Getting Kepler wrong

In recent times a bit of philosophy of science bun fight took place on the Intertubes. It started off in the New York Times with an opinion piece by James Blachowicz entitled, There is no Scientific Method. The title is actually a misnomer, as what Blachowicz actually argues is that the problem solving procedure usually called the scientific method is not unique to science. I’m not going to discuss it here but it is hardly an original theory, in fact I’ve argued something very similar myself in the past. I will, however, say that I don’t think that Blachowicz argues his case very well. Above all I think that his final three paragraphs in which he explains why, if the method is not exclusive to science, science is different to other form of knowledge are pretty crappy and largely wrong. Someone who also disparages those final three paragraphs in physics blogger Chad Orzel, who has written a pretty nifty book about the scientific method himself.[1] Chad wrote a post on his Uncertain Principles blog entitled, Why Physicists Disparage Philosophers, In Three Paragraphs, which if your read or have already read Blachowicz’s opinion piece you should definitely also read.

Chad was not the only physicist who weighed in on Blachowicz’s opinion piece with Ethan Siegel posting on his Forbes blog, Starts with a Bang, a rejoinder entitled Yes, New York Times, There Is a Scientific Method. In his piece Blachowicz illustrates his interpretation of the use of the scientific method in actual science with a brief discussion of Kepler’s search for the shape of the orbit of Mars using Tycho Brahe’s observational data as extensively described by Kepler in his Astronomia Nova in 1609. Here are the actual paragraphs from Blachowicz:

Now compare this with a scientific example: Johannes Kepler’s discovery that the orbit of Mars is an ellipse.

In this case, the actual meaning of courage (what a definition is designed to define) corresponds with the actual observations that Kepler sought to explain — that is, the data regarding the orbit of Mars. In the case of definition, we compare the literal meaning of a proposed definition with the actual meaning we want to define. In Kepler’s case, he needed to compare the predicted observations from a proposed explanatory hypothesis with the actual observations he wanted to explain.

 Early on, Kepler determined that the orbit of Mars was not a circle (the default perfect shape of the planetary spheres, an idea inherited from the Greeks). There is a very simple equation for a circle, but the first noncircular shape Kepler entertained as a replacement was an oval. Despite our use of the word “oval” as sometimes synonymous with ellipse, Kepler understood it as egg-shaped (in the asymmetrical chicken-egg way). Maybe he thought the orbit had to be lopsided (rather than symmetrical) because he knew the Sun was not at the center of the oval. Unfortunately, there is no simple equation for such an oval (although there is one for an ellipse).

When a scientist tests a hypothesis and finds that its predictions do not quite match available observations, there is always the option of forcing the hypothesis to fit the data. One can resort to curve-fitting, in which a hypothesis is patched together from different independent pieces, each piece more or less fitting a different part of the data. A tailor for whom fit is everything and style is nothing can make me a suit that will fit like a glove — but as a patchwork with odd random seams everywhere, it will also not look very much like a suit.

The lesson is that it is not just the observed facts that drive a scientist’s theorizing. A scientist would, presumably, no more be caught in a patchwork hypothesis than in a patchwork suit. Science education, however, has persistently relied more on empirical fit as its trump card, perhaps partly to separate science from those dangerous seat-of-the-pants theorizings (including philosophy) that pretend to find their way apart from such evidence.

Kepler could have hammered out a patchwork equation that would have represented the oval orbit of Mars. It would have fit the facts better than the earlier circle hypothesis. But it would have failed to meet the second criterion that all such explanation requires: that it be simple, with a single explanatory principle devoid of tacked-on ad hoc exceptions, analogous to the case of courage as acting in the face of great fear, except for running away, tying one’s shoelace and yelling profanities.

 It is here that Ethan launches his attack accusing Blachowicz of not having dug deep enough and of misrepresenting what Kepler actually did. After posting a picture of Kepler’s wonderful 3D model of his Platonic cosmos:


Ethan posted the following:

Kepler’s original model, above, was the Mysterium Cosmographicum, where he detailed his outstandingly creative theory for what determined the planetary orbits. In 1596, he published the idea that there were a series of invisible Platonic solids, with the planetary orbits residing on the inscribed and circumscribed spheres. This model would predict their orbits, their relative distances, and — if it were right — would match the outstanding data taken by Tycho Brahe over many decades.

But beginning in the early 1600s, when Kepler had access to the full suite of Brahe’s data, he found that it didn’t match his model. His other efforts at models, including oval-shaped orbits, failed as well. The thing is, Kepler didn’t just say, “oh well, it didn’t match,” to some arbitrary degree of precision. He had the previous best scientific model — Ptolemy’s geocentric model with epicycles, equants and deferents — to compare it to. In science, if you want your new idea to supersede the old model, it has to prove itself to be superior through experiments and observations. That’s what makes it science. And that’s why the ellipses succeeded, because they gave better, more accurate prediction than all the models that came before, including Ptolemy’s, Copernicus’, Brahe’s and even Kepler’s own earlier models.

