Category Archives: History of science

If you can’t tell your Cassini from your Huygens then you shouldn’t be writing about the history of astronomy.

There I was, mild mannered historian of early modern science, enjoying my first cup of tea on a lazy Sunday morning, whilst cruising the highway and byways of cyberspace, when I espied a statement that caused an explosion of indignation, transforming me into the much feared, fire spitting HISTSCI_HULKTM. What piece of histSTM crap had unleashed the pedantic monster this time and sent him off on a stamping rage?

The object of HSH’s rage was contained in an essay by Vahe Peroomian (Associate Professor of Physics and Astronomy, University of Southern California – Dornsife College of Letters, Arts and Sciences) A brief astronomical history of Saturn’s amazing rings, published simultaneously on both The Conversation and PHYS.ORG 15 August 2019. Peroomian writes:

I am a space scientist with a passion for teaching physics andastronomy, and Saturn’s rings have always fascinated me as they tell the story of how the eyes of humanity were opened to the wonders of our solar system and the cosmos.

He continues:

When Galileo first observed Saturn through his telescope in 1610, he was still basking in the fame of discovering the four moons of Jupiter. But Saturn perplexed him. Peering at the planet through his telescope, it first looked to him as a planet with two very large moons, then as a lone planet, and then again through his newer telescope, in 1616, as a planet with arms or handles.

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Galileo Portrait by Ottavio Leoni Source: Wikimedia Commons

Galileo actually observed Saturn three times. The first time in 1610 he thought that the rings were handles or large moons on either side of the planet, “I have observed the highest planet [Saturn] to be triple bodied. This is to say to my very great amazement Saturn was seen to me to be not a single star, but three together, which almost touch each other.”

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Galileo’s 1610 sketch of Saturn and its rings

The second time was in 1612 and whatever it was that he observed in 1610 had simply disappeared, “I do not know what to say in a case so surprising, so unlooked for and so novel.” The Earth’s position relative to Saturn had changed and the rings were no longer visible but Galileo did not know this. In 1616 the rings were back but with a totally altered appearance, “The two companions are no longer two small perfectly round globes … but are present much larger and no longer round … that is, two half eclipses with two little dark triangles in the middle of the figure and contiguous to the middle globe of Saturn, which is seen, as always, perfectly round.” [1]

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Galileo’s 1616 sketch of Saturn and its rings

There is no mention of a new telescope and it is fairly certain that all three periods of observation were either carried out with the same or very similar telescopes. The differences that Galileo observed were due to the changing visibility of Saturn’s rings caused by its changing relative position to Earth and not to any change of instrument on Galileo’s part.

Although sloppy and annoying, the minor errors in Peroomian’s account of Galileo’s observations of Saturn are in themselves not capable of triggering the HSH’s wrath but what he wrote next is:

Four decades later, Giovanni Cassini first suggested that Saturn was a ringed planet, and what Galileo had seen were different views of Saturn’s rings. Because of the 27 degrees in the tilt of Saturn’s rotation axis relative to the plane of its orbit, the rings appear to tilt toward and away from Earth with the 29-year cycle of Saturn’s revolution about the Sun, giving humanity an ever-changing view of the rings.

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Giovanni Cassini (artist unknown) Source: Wikimedia Commons

Now, Giovanni Cassini did record some important observations of Saturn; he discovered four of Saturn’s largest moons and also the gap in the rings that is named after him. Although, Giuseppe Campani, Cassini’s telescope maker, observed the gap before he did without realising that it was a gap. However, it was not Cassini who first suggested that what people had been observing were rings but Christiaan Huygens.

Christiaan Huygens first proposed that Saturn was surrounded by a solid ring in 1655, “a thin, flat ring, nowhere touching, and inclined to the ecliptic.” In 1659 he published his book, Systema Saturnium : sive, De causis mirandorum Saturni phaenomenôn, et comite ejus Planeta Novo detailing how the appearance of the rings varied as the Earth and Saturn orbited the sun.

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Plate from Huygens’ Systema Saturnium showing the various recorded observations of Saturn made by astronomers before his own times

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Plate from Huygens’ Systema Saturnium explaining why the appearance of Saturn and its rings changes over time and that all those different appearances can be explained by assuming the existence of the rings

Confusing Cassini and Huygens, two of the greatest observational astronomers of the seventeenth century, who were scientific rivals, is not a trivial error and shouldn’t be made anywhere by anyone. However, to make this error in an essay that is published  on two major Internet websites borders on the criminal. I have no idea what the reach of PHYS.ORG is but The Conversation claims to have a readership of ten million plus. This means that a lot of people are being fed false history of astronomy facts by a supposed expert.

If the good doctor Peroomian had bothered to check his facts, a thing that I thought all scientists were taught to do when receiving their mother milk, he could have easily discovered his crass error and corrected it, even the much maligned Wikipedia gets it right, but apparently he didn’t consider it necessary to do so, after all it’s just history and not real science.

[1]The Galileo and Huygens quotes are taken from Ron Baalke’s excellent time line, Historical Background of Saturn’s Rings.

 

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Vienna and Astronomy the beginnings.

Vienna and its university played a very central role in introducing the study of mathematics, cartography and astronomy into Northern Europe in the fifteenth and sixteenth century. In early blog posts I have dealt with Georg von Peuerbach and Johannes Regiomontanus, Conrad Celtis and his Collegium poetarum et mathematicorum, Georg Tannstetter and the Apians, and Emperor Maximilian and his use of the Viennese mathematici. Today, I’m going to look at the beginnings of the University of Vienna and the establishment of the mathematical science as a key part of the university’s programme.

The University of Vienna was founded in 1365 by Rudolf IV, Duke of Austria (1339–1365) and his brothers Albrecht III, (c. 1349–1395) and Leopold III (1351–1386) both Dukes of Austria.

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Rudolf IV, Duke of Austria Source: Wikimedia Commons

Like most young universities it’s early decades were not very successful or very stable. This began to change in 1384 when Heinrich von Langenstein (1325–1397) was appointed professor of theology.

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Presumably Heinrich von Langenstein (1325-1397), Book miniature in Rationale divinorum officiorum of Wilhelmus Durandus, c. 1395

Heinrich von Langenstein studied from 1358 in Paris and in 1363 he was appointed professor for philosophy on the Sorbonne advancing to Vice Chancellor. He took the wrong side during the Western Schism (1378–1417) and was forced to leave the Sorbonne and Paris in 1382. Paris’ loss was Vienna’s gain. An excellent academic and experienced administrator he set the University of Vienna on the path to success. Most important from our point of view is the study of mathematics and astronomy at the university. We tend to think of the curriculum of medieval universities as something fixed: a lower liberal arts faculty teaching the trivium and quadrivium and three higher faculties teaching law, medicine and theology. However in their early phases new universities only had a very truncated curriculum that was gradually expanded over the early decades; Heinrich brought the study of mathematics and astronomy to the young university.

