Hans Christian Ørsted’s Dynamo
Back to Contents
Some time on April 21 of 1820 Hans Christian Ørsted became one of the first people to witness a connection between electricity and magnetism. He had been giving a lecture in physics and he showed his students an experiment that he had prepared. He had suspended a wire above a magnetic compass and connected it to a voltaic pile through a simple switch. When he closed the switch and thereby allowed electric current to flow in the wire, Ørsted and his students saw the compass needle swing around to point in a direction perpendicular to the line defined by the part of the wire suspended over the compass. With that experiment Ørsted demonstrated that an electric current exerts a magnetic force.
Ørsted’s discovery was no accident, as some folklore has it. Before conducting the experiment Ørsted reminded his students that Benjamin Franklin and other researchers had demonstrated that thunderstorms contain huge quantities of electricity. Then he added the information that cross-country travelers who had been caught in thunderstorms sometimes reported that their compasses would not point in a single direction; rather, the needles would turn clockwise and counterclockwise at random. From that information Ørsted inferred that thunderstorms exert random magnetic force and he hypothesized that the electric currents in the storm produced that force. He then performed his experiment to prove and verify his hypothesis.
Could he have gone another step further? Having shown that an electric current exerts a magnetic force, could he have then deduced how magnetism exerts an electric force? He certainly had the intellectual tools to do the job.
Like many scientists of his day, Ørsted believed in an underlying unity among the laws of Nature. And he believed the human reason, given sufficient information, can discover the unifying relations among those laws. Further, in 1812 he had devised the word Gedankenexperiment (thought-out experiment) to denote something that he himself had done. So how might he have taken that extra step beyond the discovery that an electric current exerts a magnetic force?
He certainly knew the principle of relativity, which Galileo had described in his Dialogue Concerning the Two Chief World Systems and which Isaac Newton described in his Principia. And we would think that he would have understood the relevance of that principle to his discovery. He had discovered that moving electric charges, an electric current, exert a force on stationary magnetic charges (presumed by scientists at the time to exist in magnetized materials), so he knew, in accordance with Newton’s third law of motion, that stationary magnetic charges exert an equal and oppositely directed force upon the moving electric charges. If he had conceived the idea of an observer moving with the electric charges, he would know that the observer would also detect equal and oppositely directed forces acting between the magnet and the electric charges. That observer would have to attribute those forces to magnetic charges moving relative to stationary electric charges: that attribution is one form of Faraday’s law of electromagnetic induction.
It seems such an easy step to take and it has the additional advantage of producing a neat symmetry between electricity and magnetism. So why did Ørsted not take that step?
Perhaps we should ask first why the fourth of Maxwell’s Equations is called Ampère’s law instead of Ørsted’s law. In 1821 André-Marie Ampère conducted a series of experiments that enabled him to work out a mathematical description of the magnetic force between two electric currents, a description that formed the basis for the Biot-Savart law. He noticed, via Newton’s third law of motion, that an electric current can receive a magnetic force as well as exert it, so he measured the forces exerted between variously shaped pairs of current-carrying wires. As an aid in understanding his findings, Ampère conceived the idea of the electric current consisting of myriads of examples of an electrodynamic molecule, the conceptual precursor of the electron. All of this was just a straightforward extension of Ørsted’s experiment.
For Ørsted it should have been the obvious next step in his study of the magnetic effect of an electric current. Having established the fact of electric current exerting a magnetic force, he certainly should have wanted to know how much magnetic force a given electric current exerted. He certainly had the means to fill that want, so why didn’t he employ them? The best explanation claims that he simply lost interest in the project, perhaps distracted by more important demands on his attention (remember that he was a professor teaching at a university). Simply put, he didn’t have sufficient time free for the rather demanding (if conceptually simple) experiments and the analysis of the data coming from those experiments. Unable to immerse himself fully in his electrical studies, he would not have been in a frame of mind to discover electromagnetic induction as described above (and to be fair Ampère didn’t discover electromagnetic induction, either).
But suppose that Ørsted had been given enough time to immerse himself in electrical studies, that he discovered electromagnetic induction, and that he had verified the phenomenon experimentally. How might History have evolved differently from the pattern of our timeline?
