Mar 162018

Today is the birthday (1789) of Georg Simon Ohm a Bavarian physicist and mathematician who gave his name to the equation relating voltage, resistance, and current: Ohm’s law. Ohm was born in Erlangen, Brandenburg-Bayreuth (then a part of the Holy Roman Empire), son to Johann Wolfgang Ohm, a locksmith and Maria Elizabeth Beck, the daughter of a tailor in Erlangen. Although his parents had not been formally educated, Ohm’s father was a respected man who had educated himself, and, in consequence, was able to give his sons an excellent education through his own instruction. Of the seven children of the family only three survived to adulthood: Georg Simon, his younger brother Martin, who later became a well-known mathematician, and his sister Elizabeth Barbara. His mother died when he was ten.

From early childhood, Georg and Martin were taught by their father who brought them to a high standard in mathematics, physics, chemistry and philosophy. Georg attended Erlangen Gymnasium from age 11 to 15 where he received little in the area of scientific training, which sharply contrasted with the inspired instruction that both he and his brother received from their father. Ohm’s father, concerned that his son was wasting his educational opportunity, sent him to Switzerland, where in September 1806 he accepted a position as a mathematics teacher in a school in Gottstadt bei Nidau. Ohm left his teaching post in Gottstatt Monastery in March 1809 to become a private tutor in Neuchâtel. For two years he carried out his duties as a tutor while and continued his private study of mathematics. Then in April 1811 he returned to the University of Erlangen.

Ohm’s own studies prepared him for his doctorate which he received from the University of Erlangen on 25th October 1811. He immediately joined the faculty there as a lecturer in mathematics but left after three terms because of unpromising prospects. He could not survive on his salary as a lecturer. The Bavarian government offered him a post as a teacher of mathematics and physics at a poor-quality school in Bamberg which Ohm accepted in January 1813. Unhappy with his job, Georg began writing an elementary textbook on geometry as a way to prove his abilities. That school was closed in February 1816. The Bavarian government then sent Ohm to an overcrowded school in Bamberg to help out with the teaching of mathematics.

After his assignment in Bamberg, Ohm sent his completed manuscript to King Wilhelm III of Prussia. The King was impressed with Ohm’s book, and offered him a position at the Jesuit Gymnasium of Cologne on 11th September 1817. This school had a reputation for good science education and Ohm was required to teach physics in addition to mathematics. The physics laboratory was well equipped, allowing Ohm to begin experiments in physics. As the son of a locksmith, Ohm also had some practical experience with mechanical devices.

Ohm published Die galvanische Kette, mathematisch bearbeitet (The Galvanic Circuit Investigated Mathematically) in 1827. Ohm’s law [current (I) = voltage (V) divided by resistance (R)] first appeared in this book, as did his comprehensive theory of electricity. The book begins with the mathematical background necessary for an understanding of the rest of the work. While his work greatly influenced the theory and applications of current electricity, it was coldly received at that time. It is interesting that Ohm presents his theory as one of contiguous action, a theory which opposed the concept of action at a distance. Ohm believed that the communication of electricity occurred between “contiguous particles” which is the term he himself used. The paper is concerned with this idea, and in particular with illustrating the differences in this scientific approach of Ohm’s and the approaches of Joseph Fourier and Claude-Louis Navier.

Ohm’s college did not appreciate his work and so he resigned from his position. He then made an application to, and was employed by, the Polytechnic School of Nuremberg. Ohm arrived at the Polytechnic School of Nuremberg in 1833, and in 1852 he became a professor of experimental physics at the University of Munich.

In 1849, Ohm published Beiträge zur Molecular-Physik, ( Molecular Physics). In the preface of this work he stated he hoped to write a second and third volume “and if God gives me length of days for it, a fourth”. However, on finding that an original discovery recorded in it was being anticipated by a Swedish scientist he did not publish it, stating: “The episode has given a fresh and deep sense for my mind to the saying ‘Man proposes, and God disposes’. The project that gave the first impetus to my inquiry has been dissipated into mist, and a new one, undesigned by me, has been accomplished in its place.”

Ohm died in Munich in 1854 and is buried in the Alter Südfriedhof. Ohm’s name has been incorporated in the terminology of electrical science in Ohm’s Law, and adopted as the SI unit of resistance, the ohm (symbol Ω). Although Ohm’s work strongly influenced theory, at first it was received with little enthusiasm. However, his work was eventually recognized by the Royal Society with its award of the Copley Medal in 1841. He became a foreign member of the Royal Society in 1842.