Heinrich was a committed and knowledgeable astronomer, who established a high level of tuition in mathematics and astronomy. When he died he left his collection of astronomical manuscripts and instruments to the university. Henry’s efforts to establish astronomy as a discipline in Vienna might well have come to nothing if a successor to teach astronomy had not been found. However one was found in the person of Johannes von Gmunden (c. 1380–1442).

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Initial from British Library manuscript Add. 24071 Canones de practica et utilitatibus tabularum by Johannes von Gmunden written 1437/38 by his student Georg Prunner Possibly a portrait of Johannes Source: Johannes von Gmunden (ca. 1384–1442) Astronom und Mathematiker Hg. Rudolf Simek und Kathrin Chlench, Studia Medievalia Septentrionalia 12

Unfortunately, as is often the case with medieval and Renaissance astronomers and mathematicians, we know almost nothing personal about Johannes von Gmunden. There is indirect evidence that he comes from Gmunden in Upper Austria and not one of the other Gmunden’s or Gmund’s. His date of birth is an estimate based on the dates of his studies at the University of Vienna and everything else we know about him is based on the traces he left in the archives of the university during his life. He registered as a student at the university in 1400, graduating BA in 1402 and MA in 1406.

His MA was his licence to teach and he held his first lecture in 1406 on the Theoricae planetarum by Gerhard de Sabbioneta (who might well not have been the author) a standard medieval astronomy textbook, establishing Johannes’ preference for teaching astronomy and mathematics. In 1407, making the reasonable assumption that Johannes Kraft is Johannes von Gmunden, thereby establishing that his family name was Kraft, he lectured on Euclid. 1408 to 1409 sees him lecturing on non-mathematical, Aristotelian texts and 1410 teaching Aristotelian logic using the Tractatus of Petrus Hispanus. In the same year he also taught Euclid again. 1411 saw a return to Aristotle but in 1412 he taught Algorismus de minutiis i.e. sexagesimal fractions. The Babylonian sexagesimal number system was used in European astronomy down to and including Copernicus in the sixteenth century, Aristotelian logic again in 1413 but John Pecham’s Perspectiva in 1414.

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Johannes von Gmunden Algorismus de minutiis printed by Georg Tannstetter 1515 Source: Johannes von Gmunden (ca. 1384–1442) Astronom und Mathematiker Hg. Rudolf Simek und Kathrin Chlench, Studia Medievalia Septentrionalia 12

Around this time Johannes took up the study of theology, although he never proceeded past BA, and 1415 and 16 see him lecturing on religious topics although he also taught Algorismus de minutiis again in 1416. From 1417 till 1434, with breaks, he lectured exclusively on mathematical and astronomical topics making him probably the first dedicated lecturer for the mathematical disciplines at a European university. Beyond his lectures he calculated and wrote astronomical tables, taught students how to use astronomical instruments (for which he also wrote instruction manuals), including the construction of cheap paper instruments.

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Johannes von Gmunden instructions for constructing an astrolabe rete Wiener Codex ÖNB 5296 fol. 6r Source: Johannes von Gmunden (ca. 1384–1442) Astronom und Mathematiker Hg. Rudolf Simek und Kathrin Chlench, Studia Medievalia Septentrionalia 12

He collected and also wrote extensive astronomical texts. As well as his teaching duties, Johannes served several times a dean of the liberal arts faculty and even for a time as vice chancellor of the university. His influence in his own time was very extensive; there are more than four hundred surviving manuscripts of Johannes Gmunden’s work in European libraries and archives.

When he died Johannes willed his comparatively large collection of mathematical and astronomical texts and instruments to the university establishing a proper astronomy department that would be inherited with very positive results by Georg von Peuerbach and Johannes Regiomontanus. Perhaps the most fascinating items listed in his will are an Albion and an instruction manual for it.

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Albion front side Source: Seb Falk’s Twitter feed

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Albion rear Source: Seb Falk’s Twitter feed

The Albion is possibly the most fascinating of all medieval astronomical instruments. Invented by Richard of Wallingford (1292–1336), the Abbot of St Albans, mathematician, astronomer, horologist and instrument maker, most well known for the highly complex astronomical clock that he designed and had constructed for the abbey.

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Richard of Wallingford Source: Wikimedia Commons

The Albion, ‘all by one’, was a highly complex and sophisticated, multi-functional astronomical instrument conceived to replace a whole spectrum of other instruments. Johannes’ lecture from 1431 was on the Albion.

Johannes von Gmunden did not stand alone in his efforts to develop the mathematical sciences in Vienna in the first half of fifteenth century; he was actively supported by Georg Müstinger (before 1400–1442), the Prior of the Augustinian priory of Klosterneuburg.

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Klosterneuburg

Müstinger became prior of Klosterneuburg in 1418 and worked to turn the priory into an intellectual centre. In 1421 he sent a canon of the priory to Padua to purchase books for over five hundred florins, a very large sum of money. The priory became a centre for producing celestial globes and cartography. It produced a substantial corpus of maps including a mappa mundi, of which only the coordinate list of 703 location still exist. Scholar who worked in the priory and university fanned out into the Southern German area carrying the knowledge acquired in Vienna to other universities and monasteries.

Johannes’ status and influence are nicely expressed in a poem about him and Georg von Peuerbach written by Christoph Poppenheuser in 1551:

The great Johannes von Gmunden, noble in knowledge, distinguished in spirit, and dignified in piety                                                                                                                                         And you Peuerbach, favourite of the muses, whose praise nobody can sing well enough                                                                                                                                           And Johannes, named after his home town, known as far away as the stars for his erudition

The tradition established in Vienna by Heinrich von Langenstein, Johannes von Gmunden and Georg Müstinger was successfully continued by Georg von Peuerbach (1423–1461), who contrary to some older sources was not a direct student of Johannes von Gmunden arriving in Vienna only in 1443 the year after Johannes death. However Georg did find himself in a readymade nest for the mathematical disciplines, an opportunity that he grasped with both hands developing further Vienna’s excellent reputation in this area.

 

 

 

 

 

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The emergence of modern astronomy – a complex mosaic: Part XVI

One of the things attributed to Tycho Brahe is the geo-heliocentric model of the cosmos. In this system the Earth remains at the centre and the Moon and the Sun both orbit the Earth, whereas the other five planets orbit the Sun. This system combines most of the advantages of Copernicus’ heliocentric system without the problems caused by a moving Earth. As such, as we shall see, the Tychonic system became one of the two leading contenders later in the seventeenth century. The only problem is that although it is named after him, Tycho wasn’t the only person to suggest this model and he almost certainly wasn’t the first to think of it.

