Category Archives: History of science

The Jesuit Mirror Man

Although the theory that a curved mirror can focus an image was already known to Hero of Alexandria in antiquity and also discussed by Leonardo in his unpublished writings; as far as we know, the first person to attempt to construct a reflecting telescope was the Italian Jesuit Niccolò Zucchi.


Niccolò Zucchi Source: Wikimedia Commons

Niccolò Zucchi, born in Parma 6 December 1586, was the fourth of eight children of the aristocrat Pierre Zucchi and his wife Francoise Giande Marie. He studied rhetoric in Piacenza and philosophy and theology in Parma, probably in Jesuit colleges. He entered the Jesuit order as a novice 28 October 1602, aged 16. Zucchi taught mathematics, rhetoric and theology at the Collegio Romano and was then appointed rector of the new Jesuit College in Ravenna by Cardinal Alessandro Orsini, who was also a patron of Galileo.

In 1623 he accompanied Orsini, the Papal legate, on a visit to the court of the Holy Roman Emperor Ferdinand II in Vienna. Here he met and got to know Johannes Kepler the Imperial Mathematicus. Kepler encouraged Zucchi’s interest in astronomy and the two corresponded after Zucchi’s return to Italy. Later when Kepler complained about his financial situation, Zucchi sent him a refracting telescope at the suggestion of Paul Guldin (1577–1643) a Swiss Jesuit mathematician, who also corresponded regularly with Kepler. Kepler mentions this gift in his Somnium. These correspondences between Kepler and leading Jesuit mathematicians illustrate very clearly how the scientific scholars in the early seventeenth century cooperated with each other across the religious divide, even at the height of the Counter Reformation.

Zucchi’s scientific interests extended beyond astronomy; he wrote and published two books on the philosophy of machines in 1646 and 1649. His unpublished Optica statica has not survived. He also wrote about magnetism, barometers, where he a good Thomist rejected the existence of a vacuum, and was the first to demonstrate that phosphors generate rather than store light.

Today, however Zucchi is best remember for his astronomy. He is credited with being the first, together with the Jesuit Daniello Bartoli (1608–1685), to observe the belts of Jupiter on 17 May 1630.  He reported observing spots on Mars in 1640. These observations were made with a regular Galilean refractor but it is his attempt to construct a reflecting telescope that is most fascinating.

In his Optica philosophia experimentis et ratione a fundamentis constituta published in 1652 he describes his attempt to create a reflecting telescope.


Optica philosophia title page Source: Linder Hall Library

As I said at the beginning, and have described in greater detail here, the principle that one could create an image with a curved mirror had been known since antiquity. Zucchi tells us that he replaced the convex objective lens in a Galilean telescope with bronze curved mirror. He tried viewing the image with the eyepiece, a concave lens looking down the tube into the mirror. He had to tilt the tube so as not to obstruct the light with his head. He was very disappointed with the result as the image was just a blur, although as he said the mirror was, “ab experto et accuratissimo artifice eleboratum nactus.” Or in simple words, the mirror was very well made by an expert.


Optica philosophia frontispiece

Zucchi had stumbled on a problem that was to bedevil all the early attempts to construct a reflecting telescope. Mirror that don’t distort the image are much harder to grind and polish than lenses. (The bending of light in a lens diminishes the effect of imperfections, whereas a mirror amplifies them). The first to solve this problem was Isaac Newton, proving that he was as skilled a craftsman as he was a great thinker. However, it would be more that fifty years before John Hadley could consistently repeat Newton’s initial success.

All the later reflecting telescope models had, as well as their primary mirrors, a secondary mirror at the focal point that reflected the image either to the side (a Newtonian), or back through the primary mirror (a Gregorian or a Cassegrain) to the eyepiece; the Zucchi remained the only single mirror telescope in the seventeenth century.

In the eighteenth century William Herschel initially built and used Newtonians but later he constructed two massive reflecting telescopes, first a twenty-foot and then a second forty-foot instrument.


Herschel’s Grand Forty feet Reflecting Telescopes A hand-coloured illustration of William Herschel’s massive reflecting telescope with a focal length of forty feet, which was erected at his home in Slough. Completed in 1789, the telescope became a local tourist attraction and was even featured on Ordnance Survey maps. By 1840, however, it was no longer used and was dismantled, although part of it is now on display at the Royal Observatory, Greenwich. This image of the telescope was engraved for the Encyclopedia Londinensis in 1819 as part of its treatment of optics. Herschel’s Grand Forty feet Reflecting Telescopes Source: Wikimedia Commons

These like Zucchi’s instrument only had a primary mirror with Herschel viewing the image with a hand held eyepiece from the front of the tube. As we name telescopes after their initial inventors Herschel giant telescopes are Zucchis, although I very much doubt if he even knew of the existence of his Jesuit predecessor, who had died at the grand old age of eighty-three in 1670.