Knieküchle is a traditional Franconian fried dough pastry that is very popular in Old Bavaria as well. Depending on region it has several other names, including Auszogne, Krapfen, Küchl, or Rottnudel. As a general rule they are made of yeast dough but some recipes vary slightly. Very common for example is the addition of raisins. The dough is shaped so it is very thin in the middle and thicker on the edges. They are then fried in lard and dusted with confectioner’s sugar. The pastry is mostly eaten for celebrations, so it is appropriate today to celebrate Ohm. In Franconia, people differentiate between “Catholic” and “Protestant” Knieküchle depending whether it is dusted with confectioner’s sugar or not. Ohm was Protestant, so you decide.


1 ¼ sticks unsalted butter
4 eggs
2 cups milk
½ cup sugar
1 package yeast
3 cups (approx.) all-purpose flour
oil for frying (or lard)
powdered sugar


In a small bowl, combine the yeast and ½ cup of the milk (lukewarm). Mix in 3 tablespoons flour and 1 teaspoon of the sugar. Allow this mixture to sit in a warm place for 1 hour.

Combine the remaining dough ingredients then add in the yeast mixture. Mix until a smooth dough forms, adjusting the flour as necessary. Knead by hand for about 20 minutes.

Place the dough in a lightly greased bowl, cover, and let sit in a warm place until double in volume.

Punch the dough down and divide it into tablespoon size pieces. Press each piece of dough flat and allow them to rise again for 1 hour.

Heat the oil in a deep-fryer to around 370˚F/190˚C.

Take each piece of dough and stretch it out again – large enough that it would be able to cover your knee [why they are called “knee pastries]. Fry each stretched-out piece of dough until golden brown on both sides. Remove from the oil with a slotted spoon and let drain on wire racks. Dust with powdered sugar if you wish. They can be eaten plain or with fruit preserves. They are best served warm.

Jun 152017

This date in 1752 is the traditional date set for Ben Franklin’s kite flying experiment meant to prove that lightning is electricity. If he had performed the experiment as commonly thought of, and depicted, he would almost certainly have been electrocuted.  He was much more cautious, however, and it’s worth discussing Franklin and electricity on this date because what he discovered led to new directions for science. First, I will admit that I have already discussed this topic briefly here:  This is what I said:

According to the canonical tale, Franklin realized the dangers of using conductive rods and instead used a kite. According to the legend, Franklin kept the string of the kite dry at his end to insulate him while the rest of the string was allowed to get wet in the rain to provide conductivity. A house key was attached to the string and connected to a Leyden jar (a primitive capacitor), which Franklin assumed would accumulate electricity from the lightning. The kite wasn’t struck by visible lightning (had it done so, Franklin would almost certainly have been killed) but Franklin did notice that the strings of the kite were repelling each other and deduced that the Leyden jar was being charged. Franklin reportedly received a mild shock by moving his hand near the key afterwards, because as he had estimated, lightning had negatively charged the key and the Leyden jar, proving the electric nature of lightning.

Fearing that the test would fail, or that he would be ridiculed, Franklin took only his son to witness the experiment, and then published the accounts of the test in third person. The standard account of Franklin’s experiment was disputed following an investigation and experiments based on contemporaneous records by science historian Tom Tucker, the results of which were published in 2003. According to Tucker, Franklin never performed the experiment, and the kite as described is incapable of performing its alleged role. Further doubt about the standard account has been cast by an investigation by the television series MythBusters. The team found evidence that Franklin would have received a fatal current through his heart had the event actually occurred. Nevertheless, they confirmed that certain aspects of the experiment were feasible – specifically, the ability of a kite with sufficiently damp string to receive and send to the ground the electrical energy delivered by a lightning strike.

Now let’s look deeper.

Franklin started exploring the phenomenon of electricity in 1746 when he saw some of Archibald Spencer’s lectures using static electricity for illustrations. Franklin proposed that “vitreous” and “resinous” electricity were not different types of “electrical fluid” (as electricity was called then), but the same “fluid” under different pressures. He was the first to label them as positive and negative respectively, and he was the first to discover the principle of conservation of charge. In 1748 he constructed a multiple plate capacitor, that he called an “electrical battery” (not to be confused with Volta’s pile) by placing eleven panes of glass sandwiched between lead plates, suspended with silk cords and connected by wires.

In 1750, he published a proposal for an experiment to prove that lightning is electricity by flying a kite in a storm that appeared capable of becoming a lightning storm. On May 10, 1752, Thomas-François Dalibard of France conducted Franklin’s experiment using a 40-foot-tall (12 m) iron rod instead of a kite, and he extracted electrical sparks from a cloud. On June 15 Franklin may possibly have conducted his well-known kite experiment in Philadelphia, successfully extracting sparks from a cloud, but there is no definitive evidence for this. However we do know that Franklin did conduct kite experiments around this time, although the results were not written up (with credit to Franklin) until Joseph Priestley’s 1767 History and Present Status of Electricity. Franklin was careful to stand on an insulator, keeping dry under a roof to avoid the danger of electric shock. Prof. Georg Wilhelm Richmann replicated the experiment in Russia in the months following Franklin’s experiment and was, indeed, killed by electrocution.