Unfortunately Ethan has hoisted himself with his own petard. He has not dug deep enough and what he presents here is presentist interpretation of what Kepler actually thought and did over a period of around thirty years. I will explain.

At the various stages of Kepler’s development that Ethan sketches Kepler is dealing with and providing answers for different non-exclusive question, which don’t replace each other sequentially.

At the beginning Kepler was looking for an answer to the question, why there are only six planets? In the Copernican system the seven planets of the Greek’s had been reduced to six as the Earth and the Sun exchanged places and the Moon became the Earth’s satellite (a word that Kepler would coin later with reference to the newly discovered moons of Jupiter). This metaphysical question seems rather strange to us today but it fitted into Kepler’s metaphysics. Kepler was deeply religious and his God was a rational, logical creator of a mathematical (read geometrical) cosmos. Kepler’s cosmos was also finite, so there were and could only be six planets. He was later mortified when Galileo announced the discovery of four new celestial bodies and infinitely relieved when there turned out to be satellites and not planets. Kepler’s answer to his question was the model shown above with the spheres of the six planets inscribing and circumscribing the five regular Platonic solids. There are, and can only be, only five regular Platonic solids therefore there can only be six planets, Q.E.D. Using the available data on the size of the planetary orbits Kepler turned his vision into a mathematical model of the cosmos and discovered that it fit roughly but not accurately enough. His passion for precision and accuracy was a major driving force throughout Kepler’s scientific career. Kepler was aware that Tycho had been collecting new more accurate astronomical data for thirty years and this was one of his major reasons for wanting to work with Tycho in Prague; the other reason was that Kepler, as a Protestant who refused to convert to Catholicism, was being expelled from Graz and desperately needed a new job.

In Prague Tycho, who thought he had been plagiarised by Ursus, was not prepared to hand over his precious data to a comparative stranger and instead gave Kepler a couple of commissions. The first was to write an account of Tycho’s dispute with Ursus, which Kepler did producing a classic in the history and philosophy of science, which unfortunately was not published at the time. Kepler second task was to determine the orbit of Mars based on Tycho’s observational data. At this time, this had nothing to do with his previous work in the Mysterium Cosmographicum. Famously, what Kepler thought would be a simple mathematical exercise taking a couple of weeks turned into a six year battle to tame the god of war, published in all its gory detail in his Astronomia nova in 1609. Having at some point abandoned the traditional circular orbits Kepler hit upon his oval, meaning egg shaped rather than elliptical, orbit and calculated it using Tycho’s data. His calculations displayed eight arc minutes of error in places, that’s eight sixtieths of one degree, a level of accuracy way above anything that either Ptolemaeus or Copernicus had ever produced. He had superseded the old model easily to quote Ethan, however eight arc minutes of error was an affront to Kepler’s love of accuracy and in his opinion an insult to Tycho’s observational accuracy, so it was back to the drawing board. In his further efforts Kepler finally discovered his first two laws of planetary motion and his elliptical orbits[2]. This set of answers were however to a different set of questions to those in the Mysterium Cosmographicum and in no way were considered to replace them.

Throughout his life Kepler remained convinced that his Platonic model just required fine-tuning, which he meant quite literally. Already in the Mysterium Cosmographicum he muses about the Pythagorean music of the spheres and his magnum opus, the Harmonices Mundi published in 1619, is a truly amazing conglomeration of plane and spherical geometry, music theory, astrology and astronomy containing many gems but most famous for his third law of planetary motion, the harmonic law. Throughout all of this work the Platonic solids model of the Mysterium Cosmographicum remained Kepler’s vision of the cosmos and in 1621 he published a revised and extended version of his first book confirming his belief in it. It is this combination of, from our point of view, weird Renaissance heuristics, Platonic solids, harmony of the spheres, combined with the high level highly accurate modern science that it generated, the laws of planetary motion etc., that led Arthur Koestler to title his biography of Kepler, The Watershed. He saw Kepler as straddling the watershed between the Middle Ages and the Early Modern Period with one foot planted firmly in the past and the other striding determinedly into the future. The inherently contradictory duality is what leads presentists such as Ethan to misunderstand and misrepresent Kepler. He didn’t replace his metaphysical Platonic solids model of the cosmos with his mathematical elliptical model of the planetary orbits but considered them as equal parts of his whole astronomical/cosmological vision. We do not have Ethan’s Whig march of progress of one model replacing another but rather a Renaissance concept of the cosmos that can only be considered on its own terms and simply doesn’t make sense if we try to interpret it from our own modern perspective.

Since I started writing this post there have been two further contributions to the debate that inspired it. On the bigthink Jag Bhalla interviews Rebecca Newberger Goldstein on the topic under the title, What’s Behind A Science vs. Philosophy Fight?

