Category Archives: History of Technology

Renaissance Science – XX

The term the Republic of Letters is one that one can often encounter in the history of Early Modern or Modern Europe, but what does it mean and to whom does it apply? Republic comes from the Latin res publica and means res “affair, matter, thing” publica “public, people.” However, here it is the “people” or “men”, as they mostly were, of letters. So, our Republic of Letters is the affairs of the men of letters or literati, as they are today more often known. Most often the Republic of Letters is used, as for example on Wikipedia, to refer to the long-distance intellectual community in the late 17th and 18th centuries in Europe and the Americas. However, the earliest known appearance of the term in Latin, respublica literaria, appeared in a letter from the Italian politician, diplomat, and humanist Francesco Barbaro (1390–1454)

Chiesa di Santa Maria del Giglio Venezia – Francesco Barbaro Source: Wikimedia Commons

written to his fellow country man the scholar and humanist Poggio Bracciollini (1380–1459)

Riproduzione novecentesca del ritratto di Poggio Bracciolini, inciso da Antonio Luciani nel 1715. Source: Wikimedia Commons

in 1417, so the original Republic of Letters was the Renaissance literary humanist movement of Northern Italy. Here, we also have a second interpretation of the Letters part of the term, meaning literally the letters that the members of the community wrote to each other to communicate their ideas, to announce their discoveries and to comment on the ideas and discoveries of others. In fact, that first use of the term came about when Poggio was off searching through monastery libraries and sent news of one of his discoveries back to Florence. Barbaro replied to his news thanking him for the gift offered to the literaria res publica for the greater progress of humanity and culture.

Initially this community of communication by letter was restricted to the comparatively small group of the literary humanists of Northern Italy, but with time came to embrace an ever-widening community from China to the Americas and including, as we will see, the whole world of science. Such a community didn’t exist in the Middle Ages, so what changed in the Renaissance that made this happen or indeed possible? 

One simple, partial answer was the change of available writing material, when paper replaced parchment and velum. Parchment and velum were much too expensive to be used for large scale letter writing and correspondence. As I sit at my desk writing this post I’m surrounded by an abundance of paper, piles of books printed on paper, delivery notes, invoices and bank statements printed on paper, notebooks and note slips made of paper, a printer/scanner/copier filled with paper waiting to be printed and other bits and bobs made of paper. Paper is ubiquitous in our lives, and we seldom think about its history. 

If we ignore the fact that wasps were making paper millions of years before humans emerged on the Earth, then paper has only existed for about 0.1% (approximately two thousand years) of the approximately two million years that the genus Homo has been around. It has only been present in Europe for about half of that time. Invented in China sometime before the second century BCE,

Woodcuts depicting the five seminal steps in ancient Chinese papermaking. From the 1637 Tiangong Kaiwu of the Ming dynasty. Source: Wikimedia Commons

paper making was transmitted into the Islamic Empire sometime in the eighth century CE. It first appeared in Europe in Spain in the eleventh century CE. This is of course during the High Middle Ages but the knowledge and use of paper remained restricted to Spain, Italy, and Southern France until well into the fourteenth century, when paper making began to slowly spread into Northern France, The Netherlands, and Germany. The first English paper mill wasn’t built until 1588. 

Ulman Stromer’s Paper-mill. First permanent paper-mill north of the Alps 1390 (From Schedel’s Buch der Chroniken of 1493.)

New production technics and new raw materials for paper production vastly increased output and reduced costs, so that by the fifteenth century paper was much more widely available and by many factors cheaper than parchment and a growing letter writing culture could and did develop. However, before that culture could truly develop, another aspect that we take for granted had to be developed, a delivery system. 

Once again, as I sit in front of my computer, I can communicate almost instantly with people all over the world by email or at least a dozen different social media channels. I can also grab my mobile telephone and either telephone with it or send an SMS. Or I can phone them with my landline telephone and if I want to send something tangible, I can resort to the post service or anyone of a dozen international delivery companies. We live in a thoroughly network society. Most of this simply didn’t exist forty years ago but even then, the landline telephones and the postal services connected people worldwide if at much higher costs. Of course, none of this existed in the Middle Ages.

In the High Middle Ages only the rulers and the Church had courier services to deliver their missives, others were dependent on the infrequent long distant traders and travellers. This began to change in the late Middle Ages/Renaissance as long distant trade began to become more and more frequent and the large North Italian and Southern German finance house became established. Traders and financiers built up communications networks throughout Europe, which also functioned as commercial post services. Big trading centres such as Nürnberg, Venice, and the North German Hansa cities had their own major, highly efficient courier services.

Late in the fourteenth century the Dutchy of Milan set up a postal service and in the second half of the fifteenth century Louis XI set up a post service in France. In 1490 the Holy Roman Emperor Maximilian I gave the von Taxis family a licence to set up a postal service for the whole of the empire. This is claimed to be the start of the modern postal series.

Taxis postal routes 1563 Source: Wikimedia Commons

By fifteen hundred it was possible for scholars throughout Europe to communicate with each other by letter and they did so in increasing numbers, setting up their own informal networks of those interested in a given academic discipline: Natural historians communicated with natural historians, mathematici with mathematici, humanist with humanists and not least artists with artists.

Augsburg Postoffice 1600 Source: Wikimedia Commons

With the advent of the of the so-called age of discovery the whole thing took on a new dimension with missionaries and scholars exchanging information with their colleagues at home in Europe from the Americas, Africa, India, China, and other Asian lands. Here it was the big international trading companies such as the Dutch East India Company and English East India Company, who served as the courier service.

A modern replica of the VOC Duyfken a small ship built in the Dutch Republic. She was a fast, lightly armed ship probably intended for shallow water, small valuable cargoes, bringing messages, sending provisions, or privateering. Source: Wikimedia Commons

There is another important aspect to this rising exchange of letters between scholars and that is the open letter meant for sharing. This was an age when the academic journal still didn’t exist, so if a scholar wished to announce a new discovery, theory, speculation, or whatever he could only do so by word of mouth or by letter if what he wished to covey was not far enough developed or extensive enough for a book or even a booklet. A scholar would write his thoughts in a long letter to another scholar in his field. If the recipient thought that the contained news was interesting or important enough, he would copy it and send it on to another scholar in the field or even sometimes several others. 

Through this process ideas gradually spread through a chain of letters within an informal network, throughout Europe.  By the seventeenth century several significant figures became living post offices each at the centre of a network of correspondence in their respective field. I recently wrote about Marin Mersenne (1588–1648), the Minim friar, who served such a function and who left behind about six hundred such letters from seventy-nine different scientific correspondence in his cell when he died.

Marin Mersenne Source: Wikimedia Commons

His younger contemporary the Jesuit professor of mathematics at the Collegio Romano, Athanasius Kircher (1602–1680), sat at the centre of a world spanning network of some seven hundred and sixty correspondents, collecting information from Jesuit missionaries throughout the world and redirecting it to other, not just Jesuit, scholars throughout Europe.

Athanasius Kircher portrait by Cornelis Bloemaert Source: Wikimedia Commons

One of his European correspondents, for example, was Leibniz (1646–1716), who himself maintained a network of about four hundred correspondents. 

Leibniz portrait by Christoph Bernhard Francke Source: Wikimedia Commons

Two members of Mersenne network, who had extensive correspondence networks of their own were Ismaël Boulliau (1605–1694), of whose correspondence, about five thousand letters written by correspondents from all over Europe and the Near East still exist although many of his letters are known to have been lost

Ismaël Boulliau portrait by Pieter van Schuppen Source: Wikimedia Commons

and Nicolas-Claude Fabri de Peiresc (1580–1637), who certainly holds the record with ten thousand surviving letters covering a wide range of scientific, philosophical, and artistic topics.

Nicolas-Claude Fabri de Peiresc portrait by Louis Finson Source: Wikimedia Commons

Later in the century the European mathematical community was served by the very active English mathematics groupie John Collins (1626–1683), collecting and distributing mathematics news. His activities would contribute to the calculus priority dispute and accusations of plagiarism between Newton and Leibniz, he, having supposedly shown Newton’s unpublished work to Leibniz. Another active in England at the same time as Collins was the German, Henry Oldenburg (c. 1618–1677), who maintained a vast network of correspondents throughout Europe.

Henry Oldenburg portrait by Jan van Cleve (III)

Oldenburg became Secretary of the newly founded Royal Society and used his letters to found the society’s journal, one of the first scientific journals, the Philosophical Transactions, the early issues consisting of collections of the letters he had received. Oldenburg’s large number of foreign correspondents attracted the attention of the authorities, and he was for a time arrested and held prisoner in the Tower of London on suspicion of being a spy.

The simple letter, written on comparatively cheap paper and delivered by increasingly reliable private and state postal services, made it possible for scholars throughout Europe to communicate and cooperate with each other, starting in the Early Modern period, in a way and on a level that had not been possible for their medieval predecessors. In future episodes of this series, we will look at how these correspondence networks helped to further the development of various fields of study during the Renaissance. 

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Filed under History of Technology, Renaissance Science, Uncategorized

I do wish people wouldn’t post things like this

I stumbled across the following image on Facebook, being reposted by people who should know better, and it awoke my inner HISTSCI_HULK:

I shall only be commenting on the first three images, if anybody has any criticism of the other ones, they’re welcome to add them in the comments.

To what extent Galileo developed his own telescope is debateable. He made a Dutch, telescope a model that had first been made public by Hans Lipperhey in September 1608. By using lenses of different focal lengths, he managed to increase the magnification, but then so did several others both at the same time and even before him.

Galileo was not the first to point the telescope skywards! As I have pointed out on several occasions, during that first demonstration by Lipperhey in Den Hague, the telescope was definitely pointed skywards:

The said glasses are very useful at sieges & in similar affairs, because one can distinguish from a mile’s distance & beyond several objects very well, as if they are very near & even the stars which normally are not visible for us, because of the scanty proportion and feeble sight of our eyes, can be seen with this instrument[1]

Even amongst natural philosophers and astronomers, Galileo was not the first. We know that Thomas Harriot preceded him in making astronomical observations. It is not clear, but Simon Marius might have begun his telescopic astronomical observations before Galileo. Also, the astronomers of the Collegio Romano began telescopic observations before Galileo went public with his Sidereus Nuncius and who was earliest they or Galileo is not determinable.

I wrote a whole very detailed article about the fact that Newton definitively did not invent the reflecting telescope that you can read here.

By the standards of the day William Herschel’s 20-foot telescope, built in 1782 seven years before the 40-foot telescope, was already a gigantic telescope, so the 40-footer was not the first. Worse than this is the fact that the image if of one of his normal ‘small’ telescopes and not the 40-footer. 

Herschel’s 40-foot telescope Source: Wikimedia Commons

People spew out these supposedly informative/educational or whatever images/articles, which are sloppily researched or not at all and are full of avoidable error. To put it bluntly it really pisses me off!