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A 17th century illustration of the Hypothesis Tychonica from Hevelius’ Selenographia, 1647 page 163, whereby the Sun, Moon, and sphere of stars orbit the Earth, while the five known planets (Mercury, Venus, Mars, Jupiter, and Saturn) orbit the Sun. Source: Wikimedia Commons

The first to publish a version of the geo-heliocentric model was Nicolaus Reimers Baer (1551–1600), known as Ursus, in his Nicolai Raymari Ursi Dithmari Fundamentum astronomicum (Straßburg 1588). Ursus’ system differed from Tycho’s in that he included diurnal rotation.

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Nicolaus Reimers Baer, Fundamentum Astronomicum 1588 geo-heliocentric planetary model Source: Wikimedia Commons

Ursus was a self-taught astronomer, who in his youth had worked as a pig-herd until Heinrich Rantzau (1526–1598), a humanist scholar and astrologer, recognised his talents and employed him as a mathematician.

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Heinrich Rantzau Source: Wikimedia Commons

There followed a period as a private tutor and a year, 1586–87, in Kassel with Wilhelm. During his time in Kassel he translated De revolutionibus into German for Jost Bürgi, who couldn’t read Latin. In exchange Bürgi taught Ursus prosthaphaeresis, a method of using trigonometrical formulas to turn multiplications into sums to simplify calculations. From 1591 till his death, in 1600, Ursus was Imperial Mathematicus to Rudolf II in Prague.

Tycho was outraged that somebody published “his system” before he did and immediately accused Ursus of plagiarism, both of the geo-heliocentric system and of prosthaphaeresis, citing an earlier visit to Hven together with Rantzau, when Ursus was in his service. The two astronomers delivered a very unseemly public squabble through a series of publications; Tycho emphasising Ursus’ lowly birth and lack of formal qualifications and Ursus giving as good as he got in return. However, when Tycho left Hven and approached Prague, Ursus fled fearing the aristocrat’s wrath. When Kepler came to Prague to work with Tycho the first task that Tycho gave him was to write an account of the dispute, naturally expecting Kepler to find in his favour. Kepler wrote his report but didn’t ever publish it. Nicholas Jardine published a heavily annotated English translation in his The Birth of History and Philosophy of Science. Kepler’s ‘A Defence of Tycho against Ursus’ with Essays on its Provenance and Significance, CUP (2nd rev. ed. 1988)[1].

Tycho’s false accusation of theft of the trigonometrical method of prosthaphaeresis is, however, very revealing. Tycho was not the discoverer/inventor[2] of prosthaphaeresis. As far as can be ascertained, the method was originally discovered by Johannes Werner (1468–1522) but was actually taught to Tycho by the itinerant mathematician/astronomer from Breslau, Paul Wittich (c. 1546–1586). It turns out that that Wittich was probably the inspiration for both Tycho’s and Ursus’ decision to adopt a geo-heliocentric system. Wittich played around with the Capellan system, in which Mercury and Venus orbit the Sun in a geocentric system. He sketches of his thoughts are contained in his copy of De revolutionibus.

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Paul Wittich’s 1578 Capellan geoheliocentric planetary model – as annotated in his copy of Copernicus’s De revolutionibus in February 1578 Source: Wikimedia Commons

Following Wittich’s, comparatively early, death Tycho went to a lot of trouble and expense to obtain both of Wittich’s copies of Copernicus’ book, suggesting he was desperately trying to cover up the origins of “his system.” Another indication of Wittich’s possible or even probable influence is the fact that David Origanus (1558–1629), who had been influenced by Wittich at the University of Frankfurt an der Oder, also “independently” invented a geo-heliocentric system but with diurnal rotation like Ursus’ system.

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David Origanus Source: Wikimedia Commons

The route from a Capellan system to a full geo-heliocentric system was probably the route taken by both the physician and astrologer Helisaeus Roeslin (1545–1616) and the court mathematicus Simon Marius (1573–1625), who both claimed independent discovery of the system.

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Simon Marius Source: Wikimedia Commons

Geoheliocentric cosmology, 16th century

I think it should be clear by now that a geo-heliocentric system, whether with or without diurnal rotation was seen as a logical development by several astronomers following the publication of De revolutionibus, for it combined most of the advantages of Copernicus’ system, whilst not requiring the Earth to orbit the Sun, solving as it did the problem of the missing, or better said undetectable, solar stellar parallax. Such a system also solved another perceived, empirical problem, which has been largely forgotten today, that of star size.

If the cosmos were heliocentric then the lack of detectable parallax would mean that the so-called fixed stars were absurdly distant and much worse, given the naked-eye false perception the size of the star discs, all the more absurdly immense. Tycho used this as a valid empirical argument alongside religious ones to categorically reject a heliocentric system. Because the geo-heliocentric system didn’t require stellar parallax then the distance to the fixed stars was considerably shorter and thus the star size also much smaller. The apparent star size argument would continue to play a significant role in the astronomical system debate until the end of the seventeenth century.

Tycho, naturally, hoped to use his vast quantity of freshly won, comparatively accurate celestial data to prove the empirical reality of his system. Unfortunately, he died before he could really set this project in motion. On his deathbed he extracted the promise from Johannes Kepler, his relatively new assistant, to use the data to prove the validity of his system. As is well known, Kepler did nothing of the sort but actually used Tycho’s hard won data to develop his own totally novel heliocentric system, of which more later.

However, a geo-heliocentric model of the cosmos, with or without diurnal rotation, remained, as we shall see later, one of the leading contenders amongst astronomers right up to about 1660-70. The definitive version based on Tycho’s own data was produced by Christen Sørensen, known as Longomontanus, (1562-1647),

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Tycho’s longest serving and most loyal assistant, in his Astronomia Danica (1622).

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Longomontanus’ system was published in direct opposition to Kepler’s heliocentric one. Unlike Tycho’s, Longomontanus’ system had diurnal rotation.

Today we tend to view the various geo-heliocentric systems, with hindsight, as more than somewhat bizarre, but they provided an important and probably necessary bridge between a pure geocentric model and a pure heliocentric one, delivering many of the perceived advantages of heliocentricity, without having to solve the problems created by an Earth flying at high speed around the Sun.