Filed under History of Astronomy, History of Optics, History of science, History of Technology, Newton, Renaissance Science

Cosmographer to a Grand Duke and a Pope

Egnatio Danti is not a name that is known outside the circle of Renaissance historians of science. If you mention his name people often think you are talking about Dante the Italian medieval poet. Even Wikipedia asks, “Did you mean Dante?” when you type in his family name. But Egnatio Danti (1536-1586) an Italian monk friar, who was an artist, mathematician, astronomer and cartographer, was involved in several important mathematical projects in the sixteenth century.


Egnatio Danti portrait by Bartolomeo Passerotti (1529 – 1592) Source: Wikimedia Commons

Danti was born in Perugia in April 1536 into a family that basically predetermined his life and his career. His grandfather was Pier Vincenzo Rinaldi a goldsmith from profession and a poet, architect and astronomer by inclination. Nicknamed Dante by his friends he styled himself Dante de Rinaldi, which became shortened to Danti. Pier Vincenzo produced an Italian translation of Sacrobosco’s Sphere in the early 1490s the contents of which he passed on to his children, Teodora and Guilo along with his artistic talents. Teodora studied painting under Pietro Perugino, who also taught Raphael. She went on to become a successful artist in her own right. Guilo became an architect and the father of Vincenzo (born 1530) and Egnatio.

Egnatio learnt drawing from his father and mathematics from his aunt. His elder brother became a student of Michelangelo and went on to become a successful sculptor. In 1555, aged 19, having attended Perugia University Egnatio joined the Dominican order, where he continued his studies of mathematics, philosophy and theology. As a Dominican he was consistently conservative in his views: an Aristotelian in physics, a Ptolemaic astronomer and a Thomistic astrologer.

In the 1560s Giorgi Vasari the artist and historian of Renaissance art had been commissioned by Cosimo I de’ Medici Grand Duke of Tuscany


Agnolo Bronzino – Cosimo I de’ Medici in armour Source: Wikimedia Commons

to refurbish Palazzo Vecchio the official ducal residence.


Palazzo Vecchio Source: Wikimedia Commons

One of the Vasari’s projects was the Guardaroba Nuova a room conceived to house Cosimo’s chamber of curiosity or wunderkammer.


Source: Fiorani The Marvel of Maps p. 57

The room was furnished with carved walnut cabinets constructed by the master carpenter, Dionigi di Matteo Nigetti. The doors of the cabinets were to be decorated with mural maps depicting the whole world. When Vasari came to look for an artist-cartographer to complete this commission, Vincenzo Danti, who was also working in the Palazzo recommended his younger brother and Egnatio was hired.

Fifty-seven maps were commissioned, one for each cabinet door; Egnatio produced the cartoon for all of the maps but only painted thirty-one of them between 1563 and 1575; Stefano Bonsignori painted twenty-seven between 1577 and 1586. Egnatio also designed and constructed a large terrestrial globe that stands in the centre of the room.


Terrestrial Globe with cabinets in background Source: Wikimedia Commons

A matching celestial globe that was planned to be lowered from the ceiling was never realised. The maps are ordered according to the principle of Ptolemaeus’ Geographia and the original concept was that each cabinet would house the treasures from that part of the world depicted by the map on its door.


Source: Fiorani The Marvel of Maps p. 81

As can be seen the maps are three dimensional pictorial maps but where possible the latitude and longitude for the picture location are accurate.


Source: Fiorani The Marvel of Maps p. 110 Note that the map is up side down!

Much pleased with his cartographical-artist monk friar Cosimo appointed Danti ‘Cosmographer to the Grand Duke of Tuscany’ and assigned him a chair in mathematics at the university with minimal teaching obligations in 1571. Danti moved into the Palazzo, a move that did not please his superiors in the Dominican Order and began life as court cosmographer. He was required to teach cosmography–cartography, astronomy, and mathematics–to the Duke’s children, both male and female, and other assorted courtiers. A duty that he took very seriously writing and publishing a series of textbooks, many of them translations, in Italian for his pupils. A second requirement of his position was the creation and construction of mathematical and astronomical instruments for Cosimo. He also became the go-to instrument maker for the upper classes of Tuscany using the status of his position to bestow his favours in this area on carefully chosen customers for rather large sums; the money going to his order and not to him personally.