[1] Embassies of the King of Siam Sent to His Excellency Prince Maurits Arrived in The Hague on 10 September 1608, Transcribed from the French original, translated into English and Dutch, introduced by Henk Zoomers and edited by Huib Zuidervaart after a copy in the Louwman Collection of Historic Telescopes, Wassenaar, 2008 pp. 48-49 (original pagination: 9-11)


Filed under History of Optics, History of science, History of Technology

The seventeenth-century Chinese civil servant from Cologne 

From its very beginnings the Society of Jesus (the Jesuits) was set up as a missionary movement carrying the Catholic Religion to all corners of the world. It also had a very strong educational emphasis in its missions, carrying the knowledge of Europe to foreign lands and cultures and at the same time transmitting the knowledge of those cultures back to Europe. Perhaps the most well-known example of this is the seventeenth-century Jesuit mission to China, which famously in the history of science brought the latest European science to that far away and, for Europeans, exotic land. In fact, the Jesuits used their extensive knowledge of the latest European developments in astronomy to gain access to the, for foreigners, closed Chinese culture.

It was, initially, Christoph Clavius (1538–1612), who by introducing his mathematics programme into the Jesuits more general education system, ensured that the Jesuits were the best purveyors of mathematics in Europe in the early seventeenth century and it was Clavius’ student Matteo Ricci (1552–1610), who first breached the Chinese reserve towards strangers with his knowledge of the mathematical sciences.

The big question is what did the Chinese need the help of western astronomers for and why. Here we meet an interesting historical contradiction for the Jesuits. Unlike most people in the late sixteenth century and early seventeenth century, the Jesuits did not believe in or practice astrology. One should not forget that both Kepler and Galileo amongst many others were practicing astrologers. The Chinese were, however, very much practitioners of astrology at all levels and it was here that they found the assistance of the Jesuits desirable. The Chines calendar fulfilled important ritual and astrological functions, in particular the prediction of solar and lunar eclipses for which the emperor was personally responsible, and it had to be recalculated at the ascension to the throne of every new emperor. There was even an Imperial Astronomical Institute to carry out this task.

Although the Chinese had been practicing astronomy longer than the Europeans and, over the millennia, had developed a very sophisticated astronomy, in the centuries before the arrival of the Jesuits that knowledge had fallen somewhat into decay and had by that point not advanced as far as that of the Europeans. Before the arrival of the Jesuits, the Chinese had employed Muslim astronomers to aid them in this work, so the principle of employing foreigners for astronomical work had already been established. Through his work, Ricci had convinced the Chinese of his superior astronomical knowledge and abilities and thus established a bridgehead into the highest levels of Chinese society.

The man, who, for the Jesuits, made the greatest contribution to calendrical calculation in seventeenth century was the, splendidly named, Johann Adam Schall von Bell (1591–1666). Born, probably in Cologne, into a well-established aristocratic family, who trace their roots back to the twelfth century, Johann Adam was the second son of Heinrich Degenhard Schall von Bell zu Lüftelberg and his fourth wife Maria Scheiffart von Merode zu Weilerswist. He was initially educated at the Jesuit Tricoronatum Gymnasium in Cologne and then in 1607 sent to Rome to the Jesuit run seminary Pontificium Collegium Germanicum et Hungaricum de Urbe, where he concentrated on the study of mathematics and astronomy. It is thought that his parents sent him to Rome to complete his studies because of an outbreak of the plague in Cologne. In 1611 he joined the Jesuits and moved to the Collegio Romano, where he became a student of Christoph Grienberger

A portrait of German Jesuit Johann Adam Schall von Bell (1592–1666), Hand-colored engraving, artist unknown Source: Wikimedia Commons

He applied to take part in the Jesuit mission to China and in 1618 set sail for the East from Lisbon. He would almost certainly on his way to Lisbon have spent time at the Jesuit College in Coimbra, where the missionaries heading out to the Far East were prepared for their mission. Here he would probably have received instruction in the grinding of lenses and the construction of telescopes from Giovanni Paolo Lembo (c. 1570–1618), who taught these courses to future missionaries.

Schall von Bell set sail on 17 April 1618 in a group under the supervision of Dutch Jesuit Nicolas Trigault (1577–1628), Procurator of the Order’s Province of Japan and China.

Nicolas Trigault in Chinese costume, by Peter Paul Rubens, the Metropolitan Museum of Art Source: Wikimedia Commons
De Christiana expeditione apud Sinas, by Nicolas Trigault and Matteo Ricci, Augsburg, 1615. Source: Wikimedia Commons

Apart from Schall von Bell the group included the German, polymath Johannes Schreck (1576–1630), friend of Galileo and onetime member of the Accademia dei Lincei, and the Italian Giacomo Rho (1592–1638). They reached the Jesuit station in Goa 4 October 1618 and proceeded from there to Macau where they arrived on 22 July 1619. Here, the group were forced to wait four years, as the Jesuits had just been expelled from China. They spent to time leaning Chinese and literally fighting off an attempt by the Dutch to conquer Macau. 

In 1623 Schall von Bell and the others finally reached Peking. In 1628 Johann Schreck began work on a calendar reform for the Chinese. To aid his efforts Johannes Kepler sent a copy of the Rudolphine Tables to Peking in 1627. From 1627 to 1630 Schall von Bell worked as a pastor but when Schreck died he and Giacomo Rho were called back to Peking to take up the work on the calendar and Schall von Bell began what would become his life’s work.

He must first translate Latin textbooks into Chinese, establish a school for astronomical calculations and modernise astronomical instruments. In 1634 he constructed the first Galilean telescope in China, also writing a book in Chinese on the instrument. In 1635 he published his revised and modernised calendar, which still exists. 

Text on the utilisation and production of the telescope by Tang Ruowang (Chinese name of Johann Adam Schall von Bell) Source: Wikimedia Commons
Galilean telescope from Schall von Bell’s Chinese book Source: Wikimedia Commons

Scall von Bell used his influence to gain permission to build Catholic churches and establish Chinese Christian communities. This was actually the real aim of his work. He used his knowledge of mathematics and astronomy to win the trust of the Chinese authorities in order to be able to propagate his Christian mission.

In 1640 he produced a Chinese translation of Agricola’s De re metallica, which he presented to the Imperial Court. He followed this on a practical level by supervising the manufacture of a hundred cannons for the emperor. In 1644, the emperor appointed him President of the Imperial Astronomical Institute following a series of accurate astronomical prognostication. From 1651 to 1661 he was a personal advisor to the young Manchurian Emperor Shunzhi (1638–1661), who promoted Schall von Bell to Mandarin 1st class and 1st grade, the highest level of civil servant in the Chinese system.

Johann Adam Schall von Bell and Shunzhi Emperor Source: Wikimedia Commons

Following the death of Shunzhi, he initially retained his appointments and titles, which caused problems for him in Rome following a visitation in Peking by the Dominicans. The Vatican ruled that Jesuits should not take on mundane appointments. In 1664 Schall von Bell suffered a stroke, which left him vulnerable to attack from his rivals at court. He was accused of having provoked Shunzhi’s concubine’s death through having falsely calculated the place and time for the funeral of one of Shunzhi’s sons. 

The charges, that included other Jesuits, were high treason, membership of a religious order not compatible with right order and the spread of false astronomical teachings. Schall von Bell was imprisoned over the winter 1665/66 and Jesuits in Peking, who had not been charged were banned to Kanton. He was found guilty on 15 April 1665 and sentenced to be executed by Lingchi, death by a thousand cuts. However, according to legend, there was an earthquake shortly before the execution date and the judge interpreted it as a sign from the gods the Schall von Bell was innocent. On 15 May 1665 Schall von Bell was released from prison on the order of the Emperor Kangxi (1654–1722). He died 15 August 1666 and was rehabilitated by Kangxi, who ensured that he received a prominent gravestone that still exists. 

Jesuit astronomers with Kangxi Emperor by Philippe Behagle French tapestry weaver, 1641 – 1705 Source: Wikimedia Commons

Schall von Bell was represented at his trial by Flemish Jesuit Ferdinand Verbiest (1623–1688), who would later take up Schall von Bell’s work on the Chinese calendar but that’s a story for another day. Schall von Bell reached the highest ever level for a foreigner in the Chinese system of government but in the history of science it is his contributions to the modernisation of Chinese astronomy and engineering that are most important. 

Jesuit Mission to China, left to right Top: Matteo Ricci, Johann Adam Schall von Bell, Ferdinand Verbiest Artist: Jean-Baptiste Du Halde (1674 – 1743) French Jesuit historian Source: Wikimedia Commons


Filed under History of Astrology, History of Astronomy, History of Technology, Renaissance Science

Renaissance Science – XV

Vitruvius’ De architectura was by no means the only book rediscovered from antiquity that dealt with the construction and use of machines and the Renaissance artist-engineers were also not the only authors producing new texts on machines. In this episode of our series, we are going to look at another stream of writings that led to some of the most impressive publications on machines ever produced.

Ancient books, in Europe, on machines do not begin with Vitruvius, who actually comes quite late in the development of this type of literature. There are several known authors from ancient Greece, whose works did not survive but who are mentioned and even quoted by later authors such as Vitruvius and Pliny. Polyidus of Thessaly, who is mentioned by Vitruvius, served under Philip II of Macedonia in the fourth century BCE. He is credited with the development of covered battering rams and a giant siege tower (helepolis) by Byzantium in 340 BCE.  His students Diades of Pella and Charias, both also mentioned by Vitruvius, served under Philip’s son Alexander the Great. 

In Alexandria the earliest known author was Ctesibius, who invented a wide range of machines, which he described in his Commentaries, now lost but known to both Vitruvius and Hero of Alexandria. Much better know is a contemporary of Ctesibius, Philo of Byzantium (c. 280–c. 220 BCE), also known as Philo Mechanicus, who lived and worked in Alexandria. He wrote a major work in nine books covering mathematics, general mechanics, harbour building, artillery, pneumatic machines, mechanical toys, siege engines, siege craft, and cryptography. His work on artillery and siege craft survived in Greek as did fragments of his books on mathematics and mechanical toys but were first translated in the 19th century. Parts of his book on pneumatics, however, survived in a Latin translation, De ingeniis spiritualibus, from an Arabic manuscript. It can however be assumed that his works were well known to and influenced other authors later in antiquity.

We have already met Vitruvius the most well-known author on things mechanical during the Roman Empire and had a brief reference to Athenaeus Mechanicus (fl. mid first century BCE). Athenaeus, a Greek living in Rome, wrote a book on siege craft titled On Machines, which cites both Diades of Pella and Philo of Byzantium, as sources. Much of his book parallels that of Vitruvius implying the use of common sources.

In the middle of the first century CE, we meet Hero of Alexandria, whose exact dates are unknown, perhaps the most well-known Greek engineer of Antiquity, who exercised a similar influence in the Renaissance to Vitruvius. Works that are attributed with certainty are Pneumatica (on pneumatics), AutomataMechanica (written for architects and only preserved in Arabic), Metrica (measuring areas and volumes), On the DioptraBelopoeica (war machines), and Catoptrica (the science of reflected lights). His Belopoeica is attributed to Ctesibius. The Metrica first reappeared in the nineteenth century and the Mechanica was unknown in Europe. However, the Pneumatica, the Automata, and the Belopoeica were translated from Greek into Latin and printed and published in the sixteenth century.

The book About automata by Hero of Alexandria (1589 edition) Source: Wikimedia Commons

Hero was the last of the technical authors of antiquity but the later authors such as Pliny the Elder (23/24–79 CE) or Pappus of Alexander (c. 290–c. 350 CE) reference authors such as Vitruvius and Hero.

