

Science

1. B. Franklin, Experiments and Observations on Electricity, made at Philadelphia in America, London, 1751 (5th ed. 1774); ed. I. B. Cohen, Harvard University Press, 1941.
2. B. Franklin to P. Collinson, 25 May 1747, Founders Online.
3. I. B. Cohen, Franklin and Newton, American Philosophical Society, 1956.
4. J. L. Heilbron, Electricity in the 17th and 18th Centuries, University of California Press, 1979.
5. E. P. Krider, Benjamin Franklin and lightning rods, Physics Today 59 (1) (2006) 42–48.
6. Kite experiment and Leyden jar, Wikipedia.
7. B. Franklin, Of the stilling of waves by means of oil, Phil. Trans. R. Soc. 64 (1774) 445–460.
8. B. Franklin, Sundry maritime observations, Trans. Am. Phil. Soc. 2 (1786) 294–329.
9. B. Franklin, Meteorological imaginations and conjectures, Mem. Lit. Phil. Soc. Manchester 2 (1785).
10. H. Stommel, The westward intensification of wind-driven ocean currents, Trans. Am. Geophys. Union 29 (1948) 202–206.
11. Gulf Stream and Laki, Wikipedia.
12. V. A. Rakov and M. A. Uman, Lightning: Physics and Effects, Cambridge University Press, 2003.
13. No actual measurement was required: Maxwell and Cavendish’s null method for the inverse square law, arXiv:1608.01520.