In his writings, Franklin indicates that he was aware of the dangers and offered alternative ways to demonstrate that lightning was electrical, as shown by his use of the concept of electrical ground. If Franklin ever did perform the experiment he proposed he certainly did not do it in the way that is often described—flying the kite and waiting to be struck by lightning. He did however use a kite to collect some electric charge from a storm cloud to prove that lightning was electrical. On October 19 in a letter to England with directions for repeating the experiment, Franklin wrote:

When rain has wet the kite twine so that it can conduct the electric fire freely, you will find it streams out plentifully from the key at the approach of your knuckle, and with this key a phial, or Leyden jar, may be charged: and from electric fire thus obtained spirits may be kindled, and all other electric experiments [may be] performed which are usually done by the help of a rubber glass globe or tube; and therefore the sameness of the electrical matter with that of lightening completely demonstrated.

Franklin’s electrical experiments led to his invention of the lightning rod. He noted that conductors with a sharp rather than a smooth point could discharge silently, and at a far greater distance. He surmised that this could help protect buildings from lightning by attaching “upright Rods of Iron, made sharp as a Needle and gilt to prevent Rusting, and from the Foot of those Rods a Wire down the outside of the Building into the Ground; … Would not these pointed Rods probably draw the Electrical Fire silently out of a Cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible Mischief!” Following a series of experiments on Franklin’s own house, lightning rods were installed on the Academy of Philadelphia (later the University of Pennsylvania) and the Pennsylvania State House (later Independence Hall) in 1752.

In recognition of his work with electricity, Franklin received the Royal Society’s Copley Medal in 1753, and in 1756 he became one of the few 18th-century North Americans elected as a Fellow of the Society. He received honorary degrees from Harvard and Yale universities. The cgs unit of electric charge has been named after him: one franklin (Fr) is equal to one statcoulomb.

Franklin advised Harvard University in its acquisition of new electrical laboratory apparatus after the complete loss of its original collection, in a fire which destroyed the original Harvard Hall in 1764. The collection he assembled would later become part of the Harvard Collection of Historical Scientific Instruments, now on public display in its Science Center.

According to Michael Faraday, Franklin’s experiments on the non-conduction of ice are worth mentioning, although the law of the general effect of liquefaction on electrolytes is not attributed to Franklin. However, as reported in 1836 by A. D. Bache of the University of Pennsylvania, the law of the effect of heat on the conduction of bodies that are otherwise non-conductors, for example, glass, could be attributed to Franklin. Franklin writes, “A certain quantity of heat will make some bodies good conductors, that will not otherwise conduct …And water, though naturally a good conductor, will not conduct well when frozen into ice.”

Franklin took a great deal of interest in the food products grown in Britain and North America, generally expressing a preference for the latter.  He did, however, send seeds of kale (which he called “Scotch cabbage”) and rhubarb to friends back home. I suspect he was more interested in the medicinal properties of the roots of rhubarb than the food uses of the stalks. In return he asked his wife to send him apples and cranberries which she sent by the barrel load !! He could get apples in England, of course, but he preferred American Newton pippins for roasting over the apples he could find there. Cranberries of several species are indigenous to all northern temperate regions, but they did not catch on as a domesticated species in Europe in the way that they did in North America. Even in the United States they’re hard to find uncooked these days except around Thanksgiving; most are commercially processed into juice, sauces, and jellies. If you can find plain cranberries you might consider making a tart. Here’s one idea using a custard filling and quite a lot of brown sugar to counter the sourness of the cranberries. I generally use a prepared tart shell out of laziness, but you can make your own pastry if you wish.

Cranberry Custard Tart


9” tart crust
1 ½ cups granulated sugar
¼ cup water
2 cups cranberries (10 oz)
2 large eggs
½ cup brown sugar
1 ½ tsp all-purpose flour
¼ cup light cream
½ tsp almond extract
confectioners’ sugar


Preheat the oven to 350°F/175°C.

Blind bake the tart shell by lining it with foil and filling with pie weights or dried beans. Bake the tart shell for about 30 minutes, until the rim is lightly golden. Remove the foil and weights and bake for another 5 minutes, until it is lightly golden all over. Set the tart pan on a wire rack.

Increase the oven temperature to 375°F/190°C

Meanwhile, make the filling in a medium saucepan by combining the granulated sugar with the water and cook over moderately high heat, stirring, until the sugar dissolves. Add the cranberries, cover and cook over moderate heat for 3 minutes, stirring once or twice. Remove the pan from the heat and let the cranberries cool to room temperature. Drain the cranberries well and reserve the cranberry syrup.