Before moving forward to the Renaissance, we need to take a brief look at the developments in the Islamic Empire. In the ninth century the translators the Bana Musa, three Persian brother, Ahmad, Muhammad, and Hasan bin Musa ibn Shakir, published a large, illustrated work on machines the Book of Ingenious Devices in 850 CE. It drew on the work of Hero of Alexandria and Philo of Byzantium as well Persian, Chinese, and Indian engineering. It was translated into Latin by Gerard of Cremona in the thirteenth century.

Original illustration of a self trimming lamp discussed in the treatise on Mechanical Devices of Ahmad ibn Musa ibn Shakir. Drawing can be found in the “Granger Collection” located in New York. Source: Wikimedia Commons

In the twelfth century Badīʿ az-Zaman Abu l-ʿIzz ibn Ismāʿīl ibn ar-Razāz al-Jazarī (1136–1206) wrote his The Book of Knowledge of Ingenious Mechanical Devices. Truly spectacular, it contains descriptions of fifty complex machines and was the most advanced such book produced up till this time, but it was never translated into Latin and so had no influence in the Renaissance.

Diagram of a hydropowered perpetual flute from The Book of Knowledge of Ingenious Mechanical Devices by Al-Jazari in 1206. Source: Wikimedia Commons

It should be noticed that in antiquity texts on machines had an emphasis on war machines. During the fifteenth century the first texts on machines were also on war machines and were written by physicians and not artisans. Konrad Kyeser (1366–1405) wrote a book on military engineering, Bellifortis, dedicated to the Holy Roman Emperor Ruprecht III, who ruled from 1400–1410.

Konrad Kyeser, illustration on his Bellifortis manuscript (Cod. Ms. philos. 63) Source: Wikimedia Commons
War wagon (Clm 30150 manuscript) Source: Wikimerdia Commons

Giovanni Fontana (c. 1395–c. 1455), who like Kyeser studied medicine at the University of Padua, also wrote a book on military engineering, Bellicorum instrumentorum liber.

Illustration from Bellicorum instrumentorum liber, Venice c. 1420 – 1430 Source: Wikimedia Commons

In Germany in the fifteenth century there were several books on military engineering written in the vernacular as well as a German translation of Kyeser’s Bellifortis. The author of the Feuerwerksbuch from 1420 is not known. Martin Mercz (c. 1425–1501), a gunner, also wrote a Feuerwerksbuch around 1473. Philipp Mönch wrote a Kriegsbuch in 1496

The texts produced by the Renaissance artist-engineers that we looked at in the last episode, whilst distributed in manuscript, were never issued as printed books, as was the case with most of the fifteenth century books of military engineering. The introduction of printing to the genre of machine texts had a major impact. One book on military engineering that was printed and published was the Elenchus et index rerum militarium by the humanist scholar Roberto Valturio (1405–1475), a compendium of ancient authorities with an emphasis on the technological aspects of warfare.

The author’s preface to the treatise „De re militari“ in the manuscript Paris, Bibliothèque nationale de France, Lat. 7237, fol. 1r. Source: Wikimedia Commons

It was written for and dedicated to Sigismund Malatesta of Rimini (1471-1468), a successful military leader but also a humanist poet, originally between 1455 and 1460 and distributed widely in manuscript but was published in Verona in 1472. It went through many printed editions and translations. Leonardo da Vinci was known to have owned a copy.

Illustration from De re militari by Robertus Valturius Source: Wikimedia Commons

Two printed books in particular set new standards for books on machines and engineering, the Pirotechnia of Vannoccio Biringuccio (1480–died before1539) published posthumously by Curtio Navo in Venice in 1540

and De re metallica by Georgius Agricola (1494–1555) also published posthumously by Froben in Basel in 1556.

Both books deal with mining, the extraction of metallic ores and the working of metal smelted from the ores. Both are lavishly illustrated with the drawings in Agricola’s book being of a much higher standard than those in Biringuccio’s book. 

I have dealt with both books and their authors in earlier posts (see links above) and so won’t go into great detail here but in these two books with have an excellent example of the crossover between the world of the university educated theoretician and the artisan on artisanal topics. Agricola is a university educated physician writing theoretically about a group of related artisanal topics, whereas Biringuccio is an experienced artisan writing a theoretical book about his artisanal trades. 

The late sixteenth century saw the birth of a new book genre, the machine book. These were books of diagrams of machines with brief descriptions, usual presented by the author to a powerful patron. The main ones were very popular and went through several editions or reprints. These books often contained not only machines designed by the authors, but their presentations of machines drawn from other sources. Many of these studies were almost certainly not intended as serious designs to be built but were rather ingenious studies designed to impress rich patrons, in the nature of the futuristic design studies that car companies present at car shows. This also, almost certainly, applies to many of the designs to be found in the manuscripts of Leonardo da Vinci.

The earliest of the machine books by the French Protestant, inventor and mathematician, Jacques Besson (1540? – 1573). He said that he was born in Colombières near Briançon in the Alps on the south-eastern border of France, now in Italy. In the 1550s he taught mathematics in Paris and was working as a hydraulic engineer in Lausanne, Switzerland. In 1559 he published a book in Zurich and in 1561 he was awarded citizenship in Geneva as a science and mathematics teacher. In 1562 he was a pastor in Villeneuve-de-Berg in France but 1565 finds him back in Paris where he published his La Cosmolabe, a multiple instrument based on the astrolabe designed for use in navigation, surveying, cartography, and astronomy. 

Cosmolabe by Jacques Besson Source: Wikimedia Commons

In 1569 in Orléans he presented a draft of his new volume Theatrum Instrumentorum (giving the machine book genre the alternative name of Theatre of Machines) to Charles IX, as a result returning to Paris as Master of the Kings Machines. The Theatrum Instrumentorum, containing sixty plates, was printed and published in 1571-2.

In Besson case his book only contains machines that he claimed to have invented himself. Following the St Bartholomew’s Day Massacre in 1572 Besson fled to London where he died in the following year. 

In 1572, our next machine book author, Agostino Ramelli (1531–c. 1610) a Catholic military engineer, was involved in the siege of the Protestant stronghold, La Rochelle.

Agostino Ramelli author portrait Source: Wikimedia Commons

Very little is known about Ramelli other than that he was born in Ponte Tresa on Lake Lugano on the border between Switzerland and the Duchy of Milan. He seems to have served most of his early life as a military engineer and comes to prominence at La Rochelle, because he was wounded and taken prisoner. Henry, Duke of Anjou, arranged his release and when Henry became King of France in 1575, he apparently appointed Ramelli royal engineer, as he styled himself in the preface to his book, engineer of the most Christian King of France. 

In 1588 he self-published his Diverse Et Artificiose Machine, the book, the largest of the genre, contains one hundred and ninety-five plates, printed from high quality engraved copper plates.  The majority of the machines are hydraulic engines. Unlike Bresson, who included no war machines in his book, about one third of Ramelli’s book consists of war machines. 

Title: Complex machine using water-wheel, bellows, and turbine action Abstract/medium: 1 print : engraving.Source: Wikimedia Commons
Depiction of sixteenth century cannon placements from Le diverse et artificiose machine del capitano Agostino Ramelli, page 708 of 720 Source: Wikimedia Commons

Ramelli is certainly today the most well known of the machine book authors because his book-wheel has become an iconic image on social media. Due to the lavish quality of the illustrations Ramelli’s book became an instant coffee table book, which was probably his intention, and is still in print today.

Ramelli Book-Wheel Source: Wikimedia Commons

We know very little about Bresson and even less about Ramelli, but in the case of the third author of a major machine book, Vittorio Zonca (1568–1603), we know next to nothing. His book, Novo Teatro di Machine et Edificii, was published posthumously by Francesco Bertelli in Padua in 1607. Bertelli appears not to have known Zonca but describes him as a Paduan architect. Like the books of Bresson and Ramelli. Zonca’s volume went through several edition. 

Title page Source: Wikimedia Commons

Interestingly the German, Jesuit polymath, Johann Schreck (1576–1630), one time member of the Accademia dei Lincei and friend of Galileo,  published a book in Chinese in 1627, based on Zonca’s book and incorporating plates from Bresson and Ramelli titled, Diagrams and explanations of the wonderful machines of the Far West (abridged Chinese title, Qí qì túshuō).

a description of a windlass well, in Agostino Ramelli, 1588. Source: Wikimedia Commons


Description of a windlass well, in Diagrams and explanations of the wonderful machines of the Far West, 1627. Source: Wikimedia Commons
Original Pompeo Targone field mill in Zonca’s treatise of 1607. Source: Wikimedia Commons
Chinese adaptation of the field mill in Diagrams and explanations of the wonderful machines of the Far West, 1627. Source: Wikimedia Commons

The German architect and engineer, Heinrich Zeising (died 1610 or earlier) compiled the first German machine book borrowing heavily from the works of Walther Hermann Ryff’s German edition of Vitruvius, Besson, Ramelli, Zonca, Gerolamo Cardano, and others This was published as Theatrum Machinarum in six parts by Henning Grosse in Leipzig between 1607 and 1614. In the foreword to the second part in 1610, Grosse informed the reader that Zeising was deceased .


The Bishop of Czanad in Hungary, Fautus Verantius (c. 1551–1617), in his retirement, published a multilingual machine book, Machinae Novae, in 1616. It had 49 plates containing 55 machines, described in Latin and Italian in one variant and in Latin, Italian, Spanish, French, and German in another. There exists the possibility that Verantius saw and was influenced by Leonardo’s manuscripts.


Portrait of Fausto Veranzio, (Šibenik (Sebenico) circa 1551 – Venice, January 17, 1617) Source: Wikimedia Commons
Drawing of suspension cable-stayed bridge by Fausto Veranzio in his Machinae Novae Source: Wikimedia Commons

In 1617 Octavio Strada published an encyclopaedic collection of machine drawings supposedly complied by his grandfather Jacopo Strada (1517–1588)–courtier, painter, architect, goldsmith, and numismatist–under the title La premiere partie des Desseins Artificiaux in Frankfurt, about which very little in known. 

STRADA, Jacobus de (c.1523-1588) and Octavius de STRADA. Desseins Artificiaulx de Toutes Sortes des Moulins a Vent, a l’Eau, a Cheval & a la Main. Frankfurt: Paul Jacobi, 1618. Source:

The Italian engineer and architect, Giovanni Branca (1571–1645) dedicated a collection of illustrations of mechanical inventions to the governor of Loreto Ancona, which he then published as a book Le machine in 1629. The book contains 63 illustrations with descriptions in Latin and Italian, but whereas the books of Bresson and Ramelli are large format volumes with lavish copper plate engravings, Branca’s book is a small octavo volume illustrated with simple woodcuts.

Title page
Branca Le Machine

In the relatively brief period covering the last quarter of the sixteenth century and the first quarter of the seventeenth century, the Renaissance Theatre of Machines books, as they became known after the first one from Jacques Besson, were very popular. Although they continued to be reprinted throughout the seventeenth century their time was over and literature over technology moved on into different formats. This is one of the signs that Renaissance science did indeed peter out in the middle of the seventeenth century.


Filed under History of Technology, Renaissance Science

Renaissance Science – XIV

In the previous episode we saw how the Renaissance rediscovery of Vitruvius’ De architectura influenced the development of architecture during the Renaissance and dissolved the boundary between the intellectual theoreticians and the practical artisans. However, as stated there Vitruvius was not just an architect, but was also an engineer and his Book X deals quite extensively with machines both civil and military. This had a massive influence on a new type of artisan the Renaissance artist-engineer and it is to these that we now turn our attention. 