On The Multidisciplinarian, William Storage, in his The Myth of Scientific Method, takes apart Ethan’s (mis)use of Galileo in his contribution. This one is highly recommended


[1] Chad Orzel, Eureka! Discover Your Inner Scientist, Basic Books, New York, 2014

[2] As I’ve said more than once in the past the best account of Kepler’s Astronomia nova is James R. Voelkel, The Composition of Kepler’s Astronomia nova, Princeton University Press, 2001


Filed under History of Astronomy, Myths of Science

Words matter

This morning, as usual, I caught the beginning of Thought for the Day on BBC Radio’s Today Programme (I know, I know), as I was preparing to leave my flat at 7:50 am. This morning the speaker, Bishop James Jones, took as his topic Yorkshire Day, the yearly celebration of God’s own county, as the natives like to call it. Bishop Jones, informed us that Yorkshire has 10% of the population of the UK (it’s actually nearer to 7% but who’s quibbling) and then went on to say, “Yorkshire is the most British region in the UK with over 40% of the population having Anglo-Saxon ancestry.

Now I’ve got nothing against Yorkshire, some of my best friends live there, but I fail to see how being of Anglo-Saxon descent makes somebody most British, in fact when I heard this my inner historian cringed. For those of my readers who are not up on the etymology of the terms of parts of the UK and its populations I will explain why this is fundamentally wrong. If the speaker had said most English I probably wouldn’t have reacted the way I did, as the words England and English are in fact derived from our Angle ancestors – England being Angle-Land. The problem is equating Britain or British with Anglo-Saxon.

The first mention of the origin of word Britain turns up in the reports of the Greek geographer explorer Pytheas of Massalia who voyaged around the British Isles in about 300 BCE and referred to them as the Prettanikē or something similar (Pytheas’ original writings are lost and we only have later secondary accounts of his report). This evolves to Britannia in the writings of Latin scholars. Now Pytheas undertook his voyages about four hundred years before Tacitus makes the first know reference to the Anglii, then still firmly on the continent, in his Germania and at least eight hundred years before the Angles invaded North East England.

Possible locations of the Angles, Saxons and Jutes before their migration to Britain. Source: Wikimedia Commons

Possible locations of the Angles, Saxons and Jutes before their migration to Britain.
Source: Wikimedia Commons

Viewed historically, the term British references the pre-Germanic pre-Roman, Celtic, population of the British Isles in contrast to the term English, which references the Germanic post Roman invaders. Etymologically the phrase of Anglo-Saxon descent would at best indicate most English and definitely not most but rather least British.

Angles, Saxons and Jutes throughout England Source: Wikimedia Commons

Angles, Saxons and Jutes throughout England
Source: Wikimedia Commons



Filed under Odds and Ends

A Rant Roundup!

Last week saw Steve King a Member of the US House of Representatives make a really stupid white supremacist statement on television, which the media caught up with and went to town on. I don’t intend to discuss his stupidity here as there are two good blog posts from Sarah Bond on Forbes and Rebecca Onion on Slate that deal with different aspects of it much better than I could. However, I would like to comment briefly on the coverage and comments on the VOX website. Under the title US Rep. Steve King preaches literal white supremacy on national television VOX reported on the incident and included a list of non-white, non-Western achievements, which include the following claim:

Egyptians helped bring paper and ink pens to Western civilizations

Now if you are going to criticise somebody’s undeniable ignorance then it helps if you are not ignorant yourself. The Egyptians gave us papyrus and not paper, as in actually explained in the link provided by VOX to the word paper. Paper as they should have known came to Europe from China via the Islamic Empire in the thirteenth century CE. Now papyrus and paper are both made of plant fibres but their fabrication processes and their physical properties are substantially different, which is why we now write on paper and not papyrus.

 Another major Internet so-called news website that allowed itself a bit of #histsci related stupidity last week was BUZZFEED with an article with the click bait title, 17 Maps That Will Change The Way You Look At The World Forever. This article illustrates the cartographical distortions produced by the Mercator projection the further that you move away from the equator. In itself this is not a bad demonstration of a fact that everybody should be aware of but BUZZFEED rather spoiled its article with the introduction, which reads:

Historically it’s been very hard to represent a 3D planet on a 2D map. The Mercator Projection was created as a way around this

Yes it is very hard to represent a 3D spherical planet on a 2D map and not just historically (a 3D cube planet would not be a problem) and numerous solutions to this problem had been developed long before Mercator came along, three alone from Ptolemaeus in the second century CE. All of them have their advantages and disadvantages. However, and this is a very important point, the Mercator projection was not developed initially to solve this very general cartographical problem. The Mercator projection was originally developed to solve the much more specific problem of how to represent a constant compass bearing as a straight line on a 2D map.

The 1569 Mercator map of the world based on the Mercator projection Source: Wikimedia Commons

The 1569 Mercator map of the world based on the Mercator projection
Source: Wikimedia Commons

For this very specific function the size distortions that the Mercator projection produces are completely irrelevant. The problems come about because this projection, conceived as an aid to marine navigation, is misused for general geographical and political maps of the world. This cannot be repeated oft enough in the extremely tedious debate about the so-called shortcomings of the Mercator projection.