In a medium bowl, make a custard by beating the eggs with the brown sugar and flour. Whisk in the light cream and the almond extract. Spread the cranberries in the tart shell. Drizzle 1 tablespoon of the reserved cranberry syrup over the cranberries, then pour in the almond custard.

Bake the tart in the lower third of the oven until a skewer inserted in the center comes out clean, 16 to 18 minutes. Transfer the tart in the pan to a wire rack to cool completely, at least 2 hours. Dust with confectioners’ sugar.

May 032017

Today was first designated as Sun Day by United States President Jimmy Carter in 1978. It was meant as a way of promoting the use of solar power as a source of energy,following a joint resolution by Congress, H.J.Res. 715. It was modeled on the highly successful Earth Day of April 22, 1970. It was the idea of Denis Hayes, who also coordinated Earth Day in 1970. On the first Sun Day President Carter flew to Denver to visit a solar power research institute, while other people gathered at Cadillac Mountain in Maine where the sun’s ray allegedly first touch the United States (although not at the time of the year). A crowd gathered at UN Plaza in New York City listened to speeches by people such as movie star Robert Redford, who reminded them that the sun “can’t be embargoed by any foreign nation”. At the Lincoln Memorial in Washington, DC, environmental activist Barry Commoner spoke to a group of 500 people, suggesting, a little hyperbolically, that solar power was an issue as pivotal as slavery and that power was the “… one solution to the economic problems of the United States.” Let’s take a small step back and say that solar power is not the cure all for all the world’s ills, but more can be done to support advancement of solar energy worldwide.

Carter’s initiative has taken a few steps forward and a few steps backward globally. When Reagan took office he swiftly undid many of Carter’s executive orders concerning conservation and green energy. Those who are old enough to remember Reagan’s first 100 days will recall that on his first day in office he ordered all the thermostats in the White House turned up where Carter had ordered them set at no higher than 70˚F.  As far as he was concerned there was no need to conserve finite energy sources. Also, Carter had famously planted a garden on the roof of the White House and had installed solar panels that provided hot water throughout the building. Reagan had the garden and the solar panels dismantled. I’m presuming he saw them both as hippie nonsense, and that “real men” burned fossil fuels for heat and got their vegetables from the supermarket.

Sun Day did not turn out to be as big a success as Earth Day, but it still deserves a tip of the hat. Carter in place a great many federal plans that have since been undone, and in the US now there is not much of a drive forward on the solar front. Clinton and Obama did almost nothing, and you can’t expect anything from Trump. Carter provided subsidies and federal funds for research into solar technology as well as tax breaks for installing certified solar systems. Carter wanted the US to be on track to be 20% reliable on renewable energy sources by 2000. That plan got derailed by successive governments. Carter knew the road was rocky.  He had met resistance from Congress from the outset. In 1979 when the White House solar panels were installed he said, “A generation from now, this solar heater can either be a curiosity, a museum piece, an example of a road not taken, or it can be a small part of one of the greatest and most exciting adventures ever undertaken by the American people.” They are not even a museum piece; they are in storage somewhere in Maine: a forgotten part of US history.

There is so much that can be done with solar energy, but too many countries are turning their backs on it. In some ways the political struggles in places such as the US and Australia are understandable from a certain point of view. England pulled the plug on coal mining and tens of thousands lost their jobs as a result.  In addition, whole towns withered culturally. One of my favorite movies, Brassed Off, excellently documents what happens when a mining town loses its pits. Australia and the US lack the political will to promote renewable energy for two reasons.  First, closing mines is bad publicity, and, second, powerfully rich people with political clout are heavily invested in fossil fuels. There is certainly one problem here I am sympathetic to, namely, the plight of people who lose their jobs. The capitalists who benefit financially from fossil fuels are on their own. I am neither a politician nor an economist, so any solution I offer to the first problem will be simplistic. But all evidence I’ve read suggests that promotion of renewable energy sources creates jobs. The purpose of government, in my opinion, ought to be to make sure that those jobs are created in regions where they have been lost by the reduction in fossil fuel production.

Solar power has enormous potential which is still being developed. It would take me too long to break down all the statistics and provide meaningful analysis. There are plenty of sources for you. I’ll just cite two surprising results. First, China and Germany are world leaders in solar production of electricity. China has, of course, been a major polluter in the past, and many cities are still choked with air pollution. But the country is setting its sights high. Electric motor bikes are the norm in all major cities, and the country has the capacity to produce 22.5% of its electricity from solar panels. Germany is the second best with 20.6%. Compare this with Australia coming in at 2.6%. What exactly is the problem? Does Germany have more sun than Australia? My second surprising (maybe) result is that all the oil rich countries of the Middle East are 100% dependent on fossil fuels. There has to be a big element of laziness involved here. They have oil coming out the ears, so clearly feel no financial pressure to switch to renewables. Apparently they feel no moral pressure either. Who cares about pollution?