Artist-engineers were very much a Northern Italian Renaissance phenomenon, but even earlier artists had been categorised as craftsmen or artisans and not as artists as we would understand the term. The occupation of artist-engineer was very much influenced by the popularity of Vitruvius’ De architectura. The most well-known Renaissance artist engineer is, of course, Leonardo da Vinci (1452–1519), but he was by no means unique, as he is often presented in popular accounts, but he stood at the end of a line of other artist-engineers, who are known to have influenced him. Here I will deal principally with those artisan artist-engineers, who dissolved the boundary between practice and theory by witing and circulating treatises on their work.

At the beginning of the line were the Florentine rival, goldsmiths Lorenzo Ghiberti (1378–1455) and Filippo Brunelleschi (1377–1446). In 1401 there was a competition to design the first set of new doors for the Florence Baptistery. Ghiberti and Brunelleschi were two of the seven artists on the short list. Ghiberti won the commission and set up a major engineering workshop to carry out the work. 

It took Ghiberti twenty-one years to complete the first set of doors featuring twenty New Testament Bible scenes, the four evangelists and four of the Church Fathers, but once finished they established his reputation, as a great Renaissance artist. In 1425 he was awarded a second commission for another set of doors, these featuring ten Old Testament scenes in realistic perspective presentation took another twenty-seven years. The second set of doors included portraits of both Ghiberti and his father Bartolomeo Ghiberti. 

Ghiberti self portrait from his second set of doors (modern copy Source: Wikimedia Commons

We don’t need to go into any great detail here about the doors or the other commissions that Ghiberti’s workshop finished.

Ghiberti’s second set of doors, known as the Gates of Paradise (modern copy) Source: Wikimedia Commons

What is much more relevant to our theme is his activities as an author. Although he was the artisan son of an artisan father, Ghiberti crossed the medieval boundary between theory and practice with his Commentarii, a thesis on the history of art, written in Italian. He drew on various sources from antiquity including the first century BCE illustrated Greek text on machines by Athenaeus Mechanicus and Pliny’s Naturalis Historia, a text much discussed by the Renaissance Humanists, but his major source was Vitruvius’ De architectura. Ghiberti died without finishing his Commentarii and it was never published. However, many important Renaissance artist, such as Donatello and Paolo Uccello, served their apprenticeships in his workshop, so his influence on future generations was very large.

One probable graduate of Ghiberti’s workshop was Antonio Averlino (c. 1400–c. 1469) known as Filarete, a sculptor and architect. 

Filarete, Self-portrait medal, obverse, c. 1460, bronze. London, V & A

 Between 1461 and 1464, he wrote a vernacular volume on architecture in twenty-five books, his illustrated Trattato di Architettura, which circulated widely in manuscript. Central to his theory of architecture was the Vitruvian ideal of practice combined with theory. The most significant part of his book was his design for Sforzinda an ideal city named after his patron Francesco Sforza (1401–1466). This was the first of several ideal cities, which became a feature of the Renaissance. It is thought that his inspiration came from the works of Plato and his knowledge of this came from his friend at the Sforza court, the humanist scholar and philologist Francesco da Tolentino (1398–1481) known as Filelfo. Once again, we have, as in the last episode, a cooperation across the old boundaries between a scholar and an artisan.

Filarete Sforzinda

Filippo Brunelleschi poses a different problem. Like Ghiberti trained as a goldsmith, he went on to become the epitome of a Renaissance Vitruvian architect. However, there is no direct evidence that connects him with De architectura or its author. There is no direct evidence that connects him with anything except for the products of his life’s work, most notably the dome of the Santa Maria del Fiori cathedral in Florence. He is also renowned as the inventor or discoverer of the mathematical principles of linear perspective, as explained in episode seven of this series. This links him indirectly to Vitruvius, as some authors insist that he only rediscovered linear perspective, quoting Book 7 of De architectura, where Vitruvius describes the use of some form of perspective on the ancient Greek theatre flats. 

Filippo Brunelleschi in an anonymous portrait of the 2nd half of the 15th century (Louvre, Paris) Source: Wikimedia Commons

More importantly, Brunelleschi, as an architect, not only designed and supervised the construction of the buildings that he was commissioned to build but also devised and constructed the machines that he needed on his building sites to facilitate those constructions. For his work on the Santa Maria dome, for example he designed a crane to lift the building materials up to the top of the cathedral.

Brunelleschi’s revolving crane

A drawing of that crane can be found in Leonardo’s manuscripts. He was also granted a patent by the ruling council of Florence for the design of a ship to transport heavy loads of stone on rivers and canals.

Reproduction of Brunelleschi’s patent boat Source: Wikimedia Commons

Brunelleschi was also like, Vitruvius, a successful hydraulic engineer. It is hard to believe that he wasn’t influenced by De architectura.

There is no doubt about the Vitruvian influence of our next artist-engineer, Mariano di Jacopo (1382–c. 1453) known as Taccola (the jackdaw), who, as I explained in an earlier post on that Renaissance iconic figure, included a Vitruvian Man in his drawings. Taccola, who is known to have worked as a sculptor, superintendent of roads and hydraulic engineer, was from Sienna. He met and talked with Brunelleschi, one of the few people known to have done so. 

Taccola produced two annotated manuscripts the four books of De ingeneis, written between 1419 and 1433, and De machnis issued in 1449, which was partially an improved version of his De ingeneis.

Jacopo Mariano Taccola, De ingeneis, Book I. Codex Latinus 197,..

Both manuscripts contain numerous illustrations of machines for hydraulic engineering, milling (and mills were one of the most important types of machines in medieval and Renaissance culture), construction and military machinery, all topics covered by Vitruvius.

First European depiction of a piston pump by Taccola, c.1450 Source: Wikimedia Commons

His manuscripts also some of Brunelleschi’s construction machines. Taccola is in one sense a transitional figure as his representations, of three-dimensional machines, often use medieval drawing conventions rather than Brunelleschi’s recently discovered linear perspective. 

Taccola’s works were never printed but copies of his manuscripts are known to have circulated widely during his lifetime and to have been highly influential. After his death his influence waned as his work was superceded by the more advance work of Francesco di Giorgio Martini and Leonardo da Vinci both of whom were heavily influenced by Taccola.

Francesco di Giorgio Martini (1439–1501) was, like Taccola, from Siena and was an architect, engineer, painter, sculptor, and writer.

His Vitruvian influence is very obvious in his work, as also the influence of Taccola. Francesco worked for much of his life on an Italian translation of Vitruvius’ De architectura, which he never published. Like Filarete he wrote an architectural treatise Trattato di archtettura, ingegneria e arte militare, worked on over decades and finished sometime after 1482. Many of his machines are taken from Taccola’s manuscripts. As can be seen from the title, it continues the Vitruvian tradition. Like Filarete’s volume it contains a design for an ideal town. Probably inspired by Sulpizio’s first printed edition of De architectura and Alberti’s De re aedificatoria, he produced a new edition of his own book known as Trattato II. 

Edificij et machine, Martini, Francesco di Giorgio, 1439-1501, brown ink and wash, ca. 1475-ca. 1480, The volume comprises 103 drawings by Francesco di Giorgio Martini and his assistants, featuring machines and devices for lifting columns and other heavy weights, schemes for transporting water, and mechanisms for milling and moving boats. There are also a few drawings showing how people could walk or float on water standing on inflatable containers and using an oar to propel themselves. PUBLICATIONxINxGERxSUIxAUTxONLY Copyright: LCD2_180906_23583

Both Taccola and Francesco are known to have influenced the most famous of the Renaissance artist-engineers, Leonardo da Vinci. As well as the obvious direct influence of Vitruvius, many of the machines illustrated in Leonardo’s manuscripts are taken from the work of Brunelleschi, Taccola and Francesco di Giorgio. As an apprentice, Leonardo had worked on the final phase of Brunelleschi’s dome for the Santa Maria Cathedral, and he took the opportunity to study Brunelleschi’s building site machines and scaffolding. He owned copies of the manuscripts of both Taccola and Francesco, the latter of which he annotated heavily. Leonardo, as is well known, wrote reams of annotated manuscripts on his machines but never published any of them.

Watter wheel, just one of Leonardo’s hundreds of drawings of machines Source

All of the artist-engineers that I have briefly sketched here are examples of artisans who crossed over or better dissolved the boundaries between theoretical and practical knowledge. They are also, so to speak, the stars of a much larger and widespread group of Renaissance artist-engineers, whose influence spread throughout the Renaissance, changing and elevating the status of the skilled artisan.  


Filed under Book History, History of Technology, Renaissance Science

Renaissance Science – XIII

As already explained in the fourth episode of this series, the Humanist Renaissance was characterised by a reference for classical literature, mostly Roman, recovered from original Latin manuscripts and not filtered and distorted through repeated translations on their way from Latin into Arabic and back into Latin. It was also a movement that praised a return to classical Latin, away from the, as they saw it, barbaric medieval Latin. In the fifth episode we also saw that, what I am calling, Renaissance science was characterised by a break down of the division that had existed between theoretical book knowledge as taught on the medieval universities and the empirical, practical knowledge of the artisans. As also pointed there this was not so much a breaking down of boundaries or a crossover between the two fields of knowledge as a meld between the two types of knowledge that would over the next two and a half centuries lead to the modern concept of knowledge or science.

One rediscovered classical Latin text that very much filled the first criterium, which at the same time played a major role in the second was De architectura libri decem (Ten Books on Architecture) by the Roman architect and civil and military engineer Marcus Vitruvius Pollio (c.80-70–died after 15 BCE), who is usually referred to simply as Vitruvius and there are doubts about the other two names that are ascribed to him. 

From the start we run into problems about the standard story that the manuscript was rediscovered by the Tuscan, humanist scholar Poggio Bracciolini (1380–1459) in the library of Saint Gall Abbey in 1416, as related by Leon Battista Alberti (1404–1472) in his own architecture treatise De re aedificatoria (1452), which was modelled on Vitruvius’ tome. In reality, De architectura had never been lost during the Middle Ages; there are about ninety surviving medieval manuscripts of the book.

Manuscript of Vitruvius; parchment dating from about 1390 Source: Wikimedia Commons

The oldest was made during the Carolingian Renaissance in the early nineth century. Alcuin of York was consulted on the technical terms in the text. During the Middle Ages many leading scholars including Hermann of Reichenau (1013–1054), a central figure of the Ottonian Renaissance, and both Albertus Magnus (c. 1200– 1280) and Thomas Aquinas (1225–1274), who laid the foundations of medieval Aristotelian philosophy, read the text, and commented on it. 

However, although well-known it had little impact on architecture in the medieval period. The great medieval cathedrals and castle were built by master masons, whose knowledge was practical artisanal knowledge passed on by word of mouth from master to apprentice. This changed with Poggio’ rediscovery of Vitruvius’ work and the concept of the theoretical and practical architect began to emerge.

Before we turn to the impact of De architectura in the Renaissance we first need to look at the book and its author. Very little is known about Vitruvius, as already stated above, the other names attributed to him are based on speculation, most of what we do know is pieced together from the book itself. Vitruvius was a military engineer under Gaius Julius Caesar (100–44 BCE) and apparently received a pension from Octavian (63 BCE–14 CE), the later Caesar Augustus, to whom the book is dedicated. The book was written around twenty BCE. Vitruvius wrote it because he believed in making knowledge public and available to all, unlike those artisans, who kept their knowledge secret.