Gerald Mercator Source: Wikimedia Commos

Gerald Mercator
Source: Wikimedia Commons


Yesterday was the ninety-sixth anniversary of the birth of Rosalind Franklin brilliant x-ray crystallographer and physical chemist.

Rosalind Franklin (25 July 1920 – 16 April 1958) Source: Wikimedia Commons

Rosalind Franklin (25 July 1920 – 16 April 1958)
Source: Wikimedia Commons

This is certainly a #histSTM anniversary that should be widely acknowledged, as indeed it was, but unfortunately nearly all the people acknowledging it did so by repeating or linking to the same old factually and historically false myths about her role in the discovery of the structure of DNA. Yes, she did play a very central role in that discovery, but it was her publically available data on the physical measurements of the DNA structure that Francis Crick used to complete his and Watson’s model and not the legendary ‘Photo 51’.

Photo 51, showing x-ray diffraction pattern of DNA Source: Wikimedia Commons

Photo 51, showing x-ray diffraction pattern of DNA
Source: Wikimedia Commons

On Photo 51 itself, this was made by Raymond Gosling and not by Franklin.

Professor Raymond Gosling in 2003 "DNA at King's - the continuing story: 50th anniversary of the discovery of the structure of DNA" Source Wikimedia Commons: Image seen on Kings College website and permission sought from public relations office. Image not their copyright but that of Professor Gosling himself who in email stated: Re the photo. Feel free to use it. My wife took it so it does not need any acknowledgements! Kind regards, Ray Gosling

Professor Raymond Gosling in 2003 “DNA at King’s – the continuing story: 50th anniversary of the discovery of the structure of DNA”
Source Wikimedia Commons: Image seen on Kings College website and permission sought from public relations office. Image not their copyright but that of Professor Gosling himself who in email stated: Re the photo. Feel free to use it. My wife took it so it does not need any acknowledgements! Kind regards, Ray Gosling

Gosling had been Franklin’s doctoral student for a time but because she was due to leave the King’s College laboratory he had reverted to Maurice Wilkins as his supervisor when Wilkins showed James Watson the infamous photo. As Gosling’s doctoral supervisor Wilkins was fully entitled to show the photo to Watson, whether his actions were wise or ethically correct when he did so is another question. However it is a myth that Watson’s seeing Photo 51 led to the discovery of the structure of DNA, a myth unfortunately set in the world by Watson himself.

Yes Franklin certainly deserves to be acknowledged as one of those who made substantial contributions to the discovery of the structure of DNA. No, Watson and Crick did not steal the discovery of the structure of DNA from Franklin. No, Franklin did not take Photo 51 Gosling did, and no Photo 51 was not crucial to the discovery of the structure of DNA. And finally for those who refuse to pay attention, the Noble prize for the discovery of the structure of DNA was awarded in 1962; Rosalind Franklin died in 1958 and so could not, according to the rules for Noble prizes, be considered for the award.

One final plea, stop referring to Rosalind Franklin as unsung! This might have been true in 1965 or even in 1985 but it is certainly in no way true today.

For the accurate historical details on the discovery of the structure of DNA read Matthew Cobb’s excellent Life’s Greatest Secret.



Filed under Myths of Science

Not an expert

BBC Radio 4 has a series called Great Lives, which is presented by former Conservative MP and now journalist, writer and broadcaster Matthew Parris. On the programme a ‘lay person’ talks about a figure, usually from history, who is their hero or role model, their comments being filled out by an ‘expert’ on the life of the figure in question. The format is in the form of a light-hearted three-way chat. Three years ago the BBC DJ Bobby Friction chose Galileo Galilei as his Great Life. At the time I listened and not surprisingly found the programme cringe worthy, dismissed it and forgot about it. However over the weekend people, who should know better, were promoting the programme on social media. Against my better judgement I listened to the whole thing again and decided to write this brief post on just one aspect, the greatest historical blunder, of the programme.

Before turning to the main topic of this post there is an aspect of the programme that needs to be addressed first. As explained above the discussion always includes an ‘expert’ to fill out with facts the account given of the subject of the programme. A programme about Galileo, so we can expect a historian of science as expert, yes? No! Instead of a historian of science what we get is Dr David Berman a reader in theoretical physic from Queen Mary College London. This is unfortunately a very common habit amongst journalists and broadcasters. They want someone to comment on, or explicate some aspect of, or episode out of the history of science, they ask a scientist and not a historian of science. Whilst I’m quite happy to acknowledge that there are some scientists who are also competent historians of science, they are unfortunately a small minority. The majority of scientists when asked to talk about the history of their subject usually deliver something highly inaccurate, factually false and toe curlingly cringe worthy. David Berman is no exception. As I wrote above, I’m not going to waste my time, and yours, doing a blow by blow analysis of this sorry mess but just address the one truly glaring clangour that our so-called expert drops towards the end of the discussion.