To my mind, one of the most wasteful home appliances that you find throughout the US is the clothes dryer. When I lived in New York I was rebuked by neighbors for using a washing line to dry my clothes.  Apparently it was unsightly, lowering the tone of the neighborhood. Since leaving there I have never used a dryer. I never saw one in China, and have not seen one in Italy. My apartments have come equipped with the means to hang my clothes to dry. Hanging your clothes in the sun to dry is as natural as breathing.

Solar-powered, and electric-powered cars are not quite ready yet to take on petrol cars but they are gaining ground. Hybrids of electric and petrol engines have a growing market now. The nut still to be cracked with solar and electric cars concerns battery capacity. In daylight, solar cars have unlimited mileage, but at night they must rely on batteries to store a charge, and batteries cannot, yet, provide a great range between recharges.

Using passive solar heat also has great potential. Here is one design for a house that heats itself in the winter months through solar energy. It combines the greenhouse effect of glass, with walls that store heat during the day and then release it at night.

This in turn brings me to the greenhouse, which I think of as one of the greatest inventions of all time for the gardener. I had plans to build one as an extension on my house but it never came to fruition. One of my best friends in England has two greenhouses on a small plot in Oxford City where he propagates all manner of rare and exotic cacti. This is England we’re talking about, not the Gobi or the Kalahari.  A greenhouse transforms your gardening possibilities immensely. Most especially I wanted one to be able to start plants from seed indoors that needed a warm and frost-free growing season that was longer than I had outdoors. I made use of available sunny window ledges but a greenhouse would have expanded my possibilities immeasurably.   But I am sure I would quickly have got into exotics as well.

I gave some recipe ideas here for the pads and fruit of the prickly pear  Let’s turn instead to sunflower seeds. These days baseball players in the US, if they are not chewing tobacco, love to crack sunflower seeds in their mouths, swallow the kernels, and spit out the husks. I’m happier just buying the kernels, which you can get at health food stores. This recipe calls for them roasted. I do this by spreading them in a single layer on a roasting pan and roasting them in a hot oven (400˚F) for no more than 10 minutes, checking constantly to be sure they don’t burn, and shaking the pan now and again to make sure they roast uniformly. You can also do this on top of the stove in a dry skillet over high heat.

Linguine with Roquefort and Sunflower Seeds


10 oz linguini
2 green onions, sliced
3 oz Roquefort
1 tbsp butter
1  cups sour cream
salt and pepper
⅓ cup roasted sunflower kernel
chopped parsley


Melt the butter in a large skillet over medium heat. Add the green onion and sauté for 1 or 2 minutes, until soft. Add the sour cream and crumble in the Roquefort. Add the sunflower kernels and season to taste with salt and pepper. Turn the heat down to low, and stir the sauce until the cheese melts and the sauce thickens.

Cook the linguini in boiling water until it is al dente. Drain well and toss into the sauce. Mix the sauce and pasta thoroughly, turn on to a serving plate and garnish with parsley.

Dec 202016


Today is the birthday (1901) of Robert Jemison Van de Graaff, a US physicist, noted for his design and construction of high-voltage Van de Graaff generators. When I was studying physics in England in the 1960s my school’s Van de Graaff generator was one of my favorite “toys” although I was not aware that at the time its inventor was still alive. It seemed rather Victorian. These generators can produce well over one million volts, but they are not necessarily dangerous because the current (amperage) is weak. The high voltage is, however, useful in certain applications in physics.  I will also note that today is the birthday of physicist David Bohm who I wrote about 3 years ago  Definitely a physicists’ day.


The Van de Graaff generator uses a motorized insulating belt (usually made of rubber) to conduct electrical charges from a high voltage source on one end of the belt to the inside of a metal sphere on the other end. Since electrical charge resides on the outside of the sphere, it builds up to produce an electrical potential much higher than that of the primary high voltage source. Practical limitations restrict the potential produced by large Van de Graaff generators to about 7 million volts. Van de Graaff generators are used primarily as DC power supplies for linear atomic particle accelerators in nuclear physics experiments. Tandem Van de Graaff generators are essentially two generators in series, and can produce about 15 million volts.