The ten books are organised as follows:

  1. Town planning, architecture or civil engineering in general and the qualification required by an architect or civil engineer
  2. Building materials
  3. Temples and the orders of architecture
  4. As book 3
  5. Civil buildings
  6. Domestic buildings
  7. Pavements and decorative plasterwork
  8. Water supplies and aqueducts
  9. The scientific side of architecture – geometry, measurement, astronomy, sundials
  10. Machines, use and construction – siege engines, water mills, drainage machines, technology, hoisting, pneumatics

In terms of its reception and influence during the Renaissance the most important aspect is Vitruvius’ insistence that architecture requires both ratiocinatio and fabrica, that is reasoning or theory, and practice or construction. This Vitruvian philosophy of architecture took architecture out of the exclusive control of the master mason and into the hands of the theoretical scholars in union with the artisans. This move was also motivated by the humanist drive to study archaeologically the Roman remains in Rome the Eternal City. Vitruvius provided a guide to understanding the Roman architecture, which would become the model for the construction of new buildings. 

But for it to become influential Vitruvius’s text first had to become widely available. The first printed Latin edition was edited by the humanist scholar Fra. Giovanni Sulpizio da Veroli (fl. c. 1470–1490) and published in 1486 with a second edition in 1495 or 1496.


The first printed edition had no illustrations. Fra. Giovanni Giocondo da Verona (c. 1433–1515) produced the first edition with woodcut illustrations, published in Venice in 1511. A second improved edition was published in Florence in 1521. 


In order for De architectura to reach artisans it needed to be translated into the vernacular, as most of them couldn’t read Latin. This process began in Italy and during the sixteenth century spread throughout Europe. The process started already before De architectura appeared in print. As mentioned above Alberti’s De re aedificatoria (On the Art of Buildings), not a translation of De architectura but a book strongly modelled on it appeared in Latin in print in 1452.

Source: Wikimedia Commons

The first Italian edition appeared in 1486 A second Italian edition, by the humanist mathematician Cosimo Bartoli (1503-1572), which became the standard edition, appeared in 1550. Alberti was very prominent in Renaissance culture and very widely read. His influence can be measured by the fact that a collective bilingual, English/Italian, edition of his works on architecture, painting and sculpture was published as late as 1726. 

The first Italian edition of De architectura with new illustration and added commentary by Cesare Cesariano (1475-1543) was published at Como in 1521.

1521 Italian edition title page Source
1521 Italian edition

A plagiarised version was published in Venice in 1524. The first French edition, translated by Jean Martin (died 1553), which is said to contain many errors, was published in Paris in 1547.


The first German edition was translated by Walther Hermann Ryff (c. 1500–1548). As far as can be determined, it appears the Ryff was an apothecary but work mostly as what today would probably be described as a hack. He published as editor, translator, adapter, and compiler a large number of books, around 40, over a wide range of topics, although the majority were in some sense medical, and was seemingly very successful. He was often accused of plagiarism. The physician and botanist, Leonhart Fuchs (1501–1566) described him as an “extremely brazen, careless, fraudulent author.” Apart from his medical works, Ryff obviously had a strong interest in architecture. He edited and published a Latin edition of De architectura in Strasbourg in 1543. This was followed by a commentary on De architectura in German, Der furnembsten, notwendigsten, der gantzen Architectur angehörigen Mathematischen vnd Mechanischen künst, eygentlicher bericht, vnd vast klare, verstendliche vnterrichtung, zu rechtem verstandt der lehr Vitruuij, in drey furneme Bücher abgetheilet (The most distinguished, necessary, mathematical and mechanical arts belonging to the entire architecture, actual report and clear, understandable instruction of the teachings of Vitruvius shared in three distinguished books), published by Johannes Petreius, the leading European scientific publisher of the period, in Nürnberg in 1547. For obvious reasons this is usually simply referred to as Architektur. This was obviously a product of the German translation of De architectura, which Petreius had commissioned Ryff to produce and, which he published in Nürnberg in 1548 under the title, Vitruvius Teutsch. Nemlichen des aller namhafftigisten vñ hocherfahrnesten römischen Architecti vnd kunstreichen Werck zehn Bücher von der Architectur und künstlichem Bawen… (Vitruvius in German…).


We return now to Italy and the story of the stone mason, Andrea di Pietro della Gondola, born in Padua in 1508. Having served his apprenticeship, he worked as a stone mason until he was thirty years old. In 1538–39, he was employed to rebuild the villa of the humanist poet and scholar, Gian Giorgio Trissino (1478–1550) to rebuild his villa in Cricoli.

Gian Giorgio Trissino, portrayed in 1510 by Vincenzo Catena Source: Wikimedia Commons
Villa Trissino Source: Wikimedia Commons

Trissino ran a small private learned academy for young gentlemen in his renovated villa and apparently, having taken a shine to the young stone mason invited him to become a member. Andrea accepted the offer and Trissino renamed him Palladio.

Portrait of Palladio by Alessandro Maganza Source: Wikimedia Commons

The two became friends and colleagues, and Trissino, who was deeply interested in classical architecture and Vitruvius took the newly christened Palladio with him on trips to Rome to study the Roman ruins. Palladio became an architect in 1540 and became a specialist for designing and building neo-classical, Palladian, villas. 

Villa Barbaro begun 1557 Source: Wikimedia Commons

Trissino died in 1550 but Palladio acquired a new patron, Daniele Barbaro (1514–1570), a member of one of the most prominent and influential aristocratical families of Venice.

Daniele Barbaro by Paolo Veronese (the book in the painting is Barbaro’s translation of De architectura)

Daniele Barbaro studied philosophy, mathematics, and optics at the University of Padua. He was a diplomat and architect, who like Trissino, before him, accompanied Palladio on expeditions to study Roman architecture. In 1556, Barbaro published a new Italian translation of De architectura with an extended commentary, Dieci libri dell’architettura di M. Vitruvio.

I dieci libri dell’architettura di M. Vitruvio tradutti et commentati da monsignor Barbaro eletto patriarca d’aquileggia 1556 Images by Palladio Source

In 1567, he, simultaneously published, a revised Italian and a Latin edition entitled M. Vitruvii de architectura. The illustrations for Barbaro’s editions were provided by Palladio. Barbaro provided the best, to date, explanations of much of the technical terminology in De architectura, also acknowledging Palladio’s theoretical contributions to the work.

Palladio had become one of the most important and influential architects in the whole of Europe, designing many villas, palaces, and churches. He also became an influential author publishing L’Antichida di Roma (The Antiquities of Rome) in 1554,


and I quattro libri dell’architettura (The Four Books of Architecture) in 1570, which was heavily influenced by Vitruvius. His books were translated into many different languages and went through many editions right down into the eighteenth and nineteenth centuries. His work inspired leading architects in France and Germany.

Title page from 1642 edition Source: Wikimedia Commons

Up till now we have said nothing about England, which as usual lagged behind the continent in things mathematical, although in the second half of the sixteenth century both Leonard Digges and John Dee, of the so-called English school of mathematics, counted architecture under the mathematical disciplines. In 1563 John Shute (died 1563) included Vitruvian elements in his The First and Chief Grounds of Architecture.

John Shute The First and Chief Grounds of Architecture.

Inigo Jones (1573–1652) was born into a Welsh speaking family in Smithfield, London. There is minimal evidence that he was an apprentice joiner but at some point, before 1603 he acquired a rich patron, who impressed by his sketches, sent him to Italy to study drawing in Italy.

Inigo Jones by Anthony van Dyck

In a second visit to Italy in 1606 he came under the influence of Sir Henry Wotton (1568–1639) the English ambassador to Venice.

Henry Wotton artist unknown Source: Wikimedia Commons

Wotton was interested in astronomy, and it was he, who sent two copies of Galileo’s Sidereus Nuncius (1610) to London on the day it was published. Wotton convinced Jones to learn Italian and introduced him to Palladio’s I quattro libri dell’architettura. Jones’ copy of the book has marginalia that references Wotton. In 1624, Wotton published The Elements of Architecture a loose translation of De architectura into English. The first proper translation appeared only in 1771. 

19th century reprint Source

Inigo Jones introduced the Vitruvian–Palladian architecture into England and became the most influential architect in the country, becoming Surveyor of the King’s Works.

The Queen’s House in Greenwich designed and built by Inigo Jones Source: Wikimedia Commons

His career was ended with the outbreak of the English Civil War in 1642. England’s most famous architect Christopher Wren (1632–1723), a mathematician and astronomer turned architect stood in a line with Vitruvius, Palladio, and Jones. It is very clear that the humanist rediscovery and promotion of De architectura had a massive influence on the development of architecture in Europe in the sixteenth and seventeenth centuries, in the process dissolving the boundaries between the theoretical intellectuals and the practical artisans. 


Filed under History of Mathematics, History of Technology, Renaissance Science

The deviser of the King’s horologes

There can’t be many Renaissance mathematici, whose existence was ennobled by a personal portrait by the master of the Renaissance portraits, Hans Holbein the younger. In fact, I only know of one, the German mathematicus, Nicolas Kratzer.

Nicolas Kratzer Portrait by Hans Holbein the younger

One might be excused for thinking that having received this singular honour that Kratzer had, in his lifetime, achieved something truly spectacular in the world of the Renaissance mathematical disciplines; however, almost the opposite is true. Kratzer appears to have produced nothing of any significance, was merely the designer and maker of sundials, and an elementary maths teacher, who was only portrayed by Holbein, because for a time they shared the same employers and were apparently mates. 

So, who was Kratzer and how did he and Holbein become mates? Here we find a common problem with minor scientific figures in the Renaissance, there are no biographies, no handy archives giving extensive details of his life. All we have are a few, often vague, sometimes contradictory, traces in the proverbial sands of time from which historians have attempted to reconstruct at least a bare outline of his existence. 

Kratzer was born in 1487 in Munich, the son of a saw-smith and it is probably that he learnt his metal working skills, as an instrument maker, from his father. He matriculated at the University of Köln 18 November 1506 and graduated BA 14 June 1509. He moved onto the University of Wittenberg, famous as the university of Martin Luther. However, this was before the Reformation and Wittenberg, a young university first founded in 1502, was then still Catholic. We now lose track of Kratzer, who is presumed to have then worked as an instrument maker. Sometime in the next years, probably in 1517, he copied some astronomical manuscripts at the Carthusian monastery of Maurbach, near Vienna. 

In January 1517, Pieter Gillis (1486–1533) wrote to his erstwhile teacher Erasmus (1466–1536) that the skilled mathematician Kratzer was on his way with astrolabes and spheres, and a Greek book.

HOLBEIN, Hans the Younger (b. 1497, Augsburg, d. 1543, London) Portrait of Erasmus of Rotterdam 1523 Wood, 76 x 51 cm National Gallery, London

This firmly places Kratzer in the circle of humanist scholars, most famously Erasmus and Thomas More (1478–1535) author of Utopia, who founded the English Renaissance on the court of Henry VIII (1491–1547). Holbein was also a member of this circle. Erasmus and Holbein had earlier both worked for the printer/publisher collective of Petri-Froben-Amerbach in Basel. Erasmus as a copyeditor and Holbein as an illustrator. Holbein produced the illustrations for Erasmus’ In Praise of Folly (written 1509, published by Froben 1511)

Holbein’s witty marginal drawing of Folly (1515), in the first edition, a copy owned by Erasmus himself

Kratzer entered England either at the end of 1517 or the beginning of 1518. His first identifiable employment was in the household of Thomas More as maths teacher for a tutorial group that included More’s children. It can be assumed that it was here that he got to know Holbein, who was also employed by More. 