[1]A highly recommended read

[2]Chose your word according to your philosophy of mathematics

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The emergence of modern astronomy – a complex mosaic: Part XV

Before continuing with Tycho Brahe’s contributions to the development of modern astronomy it pays to take stock of the existing situation in the last quarter of the sixteenth century. The Middle Ages had cobbled together a model of the cosmos that consisted of three separate but interlocking blocks: Aristotelian cosmology, Ptolemaic astronomy and Aristotelian physics, whereby it should be noted that the medieval Aristotelian physics was, to paraphrase Edward Grant, not Aristotle’s physics. In order for a new astronomy to come into use, as we shall see, the whole model had to dissembled and each of the three blocks replaced with something new.

As we saw at the beginning, some aspects of Aristotelian cosmology–supralunar perfection and cometary theory–were already under scrutiny well before Copernicus published his De revolutionibus. They now fell following the European wide observations of the supernova in 1572 and the great comet of 1577; the Aristotelian crystalline spheres went with them, although Clavius, the leading Ptolemaic astronomer of the age, whilst prepared to sacrifice supralunar perfection and Aristotelian cometary theory, was not yet prepared to abandon the crystalline spheres. The model was beginning to crumble at the edges.

The acceptance of Copernicus’ heliocentric system had been very meagre but the interest in his mathematical models, his astronomical data and the planetary tables and ephemerides based on them had originally been very great. However, it quickly became clear that they were no more accurate or reliable than those delivered by the Ptolemaic system and the initial interest and enthusiasm gave way to disappointment and frustration. Out of this situation both Wilhelm IV in Kassel and Tycho Brahe in Denmark, following Regiomontanus’ initiative from a century earlier, decided that what was needed was to go back to basics and produce new star catalogues and planetary tables based on new accurate observations and set about doing just that. We have already looked to Wilhelm’s efforts; we now turn to Tycho’s.

Granted the island of Hven and the necessary financial support to carry out his project by Frederick II, the Danish king, Tycho set to work.

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Frederick II of Denmark Portrait by Hans Knieper or Melchior Lorck, 1581.

Whereas it is theoretically possible to question the claim that Wilhelm IV had built an observatory, no such doubt exists in Tycho’s case. What he erected on his island was not so much an observatory, as a research institute the like of which had never existed before in Europe.

The centrepiece of Tycho’s establishment was his palace Uraniborg, a magnificent purpose built red brick residence and observatory. The structure included a large mural quadrant and outer towers on the balconies of which a large array of self designed and constructed instruments were situated.

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Source: Wikimedia Commons

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Engraving of the mural quadrant from Brahe’s book Astronomiae instauratae mechanica (1598) Source: WIkimedia Commons

As it turned out that the accuracy of the tower-mounted instrument was affected by vibration caused by the wind, Tycho constructed a second observatory, Stjerneborg. This observatory was effectively situated underground in a large pit to reduce wind vibration of the instruments.

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Drawing of an above ground view of Stjerneborg Willem Blaeu – Johan Blaeu, Atlas Major, Amsterdam, 1662 Source: Wikimedia Commons

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Schematic of Stjerneborg showing underground chambers: Woodcut from F.R. Friis “Tyge Brahe”, Copenhagen, 1871 Source: Wikimedia Commons

As well as his two state of the art observatories, Tycho also constructed alchemical laboratories in the cellars of Uraniborg, to carry out experiments in Paracelsian pharmacology. To publish the results of his researches Tycho constructed his own printing press and to ensure that he would have enough paper for those publications, he also constructed a water powered paper mill.

Whereas Wilhelm’s astronomical activities were a side project to his main occupation of ruling Hesse-Kassel and the work on his star catalogue was carried out by just two people, Rothmann and Bürgi, Tycho’s activities on Hven were totally dedicated to astronomy and he employed a small army of servants and assistants. Alongside the servants he needed to run his palace and its extensive gardens Tycho employed printers and papermakers and a large number of astronomical observers. Some of those who worked as astronomers on Hven and later in Prague, such as Longomontanus, who later became professor for astronomy in Copenhagen, did so for many years. Others came to work for him for shorter periods, six or nine months or a year. These shorter-term periods working for Tycho worked like a form of postgrad internship for those thus employed. Good examples of this are the Dutch cartographer and Globemaker Willem Janszoon Blaeu (1571–1638), who spent six months on Hven in 1595-96

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Willem Janszoon Blaeu Source: Wikimedia Commons

and the Franconian mathematician and astronomer Simon Marius (1573–1625) who spent six months in Tycho’s observatory in Prague in 1601 shorty before Tycho’s death.

Tycho’s observation programme was massive and very much for the duration, starting in the mid 1570s and continuing up to his death in 1601[1]. His teams spent every night of the year, weather permitting, systematically observing the heavens. Two teams, one in Uraniborg and the other in Stjerneborg, made the same observations parallel to but completely independent of each other, allowing Tycho to compare the data for errors. They not only, over the years, compiled a star catalogue of over 700 stars[2] with an accuracy of several factors higher than anything produced earlier but also systematically tracked the orbits of the planets producing the data that would later prove so crucial for Johannes Kepler’s work.

When Tycho was satisfied with the determination of the position of a given star then it was engraved on a large celestial globe that he had had constructed in Germany on one of his journeys. When Willem Janszoon Blaeu was on Hven, Tycho allowed him to make a copy of this globe with the new more accurate stellar positions, which he took with him when he returned to The Netherlands. So from the very beginning Blaeu’s commercial celestial spheres, which dominated the market in the seventeenth century, were based on the best astronomical data available.

Tycho not only systematically observed using instruments and methods known up to his times but devoted much time, effort and experimentation to producing ever better observing instruments with improved scales for more accurate readings. He also studied and developed methods for recognising and correcting observational errors. It is not an exaggeration to say that Tycho dedicated his life to producing observational astronomical data on a level and of a quality never before known in European astronomy.

In 1588 Tycho’s patron and benefactor Frederick II died and after a period of regency his son, who was only eleven years old when he died, was crowned king as Christian IV in 1596.

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Portrait Christian IV by Pieter Isaacsz 1612 Source: Wikimedia Commons

Due to a mixture of court intrigue and his own arrogance, Tycho fell into disfavour and Christian cut off his finances from the crown. Still a wealthy man, from his private inheritances, Tycho packed up his home and some of his instruments and left Denmark heading south through Germany in 1597, looking for a new patron. In 1599 he settled in Prague under the patronage of Rudolf II as Imperial Mathematicus,

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Rudolf II Portrait by Martino Rota Source: Wikimedia Commons

erecting a new observatory in a castle in Benátky nad Jizerou about fifty kilometres from Prague.