The Van de Graaff generator is a simple mechanical device to build. Small Van de Graaff generators are built by hobbyists and scientific apparatus companies and are used to demonstrate the effects of high DC potentials. Even small hobby machines produce impressive sparks several centimeters long. The largest air insulated Van de Graaff generator in the world, built by Van de Graaff himself, is operational and is on display at the Boston Museum of Science. Demonstrations throughout the day are a popular attraction. More modern Van de Graaff generators are insulated by pressurized dielectric gas, usually freon or sulfur hexafluoride. In recent years, Van de Graaff generators have been slowly replaced by solid-state DC power supplies without moving parts. The energies produced by Van de Graaff atomic particle accelerators are limited to about 30 MeV, even with tandem generators accelerating doubly charged particles. More modern particle accelerators using different technology produce much higher energies, thus Van de Graaff particle accelerators have become largely obsolete. They are still used to some extent for graduate student research at colleges and universities and as ion sources for high energy bursts.


Van de Graaff built his first  generator in 1929 at Princeton University on a fellowship, with help from colleague Nicholas Burke. The first model used an ordinary tin can, a small motor, and a silk ribbon bought at a five-and-dime store. After this initial success he went to the head of the physics department requesting $100 to make an improved version. He did get the money, but with some difficulty. By 1931 he could report achieving 1.5 million volts. According to his first patent application, it had two 60-cm-diameter charge-accumulation spheres mounted on borosilicate glass columns 180 cm high. The apparatus cost $90 in 1931.

In 1933, Van de Graaff built a 40-foot (12-m) model at MIT’s Round Hill facility, the use of which was donated by Colonel Edward H. R. Green. One of Van de Graaff’s accelerators used two charged domes of sufficient size that each of the domes had laboratories inside – one to provide the source of the accelerated beam, and the other to analyze the actual experiment. The power for the equipment inside the domes came from generators that ran off the belt, and several sessions came to a rather gruesome end when a pigeon would try to fly between the two domes, causing them to discharge. (The accelerator was set up in an airplane hangar.)


In 1937, the Westinghouse Electric company built a 65 feet (20 m) Van de Graaff generator capable of generating 5 MeV in Forest Hills, Pennsylvania. It marked the beginning of nuclear research for civilian applications. It was decommissioned in 1958 and was demolished in 2015.

A more recent development is the tandem Van de Graaff accelerator, containing one or more Van de Graaff generators, in which negatively charged ions are accelerated through one potential difference before being stripped of two or more electrons, inside a high voltage terminal, and accelerated again. An example of a three-stage operation has been built in Oxford Nuclear Laboratory in 1964 of a 10 MV single-ended “injector” and a 6 MV EN tandem.


By the 1970s, up to 14 million volts could be achieved at the terminal of a tandem that used a tank of high-pressure sulfur hexafluoride (SF6) gas to prevent sparking by trapping electrons. This allowed the generation of heavy ion beams of several tens of megaelectronvolts, sufficient to study light ion direct nuclear reactions. The highest potential sustained by a Van de Graaff accelerator is 25.5 MV, achieved by the tandem at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory.

Static electricity is not much use for cooking except under very special circumstances. This, and dozens of videos like it, is fake:

Static electricity can generate millions of volts, but it’s not just voltage that matters. You have to have a current as well. Without a current you can’t cook much of anything. Use your microwave and make some popcorn to celebrate Van de Graaff.

Jan 172016


Today is the birthday (1706) of Benjamin Franklin, one of the so-called Founding Fathers of the United States, a renowned polymath – author, printer, political theorist, politician, freemason, postmaster, scientist, inventor, civic activist, statesman, and diplomat. As a scientist, he was a major figure in the American Enlightenment and the history of physics for his discoveries and theories regarding electricity. As an inventor, he is known for the lightning rod, bifocals, and the Franklin stove, among other inventions. He facilitated many civic organizations, including Philadelphia’s fire department and a university.

Franklin earned the title of “The First American” for his early and indefatigable campaigning for colonial unity, first as an author and spokesman in London for several colonies. As the first United States ambassador to France, he exemplified the emerging American nation (famous for his “natural” appearance by arriving at the French court for the first time showing his natural hair and not in a powdered wig). Franklin was foundational in defining the American ethos as a marriage of the practical values of thrift, hard work, education, community spirit, self-governing institutions, and opposition to authoritarianism both political and religious, with the scientific and tolerant values of the Enlightenment.

Franklin became a successful newspaper editor and printer in Philadelphia, the leading city in the colonies. With two partners he published the Pennsylvania Chronicle, a newspaper that was known for its revolutionary sentiments and criticisms of British policies. He became wealthy publishing Poor Richard’s Almanack and The Pennsylvania Gazette.


He played a major role in establishing the University of Pennsylvania and was elected the first president of the American Philosophical Society. Franklin became a national hero in America when as agent for several colonies he spearheaded the effort to have Parliament in London repeal the unpopular Stamp Act. An accomplished diplomat, he was widely admired among the French as American minister to Paris and was a major figure in the development of positive Franco-American relations. His efforts to secure support for the American Revolution by shipments of crucial munitions proved vital for the war effort.