In an exchange beginning at about 22.20mins we hear the following:

MP: But he was friends with the Pope, why didn’t the Pope stick up for him?

DB: Oh, so he was friends with Urban VII who was the Pope, who was around the time when he started the book and the original censor but by then he died and we had Urban VIII…

He we have the classic example of a so-called expert who has literally no idea what he’s talking about and just makes something up that he thinks sounds plausible. For those that don’t know their papal history and/or the story of Galileo’s interaction with the papacy I will explain.

Paul V (1552–1621) was the Pope (1605–1621) who set up the commission of theologians in 1616 to consider the status of heliocentricity, which ruled it “foolish and absurd in philosophy, and formally heretical since it explicitly contradicts in many places the sense of Holy Scripture”. He then instructed Cardinal Bellarmine to meet with Galileo and to inform him that he was no longer allowed to teach the truth of heliocentricity.

Pope Paul V by Caravaggio. Source: Wikimedia Commons

Pope Paul V by Caravaggio.
Source: Wikimedia Commons

Both Bellarmine and Paul, however, assured Galileo that he was, at this time, in no personal danger. Paul died in 1621 and was succeeded by Gregory XV (1554–1623) who as Pope (1621–1623) played no significant role in the life of Galileo.

Pope Gregory XV Source: Wikimedia Commons

Pope Gregory XV
Source: Wikimedia Commons

Gregory was succeeded in 1623 by Cardinal Maffeo Barberini (1568–1644) who became Urban VIII.

Circa 1598 painting of Maffeo Barberini at age 30 by Caravaggio. Source: Wikimedia Commons

Circa 1598 painting of Maffeo Barberini at age 30 by Caravaggio.
Source: Wikimedia Commons

Those of you wondering where Urban VII fits into this, he doesn’t. Giovanni Battista Castagna (1521–1590) ruled as Pope Urban VII for just twelve days between 15 and 27 September 1590, when Galileo was just beginning his career as professor for mathematics in Pisa. Urban VII’s twelve-day papacy was the shortest in history.

Pope Urban VII – Pope for Twelve Days Source: Wikimedia Commons

Pope Urban VII – Pope for Twelve Days
Source: Wikimedia Commons

As an additional comment no Pope was ever the censor, as claimed by Berman, but naturally employed others to do this work for the Church.

As Matthew Parris rightly claims Cardinal Maffeo Barberini had been a friend and supporter of Galileo’s since the publication of the Sidereus nuncius in 1610 as well as being a patron of the Accademia dei Lincei, the small elite scientific society that had elected Galileo a member in 1611 on the strength of his telescopic discoveries. It was also the Lincei who gave the telescope its name. When Barberini was elected Pope in 1623 the Lincei published a broadsheet celebrating his election, which contained the first every illustrations made with a microscope.

Accademia dei Lincei Flyer celebrating the elevation of Maffeo Barberini to Pope 1623 Stelutii Melissographia

Accademia dei Lincei Flyer celebrating the elevation of Maffeo Barberini to Pope 1623
Stelutii Melissographia

The Lincei also published Galileo’s Il Saggiatore (The Assayer), which was dedicated to the new Pope in 1623.

Title page Il Saggiatore !623 Source: Wikimedia Commons

Title page Il Saggiatore !623
Source: Wikimedia Commons

Barberini much enjoyed Il Saggiatore and showed Galileo much favour. Galileo grasped the opportunity and persuaded the Pope to let him write a book describing the geocentric and heliocentric systems to prove that the Catholics did not favour the former out of ignorance of the latter, as he claimed the Protestants were alleging. Urban agreed to his request but under the condition that the two systems were presented equally without bias and without favouring either.

A portrait of Pope Urban VIII by Pietro da Cortona (1627) Source: Wikimedia Commons

A portrait of Pope Urban VIII
by Pietro da Cortona (1627)
Source: Wikimedia Commons

The book that Galileo wrote, his Dialogo, a polemic masterpiece, was of course anything but unbiased, tilting the arguments so far that any reader would be led to the conclusion that the heliocentric system was vastly superior to the geocentric one; a claim for which he had no empirical proof. He topped the whole thing off by putting the Pope’s own thoughts on the subject, a direct quote, into the mouth of a figure who was close to being a simpleton at the climax of the book.

Frontispiece and title page of the Dialogo, 1632 Source: Wikimedia Commons

Frontispiece and title page of the Dialogo, 1632
Source: Wikimedia Commons

That Urban was pissed off by the results should not have come as a surprise to Galileo and things took their inevitable course. The motto of the story is don’t play your friend for a fool when he happens to be an all powerful absolutist ruler.