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Benátky Castle Source: Wikimedia Commons

Tycho’s biggest problem was that he had vast quantities of, for the time, highly accurate astronomical data that now needed to be processed and he was in desperate need of a mathematician who was capable of carrying out the work. Fate intervened in the form of the still relatively young Johannes Kepler ((1571–1630), who turned up in Prague in 1600 frantically looking for employment.

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Johannes Kepler Source: Wikimedia Commons

This was a partnership made in hell rather than heaven but it did not last long as Tycho died under unclear circumstances[3] in October 1601, with Kepler inheriting his position as Imperial Mathematicus. I will deal with Kepler’s leading role in the story of modern astronomy in later episodes but we still need to look at Tycho’s last contribution, the so-called Tychonic system.

[1]In his Bibliographical Directory of Tycho Brahe’s Artisans, Assistants, Clients, Students, Coworkers and Other Famuli and Associates, pages 251–309 in his On Tycho’s Island: Tycho Brahe, Science, and Culture in the Sixteenth Century, John Robert Christianson list 96 names.

[2]When he left Hven Tycho increased his star catalogue to 1000, taking the missing stars from the Ptolemaic star catalogue

[3]Anybody who brings up, in the comments, the harebrained theory that Kepler murdered Tycho in order to obtain his astronomical data will not only get banned from the Renaissance Mathematicus in perpetuity but will be cursed by demons, who will visit them in their sleep every night for the rest of their pathetic lives.

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Kepler was wot, you don’t say?

 

The Guardian is making a serious bid for the year’s worst piece of #histsci reporting or as Adam Shapiro (@tryingbiology) once put it so expressively, #histsigh! The article in question has the shock, horror, sensation headline: Groundbreaking astronomer Kepler ‘may have practised alchemy’. Ignoring the fact for the moment that he probably didn’t, given the period and the milieu in which Kepler lived and worked saying that he may have been an alchemist is about as sensational as saying he may have been a human being.

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Johannes Kepler Source: Wikimedia Commons

The period in which Kepler lived was one in which the interest in alchemy was very widespread, very strong and very open. For eleven years he was Imperial Mathematicus at the court in Prague of the German Emperor Rudolph II, which was a major centre for all of the so-called occult sciences and in particular alchemy. In Prague Kepler’s original employer Tycho Brahe had been for years a practitioner of Paracelsian alchemical medicine (a very widespread form of medicine at the time), which to be fair the article sort of says. What they say is that Tycho was an alchemist, without pointing out that his alchemy was restricted to medical alchemy.

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Tycho Brahe Source: Wikimedia Commons

One of his colleagues was the Swiss clockmaker Jost Bürgi, who had come to Prague from Hesse-Kassel,

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Jost Bürge Source: Wikimedia Commons

where the Landgrave Moritz was a major supporter of alchemy, who appointed Johannes Hartmann (1568–1631) to the first ever chair for chemistry, actually Paracelsian medicine, at the university of Marburg. The real surprise is not that Kepler was an alchemist or practiced alchemy but rather that given the time and milieu in which he lived and worked that he wasn’t and didn’t.

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Johannes Hartmann Source: Wikimedia Commons

How can I be so sure that Kepler didn’t dabble in alchemy? Simply because if he had, he would have written about it. Kepler is a delight, or a nightmare, for the historian, there is almost no figure that I know of in #histSTM, who was as communicative as Kepler. He wrote and published eighty three books and pamphlets in his lifetime covering a very wide range of topics and in all his written work he was always keen to explain in great detail to his readers just what he was doing and his thoughts on what he was doing. He wrote extensively and very openly on his mathematics, his astronomy, his astrology, his family, his private affairs, his financial problems and all of his hopes and fears. If Kepler had in anyway been engaged with alchemy, he would have written about it. If anybody should chime in now with, yes but alchemists kept they activities secret, I would point out in Kepler’s time the people practicing alchemy, particularly the Paracelsians, were anything but secretive. And it was with the Paracelsians that Kepler had the closest contact.

There are a few letters exchanged between Kepler and his Paracelsian physician friends, which show quite clearly that although Kepler displayed the natural curiosity of a scientific researcher in their alchemistic activities he did not accept the basic principles of alchemy. In his notorious exchange with Robert Fludd, he is very dismissive of Fludd’s alchemical activities. Kepler was not an alchemist.

From a historical point of view particularly bad is the contrast deliberately set up in the article between good science, astronomy and mathematics, and ‘dirty’ pseudo- science’, alchemy. This starts with the title:

Groundbreaking astronomer Kepler ‘may have practised alchemy’

Continues with the whole of the first paragraph:

The pioneering astronomer Johannes Kepler may have had his eyes on the heavens, but chemical analysis of his manuscripts suggests he was “willing to get his hands dirty” and may have dabbled in alchemy.

“Kepler, who died in 1630, drew on Copernicus’s work to find laws of planetary motion that paved the way for Isaac Newton’s theory of gravity” is contrasted with “The authors speculate that Kepler could have learned the “pseudo-chemical science.” 

A ‘pioneering astronomer’ with ‘his eyes on the heavens’, serious scientific activity, but ‘dabbled in alchemy’. Whoever wrote these lines obviously knows nothing about Kepler’s astronomical writing nor about early 17thcentury alchemy.

The article through its choice of descriptive terms tries to set up a black/white dichotomy between the man who paved the way for modern astronomy, good, and the practitioners of alchemy in the early seventeenth century, bad. However if we actually look at the real history everything dissolves into shades of grey.

Kepler was not just an astronomer and mathematician but also a practicing astrologer. People might rush in here with lots of Kepler quotes condemning and ridiculing the nativity horoscope astrology of his age, all of them true. However, he famously said one shouldn’t throw the baby out with the bath water defending the basic idea of astrology and presenting his own unique system of astrology based entirely on aspects, that is the angular position of the planets relative to each other. The author of the piece has obviously never turned the pages of either Kepler’s Mysterium Cosmographicum or his Harmonice Mundi. As I commented on Twitter, during a discussion of this article, Kepler’s cosmological heuristic with which he generated all of his successful astronomy was, viewed from a modern rational standpoint, quite simply bat shit insane. Things are not looking good for our pioneering astronomer.

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Kepler’s Platonic solid model of the solar system, from Mysterium Cosmographicum (1596) Kepler’s explanation as to why there are only five planets and their order around the sun! Source: Wikimedia Commons

On the other side, as I have noted on several occasions, alchemy included much that we now label applied and industrial chemistry.  For example, alchemists were responsible for the production of pigments for painters and gunpowder for fireworks and cannons, and were often glassmakers. Alchemists were historically responsible for developing the laboratory equipment and methodology for chemical analysis. In the period under discussion many alchemists, including Tycho, were Paracelsian physicians, who are credited with the founding of the modern pharmacological industry. Historians of alchemy tend to refer to the alchemy of the seventeenth century as chymistry because it represents the historical transition from alchemy to chemistry. Not so much a pseudo-science as a proto-science.