Source: Fiorani The Marvel of Maps p. 48


Egnation Danti, Astrolabe, ca. 1568, brass and wood. Florence, Museo di Storia della Scienza Source: Fiorani The Marvel of Maps p. 49

Many of Cosimo’s activities were intended to project his image as a great Renaissance Prince and to this end he offered his support and sponsorship to the Catholic Church in the question of the necessary calendar reform; in this role he saw himself as Caesar and Danti as his Sosigenes. Sosigenes of Alexander was the Greek astronomer, who, according to Pliny the Elder, was consulted by Julius Caesar on the design of the Julian calendar. To this end Cosimo sponsored the instillation of an armillary sphere and a quadrant on the façade of the Santa Maria Novella church in Florence by Danti in 1574 to better determine the length of the year, a necessary prerequisite for a calendar reform.


Source: Heilbron p. 64


Source: Heilbron p. 66

Along with the two instruments mounted on the façade of the church Danti drew up plans for and began the construction of a meridiana within the building. This is a straight line scale laid out on the floor of the building along which a beam of sunlight. projected through a hole high up in the wall, travels throughout the year, which can be used to exactly mark the times of the equinoxes. In Florence this project remained incomplete.

This exercise gained Danti the patronage of Cosimo’s son Cardinal Ferdinando de’ Medici for whom he procured an excellent Mercator astrolabe.


Ferdinando I de’ Medici Source: Wikimedia Commons

To help the Cardinal understand to workings of his fine gift, Danti wrote a treatise on the astrolabe dedicated to the Cardinal. However, even Ferdinando’s patronage could not avert the disaster looming on the horizon in Danti’s live. Already too ill to attend the inauguration of the armillary sphere at the vernal equinox on 11 March 1574, Cosimo died on 21 April in the same year to be succeeded by his eldest son Francesco I de’ Medici.


Agnolo Bronzino–Francesco I de’ Medici

Francesco did not share his father’s interest in cosmography and appears to have had a personal antipathy towards the Dominican astronomer. Following pressure from Francesco, Danti was ordered by the Dominican General on 23 September 1575 to repair to a convent outside of Tuscany within 24 hours. This was just two weeks after the autumn equinox, suggesting that there had been an agreement to allow Danti to measure the equinoxes of 1575 before his banishment. Danti was sent to San Domenico in Bologna.

The civic authorities of Bologna were delighted to have a mathematicus of Danti’s rank in their city and immediately planned a second chair of mathematics for him at the local university. However, the Superior of the Dominican Order initially blocked the move, on the one hand disturbed by Danti’s increasing celebrity status and on the other wishing to retain his services as a teacher for their own monks. However the recently elected Pope, Gregory XIII, who was Bolognese, a great admirer of cartography and having himself been a professor at the university, supported the appointment. His illegitimate son Giacomo Boncompagni intervened on Danti’s behalf and he became professor for mathematics at the University of Bologna on 28 November 1576.


Scipione Pulzone – Giacomo Boncompagni

Here he taught courses in cosmography similar to those that he had taught in the de’ Medici palace in Florence. In Bologna Danti constructed a small meridiana in the Inquisition chamber of the San Domenico, which was too short to fulfil the desired function, so he constructed a full length one in the San Petronio Basilica. During his time in Bologna Danti continued to win influential patrons by the selective construction of high quality astronomical instruments as gifts.


Source: Heilbron p. 73

In 1577 he returned to his hometown of Perugia to attend to his brother Vincenzo, who was ailing. Whilst in the town he was commissioned by the town authorities to carry out a survey and cadaster (public register showing the details of ownership and value of land; made for the purpose of taxation) of Perugia, a task that he completed in a month making all of his measurements from horseback using a radio latino.


Source: Heilbron p. 76

Danti presented the results of his labours in the form of a fifteen feet square mural map on the governor’s palace.


Source: Fiorani p. 160

He also presented a copy of the map to the Pope’s illegitimate son Giacomo Boncompagni, who then commissioned him to carry out a similar survey of the Papal States supplying him with the necessary finances and manpower to complete the task. Once more he distinguished himself with the speed and quality with which he carried out the work.


Examples of Danti’s survey drawings Source: Fiorani p. 169

Danti was now brought to the Vatican to work directly for Pope Gregory.


Lavinia Fontana–Pope Gregory XIII

In 1579 he was commissioned to produce his second great gallery of maps along the walls of the recently constructed upper gallery on the east wing of the Belverdere. This time the theme was not the world, as in Florence, but the whole of Italy. At the top end of the gallery were two complete maps of Italy, Italia antiqua and Italia nova.