Filed under History of Astronomy, Renaissance Science

If you are going to blazon out history of science ‘facts’ at least get them right

Today’s Torygraph has a short video entitled 10 Remarkable Facts about rainbows, at 57 seconds it displays the following text:

Until the 17th Century, no one had

the faintest idea what a rainbow

was, how it got there or what it was

made of…

This is, of course, simply not true. In the 14th century the Persian scholar Kamal al-Din Hasan ibn Ali ibn Hasan al-Farisi (1267–1319) gave the correct scientific explanation of the rainbow in his Tanqih al-Manazir (The Revision of the Optics). Almost contemporaneously the German scholar Theodoric of Freiberg (c. 1250–c. 1310) gave the same correct explanation in his De iride et radialibus impressionibus (On the Rainbow and the impressions created by irradiance). The two scholars arrived at their conclusion independently of each other but both of them did experiments involving the study of light rays passing through glass spheres full of water and both scholars were influenced by the optical theories of Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham. Unfortunately both explanations disappeared and it was in fact first in the 17th Century that the Croatian scholar Marco de Antonio Dominis (1560–1624) once again gave an almost correct explanation of the rainbow in his Tractatus de radiis visus et lucis in vitris, perspectivis et iride.

De Dominis' explanation of the rainbow Source: Wikimedia Commons

De Dominis’ explanation of the rainbow
Source: Wikimedia Commons


Filed under History of Optics, History of Physics, History of science, Myths of Science

He died fighting for his King

On 2 June 1644 one of the biggest battles of the English Civil War took place on Marston Moor just outside of the city of York. The Parliamentary forces under Fairfax had, together with the Scottish Covenanters under the Earl of Leven had been besieging York, the principle Royalist stronghold in the North, the defence being led by the Marquess of Newcastle. Prince Rupert came to the aid of the beleaguered city with a substantial royalist army. Newcastle boke out of the city with his cavalry and joined Rupert and the two armies clashed on Marston Moor. The battle ended in a disastrous defeat for the royalist forces and marks a significant turning point in the war.

The Battle of Marston Moor 1644, by J. Barker Source: Wikimedia Commons

The Battle of Marston Moor 1644, by J. Barker
Source: Wikimedia Commons

This is all well and good but at first glance doesn’t appear to have a lot to do with the history of science. However if we zoom in a little closer Marston Moor actually has two connections with that history. William Cavendish, the Marquess of Newcastle, and his brother Charles were both actively engaged supporters of the new sciences developing at the time in Europe and having fled England following the royalist defeat, they eventually ended up in Paris as part of the court of Queen Henrietta Maria. Here the Cavendish brothers became part of a philosophical circle dedicated to the investigation of science that included Marin Mersenne, Kenelm Digby and Thomas Hobbes. In Paris William also met and married Margaret Lucas, one of Henrietta Maria’s chamber maids, who would later become notorious as Margaret ‘Mad Madge’ Cavendish, a female philosopher of science and extensively published author.

Our second history of science connection to the Battle of Marston Moor is a less happy one because amongst the 4 000 royalist soldiers who are estimated to have died there was the astronomer, inventor and instrument maker William Gascoigne (1612–1644). Gascoigne is today mostly only known to those interested in the fine details of the history of the telescope, something that hasn’t changed much since his own times when he only became widely known after his most important invention, the micrometer, was claimed by the Frenchman Adrien Auzout (1622–1691) in 1666, twenty two years after his untimely death.

Adrien Auzout's (1621-1692) Micrometer published in his book (1662) Source: Wikimedia Commons

Adrien Auzout’s (1621-1692) Micrometer published in his book (1662)
Source: Wikimedia Commons

Gascoigne was born into the landed gentry in the village of Thorpe-on-the Hill near Leeds. Little is known of his childhood or education, although he claimed to have studied at Oxford University, a claim that cannot be confirmed. Like many amateur astronomers Gascoigne was self taught and appears to have been a very skilled instrument maker as he made all of his telescopes himself, including grinding his own lenses. One of the problems of early telescopes was measuring the size of celestial objects viewed through them. There is no easy solution to this problem when using a Dutch or Galilean telescope, i.e. with a plano-convex objective and a plano-concave eyepiece, and Galileo soled the problem by attaching a metal grid to the side of his telescope and viewing the object under observation through the telescope with one eye whilst observing the grid with his other eye. A trick that is thought to have been possible for Galileo because of an optical peculiarity he seems to have been born with. This method could only produce rough approximate sizes.

The Keplerian or astronomical telescope, where both objective and eyepiece lenses are convex, provides a much simpler solution. The Focal plane is at the juncture of the two focal lengths of the lenses, which is inside the telescope tube, and here the Keplerian telescope produces a its image. It appears that Gascoigne was the first to utilize this fact. There is a story that Gascoigne was made aware of this phenomenon by a spider that had woven its web in his telescope tube in the crucial position allowing him to focus on what he was viewing and the spider’s web at the same time. The story is probably apocryphal bur astronomers continued to collect spider’s silk from the hedgerows to form the crosshairs in their astronomical telescope well into the nineteenth century. Whatever led Gascoigne to the discovery of the internal image, he soon went beyond the simple expedient of installing crosshairs into his telescopes.