Let us now consider the so-called evidence for the articles principle claim. Throughout the article it is stated that the evidence was found on Kepler’s manuscripts, plural. But when the evidence is actually discussed it turns out to be a single manuscript about the moon. On this manuscript the researchers found:

“…very significant amounts of metals associated with the practice including gold, silver, mercury and lead on the pages of Kepler’s manuscript about the moon, catalogued as “Hipparchus” after the classical astronomer.”

Is alchemy the only possible/plausible explanation for the traces of metals found on this manuscript? Could one suggest another possibility? All of these metals could have been and would have been used by a clock and instrument maker such as Jost Bürgi, who was Kepler’s close colleague and friend throughout his eleven years in Prague. Bürgi also had a strong interest in astronomy and might well have borrowed an astronomical manuscript. Of course such a solution doesn’t make for a sensational article, although all the available evidence very strongly suggests that Kepler was not an alchemist.

One final point that very much worries me is the provenance of this document. It is four hundred years old, who has owned it in the meantime? Where has it been stored? Who has had access to it? Until all of these questions can be accurately answered attributing its contamination to Kepler is just unfounded speculation.

 

 

 

 

 

 

 

 

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Filed under History of Alchemy, History of Astrology, History of Astronomy, History of science, Myths of Science, Renaissance Science

The House of Wisdom is a Myth

When I first got really interested in the history of science, the history of science of the Islamic empires was not something dealt with in any detail in general works on the topic. If you wanted to get to know anything much about what happened in the various areas of the world dominated by Islamic culture in the period between the seventh and sixteenth centuries then you had to find and read specialist literature produced by experts such as Edward Kennedy. Although our knowledge of that history still needs to be improved, the basic history has now reached the popular market and people can inform themselves about major figures writing in Arabic on various areas of science between the demise of classical antiquity and the European Renaissance such as the mathematician Muḥammad ibn Mūsā al-Khwārizmī, the alchemist Abū Mūsā Jābir ibn Hayyān, the optician, Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham or the physician Abū Bakr Muhammad ibn Zakariyyā al-Rāzī. These and a handful of other ‘greats’ are not as well known as their later European counterparts but knowledge of them, usually under their popular names, so al-Khwarizmi, Jabir, al-Haytham and al-Razi, is these days quite widespread amongst well educated and well read people. There is even a flourishing popular book market for titles about Islamic science.

Amongst those non-professionals, who interest themselves for the topic, particularly well known is the so-called House of Wisdom, a reputed major centre for scientific translation and research in Baghdad under the Abbasid Caliphs. This reputed academic institution even provided the title for two of the biggest selling popular books on Islamic science Jim al-Khalili’s The House of Wisdom: How Arabic Science Saved Ancient Knowledge and Gave Us the Renaissance and Jonathan Lyons’ The House of Wisdom: How the Arabs Transformed Western Civilisation. Neither Jim al-Khalili nor Jonathan Lyons is a historian of science, let alone Islamic science; al-Khalili is a physicist and broadcaster and Lyons is a journalist and herein lies the rub. Real historians of Islamic science say that the House of Wisdom never existed, at least not in any form remotely resembling the institution presented by al-Khalili, Lyons and other popular sources including, unfortunately Wikipedia, where the article is largely based on Lyons’ pop book.

The picture painted by al-Khalili and Lyons, and to be fair they didn’t create it but copied it from other fantasts, is of a special academic research institution set up by the early Abbasid Caliphs, staffed with leading scientific scholars, who carried out a sponsored programme of translating Greek scientific texts, which they them analysed, commented and developed further. Here academic exchanges, discussions, conferences took place amongst the leading scientific scholars in the Abbasid Empire.

The reality looks very different.[1]To quote Gutas (page 54):

It is in this light that the very scanty reliable reports about the bayt al-hikmashould be evaluated. Much ink has been used unnecessarily on description of the bayt al-hikma, mostly in fanciful and sometimes wishful projections of modern institutions and research projects back into the eighth century. The fact is that we have exceedingly little historical [emphasis in original] information about the bayt al-hikma. This in tself would indicate that it was not something grandiose or significant, and hence a minimalist interpretation would fit the historical record better.

The bayt al-hikma, to give it its correct name, which doesn’t really translate as house of wisdom, was the palace archive and library or repository, a practice taken over by the Abbasid Caliphs from the earlier Sassanian rulers along with much other royal court procedure to make their reign more acceptable to their Persian subjects. The wisdom referred to in the translation refers to poetic accounts of Iranian history, warfare, and romance. The Abbasid Caliphs appear to have maintained this practice now translating Persian historical texts from Persian into Arabic. There is absolutely no evidence of Greek texts, scientific or otherwise, being translated in the bayt al-hikma.

Much is made of supposed leading Islamic scientific scholars working in the bayt al-hikmaby the al-Khalili’s, Lyons et al. In fact the first librarian under the Abbasids was a well-known Persian astrologer, again a Sassanian practice taken over by the Abbasids. Later al-Khwarizmi and Yahya ibn Abi Mansur both noted astronomers but equally noted astrologers served in the bayt al-hikmaunder the Abbasid Caliph al-Ma’mun.

We will give Gutas the final word on the subject (page 59):

The bayt al-hikmawas certainly also not an “academy” for teaching the “ancient” sciences as they were being translated; such a preposterous idea did not even occur to the authors of the spurious reports about the transmission of the teaching of these sciences that we do have. Finally it is not a “conference centre for the meeting of scholars even under al-Ma’mun’s sponsorship. Al-Ma’mun, of course (and all the early Abbasid caliphs), did host scholarly conferences or rather gatherings, but not in the library; such gauche social behaviour on the part of the caliph would have been inconceivable. Sessions (magalis) were held in the residences of the caliphs, when the caliphs were present, or in private residences otherwise, as the numerous descriptions of them that we have indicate.

As a final comment we have the quite extraordinary statement made by Jim al-Khalili on the BBC Radio 4 In Our Time discussion on Maths in the Early Islamic World:

In answer to Melvyn Braggs question, “What did they mean by the House of Wisdom and what sort of house was it? It is supposed to have lasted for 400 years, it is contested”

Jim al-Khalili: “It is contested and I’ll probably get into hot water with historians but let’s say what I think of it. There was certainly potentially something called the house of wisdom a bit like the Library of Alexandria many centuries earlier, which was a place where books were stored it may have also been a translation house. It was in Baghdad this was in the time of al-Ma’mun, it may have existed in some form or other in his father’s palace…”

Bragg: “Was it a research centre, was it a place where people went to be paid by the caliphs to get on with the work that you do in mathematics?”