Thomas More Portrait by Hans Holbein 1527

For his portraits, Holbein produced very accurate complete sketches on paper first, which he then transferred geometrically to his prepared wooden panels to paint them. Around 1527, Holbein painted a group portrait of the More family that is no longer extant, but the sketch is. The figures in the sketch are identified in writing and the handwriting has been identified as Kratzer’s. 

Like Holbein, Kratzer moved from More’s household to the court of Henry VIII, where he listed in the court accounts as the king’s astronomer with an income of £5 a quarter in 1529 and 1531. It is not very clear when he entered the King’s service but in 1520 Cuthbert Tunstall (1474–1559), later Prince-Bishop of Durham, wrote in a letter:

Met at Antwerp with [Nicolas Kratzer], an Almayn [German], devisor of the King’s horologes, who said the King had given him leave to be absent for a time.

Both Tunstall and Kratzer were probably in Antwerp for the coronation of Charles V (1500–1558) as King of Germany, which took place in Aachen. There are hints that Kratzer was there to negotiate with members of the German court on Henry’s behalf. Albrecht Dürer (1471–1528) was also in the Netherlands; he was hoping that Charles would continue the pension granted to him by Maximilian I, who had died in 1519. Dürer and Kratzer met in the house of Erasmus and Kratzer was present as Dürer sketched a portrait of Erasmus. He also drew a silver point portrait of Kratzer, which no longer exists. 


Dürer sketch of Erasmus 1520
Dürer engraved portrait of Erasmus based on 1520 sketch finished in 1526. Erasmus reportedly didn’t like the portrait

Back in England Kratzer spent some time lecturing on mathematical topics at Oxford University during the 1520s. Here once again the reports are confused and contradictory. Some sources say he was there at the behest of the King, others that he was there in the service of Cardinal Wolsey. There are later claims that Kratzer was appointed a fellow of Corpus Christi College, but the college records do not confirm this. However, it is from the Oxford records that we know of Kratzer’s studies in Köln and Wittenberg, as he was incepted in Oxford as BA and MA, on the strength of his qualifications from the German institutions, in the spring of 1523. 

During his time in Oxford, he is known to have erected two standing sundials in the college grounds, one of which bore an anti-Lutheran inscription.

Drawing of Kratzer’s sundial made for the garden of Corpus Christi College Oxford

Neither dial exists any longer and the only dial of his still there is a portable brass dial in the Oxford History of Science Museum, which is engraved with a cardinal’s hat on both side, which suggests it was made for Wolsey.

Kratzer polyhedral sundial presumably made for Cardinal Wolsey Museum for the History of Science Oxford

On 24 October 1524 Kratzer wrote the following to Dürer in Nürnberg

Dear Master Albert, I pray you to draw for me a model of the instrument that you saw at Herr Pirckheimer’s by which distances can be measured, and of which you spoke to me at Andarf [Antwerp], or that you will ask Herr Pirckheimer to send me a description of the said instrument… Also I desire to know what you ask for copies of all your prints, and if there is anything new at Nuremberg in my craft. I hear that our Hans, the astronomer, is dead. I wish you to write and tell me what he has left behind him, and about Stabius, what has become of his instruments and his blocks. Greet in my name Herr Pirckheimer. I hope shortly to make a map of England which is a great country, and was not known to Ptolemy; Herr Pirckheimer will be glad to see it. All who have written of it hitherto have only seen a small part of England, no more… I beg of you to send me the likeness of Stabius, fashioned to represent St. Kolman, and cut in wood…

Herr Pirckheimer is Willibald Pirckheimer (1470–1530), who was a lawyer, soldier, politician, and Renaissance humanist, who produced a new translation of Ptolemaeus’ Geographia from Greek into Latin.

Engraved portrait of Willibald Pirckheimer Dürer 1524

He was Dürer’s life-long friend, (they were born in the same house), patron and probably lover.  He was at the centre of the so-called Pirckheimer circle, a group of mostly mathematical humanists that included “Hans the astronomer, who was Johannes Werner (1468–1522), mathematician, astronomer, astrologer, geographer,

Johannes Werner artist unknown

and cartographer and Johannes “Stabius” (c.1468–1522) mathematician, astronomer, astrologer, and cartographer.

Johannes Stabius portrait by Dürer

Werner was almost certainly Dürer’s maths teacher and Stabius worked together with Dürer on various projects including his star maps. The two are perhaps best known for the Werner-Stabius heart shaped map projection. 

Dürer replied to Kratzer 5 December 1524 saying that Pirckheimer was having the required instrument made for Kratzer and that the papers and instruments of Werner and Stabius had been dispersed.

Here it should be noted that Dürer, in his maths bookUnderweysung der Messung mit dem Zirkel und Richtscheyt (Instruction in Measurement with Compass and Straightedge), published the first printed instructions in German on how to construct and orientate sundials. The drawing of one sundial in the book bears a very strong resemblance to the polyhedral sundial that Kratzer made for Cardinal Wolsey and presumably Kratzer was the original source of this illustration. 

Dürer drawing of a sundial

Kratzer is certainly the source of the mathematical instruments displayed on the top shelf of Holbein’s most famous painting the Ambassadors, as several of them are also to be seen in Holbein’s portrait of Kratzer.

in’s The AmbassadorsHolbe

Renaissance Mathematicus friend and guest blogger, Karl Galle, recently made me aware of a possible/probable indirect connection between Kratzer and Nicolas Copernicus (1473–1543). Georg Joachim Rheticus (1514–1574) relates that Copernicus’ best friend Tiedemann Giese (1480–1550) possessed his own astronomical instruments including a portable sundial sent to him from England. This was almost certainly sent to him by his brother Georg Giese (1497–1562) a prominent Hanseatic merchant trader, who lived in the Steelyard, the Hansa League depot in London, during the 1520s and 30s.

London’s Steelyard

He was one of a number of Hanseatic merchants, whose portraits were painted by Holbein, so it is more than likely that the sundial was one made by Kratzer. 

Georg Giese portrait by Hans Holbein 1532

Sometime after 1530, Kratzer fades into the background with only occasional references to his activities. After 1550, even these ceased, so it is assumed that he had died around this time. In the first half of the sixteenth century England lagged behind mainland Europe in the mathematical disciplines including instrument making, so it is a natural assumption that Kratzer with his continental knowledge was a welcome guest in the Renaissance humanist circles of the English court, as was his younger contemporary, the Flemish engraver and instrument maker, Thomas Gemini (1510–1562). Lacking homegrown skilled instrument makers, the English welcomed foreign talent and Kratzer was one who benefited from this. 

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Christmas Trilogy 2020 Part 2: Charles brightens up the theatre

There is a strong tendency in the present to view Charles Babbage as a one trick pony i.e., Babbage the computer pioneer. In reality he was a true polymath whose intellectual activities covered a very wide spectrum.

Already as a student at Cambridge, he agitated for major curriculum reform in the mathematics taught and practiced in Britain. He also produced some first class cutting edge mathematics, much of which for some reason he never published. His interest in automation stretched way beyond his computing engines and after extensive research on automations in industry, both throughout Europe and in Britain, he wrote and published a book on the organisation of industrial production, On the Economy of Machinery and Manufactures (1832), which became a highly influential bestseller, influencing the work of both John Stuart Mill and Karl Marx. He was a leader in a campaign to improve the standard of science research in Britain, largely aimed at what he saw as the moribund Royal society, which resulted in his Reflections on the Decline of Science and some of its Causes (1830). As part of this campaign, he was a leading figure in the establishment of the British Association for the Advancement of Science (BAAS).


Engraving of Charles Babbage dated 1833 Source: Wikimedia Commons 

His achievements were not confined to purely intellectual activities, he was also an assiduous inventor of mechanical devices and improvement, well outside of his proto computers. For example, he designed and had constructed a four wheeled light carriage for one of his extensive tours of Europe. It was so designed that he could sleep on board and had drawers large enough to stow frock coats and technical plans without folding, as well as a small on board kitchen. However, it is his activities in practical optics that interest me here, in particular his foray into early theatre lighting, which I found fascinating, having, for several years in my youth, been a lighting technician both in theatre and live music.  

An ophthalmoscope is a medical instrument designed to make it possible to observe the interior of the eye by means of a beam of light. The invention of the ophthalmoscope is traditionally attributed to Hermann von Helmholtz in 1851. However, it would appear that Babbage preceded him by four years.

Charles Babbage, the mathematic genius and inventor of what many consider to be the forerunner of today’s computer, his analytical machine, was the first to construct an instrument for looking into the eye. He did this in 1847 but when showing it to the eminent ophthalmologist Thomas Wharton Jones he was unable to obtain an image with it and, thus discouraged, did not proceed further. Little did he know that his instrument would have worked if a minus lens of about 4 or 5 dioptres had been inserted between the observer’s eye and the back of the plano mirror from which two or three holes had been scraped. Some seven years later it was his design and not that of Helmholtz which had been adopted.


The image shows a reconstruction of Babbage’s ophthalmoscope, c. 1847. No actual example survives but this replica was made for the Science Museum in 2003, based upon Wharton Jones’ written description.

Dr. Helmholtz, of Konigsberg, has the merit of specially inventing the ophthalmoscope. It is but justice that I should here state, however, that seven years ago Mr. Babbage showed me the model of an instrument which he had contrived for the purpose of looking into the interior of the eye. It consisted of a bit of plain mirror, with the silvering scraped off at two or three small spots in the middle, fixed within a tube at such an angle that the rays of light falling on it through an opening in the side of the tube, were reflected into the eye to be observed, and to which the one end of the tube was directed. The observer looked through the clear spots of the mirror from the other end. This ophthalmoscope of Mr Babbage, we shall see, is in principle essentially the same as those of Epkens and Donders, of Coccius and of Meyerstein, which themselves are modifications of Helmhotlz’s.

         Wharton-Jones, T., 1854, ‘Report on the Ophthalmoscope’, Chronicle of Medical Science (October 1854).

Around the same time as he built his ophthalmoscope, Babbage designed and built a mechanical, clockwork, programmable, self-occulting, signalling lamp to aid ship to ship and ship to shore communications. He was disappointed that the British marine fleets showed no interest in his invention, but the Russian navy used it against the British during the Crimean War. During the Great Exhibition of 1851, in which Babbage played a central role, he set his signal lamp in the window of his house in the evenings and people passing by would drop in their visiting card with the signalled number written on them. Babbage’s occulting lights were later used in lighthouses in various parts of the world starting in the USA.


Babbage’s mechanical, clockwork, programmable, self-occulting, signalling lamp mechanism

Babbage was a theatre goer and during his phase of light experiments and invention he undertook an interesting project in theatre lighting. During the Renaissance, theatres, such as Shakespeare’s Globe, were open air arenas and performances took place in daylight. Later closed theatre and opera house were lit with chandeliers with the cut glass or crystal prisms dispersing the candlelight in all directions. Of course, the large number of candles needed caused much smoke and the dripping wax was a real problem. By the early nineteenth century theatres were illuminated with gas lamps.