It’s likely that in 1822 someone would have invented the dynamo, a simple electric generator, just as Hippolyte Pixii actually invented the dynamo the year after Michael Faraday discovered electromagnetic induction on our timeline. That invention would have come ten years early. The primary benefit of that invention was cheap and plentiful electricity. We also got the electric motor (a dynamo run backward), which changed manufacturing significantly.
Before the advent of the dynamo a steady electric current could only be had from a voltaic pile, what we now call an electric battery. Voltaic piles were expensive and when they ran out of electricity, they had to be discarded and replaced (imagine how practical your car would be if you had to replace the engine every month). The dynamo changed that situation radically: as long as it didn’t break, it could generate electricity endlessly. That fact made electric current cheap and thus solicited innovation. Electricity became a resource and inventors looked for practical ways to exploit it.
It would take only one person to conceive what seems obvious to us. Instead of building a factory on a river and using a waterwheel to drive the factory’s machinery directly, through a system of shafts, belts, and pulleys, that visionary would have built a powerhouse on the river, to convert river current into electrical current, and then transmitted the electricity to multiple factories built at more convenient locations. In those factories electric motors would drive the machinery. Electric factories would compete quite well against steam-driven factories with their continuous need for coal.
How far those factories could be built from the powerhouse depends upon the kind of electricity used – alternating current or direct current. On our timeline Hippolyte Pixii started out using alternating current, because that’s what the first simple dynamos produced. Later he introduced the use of commutators, so that the machinery would produce and use direct current. That same change would happen on our imaginary timeline, around 1822, because alternating-current electricity does not work well in simple multiple-circuit systems (as in a factory). Alternating current only became feasible when Nicola Tesla designed machines and multiple-circuit systems that could use it, doing so in the 1880's.
But alternating current has its own advantage. Using a simple transformer (like the one that Michael Faraday used in 1831 on our timeline) a system converts low-voltage, high-current electricity into high-voltage, low-current electricity, which travels over wires greater distances with small loss of power. It wouldn’t have taken long for some electrical engineer to figure that the best system for running factories consists of generating electricity as alternating current, stepping up the voltage in a transformer, sending the electricity over wires to a place near the factories, using a transformer to reduce the voltage, and sending it through a loadless motor that then sends it through commutators to convert it into direct current, which can then be distributed to the factories.
In addition, the direct current can be sent to the factories through cables that consist of multiple single insulated wires. Because the rate of power loss in a circuit stands in direct proportion to the square of the electric current in the circuit, sending a given amount of current through N wires instead of one wire reduces the loss in a given circuit by a factor of N. With such ploys in use to improve efficiency, electrical engineers could have begun the electrification of industry in the late 1820's or the 1830's.
Electric factories would have come first. They were expensive, certainly, but the improved efficiency and more convenient locations for them would have made the electric factories more profitable. Profit and the promise of profit drive improvement, so more electric factories would have been built across the country. As electrification spread, more people would have gained an understanding of electricity and that fact would have enabled more innovation. Someone almost certainly would have conceived the idea of an electric locomotive for use in mines. As an enterprise, mining would have become much more productive with little electric railroads carrying ore and debris. Coal would have become cheaper, making electricity even cheaper.
Comfort in a factory enhances productivity, so it wouldn’t have taken long for someone to invent the electric fan: the basic design is just too simple. An electric motor set up with its axle mounted vertically has paddle-shaped blades attached to the axle. As the blades turn, the paddles draw air from near the axle and force it outward, thereby providing a cooling breeze. Some of the larger plantations in the south might have had the wherewithal to build their own coal-fired powerhouses (and we know who would have been shoveling coal in the heat of summer) to provide electricity to run fans set on tables in the big house. People would then sit around the tables, enjoying the breeze. Eventually someone would have improved the fan into the modern airscrew type.
These things would have been nice, but they don’t really constitute what we think of as History. They are micro-History and we want to consider macro-History. So how would Large History have changed if electromagnetic induction and the dynamo had been discovered ten years before they were discovered on our timeline? What could have been different?