Al-Khalili: “I believe it very well could have been…” He goes on spinning a fable, drawing parallels with the Library of Alexandria

History is not about what you choose to believe but is a fact-based discipline. Immediately after al-Khalili’s fairy story Peter Pormann, Professor of Classics & Graeco-Arabic Studies at the University of Manchester chimes in and pricks the bubble.

Pormann: “There’s the myth of the House of Wisdom as this research school, academy and so on and so forth, basically there is very little evidence…”

Listen for yourselves!

I find Bragg’s choice of words, repeated by al-Khalili, “it is contested” highly provocative and extremely contentious. It is not contested; there is absolutely no evidence to support the House of Wisdom myth as presented by Lyons, al-Khalili et al. What we have here is another glaring example of unqualified pop historians propagating a myth and blatantly ignoring the historical facts, which they find boring.

[1]The facts in the following are taken from Dimitri Gutas, Greek Thought, Arabic Culture: The Graeco-Arabic Translation Movement in Baghdad and Early Abbasid Society (2nd–4th/8th–10th centuries), Routledge, Oxford, ppb. 1998 pp. 53-60 and Lutz Richter-Bernburg, Potemkin in Baghdad: The Abbasid “House of Wisdom” as Constructed by 1001 inventions In Sonja Brentjes–Taner Edis­–Lutz Richter-Bernburg eds., 1001 Distortions: How (Not) to Narrate History of Science, Medicine, and Technology in Non-Western Science, Biblioteca Academica Orientalistik, Band 25, Ergon Verlag, Würzburg, 2016 pp. 121-129

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Filed under History of Islamic Science, History of science, Myths of Science

Nit-picking – Authors who should know better

In my most recent reading I have come across three separate examples of professional historians making a mess of things when they turn the hand to the history of science.

First up we have Jerry Brotton’s The Renaissance: A Very Short Introduction[1]. I’m a fan of Oxford University Press’ Very Short Introduction series and also of Brotton’s A History of the World in Twelve Maps[2], so I was expecting to enjoy his Very Short Introduction to the Renaissance and in general I wasn’t disappointed.

Nit Picking001

He chooses to lay the emphasis in his book on the fact that the Renaissance wasn’t a purely European phenomenon but a global one and writing from this perspective he opens up a novel vista on this period of history. However when he turns to the history of Renaissance science he, in my opinion, drops a major clangour.

He introduces his chapter on the topic with Christopher Marlowe’s Doctor Faustus, telling us that:

Once Faustus has sold his soul, he asks Mephistopheles for a book ‘where I might see all characters and planets of the heavens’. The most controversial book that Faustus could have consulted was On the Revolutions of the Celestial Spheres by the Polish canon and astronomer Nicolaus Copernicus.[3]

We’ll ignore the Polish on this occasion and turn instead to what Brotton says about the book:

Copernicus’s revolutionary book overturned the medieval belief that the earth lay at the centre[my emphasis] of the universe. Copernicus’s vision of the heavens showed, along with all the other known planets, rotated around the sun. Copernicus subtly revised the work of classical Greek and Arabic astronomy scholars. He argued that ‘they did not achieve their aim, which we hope to reach by accepting the fact that the earth moves’.

Copernicus tried to limit the revolutionary significance of his ideas by accommodating them within a classical scientific tradition. But the Catholic Church was horrified and condemned the book. Copernicus’s argument overturned the biblical belief that the earth – and humanity with it – stood at the centre of the universe[4][my emphasis].

 

It was neither the biblical nor the medieval belief that the earth stood at the centre of the universe and removing the earth from this centre was not Copernicus’ offence. It was setting the earth in motion and stopping the motion of the sun that the Church found intolerable, as it contradicted several biblical passages. The myth about Copernicus displacing humanity from the centre of the universe is as far as I know and eighteenth or even nineteenth century invention and actually contradicts the medieval view of the position of the earth. The earth was not at the centre but at the bottom of the universe in the dregs. I once wrote a short blog post quoting Otto von Guericke on this subject, for those to lazy to click through:

OBJECTIONS OF THE ASTRONOMERS AND NATURAL PHILOSOPHERS TO THE COPERNICAN SYSTEM

Since, however, almost everyone has been of the conviction that the earth is immobile since it is a heavy body, the dregs, as it were, of the universe and for this reason situated in the middle or the lowest region of the heaven

Otto von Guericke; The New (So-Called) Magdeburg Experiments of Otto von Guericke, trans. with pref. by Margaret Glover Foley Ames. Kluwer Academic Publishers, Dordrecht/Boston/London, 1994, pp. 15 – 16. (my emphasis)

Need I really point out that the Church didn’t condemn De revolutionibus but in 1616 merely placed it on the Index until corrected, a procedure that was carried out with surprising rapidity. A small number of statements claiming that heliocentricity was a fact rather than a hypothesis were removed and the book approved for use by 1620.

Our next offender is another respected Renaissance historian, Andrew Pettegree, in his The Book in the Renaissance[5].

Nit Picking002

Once again this is a book that in general I find excellent and highly stimulating but like Brotton he disappoints when dealing with the history of science. Like Brotton he starts with Copernicus and De revolutionibus, he tells us:

In 1539 a young mathematician, Georg Joachim Rheticus, embarked on a journey of momentous consequence for the history of science. Rheticus is not a name well known even to scholars. At this point in his life he had little to distinguish him from other graduates at Wittenberg University apart from a family scandal: his father, a medical doctor, had been convicted of embezzlement and beheaded. In 1538 Rheticus left Wittenberg and settled in Nuremberg. Here he fell in with Johann Schoener, the city’s most distinguished astronomer: the following year he set off alone for Frauenberg, a small cathedral city on the Baltic coast beyond Danzig.

The purpose of this journey was to visit the renowned astronomer, Nicolas Copernicus. Although Copernicus had travelled in Europe earlier in his life, from 1510 he was permanently settled in his Polish-Prussian homeland, relatively remote from the major centres of European Scholarship. To ingratiate himself with the older man Rheticus had been provided with three valuable scientific volumes for Copernicus’s library. This was a gift with a purpose. The texts were the work of a Nuremberg printer, Johannes Petreius, who wanted Rheticus to persuade Copernicus to let him publish the master-work it was widely believed he would soon have ready for the press. The gift of the three texts was to demonstrate that only Germany’s greatest centre of scientific publishing could do justice to Copernicus’s work: and to help Rheticus prise the precious manuscript from the old man’s hands.