Focal plane with image at (5) Source: Wikimedia Commons

Focal plane with image at (5)
Source: Wikimedia Commons

Gascoigne realised that this phenomenon would enable him to introduce a measuring device into the focal plane of his telescope and this is what he did. He produced a calliper the points of which could be moved towards or away from each other by means of turning a single screw. Along the base along which the calliper points moved was a measuring scale. Gascoigne could now make accurate measurements of the celestial objects he observed.

Being a self taught amateur astronomer and living as he did in a small northern village in an age when long distance communication was difficult and unreliable one might be forgiving for thinking that Gascoigne was isolated and to some extent he was but not completely. He communicated by mail, for example, with William Oughtred inventor of the slide rule and mathematics teacher of several notable seventeenth century mathematicians. This contact seems to have been initiated by Gascoigne who was surprisingly well informed about actual developments in mathematics and astronomy and is known to have owned all of the relevant literature. Through Oughtred Gascoigne was also introduced to Kenelm Digby with whom he also corresponded.

Perhaps more significantly Gascoigne was in contact with the Towneley family of Towneley Hall near Burnley, landed gentry who took an interest in the actual developments in mathematics and astronomy.

Towneley Hall Source: Wikimedia Commons

Towneley Hall
Source: Wikimedia Commons

Christopher Towneley (1604–1674) introduced a group of northern astronomers to each other including William Milbourne of Christ’s College Cambridge (M.A. 1623), William Crabtree a merchant from Salford, Jeremiah Horrocks curate from Much Hoole near Preston and Gascoigne. Crabtree and Horrocks, famously, were the first astronomers to observe a transit of Venus. Crabtree and Gascoigne became good friends with Crabtree visiting Gascoigne to view and inspect his instruments and the two of them corresponding extensively on both Gascoigne’s instrumental novelties and the contemporary developments in astronomy, in particular the theories of Johannes Kepler, which both Crabtree and Horrocks accepted and Gascoigne under Crabtree’s influence came to accept. It was through this correspondence that we have Crabtree’s account of Horrocks’ death.

"Crabtree watching the Transit of Venus A.D. 1639" by Ford Madox Brown, a mural at Manchester Town Hall. Source: Wikimedia Commons

“Crabtree watching the Transit of Venus A.D. 1639” by Ford Madox Brown, a mural at Manchester Town Hall.
Source: Wikimedia Commons

All of this might have been lost following the deaths of Horrocks (1641), Gascoigne (1644) and Crabtree (1644) if not for the Towneleys. When the Royal Society announced Auzout’s invention of the micrometre screw gauge in 1666 it was Richard Towneley (1629–1704), Christopher’s nephew and a mathematician and astronomer in his own right, who piped up and said I beg to differ. John Flamsteed (1646–1719) (another northerner, later to become the first Astronomer Royal, who was a protégée of Jonas Moore (1617–1679), yet another Lancastrian and a pupil of William Milbourne) travelled up north to investigate Towneley’s claims. Towneley demonstrated his micrometer screw gauge based on Gascoigne’s design to Flamsteed and the two of them travelled to Salford where Crabtree’s widow gave them the Crabtree Gascoigne correspondence. Flamsteed made notes from the correspondence but the originals remained in the possession of the Towneley family.

Robert Hooke drew diagrams of Towneley’s version of Gascoigne’s micrometer, which were published in the Philosophical Transactions of the Royal Society thus establishing Gascoigne’s priority and his right to be acknowledged the inventor of the micrometer screw gauge.

Robert Hooke - A Description of an Instrument for Dividing a Foot into Many Thousand Parts, and Thereby Measuring the Diameters of Planets to a Great Exactness, &c. as It Was Promised, Numb. 25. In: Philosophical Transactions. Band 2, Nummer 29, 11.  Source: Wikimedia Commons

Robert Hooke – A Description of an Instrument for Dividing a Foot into Many Thousand Parts, and Thereby Measuring the Diameters of Planets to a Great Exactness, &c. as It Was Promised, Numb. 25. In: Philosophical Transactions. Band 2, Nummer 29, 11.
Source: Wikimedia Commons

As a small side note it was Richard Towneley together with Henry Power (1623–1668) who first discovered what is now known as Boyle’s Law, which Power published in his Experimental Philosophy, in three Books in 1664, an important early work on microscopy and the corpuscular theory.

Henry Power, Experimental philosophy, in three books : containing new experiments microscopical, mercurial, magnetical ; with some deductions, and probable hypotheses, raised from them, in avouchment and illustration of the now famous atomical hypothesis. London, 1664 Source: NIH U.S:.National Library of Medicine

Henry Power, Experimental philosophy, in three books : containing new experiments microscopical, mercurial, magnetical ; with some deductions, and probable hypotheses, raised from them, in avouchment and illustration of the now famous atomical hypothesis. London, 1664
Source: NIH U.S:.National Library of Medicine

Much of Gascoigne’s original correspondence has become lost of time but enough has been recovered to give a vivid picture of this inventive and highly skilled astronomer and his contributions to the history of astronomy. More important the fragments of the Gascoigne story demonstrate very clearly that progress in science in not achieved through lone geniuses but through networks of researchers exchanging views and discoveries and encouraging each other to make further developments.