One day during a theatre visit, Babbage noticed that during a moonlit scene the white bonnet of his companion had a pink taint and wondered about the possibility of using coloured light in theatre. He began a serious of interesting experiments with the then comparatively new limelight.

Limelight is an intense illumination created when an oxyhydrogen flame is directed at a cylinder of quicklime (calcium oxide). Quicklime can be heated to 2,572°C before melting and the light is produced by a combination of incandescence (the emission of electromagnetic radiation such as visible light e.g., red hot steel) and candoluminescence a form of radiation first observed and investigated in the early nineteenth century.


Diagram of a limelight burner Source: Wikimedia Commons

As with many inventions the oxyhydrogen blowpipe has many fathers and was first developed in the late eighteenth and early nineteenth centuries by Jean-Baptiste-Gaspard Bochart de Saron (1730–1794), Edward Daniel Clarke (1769–1822) and Robert Hare (1781–1858) all of whose work followed out of the pneumatic discoveries of Carl Wilhelm Scheele (1742–1786), Joseph Priestly (1733–1804), who both discovered oxygen, and Henry Cavendish (1731–1810), who discovered hydrogen.


Nineteenth century bellows-operated oxy-hydrogen blowpipe, including two different types of flashback arrestor John Griffen – A Practical Treatise on the Use of the Blowpipe, 1827 Source: Wikimedia Commons

The first to discover and experiment with limelight was the English chemist Goldsworthy Gurney (1792–1875)


Goldsworthy Gurney Source: Wikimedia Commons

but it was the Scottish engineer Thomas Drummond (1797–1840) who, having seen it demonstrated by Michael Faraday (1791–1867),  first exploited its potential as a light source. Drummond built a practical working light in 1826, which he then used as a signal lamp in trigonometrical surveying. The light was bright enough to be seen at a distance of 68 miles by sunlight. Drummond’s application was so successful that limelight was also known as Drummond light and he was falsely credited with its discovery, instead of Gurney.


Thomas Drummond by Henry William Pickersgill. The original picture is in the National gallery of Ireland Source: Wikimedia Commons

The earliest know public performance illuminated with limelight was an outdoor juggling performance by the magician Ching Lau Lauro (real name unknown) Herne Bay Pier in Kent in 1836. It was first used in theatre lighting in Covent Garden Theatre in 1837. By the 1860s and 1870s limelight was used worldwide in theatres and operas, used to highlight solo performers in the same way as modern spotlights, hence the expression, standing in the limelight. By the end of the nineteenth century, it had been largely replaced by electrical, carbon arc lighting.

 Babbage wanted to take the process one step further and use limelight not just as a very bright white light, but to introduce colour into theatre lighting. Babbage began to experiment with glass cells constructed out of two parallel sheets of glass and filled with solutions of various metal salts, such as chrome and copper. His experiment proved very successful and he developed coloured, limelight spots. Babbage now developed a dance scenario to display his new invention. He proposed replacing the stage footlights with four limelight projectors in the colours red, blue, yellow and purple. His imagined piece had four groups of dancers dressed in white, each of which entered the stage dancing in one of the four pools of light. Dancers springing from one pool of light into another would change colour. Gradually the apertures would widen with the lights crossing each other producing a rainbow of colours through which the dancers would circle. Babbage went on to develop a dramaturgy with dioramas telling an allegorical story.

Babbage discussed his project with Benjamin Lumley, the manager of the Italian Opera House (now Her Majesty’s Theatre) and arranged a demonstration of his new lights. The demonstration took place in the theatre with a smaller group of dancers, and it was apparently a great success. However, because of the fire risk he had two fire engines and their crews on standby during his demonstration and although impressed, Lumley declined a real performance with an audience because of the fire risk. Babbage didn’t develop the idea further.


Portrait of Benjamin Lumley by D’Orsay Source: Wikimedia Commons

As a onetime theatre lighting technician and a historian of science, I would would quite like the idea of staging a modern version of Babbage’s little dance fantasy. I would also like to draw this episode in his life to the attention of all the Ada Lovelace acolytes, who are firmly of the opinion that Babbage was only capable of thinking about mathematics and therefore the imaginative flights of fancy in the Analytical Engine memoir notes must be entirely the work of Lady King.

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


By the middle of the nineteenth century there was no doubt that the Earth rotated on its own axis, but there was still no direct empirical evidence that it did so. There was the indirect evidence provided by the Newton-Huygens theory of the shape of the Earth that had been measured in the middle of the eighteenth century. There was also the astronomical evidence that the axial rotation of the other known solar system planets had been observed and their periods of rotation measured; why should the Earth be an exception? There was also the fact that it was now known that the stars were by no means equidistant from the Earth on some sort of fixed sphere but distributed throughout deep space at varying distances. This completely destroyed the concept that it was the stars that rotated around the Earth once every twenty-four rather than the Earth rotating on its axis. All of this left no doubt in the minds of astronomers that the Earth the Earth had diurnal rotation i.e., rotated on its axis but directly measurable empirical evidence of this had still not been demonstrated.

From the beginning of his own endeavours, Galileo had been desperate to find such empirical evidence and produced his ill-fated theory of the tides in a surprisingly blind attempt to deliver such proof. This being the case it’s more than somewhat ironic that when that empirical evidence was finally demonstrated it was something that would have been well within Galileo’s grasp, as it was the humble pendulum that delivered the goods and Galileo had been one of the first to investigate the pendulum.

From the very beginning, as the heliocentric system became a serious candidate as a model for the solar system, astronomers began to discuss the problems surrounding projectiles in flight or objects falling to the Earth. If the Earth had diurnal rotation would the projectile fly in a straight line or veer slightly to the side relative to the rotating Earth. Would a falling object hit the Earth exactly perpendicular to its starting point or slightly to one side, the rotating Earth having moved on? The answer to both questions is in fact slightly to the side and not straight, a phenomenon now known as the Coriolis effect produced by the Coriolis force, named after the French mathematician and engineer Gaspard-Gustave de Coriolis (1792–1843), who as is often the case, didn’t hypothesise or discover it first. A good example of Stigler’s law of eponymy, which states that no scientific discovery is named after its original discoverer.


Gaspard-Gustave de Coriolis. Source: Wikimedia Commons

As we saw in an earlier episode of this series, Giovanni Battista Riccioli (1594–1671) actually hypothesised, in his Almagustum Novum, that if the Earth had diurnal rotation then the Coriolis effect must exist and be detectable. Having failed to detect it he then concluded logically, but falsely that the Earth does not have diurnal rotation.


Illustration from Riccioli’s 1651 New Almagest showing the effect a rotating Earth should have on projectiles.[36] When the cannon is fired at eastern target B, cannon and target both travel east at the same speed while the ball is in flight. The ball strikes the target just as it would if the Earth were immobile. When the cannon is fired at northern target E, the target moves more slowly to the east than the cannon and the airborne ball, because the ground moves more slowly at more northern latitudes (the ground hardly moves at all near the pole). Thus the ball follows a curved path over the ground, not a diagonal, and strikes to the east, or right, of the target at G. Source: Wikimedia Commons

Likewise, the French, Jesuit mathematician, Claude François Millet Deschales (1621–1678) drew the same conclusion in his 1674 Cursus seu Mondus Matematicus. The problem is that the Coriolis effect for balls dropped from towers or fired from cannons is extremely small and very difficult to detect.


The question remained, however, a hotly discussed subject under astronomers and natural philosophers. In 1679, in the correspondence between Newton and Hooke that would eventually lead to Hooke’s priority claim for the law of gravity, Newton proffered a new solution to the problem as to where a ball dropped from a tower would land under the influence of diurnal rotation. In his accompanying diagram Newton made an error, which Hooke surprisingly politely corrected in his reply. This exchange did nothing to improve relations between the two men.

Leonard Euler (1707–1783) worked out the mathematics of the Coriolis effect in 1747 and Pierre-Simon Laplace (1749–1827) introduced the Coriolis effect into his tidal equations in 1778. Finally, Coriolis, himself, published his analysis of the effect that’s named after him in a work on machines with rotating parts, such as waterwheels in 1835, G-G Coriolis (1835), “Sur les équations du mouvement relatif des systèmes de corps”. 

What Riccioli and Deschales didn’t consider was the pendulum. The simple pendulum is a controlled falling object and thus also affected by the Coriolis force. If you release a pendulum and let it swing it doesn’t actually trace out the straight line that you visualise but veers off slightly to the side. Because of the controlled nature of the pendulum this deflection from the straight path is detectable.

For the last three years of Galileo’s life, that is from 1639 to 1642, the then young Vincenzo Viviani (1622–1703) was his companion, carer and student, so it is somewhat ironic that Viviani was the first to observe the diurnal rotation deflection of a pendulum. Viviani carried out experiments with pendulums in part, because his endeavours together with Galileo’s son, Vincenzo (1606-1649), to realise Galileo’s ambition to build a pendulum clock. The project was never realised but in an unpublished manuscript Viviani recorded observing the deflection of the pendulum due to diurnal rotation but didn’t realise what it was and thought it was due to experimental error.


Vincenzo Viviani (1622- 1703) portrait by Domenico Tempesti Source: Wikimedia Commons

It would be another two hundred years, despite work on the Coriolis effect by Giovanni Borelli (1608–1679), Pierre-Simon Laplace (1749–1827) and Siméon Denis Poisson (1781–1840), who all concentrated on the falling ball thought experiment, before the French physicist Jean Bernard Léon Foucault (1819–1868) finally produced direct empirical evidence of diurnal rotation with his, in the meantime legendary, pendulum.

If a pendulum were to be suspended directly over the Geographical North Pole, then in one sidereal day (sidereal time is measured against the stars and a sidereal day is 3 minutes and 56 seconds shorter than the 24-hour solar day) the pendulum describes a complete clockwise rotation. At the Geographical South Pole the rotation is anti-clockwise. A pendulum suspended directly over the equator and directed along the equator experiences no apparent deflection. Anywhere between these extremes the effect is more complex but clearly visible if the pendulum is large enough and stable enough.

Foucault’s first demonstration took place in the Paris Observatory in February 1851. A few weeks later he made the demonstration that made him famous in the Paris Panthéon with a 28-kilogram brass coated lead bob suspended on a 67-metre-long wire from the Panthéon dome.


Paris Panthéon Source: Wikimedia Commons

His pendulum had a period of 16.5 seconds and the pendulum completed a full clockwise rotation in 31 hours 50 minutes. Setting up and starting a Foucault pendulum is a delicate business as it is easy to induce imprecision that can distort the observed effects but at long last the problem of a direct demonstration of diurnal rotation had been produced and with it the final demonstration of the truth of the heliocentric hypothesis three hundred years after the publication of Copernicus’ De revolutionibus.


Léon Foucault, Pendulum Experiment, 1851 Source


Filed under History of Astronomy, History of Physics, History of Technology

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


By the end of the eighteenth century, Newton’s version of the heliocentric theory was firmly established as the accepted model of the solar system. Whilst not yet totally accurate, a reasonable figure for the distance between the Earth and the Sun, the astronomical unit, had been measured and with it the absolute, rather than relative, sizes of the orbits of the known planets had been calculated. This also applied to Uranus, the then new planet discovered by the amateur astronomer, William Herschel (1738–1822), in 1781; the first planet discovered since antiquity. However, one major problem still existed, which needed to be solved to complete the knowledge of the then known cosmos. Astronomers and cosmologists still didn’t know the distance to the stars. It had long been accepted that the stars were spread out throughout deep space and not on a fixed sphere as believed by the early astronomer in ancient Greece. It was also accepted that because all attempts to measure any stellar parallax down the centuries had failed, the nearest stars must actually be at an unbelievably far distance from the Earth.

