Field of Science

The electric science of Captain Swing

posted by @ulaulaman about @warrenellis comics #electromagnetism #Faraday #diamagnetism
Later that year [1830], there was a spate of riots by farm workers in the south of England who were reduced to starvation by the introduction of machinery that could do their jobs cheply and tirelessly. They destroyed threshers, burned workhouses and sent manifestos of fiery intent to the landlords and magistrates.
These letters were signed: "Captain Swing".
In this way Warren Ellis tells us the main inspiration for his story, Captain Swing and the Electrical Pirates of Cindery Island, drawned by Raulo Caceres: the protests by farmers against the introduction of machinery in country work. But Ellis' graphic novel is not an historical novel, but, first of all, a teslatopia (or a teslapunk novel) or an electrical romance of a pirate utopia thwarted, following Ellis' definition. If you want, from a more simple point of view, the Electric Pirates is a steampunk novel, but it is also a scientific comics. The fil rouge of the novel is, indeed, the electromagnetism research, and the diary of Captain Swing is a source of precious information that the reader could study in deep as soon as the closing of the book.
For example the reader could say himself if a ship could fly thanks to the electromagnetic force, or if the instruments illustrated in the pages of Captain's diary are true or not (in this last case the main source is probably Joseph Priestley's books, see for example The History and Present State of Electricity). Or we could ask if Ellis/Swing is lieing when he writes, for example, the following passage:
Ionic air propulsion(1). Electrostatic levitation(2). Electrogravitics. The Biefeld-Brown Effect and the electro-fluid-dynamics(3). Nothing here is invented. It simply appears to be uchronic, counterfactual, sitting in the break of a time out of joint.
In fact, many of the questions mentioned by Ellis are really studied by physics and electromagnetism.
Electromagnetism is the branch of physics that deals with the study of electric and magnetic fields. As demonstrated by James Clerck Maxwell, the two fields, electric and magnetic, are very closely related to each other and only in a static situation can, with good approximation, be considered separately.
In fact, however, the two concepts of electricity and magnetism were initially separated, and in particular the first observations about electricity date back to the Ancient Greece:
Thales first transcribed the induction of static electricity in 600 BC.
Only about one thousand of years we have a significative progress in the field:
Otto von Guericke built friction-machines for the accumulation of static electrical charge around 1650 AD.
Guericke, a prussian phisicist, is known primarily for his experiments on the air, which actually dates back to 1650 (according to the Britannica). In particular, he realized a famous experiment with a hollow sphere inside which was a vacuum: the horses tied to the two spherical caps that made the ball could not to separate them, thus demonstrating the tremendous pressure exerted by the air on the objects.
The invention cited by Warren Ellis come from 1663, which is the first electric generator in history.
The real high jump, however, comes with 1800s:
Upon thye founding date of the Metropolitan Police, Francesco Zantedeschi discovered electromagnetic induction (although, in this slow world, Michael Faraday would have been unaware of this when he published his more famous discovery of same, a year from now).
A simple experiment of electric induction (in this case electrostatic) is rub a pen on a knitted wool and then see his effects on some pieces of paper. Or you can try to do the same thing with a ball and a rod, using different materials to determine which of these is able to attract the ball after a suitable scrubbing:
We could classify the two experiments like inductive experiments: indeed the charge in the neutral matter is induced to a new disposal, that we call polarization, and the positive and negative charges ordering themselves following the Coulomb force.
Historically, as noted by Ellis, the priest and the Italian physicist Francesco Zantedeschi was the first to discover the electromagnetic induction in 1829, anticipating the experiments of Faraday in 1831 with two publications, one in 1829 and another in 1830(4, 5, 6).
Faraday's (and Zantedeschi's) result could be reasumed in this way:
There is induced current whenever there is a relative motion between the conductor and the magnetic lines of force considered as physically existing.(7)
Faraday's work was exclusively experimental. Indeed he described his discover in Experimental Researches in Electricity, a book in three volumes with all of his observations, in these terms:
It is also evident, by the results of the rotation of the wire and magnet (3097, 3106), that when a wire is moving amongst equal lines (or in a filed of equal magnetic force), and with an uniform motion, then the current of electricity produced is proportionate to the time; and also to the velocity of the motion.
They also prove, generally, that the quantity of electricity thrown into a current is directly as the amount of curves intersected.(8)
The mathematical formulation of Faraday's laws was written by James Clerck Maxwell, who writes A Treatise on Electricity and Magnetism for this purpose. In particular he writes about induction:
Instead of speaking of the number of lines of magnetic force, we may speak of the magnetic induction through the circuit, or the surface-integral of magnetic induction extended over any surface bounded by the circuit.(9)
that has the following mathematical form: \[f_{em} = - \frac{\text{d} \phi}{\text{d} t}\] where $\phi$ is the flow of the magnetic field.
This, better known as flow rule, has not been obtained by Maxwell, first of all because the British physicist was interested in writing a field equation, much more general than a simple calculation rule as the above equation. Not surprisingly, at the end of two pages of calculations, 221 and 222 on the second volume, he derived the expression for the induced electric field: \[\vec{E}_i = \vec v \times \vec B - \frac{\partial \vec A}{\partial t} - \nabla \varphi\]
Let us return, however, to the pioneering experimental studies on electromagnetism. In this field there is certainly a discovery that brings the Italian trademark: the diamagnetism in gases. The initial idea was by Louis Codde who proposed the experiment suggesting that property during the Eighth Congress of Italian Scientists held in Genoa in September 1846: in practice it was enough approach a magnet horseshoe-like to the flame of a candle in order to observe an elongation and an increase of light intensity in the flame itself(10).
It seems that also the physicist Jean-Alexandre Duran claimed to have observed a similar effect, and so Giovanni Battista Amici, who chaired the session, decided to repeat the experiment of Coddé using the tools available in the local Physics' Cabinet. Unfortunately for Coddé the experiment didn't reproduce his results, but the road to the diamagnetism of the gas was simply opened.
Indeed, almost simultaneously with the Genoa Congress, Faraday had start again his experiments (the year is 1845) in particular trying to understand the relationship between magnetism and matter
(...) taking a new series of experiments in which it was used an electromagnet with expansions suitably elongated and powered by batteries of Grove, capable of providing a magnetic field inhomogeneous and relatively powerful.(10)
Using its experimental apparatus, Faraday first of all observed what he calls a new magnetic property, the diamagnetism: materials placed under the action of the magnetic field is going to arrange along the equatorial plane of symmetry, i.e. the plane perpendicular to that on which lies the magnet. Obviously he was also interested to gases and so he made ​​a series of experiments with air at different densities placed inside some tubes. The observed effect was extremely small and so it was not possible to understand if solely dued to the glass of the tube or even, minimally, to the air contained in the tube. The conclusion was therefore the absence of diamagnetism in the gas, although Faraday wrote:
Whether the negative results obtained by the use of gases and vapours depend upon the smaller quantity of matter in a given volume, or whether they are direct consequences of the altered physical condition of the substance, is a point of very great importance in the theory of magnetism.(8)