One of the most important components of the electric factory system is the transformer, so it would have been the subject of a lot of research. If one researcher had noticed the fact that the two coils cannot be in electrical contact with each other, that there must be an electrical insulator between them, he might have carried that knowledge further. He had noticed that there’s a gap between the coils and yet electricity somehow flows from one coil to the other. A reasonable inference would have told him that some kind of aetherial wave must be carrying the electricity between the coils. That is a phenomenon that the researcher could explore experimentally.
It likely would not have happened in the 1820's. But sometime in the late 1830's or in the 1840's someone could have been conducting experiments similar to the ones the Heinrich Hertz carried out in the 1880's on our timeline. People would have been exploring the generation and detection of electric waves. Samuel Morse’s electric telegraph would barely have been established when people began conducting experiments aimed at the development of a wireless telegraph, half a century before Guglielmo Marconi. By 1860 wireless telegraphy might have achieved a level of development that it had achieved by 1910 on our timeline. Thus, the full value of wireless telegraphy might have been established, not by distress calls from the Titanic in April 1912, but by requests for reinforcements from Major General Irvin McDowell at the first battle of Bull Run (First Manassas) in July 1861.
Imagine how the Civil War might have gone different if the armies had been accompanied by wagons carrying wireless telegraphs and their batteries or steam-powered generators. Or in the post-war era might the Indian Wars have ended more quickly. Imagine how the Battle of the Little Big Horn might have gone different if Custer’s troops had taken a telegraph wagon with them.
But the changes would not have ended there. The enthusiasm for electricity would have led to further developments coming before their time (as we see it). Specifically, wireless telegraphy might have evolved into true radio prior to 1900. The effects could have been interesting, to say the least.
Radio as we understand it required the use of vacuum tubes, especially the triode (invented by Lee de Forest in 1907). Radio engineers can also use diodes to detect radio waves, as John A. Fleming did in 1904, using diodes based on thermionic emission, the emission of electrons from a heated filament. However, if the tubes didn’t exist at the right time,... but they did. On our timeline the Crookes tube was invented around 1869, it can function as a crude diode, and it can be modified into a triode by the addition of a wire-mesh grid. It was weak, but it might have been sufficient, so we might have had tunable radio in the 1870's. With tunable radio many people can use the wireless telegraph without interfering with each other.
Alexander Graham Bell’s invention of the telephone in 1876 would certainly have inspired ideas of wireless telephony analogous to wireless telegraphy. The discovery of thermionic emission in 1873 (assuming it occurred at the same time as on our timeline) would have led to improvements in the Crookes tubes, evolving them into modern vacuum tubes, thereby making radio more efficient. (Thermionic emission is also called the Edison effect because it gained greater public notice from Thomas Edison’s experiments in 1884.) By sometime in the 1880's radio telephony would have been available, but not in wide public use. It likely would have been given its primary use among ships at sea.
Commercial radio could have appeared sometime in the 1890's, but not quite the way it happened on our timeline. Radio stations would have likely been established and subsidized by corporate trusts as a means of disseminating pro-corporate propaganda ("And now the Standard Oil Company presents the news!"). What would that have done to the Progressive Movement? Nothing? It helps to remember how effectively Hitler used radio in the 1930's on our timeline. John D. Rockefeller and his cronies, portraying themselves as benign patriarchs, could have used radio just as effectively to subvert democracy... perhaps.
President Theodore Roosevelt would certainly have conceived radio as a splendid expansion of his "bully pulpit", a full generation prior to his cousin’s Fireside Chats. And sufficiently large organizations, such as the American Federation of Labor and some of the larger churches, could also have had their own radio stations. So the plutocrats would not have had free rein over the dissemination of information.
The Crookes tube is a crude example of a cathode-ray tube and in the 1880's researchers experimented with forming the cathode rays (electrons) into beams and deflecting them. On our alternate timeline we might have had television in the 1920's or earlier. Imagine the Great Depression and the Dust Bowl coming into people’s living rooms every evening. Imagine the horrors of the Jim Crow era coming into people’s homes and evoking the moral revulsion against racism that only came to us in the 1960's.
Imagine all of those differences and more coming from the discovery of electromagnetic induction ten years early and the enthusiasm for all things electrical that would have accompanied it. Would a more rapid pace of scientific discovery and technological development have been a bad thing? Or would it have stimulated a more rapid advance of our society’s moral development? How could we ever find out? That’s what science fiction is for.
Back to Contents