Filed under Uncategorized

The Goddess, her husband and his lovers

In recent days the science sections of the media have been full of the successful entering of orbit around Jupiter by the NASA probe Juno after its five-year, 2.8 billion kilometre journey from the Earth. Many of the reports also talk about the so-called Galilean moons, Jupiter’s four largest moons (there are currently 67 known moons of Jupiter), and Galileo’s discovery of them with the recently invented telescope in early 1610.


Montage of Jupiter’s four Galilean moons, in a composite image depicting part of Jupiter and their relative sizes (positions are illustrative, not actual). From top to bottom: Io, Europa, Ganymede, Callisto. Source: Wikimedia Commons

Juno was even carrying Lego models of the god Jupiter, the goddess Juno and Galileo holding a telescope.


With the notable exception of the New York Times none of the reports mentioned that the Ansbach court mathematicus, Simon Marius, independently discovered the Galilean moons just one day later than Galileo. However, whereas Galileo rushed into print with his telescopic discoveries in his Sidereus nuncius in 1610, Marius waited until 1614 before publishing his discoveries in his Mundus Iovialis.


Title page of Sidereus nuncius, 1610, by Galileo Galilei (1564-1642). *IC6.G1333.610s, Houghton Library, Harvard University

The four moons are named Io, Europa, Ganymede and Callisto after four of the lovers of Zeus, the Greek equivalent to Jupiter, and many people have made a joke about the fact that Juno, his wife, was on her way.


Once again what none of the reports, with the exception of the New York Times, mention is that the names were not given to the moons by Galileo. Wishing to use his telescopic discoveries to leverage a position at the Medici court in Florence Galileo wrote a letter to Grand Duke Cosimo’s secretary on 13 February 1610 asking if the Grand Duke would prefer the moons to be called Cosmania after his name or, rather, since they are exactly four in number, dedicate them to all four brothers with the name Medicean Stars (All heavenly bodies were referred to as stars in the Renaissance). The secretary replied that Cosimo would prefer the latter and so the moons became the Medicean Stars in the Sidereus nuncius.

The New York Times report attributed the names Io, Europa, Ganymede and Callisto to Simon Marius and they did indeed first appear in print in his Mundus Iovialis. However the names were not thought up by Marius.


Title page Mundus Iovialis Simon Marius 1614. Internet Archive

In the Mundus Iovialis Marius makes several naming suggestions. His first suggestion is to just number the moons I to IV, a system that was actually used by astronomers. His second suggestion follows Galileo in that he wishes to name them after his employer/patron the Margrave of Ansbach’s family and call them the Brandenberger Stars. Marius’ third suggestion is more than somewhat bizarre as he suggests naming them in analogy to the solar system planets, so the moon with the smallest orbit would be the Jupiter Mercury, the next the Jupiter Venus, the third the Jupiter Jupiter and the fourth the Jupiter Saturn. As I said bizarre. It is with Marius’ fourth suggestion that we finally arrive at Zeus’ lovers. After talking about Jupiter’s reputation for a bit on the side and describing his most notorious affairs Marius write the following:

 In Europa, Ganimedes puer, atque Calisto,

Lascivo nimium perplacuere Jovi.

Io, Europa, the young Ganymede and Calisto

appealed all too much to the lascivious Jove

In the next paragraph Marius goes on to explain that the idea for using these names for the moons was suggested to him by Johannes Kepler[1] when the two of them met at the Imperial Parliament in Regensburg in October 1613. He then names Kepler as co-godfather of these four stars. Marius closes his list of suggestions by saying that the whole thing should not be taken too seriously and everybody is free to adopt or reject his suggestions as they see fit.

So as we now know it was Kepler’s suggestion which finally won the naming contest for the four largest moons of Jupiter but it should be noted that the names were first adopted by the astronomical community in the nineteenth century but they first became the official names of the Galilean Moons in 1975 through a decision of the IAU (International Astronomical Union)

Anybody who wants to learn more about Simon Marius can do so at the Simon Marius Portal or become a member of the Simon Marius Society (Simon Marius Gesellschaft e.V.) via the portal, membership is free!

Addendum 7 July 2016: My attention has been drawn to a delightful pop song about the lascivious Jupiter, his dalliances with his satellites and the impending arrival of his wife, She’s Checking In (The NASA Juno Song) by Adam Sakellarides  h/t Daniel Fischer (@cosmos4u)

[1] It should be noted that Johannes Kepler loved coining names and terms for all things scientific. It is to him, for example, that we owe the term satellite, coined specifically for the Jupiter moons, and also the term camera obscura, which in shortened form is our modern camera.


Filed under Uncategorized