Italia antiqua Source: Wikimedia Commons


Italia nova Source: Wikimedia Commons

As one proceeded down the gallery the states on the east coast were presented on the left-hand west wall and those on the west coast on the right-hand east wall. This created the illusion of a walk along the Apennine ridge from Northern Italy to Sicily in the south. Danti planned and designed all of the maps but they were painted by a team of artists. The whole project took just two years to complete.


Campania Source: Wikimedia Commons


Pedemontium et Monsferratus Source: Wikimedia Commons

Each of the murals not only contains the map of its given district but also contains illustrations of significant historical happenings that took place there.


The Siege of Malta Source: Atlas Obscura

Fiorani (see below) says that this was the first ever atlas of Italy. Given that Italy as a country didn’t exist at this time but was an uneasy collection of independent states the project throws up some interesting questions as to Gregory’s intentions in commissioning it. Did he envisage a united Italy under his leadership?

In 1580 Danti was officially appointed Papal Cosmographer and at the same time appointed astronomical advisor to the Papal commission on calendar reform. His is one of the nine signatures on the final recommendations as presented to the Pope.

Whilst working in the Vatican Danti also created a new meridiana in the Tower of Winds.


Source: Heilbron between pp 180-181

On 14 November 1583 in recognition of his services Gregory appointed him Bishop of Altari. Gregory’s successor Pope Sixtus V summoned back to Rome in 1586 to assist in the re-erection of the Vatican Obelisk.


Re-erection of the Vatican Obelisk by the Renaissance architect Domenico Fontana in 1586 Source: Wikimedia Commons

Egnatio Danti died on 19 October 1586, today he is largely forgotten but, although often restored and modified over the centuries, Danti’s two great galleries of maps still exist as a monument to a great Italian Renaissance artist, cosmographer, mathematician, astronomer, instrument maker, textbook author and teacher.

This blog post is largely based on two excellent books: John Heilbron’s The Sun in the Church[1]a fascinating history of the construction of meridiana in the Early Modern Period and Francesca Fiorani’s The Marvel of Maps[2]a beautiful book on the Renaissance map galleries. Heilbron’s book is really a must read for anybody interested in the history of Early Modern astronomy and is available as a good value paperback. Fiorani’s book is one of the best books that I have read in recent years. It covers an extensive range of historical aspects of the central theme, all of them excellently researched and presented. The book is a real pleasure to read and the illustrations are first class. The only drawback is the price, weighing in at $150 on and more expensive elsewhere. I got lucky and picked up a ridiculously cheap second hand copy in perfect condition.







[1]J. L. Heilbron, The Sun in the Church: Cathedrals as Solar Observatories, Harvard University Press, Cambridge, Massachusetts & London England, 1999

[2]Francesca Fiorani, The Marvel of Maps: Art,Cartography and Politics in Renaissance Italy, Yale University Press, New Haven & London, 2005


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

Two Greek scholars butting heads in the Renaissance and the consequences for astronomy

The adversaries of the title were Georg of Trebizond (1395–1472) and Basilios Bessarion (1403–1472). There is an ironic twist to their names. George of Trebizond derived his name from his ancestors, who originated in the Empire of Trebizond but he was born in Crete. His later antagonist Basilios Bessarion, however, was born in Trebizond.

At sometime unknown point, whilst he was still relatively young, George of Trebizond moved to Italy, where he learnt Latin and acted as amanuensis to the politician Francesco Barbaro (1390–1454) in Venice. A brilliant Aristotelian scholar he entered the entourage of Pope Nicholas V (1397–1455) a convinced Aristotelian.


George of Trebizond Source: Wikimedia commons

Basilios Bessarion was educated in Constantinople then went in 1423 to study Plato under Georgius Gemistus (c.1355–c. 1452), known as Plethon, a highly influential revivalist and teacher of Neo-Platonism. He became an orthodox monk, advancing to abbot in 1436 and metropolitan of Nicaea in 1437. In 1439 he travelled with the Orthodox delegation to Italy to try to persuade the Catholic Church to join the Orthodox Church in a crusade against the Ottoman Turks. Bessarion’s political position led to him being heavily criticised in Byzantium and so he stayed in Italy where Pope Eugene IV (1383–1447) appointed him a cardinal of the Catholic Church. A convinced humanist he devoted his life to spreading support for humanism and to amassing a large private library, containing an extensive collection of Greek manuscripts. He presented his library to the Senate of Venice in 1468 and the 482 Greek manuscripts and 264 Latin manuscripts today still form the core of the St. Mark’s Biblioteca Marciana.