Some materials studied by Faraday and classified according to their diamagnetism
Now Michele Alberto Bancalari takes the field: he leaded the Genoa Physics' Cabinet where Amici replicated the observations of Coddé.
Probably this failed experiment, together with the known observations of Faraday about diamagnetism suggested to Bancalari to try himself and for this purpose he built a singular magnet starting from the instruments in the Cabinet. In particular, he decided to dismantle the so-called Pixii machine, built in 1832 by the parisian manufacturer Antoine-Hippolyte Pixii with the help of Andre-Marie Ampére. Disassembling the machine, Bancalari built an instrument capable to generate an inhomogeneous magnetic field, so, in this way, any diamagnetic effect would be exalted by the device. Evidently remembering the experiment of Coddé, Bancalari placed between the two poles of the magnet a flame just observing the effect announced in 1846 by Coddé(10).

Tha magnet assembled by Bancalari
So, during the Nine Congress in Venice on September, 1847, Bancalari announced his discovery, and also in this case a replication of Bancalari's experiment was arranged, in this case leaded by Giuseppe Belli, one of the physicists who objected to the Bancalari's results using the Faraday observations. Three days later the experiment was succesfully reproduced:
(...) all people with full satisfaction and in a way we saw evident, that whenever the current was put about the flame showed to hear from the two pieces of iron a repulsive action, being rejected any little apart, and that this action ceased immediately when we remove the current.(10)
Bancalari's result was communicated only through the proceedings of the congress, and not with a direct communication from the discoverer. But the aforementioned Zantedeschi, which reproduced the positive result at the University of Turin, spread the discovery of Bancalari in one of his papers. Thanks to this paper, Faraday heared the result and, given the importance of the observation made by the italian physicists, decided to propose the translation of the Zantedeschi's paper(11), writing also an introduction to the work(12).
This is only a part of the story about the electromagnetic experiments, a part that is very interesting for italian physicists and proof that physics in Italy during Nineteenth Century is not limited only to Alessandro Volta but had some beutiful minds like Zantedeschi and Bancalari.
(1) The ionic air propulsion has been used by NASAas main propulsion since 1998.
(2) We speak not about electrostatic levitation but magnetic levitation. In this field Michael Berry with Andre Geim, Nobel Prize in Physics in 2010, published a paper (pdf) about frog's levitation, in which they describe how a frog can levitate:
Thanks to this work the two physicists won the IgNoble in 2000: more details on Rangle (eng).
Also the electrogravitics is another version of the same research line.
(3) The Biefeld-Brown effect is a result of the so colled electrohydrodynamics, or electro fluid dynamics, and involves the production of an ion wind which transfers its momentum to the neighboroud neutral particles and was discovered for the first time by German Paul Alfred Biefeld and by the American Thomas Townsend Brown. In particular, Brown has licensed a lot of patents about some devices that remember the flying boats in the comic book written by Ellis.
(4) Ohry A., Michael Faraday (1791 – 1867), science, medicine, literature and his disability (pdf)
(5) Martins, R.D.A. (2007). Ørsted, Ritter, And Magnetochemistry, Boston Studies in the Philosophy and History of Science, 241 385. DOI: 10.1007/978-1-4020-2987-5_16 (pdf)
(6) Francesco Zantedeschi, Relazione delle principali scoperte magneto elettriche (Verona: Antonelli, 1834)
(7) G. Giuliani (2008). Glossario - L'induzione elettromagnetica: un percorso didattico Il Giornale di Fisica, 49 (4), 291-304 : 10.1393/gdf/i2008-10072-8 (pdf)
(8) Michael Faraday, Experimental researches in electricity, vol.3.
See also vol.1 and vol.2
(9) James Clerck Maxwell, A Treatise on Electricity and Magnetism (1873)
(10) M. Leone, A. Paoletti, N. Robotti (2009). La Fisica nei "Gabinetti di Fisica" dell'Ottocento: il caso dell'Università di Genova Il Giornale di Fisica, 50 (3), 135-154 : 10.1393/gdf/i2009-10106-9 (pdf)
(11) Zantedeschi, F. (1847). On the motions presented by flame when under the electro-magneticinfluence, Philosophical Magazine Series 3, 31 (210) 424. DOI: 10.1080/14786444708645887 (scanned version)
(12) Faraday, M. (1847). On the diamagnetic conditions of flame and gases, Philosophical Magazine Series 3, 31 (210) 421. DOI: 10.1080/14786444708645886

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