For many years he was the British postmaster for the colonies, which enabled him to set up the first national communications network. He was active in community affairs, colonial and state politics, as well as national and international affairs. From 1785 to 1788, he served as governor of Pennsylvania. Toward the end of his life, he freed his own slaves and became one of the most prominent abolitionists.


His colorful life and legacy of scientific and political achievement have seen Franklin honored on coinage and the $100 bill; warships; the names of many towns; counties; educational institutions; corporations; and, more than two centuries after his death, countless cultural references.

It’s impossible in a short post to run through all that Franklin accomplished, so I am going to pick a few of my favorites. I’ll begin with his invention of the mechanical glass harmonica. The use of a crystal wine glass to produce a ringing tone by rubbing a wet finger around the rim is documented back to Renaissance times. The Irish musician Richard Pockrich is typically credited as the first to play an instrument composed of glass vessels filled with differing amounts of water to produce different tones. In the 1740s, he performed in London but his career was cut short by a fire in his room, which killed him and destroyed his apparatus. Edward Delaval, extended Pockrich’s experiments by creating a set of glasses that were better tuned and easier to play. During the same decade, Christoph Willibald Gluck also attracted attention playing a similar instrument in England.


Franklin invented a radically new arrangement of the glasses in 1761 after seeing Edmund Delaval play in Cambridge in England in May of 1761. Franklin worked with London glassblower Charles James to build one, and it had its world premiere in early 1762, played by Marianne Davies. In Franklin’s treadle-operated version, 37 bowls were mounted horizontally on an iron spindle. The whole spindle turned by means of a foot pedal. The sound was produced by touching the rims of the bowls with water moistened fingers. Rims were painted different colors according to the pitch of the note: A (dark blue), B (purple), C (red), D (orange), E (yellow), F (green), G (blue), and accidentals were marked in white. With the Franklin design, it is possible to play ten glasses simultaneously if desired, a technique that is very difficult if not impossible to execute using upright goblets.

Mozart, Beethoven, Richard Strauss, and more than 100 other composers composed works for the glass harmonica. Some pieces survive in the repertoire through transcriptions for more conventional instruments. Camille Saint-Saëns used this instrument in his The Carnival of the Animals (in movements 7 and 14). Donizetti originally specified the instrument in Lucia di Lammermoor as a haunting accompaniment to the heroine’s “mad scenes”, though before the premiere he was required by the producers to rewrite the part for two flutes. Here’s Mozart’s Adagio in C Major for glass harmonica (K617a).

Many storybooks tell of Franklin flying a kite with a key attached in a storm to attract lightning to prove it is electrical in nature. Such an experiment was carried out in May 1752 at Marly-la-Ville in northern France by Thomas-François Dalibard. An attempt to replicate the experiment killed Georg Wilhelm Richmann in Saint Petersburg in August 1753, thought to be the victim of ball lightning. Franklin himself is said to have conducted the experiment in June 1752, supposedly on the top of the spire on Christ Church in Philadelphia. However, doubts have been expressed about whether the experiment was actually performed.


According to the canonical tale, Franklin realized the dangers of using conductive rods and instead used a kite. According to the legend, Franklin kept the string of the kite dry at his end to insulate him while the rest of the string was allowed to get wet in the rain to provide conductivity. A house key was attached to the string and connected to a Leyden jar (a primitive capacitor), which Franklin assumed would accumulate electricity from the lightning. The kite wasn’t struck by visible lightning (had it done so, Franklin would almost certainly have been killed) but Franklin did notice that the strings of the kite were repelling each other and deduced that the Leyden jar was being charged. Franklin reportedly received a mild shock by moving his hand near the key afterwards, because as he had estimated, lightning had negatively charged the key and the Leyden jar, proving the electric nature of lightning.

Fearing that the test would fail, or that he would be ridiculed, Franklin took only his son to witness the experiment, and then published the accounts of the test in third person. The standard account of Franklin’s experiment was disputed following an investigation and experiments based on contemporaneous records by science historian Tom Tucker, the results of which were published in 2003. According to Tucker, Franklin never performed the experiment, and the kite as described is incapable of performing its alleged role. Further doubt about the standard account has been cast by an investigation by the television series MythBusters. The team found evidence that Franklin would have received a fatal current through his heart had the event actually occurred. Nevertheless, they confirmed that certain aspects of the experiment were feasible – specifically, the ability of a kite with sufficiently damp string to receive and send to the ground the electrical energy delivered by a lightning strike.