Copernicus kept Rheticus guessing. He seems to have enjoyed the younger man’s company, and it was 1541 before Rheticus could set off back to Wittenberg, clutching the manuscript of what would be Copernicus’s major text. De revolutionibus (Of the Revolution of the Heavenly Spheres). The following year he journeyed on to Nuremberg, where Petreius was waiting to set it on his press: it took until 1543 before the text, complete with its famous woodcut diagrams of Copernicus’s heliocentric system was ready for sale[6].

The story that Pettegree tells here is a very well-known one in the history of science that has been repeated, in one form or another, in numerous publications, but he still manages to get a whole series of fundamental facts wrong. Firstly, I would claim that whilst maybe not known to the general public, the name Rheticus is well-known to scholars. I think being appointed professor for the lower mathematics (i.e. arithmetic and geometry) at the University of Wittenberg in 1536 did distinguish him from other graduates of that university. He didn’t leave Wittenberg in 1538 and settle in Nuremberg but went on an official sabbatical armed with a letter of introduction written by the Rector of the university Philipp Melanchthon. One of the scholars he went to visit on that sabbatical, mentioned in that letter of introduction, was Johannes Schöner, the professor of mathematics at the Egidien Oberschule in Nürnberg a position to which he had been appointed on Melanchthon’s recommendation. Rheticus visited Schöner almost certainly to study astrology, a subject dear to Melanchthon’s heart.

Copernicus lived in Warmia (Ermland in German) an autonomous self governing Prince Bishopric. Rheticus took not three but six books as a gift to Copernicus of which four had been printed and published by Petreius in Nürnberg. When Rheticus visited Copernicus he was largely unknown and to describe him as renowned is more than a bit of a stretch. His renown came posthumously following the publication of De revolutionibus. There were rumours of a hypothesis and possibly a book, rumours created by the circulating manuscript of the Commentariolus but to state that Petreius or anybody else for that matter outside of Warmia knew of a master-work that would soon be ready for the press is once again an exaggeration. Rheticus’ mission could better be described as look see if Copernicus has anything substantial that could be of interest to a printer publisher specialised in astrological/astronomical and mathematical texts.

Copernicus did not keep Rheticus guessing. Firstly Rheticus suffered a period of illness and then travelled to Königsberg, where he wrote a chorography of Prussia for Duke Albrecht in 1541. Copernicus was reluctant to present his hypothesis to the world because he knew that he could not fulfil the promise that he had given in the Commentariolus that he would prove his hypothesis. To calm his fears Rheticus wrote and published his Narratio Prima in 1540 in Danzig, with a second edition appearing in Basel in 1541. This presented a brief first account of the heliocentric system and its positive reception convinced Copernicus to entrust Rheticus with his manuscript.

All in all a more than somewhat different story to that present to us by Pettegree

Next up we have my current bedtime reading Michael Bravo’s North Pole: Nature and Culture[7], which I’m enjoying immensely.

Nit Picking003

Although the emphasis of the book is on the polar voyages and expeditions beginning in the modern period the book starts much earlier. The first chapter contrasts the views of the North Pole of the ancient Greek astronomers, who saw it as the downwards extension of the North celestial pole and the Inuit who live/lived in the Arctic. The second chapter deals with the representations of the North Pole made by the cartographers and globe makers of the Early Modern Period, a topic of great interest to me, as regular readers will know. It is here that Bravo displays a surprising lack of accurate research. He tells us:

Apian was fortunate to have studied in nearby Vienna, introducing him to the work of a circle of highly talented mathematicians in Nuremberg, Ingolstadt and Vienna who were working under the patronage of Maximilian I, Holy Roman Emperor (1459–1519)…[8]

This is indeed correct and is something that I have written about in several posts and about which Darin Hayton has written a whole book, his The Crown and the Cosmos: Astrology and the Politics of Maximilian I, which I reviewed here. Bravo then goes on to discuss the Werner-Stabius cordiform map projection, which is of course a polar projection centred on the North Pole. All well and good up till now. After an extensive discussion of the cordiform projection, its use and its impact Bravo goes on to say:

Introducing the perspective of viewing the Earth from above brought cosmography into line with the new developments in drawing, projection and perspective pioneered in Renaissance Europe. Albrecht Dürer (1471-1528), one of the most remarkable German artists, was the son of a prominent goldsmith in Nuremberg. Dürer’s precocious talent for drawing broadened into printmaking, writing and an extraordinary rich span of philosophical interests. His studies of perspective spanned much of his life and he brought back to northern Europe the principles of linear perspective he encountered while studying in Bologna. He later moved to Vienna to work with Stabius and Werner under the patronage of Maximilian I[my emphasis] Dürer and Stabius published the first polar star chart in 1515[9].

 

As a Dürer fan, it’s nice to see him getting a nod for more than his Rhinoceros and yes Maximilian was one of his patrons, but the sentence I have placed in italics manages to include two major errors in just sixteen words. Firstly if Dürer had moved to Vienna, he would have only met Stabius and not Werner. The two knew each other from their mutual time at the University of Ingolstadt in the early 1480s but whereas Werner moved first to Rome and then to Nürnberg on the completion of his studies, Stabius stayed in Ingolstadt eventually becoming professor of mathematics before moving to Vienna as court historian and mathematician on Conrad Celtis’ Collegium poetarum et mathematicorum. The two of them continued to work together not by being in the same city but through correspondence. Needless to say Dürer never left Nürnberg and never moved to Vienna, his various shared projects with Stabius were either conducted by letter or by Stabius journeying to Nürnberg. I should point out the Dürer-Stabius-Heinfogel star maps were not the first polar star charts but the first European printed polar star charts, there are earlier manuscript ones and also earlier printed Chinese ones.

All of the things that I have criticised above are facts that are comparatively easy to find and verify with a relatively small amount of research work, so there really is no excuse for getting them wrong. It would be bad enough if the authors were beginners, amateurs or wanna be historians. But in each case we have to do with a justifiably renowned historian and author, so there is really no excuse for this level of sloppiness.

[1] Jerry Brotton, The Renaissance: A Very Short Introduction, OUP, Oxford, 2006

[2]Jerry Brotten, A History of the World in Twelve Maps, Allen Lane, London, 2012

[3] Brotton p. 99

[4] Brotton p. 99

[5] Andrew Pettegree, The Book in the Renaissance, Yale University Press, New Haven & London, 2011

[6] Pettegree pp. 273–274

[7]Michael Bravo, North Pole: Nature and Culture, Reaktion Books, London, 2019

[8] Bravo p. 56

[9] Bravo p. 60

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Filed under History of Astronomy, History of Cartography, History of science, Renaissance Science