Here we meet a relatively common phenomenon in the history of science, almost simultaneous, independent, multiple discoveries of the same fact. After literally two millennia of failures to detect any signs of stellar parallax, three astronomers each succeeded in measuring the parallax of three different stars in the 1830s. This finally was confirmation of the Earth’s annual orbit around, independent of stellar aberration and gave a yardstick for the distance of the stars from the Earth.

The first of our three astronomers was the Scotsman, Thomas Henderson (1798–1844).


Thomas Henderson Source: Wikimedia Commons

Henderson was born in Dundee where he also went to school. He trained as a lawyer but was a keen amateur astronomer. He came to the attention of Thomas Young (1773-1829), the superintendent of the HM Nautical Almanac Office, after he devised a new method for determining longitude using lunar occultation, that is when a star disappears behind the Moon. Young brought him into the world of astronomy and upon his death recommended Henderson as his successor.


Copy of a portrait of Thomas Young by Henry Briggs Source: Wikimedia Commons

Henderson didn’t receive to post but was appointed director of the Royal Observatory at the Cape of Good Hope. The observatory had only opened in 1828 after several years delay in its construction. The first director Fearon Fallows (1788–1831), who had overseen the construction of the observatory had died of scarlet fever in 1831 and Henderson was appointed as his successor, arriving in 1832.


The Royal Observatory Cape of Good Hope in 1857 Illustrated London News, 21 March 1857/Ian Glass Source: Wikimedia Commons

The Cape played a major role in British observational astronomy. In the eighteenth century, it was here that Charles Mason (1728–1786) and Jeremiah Dixon (1733–1779), having been delayed in their journey to their designated observational post in Sumatra, observed the transit of Venus of 1761. John Herschel (1792–1871), the son and nephew of the astronomers William and Caroline Herschel, arrived at the Cape in 1834 and carried extensive astronomical observation there with his own 21-foot reflecting telescope. cooperating with Henderson successor Thomas Maclear. In 1847, Herschel published his Results of Astronomical Observations made at the Cape of Good Hope, which earned him the Copley Medal of the Royal Society.

Manuel John Johnson (1805–1859), director of the observatory on St Helena, drew Henderson’s attention to the fact that Alpha Centauri displayed a high proper motion.


Ladder Hill Observatory St Helena Source

Proper motion is the perceived motion of a star relative to the other stars. Although the position of the stars relative to each other appears not to change over long periods of time they do. There had been speculation about the possibility of this since antiquity, but it was first Edmund Halley, who in 1718 proved its existence by comparing the measured positions of prominent stars from the historical record with their current positions. A high proper motion is an indication that a star is closer to the Earth.

Aimed with this information Henderson began to try to determine the stellar parallax of Alpha Centauri. However, Henderson hated South Africa and he resigned his position at the observatory in 1833 and returned to Britain. In his luggage he had nineteen very accurate determinations of the position of Alpha Centauri. Back in Britain Henderson was appointed the first Astronomer Royal for Scotland in 1834 and professor for astronomy at the University of Edinburgh, position he held until his death.

Initially Henderson did not try to determine the parallax of Alpha Centauri from his observational data. He thought that he had too few observations and was worried that he would join the ranks of many of his predecessors, who had made false claims to having discovered stellar parallax; Henderson preferred to wait until he had received more observational data from his assistant William Meadows (?–?). This decision meant that Henderson, whose data did in fact demonstrate stellar parallax for Alpha Centauri, who had actually won the race to be the first to determine stellar parallax, by not calculating and publishing, lost the race to the German astronomer Friedrich Wilhelm Bessel (1784–1846).


Portrait of the German mathematician Friedrich Wilhelm Bessel by the Danish portrait painter Christian Albrecht Jensen Source: Wikimedia Commons

Like Henderson, Bessel was a self-taught mathematician and astronomer. Born in Minden as the son of a minor civil servant, at the age of fourteen he started a seven-year apprenticeship as a clerk to an import-export company in Bremen. Bessel became interested in the navigation on which the company’s ships were dependent and began to teach himself navigation, and the mathematics and astronomy on which it depended. As an exercise he recalculated the orbit of Halley’s Comet, which he showed to the astronomer Heinrich Wilhelm Olbers (1758–1840), who also lived in Bremen.


Portrait of the german astronomer Heinrich Wilhelm Matthias Olbers (lithography by Rudolf Suhrlandt Source: Wikimedia Commons

Impressed by the young man’s obvious abilities, Olbers became his mentor helping him to get his work on Halley’s Comet published and guiding his astronomical education. In 1806, Olbers obtained a position for Bessel, as assistant to Johann Hieronymus Schröter (1745–1816) in Lilienthal.


Johann Hieronymus Schröter Source: Wikimedia Commons

Here Bessel served his apprenticeship as an observational astronomer and established an excellent reputation.


Schröter’s telescope in Lilienthal on which Bessel served his apprenticeship as an observational astronomer

Part of that reputation was built up through his extensive correspondence with other astronomers throughout Europe, including Johann Carl Fried Gauss (1777–1855). It was probably through Gauss’ influence that in 1809 Bessel, at the age of 25, was appointed director of the planned state observatory in Königsberg, by Friedrich Wilhelm III, King of Prussia.


Königsberg Observatory in 1830. It was destroyed by bombing in the Second World War. Source: Wikimedia Commons

Bessel oversaw the planning, building and equipping of the new observatory, which would be his home and his workplace for the rest of his life. From the beginning he planned to greatly increase the accuracy of astronomical observations and calculation. He started by recalculated the positions of the stars in John Flamsteed’s stellar catalogue, greatly increasing the accuracy of the stellar positions. Bessel also decided to try and solve the problem of determining stellar parallax, although it would be some time before he could undertake that task.

One of the astronomers with whom Bessel took up contact was Friedrich Georg Wilhelm von Struve (1793–1864), who became a good friend and his rival in the search for stellar parallax, although the rivalry was always good natured. Struve was born the son of Jacob Struve (1755–1841), a schoolteacher and mathematician, in Altona then in the Duchy of Holstein, then part of the Denmark–Norway Kingdom and a Danish citizen.


Friedrich Georg Wilhelm von Struve Source: Wikimedia Commons

Whilst he was still a youth, his father sent him to live in Dorpat (nowadays Tartu) in Estonia with his elder brother, to avoid being drafted into the Napoleonic army. In Dorpat he registered as a student at the university to study, at the wish of his father, philosophy and philology but also registered for a course in astronomy. He financed his studies by working as a private tutor to the children of a wealthy family. He graduated with a degree in philology in 1811 and instead of becoming a history teacher, as his father wished, he took up the formal study of astronomy. The university’s only astronomer, Johann Sigismund Gottfried Huth (1763–1818), was a competent scholar but was an invalid, so Struve basically taught himself and had free run of the university’s observatory whilst still a student, installing the Dolland transit telescope that was still packed in the crates it was delivered in. In 1813 he graduated PhD and was, at the age of just twenty, appointed to the faculty of the university. He immediately began his life’s work, the systematic study of double stars.


The old observatory building in Dorpat (Tartu) Source: Wikimedia Commons

Like Bessel, Struve was determined to increase the accuracy of observational astronomy. In 1820 whilst in München, to pick up another piece of observational equipment, he visited Europe’s then greatest optical instrument maker, Joseph Fraunhofer (1787–1826), who was putting the finishing touches to his greatest telescopic creation, a refractor with a 9.5-inch lens.


Joseph Fraunhofer Source: Wikimedia Commons

Struve had found his telescope. He succeeded in persuading the university to purchase the telescope, known as the ‘Great Refractor’ and began his search for observational perfection.


Frauenhofer’s Great Refractor Source: Wikimedia Commons

Like Struve, Bessel turned to Fraunhofer for the telescope of his dreams. However, unlike Struve, whose telescope was a general-purpose instrument, Bessel desired a special purpose-built heliometer, a telescope with a split objective lens, especially conceived to accurately measure the distance between two observed objects. The first  really practical heliometer was created by John Dolland (1706–1761) to measure the variations in the diameter of the Sun, hence the name. Bessel needed this instrument to fulfil his dream of becoming the first astronomer to accurately measure stellar parallax. Bessel got his Fraunhofer in 1829.


Königsberger Heliometer Source: Wikimedia Commons

One can get a very strong impression of Bessel’s obsession with accuracy in that he devoted five years to erecting, testing, correcting and controlling his new telescope. In 1834 he was finally ready to take up the task he had set himself. However, other matters that he had to attend to prevented him from starting on his quest.

The Italian astronomer Giuseppe Piazzi (1746–1826), famous for discovering the first asteroid, Ceres, had previously determined that the star 61 Cygni had a very high proper motion, meaning it was probably relatively close to the Earth and this was Bessel’s intended target for his attempt to measure stellar parallax.


Giuseppe Piazzi pointing at the asteroid Ceres Painting by Giuseppe Velasco (1750–1826). Source: Wikimedia Commons

It was also Struve’s favoured object for his attempt but, unfortunately, he was unable in Dorpat with his telescope to view both 61 Cygni and a reference star against which to measure any observable parallax, so he turned his attention to Vega instead. In 1837, Bessel was more than somewhat surprised when he received a letter from Struve containing seventeen preliminary parallax observations of Vega. Struve admitted that they were not yet adequate to actually determine Vega’s parallax, but it was obvious that he was on his way. Whether Struve’s letter triggered Bessel’s ambition is not known but he relatively soon began a year of very intensive observations of 61 Cygni. In 1838 having checked and rechecked his calculations, and dismantled and thoroughly examined his telescope for any possible malfunctions, he went public with the news that he had finally observed a measurable parallax of 61 Cygni. He sent a copy of his report to John Herschel, President of the Royal Astronomical Society in London. After Herschel had carefully studied the report and after Bessel had answered all of his queries to his satisfaction. Herschel announced to the world that stellar parallax had finally been observed. For his work Bessel was awarded the Gold Medal of the Royal Astronomical Society. Just two months later, Henderson, who had in the meantime done the necessary calculations, published his measurement of the stellar parallax of Alpha Centauri. In 1839 Struve announced his for Vega. Bessel did not rest on his laurels but reassembling his helioscope he spent another year remeasuring 61 Cygni’s parallax correcting his original figures. 

All three measurements were accepted by the astronomical community and both Henderson and Struve were happy to acknowledge Bessel’s priority. There was no sense of rivalry between them and the three men remained good friends. Modern measurements have shown that Bessel’s figures were within 90% of the correct value, Henderson’s with in 75%, but Struve’s were only within 50%. The last is not surprising as Vega is much further from the Earth than either Alpha Centauri or Cygni 61 making it parallax angle much, much smaller and thus considerably more difficult to measure.

In the sixteenth century Tycho Brahe rejected heliocentricity because the failure to detect stellar parallax combined with his fallacious big star argument meant that in a heliocentric system the stars were for him inconceivably far away. I wonder what he would think about the fact that Earth’s nearest stellar neighbour Proxima Centauri is 4.224 lightyears away, that is 3. 995904 x 1013 kilometres!



Filed under History of Astronomy, History of Optics, History of science, History of Technology