Franklin was purportedly the master of the pithy aphorism. “Early to bed and early to rise, makes a man healthy wealthy and wise,” for example, is found in the 1735 edition of his Poor Richard’s Almanack, and is typical in that its attribution to Franklin is only partially accurate. Yes, he printed the saying; no, he did not create it. The earliest known record of a proverb that approximates to Franklin’s comes from The Book of St. Albans, printed in 1486:

As the olde englysshe prouerbe sayth in this wyse. Who soo woll ryse erly shall be holy helthy & zely.

The Middle English word zely comes down to us now as “silly,” and could mean “foolish” in the 15th century. But it could also mean “fortunate.” “Holy helthy & zely” probably meant “wise, healthy and fortunate” and in some form came down to Franklin. It can be found in John Clarke’s Paroemiologia Anglo-Latina in 1639:

Earely to bed and earely to rise, makes a man healthy, wealthy, and wise.

Later U.S. commentators have had some fun at Franklin’s expense. In 1928, Carl Sandburg suggested that ‘Early to bed and early to rise and you never meet any prominent people’. In the New Yorker, February 1939, James Thurber turned it round:

Early to rise and early to bed makes a male healthy and wealthy and dead.

In a letter to Jean-Baptiste Leroy, dated 1789, Franklin wrote:

Our new Constitution is now established, and has an appearance that promises permanency; but in this world nothing can be said to be certain, except death and taxes.

The fact that Franklin doubted the permanence of the Constitution is interesting in itself; but we should also note that the notion of the certainty of only “death and taxes” did not originate with Franklin. It comes from Daniel Defoe’s The Political History of the Devil (1726):

Things as certain as death and taxes, can be more firmly believ’d.

I like this saying attributed to Franklin a lot:

Tell me and I forget. Teach me and I remember. Involve me and I learn.

But he never said it. Likewise I once had a T-shirt with this saying attributed to Franklin:

Beer is proof that God loves us and wants us to be happy.

Franklin never said this either, but he did say this about wine:

We hear of the conversion of water into wine at the marriage in Cana, as of a miracle. But this conversion is, through the goodness of God, made every day before our eyes. Behold the rain which descends from heaven upon our vineyards, and which incorporates itself with the grapes to be changed into wine; a constant proof that God loves us, and loves to see us happy!

Franklin has a great deal to say about food, and, in particular, promoted native American cultigens in Europe where they were largely disapproved of. Both potatoes and tomatoes were considered by some to be poisonous. He is credited, also, with introducing tofu, rhubarb, and kale into the U.S. (in the latter 2 cases sending seeds from Scotland). Here’s a defense of American cuisine from a 2 January 1766 letter:

Pray let me, an American, inform the gentleman, who seems ignorant of the matter, that Indian corn, take it for all in all, is one of the most agreeable and wholesome grains in the world; that its green leaves roasted are a delicacy beyond expression; that samp, hominy, succotash, and nokehock, made of it, are so many pleasing varieties; and that johny or hoecake, hot from the fire, is better than a Yorkshire muffin – But if Indian corn were so disagreeable and indigestible as the Stamp Act, does he imagine that we can get nothing else for breakfast? – Did he never hear that we have oatmeal in plenty, for water gruel or burgoo; as good wheat, rye and barley as the world affords, to make frumenty; or toast and ale; that there is every where plenty of milk, butter, and cheese; that rice is one of our staple commodities; that for tea, we have sage and bawm in our gardens, the young leaves of the sweet hickery or walnut, and above all, the buds of our pine, infinitely preferably to any tea from the Indies … Let the gentleman do us the honor of a visit in America, and I will engage to breakfast him every day in the month with a fresh variety.

Lots to choose from here, but I pick succotash. The word succotash may come from Narragansett sohquttahhash meaning “broken corn kernels,” or misckquatash meaning “boiled corn kernels.” In any event, it is a common dish in the U.S. South. The primary ingredients are freshly hulled corn kernels and either lima beans or other shell beans. The two together are high in amino acids. Add squash and you have complete protein. There’s hundreds of versions of succotash. Here’s how I was taught to make it in coastal North Carolina. I’ll leave you to worry about quantities and such. This recipe uses fresh ingredients, but a lot of contemporary cooks use canned vegetables and simply mix them and heat them through. Occasionally a Southern cook will bake succotash with a pastry top.



Using a sharp knife scrape the whole kernels from corn cobs. Add an equal quantity of lima beans. Seed and dice some tomato and bell pepper (green or red or both), and add them to the mix. Place the vegetables in a large pot, cover with water, and simmer. Length of cooking time is cook’s choice. I prefer the vegetables to be al dente, but my Southern friends used to boil them to death.

Succotash is normally served warm as a side dish, but you can also serve it chilled, dressed with a little vinegar, as a salad.