Basilios Bessarion Justus van Gent and Pedro Berruguete Source: Wikimedia Commons

Initially Bessarion and George of Trebizond were friends and Bessarion did much to support his colleague. However in the early 1450s their friendship began to unravel. In that year George undertook a translation from Greek into Latin of Ptolemaeus’ Mathēmatikē Syntaxis or as it is better known the Almagest, as a replacement for Gerard of Cremona’s twelfth-century translation from Arabic.  Bessarion lent him his best Greek manuscript for the purpose and suggested that he used Theon of Alexandria’s Commentary, as a guide. He duly produced his translation and an extensive commentary in nine months finishing in December 1451. His work was hurried, sloppy and strewn with errors and the Pope’s evaluator Jacopo di San Cassiano (ca.1400–ca.1454) judged the work deficient and the Pope, Nicholas V, rejected the dedication. Bessarion took issue with George’s treatment of Theon. The incident ruined George’s reputation and he was forced to flee from Rome.

The situation between the two Greek immigrants escalated when in 1458 George published a vicious attack on Plato in his Comparatio Aristotelis et Platonis, which historian James Hankins has described as “one of the most remarkable mixtures of learning and lunacy ever penned.” In this work he accused Plato of being a traitor to Athens, a besmircher of rhetoric, an advocate of paedophilia, and a pagan who lent aid and comfort to Greek Christians. Bessarion, a Platonist, could not let this stand and issued a powerful response, In calumnatorem Platonis, which was printed in 1469. The situation became even more heated when George offered to dedicate his Commentary on the Almagest to Mehmet II, the Ottoman Turk Sultan, who had conquered Constantinople and ended the Byzantine Empire. George entreated Mehmet to convert to Christianity, to conquer Rome and thus to unite Islam and Christianity under his sovereignty. Bessarion got hold of George’s correspondence with Mehmet and appealled to the Pope, Pius II (for whom George might have been working as an agent!), accusing George of treachery and George was imprisoned for four months in 1466-67. Released from prison, George now offered to dedicate both translation and commentary to Matthias Corvinus (1443–1490), the king of Hungary.

We now need to back peddle to 1460. In that year, Bessarion, who was a Papal legate, visited Vienna to negotiate with Frederick III and made the acquaintance of Georg von Peuerbach (1423–1461), who was at the time the leading astronomical scholar in Europe. Bessarion, still deeply upset by George’s abortive Almagest efforts, asked Peuerbach to produce a new commentary on Ptolemaeus’ work. Peuerbach acquiesced and began immediately to produce an epitome or digest of the Almagest. This was an updated, modernised, shortened, mathematically improved version of the Almagest. Peuerbach died in 1461, having only completed the first six of thirteen book of his epitome. He did, however, extract the deathbed promise from his star pupil, Regiomontanus, to finish the work. In the same year Regiomontanus left Vienna for Italy as a member Bessarion’s entourage, where he spent the next four years learning Greek, finishing the epitome and acting as Bessarion’s manuscript collector and librarian. The Epitome of the Almagestis a masterpiece:

The Epitome is neither a translation (an oft repeated error) nor a commentary but a detailed sometimes updated, overview of the Almagest. Swerdlow once called it “the finest textbook of Ptolemaic astronomy ever written.”[1]

I’ve already written an earlier blog post on Regiomontanus so we don’t need to outline the rest of his life but Shank does have an interesting hypothesis. He suggests that Regiomontanus went to Hungary at Bessarion’s behest in order to counter any influence that George might win at the Court of Corvinus through his second attempt to rededicate his Almagest and Commentary.


Johannes Regiomontanus, Woodcut Source: Wikimedia Commons

When he set up his printing business in Nürnberg, Regiomontanus published Peuerbach’s lectures on astronomy, Theoricae Novae Planetarum, as his first book.


Georg von Peuerbach: Theoricarum novarum planetarum testus, Paris 1515 Source: Wikimedia Commons


Peuerbach Theoricae novae planetarum 1473 Source: Wikimedia Commons

Although he included the Epitome in his publisher’s prospect he didn’t succeed in publishing it before his untimely death in 1476. The Epitoma in Almagestum Ptolemae was first published in 1496 in Venice by Johannes Hamman. Together with Peuerbach’s lectures the Epitome became the standard textbooks for teaching astronomy at the European universities for much of the next century. The influence of the Epitome goes much deeper than this in the history of astronomy.


Title page Epitoma in Almagestum Ptolemae Source: Wikimedia Commons

It is well known that Copernicus modelled his De revolutionibus on Ptolemaeus’ Almagest. In fact text analysis has shown that he actually modelled his magnum opus on the Peuerbach-Regiomontanus Epitome, for example taking most of his knowledge of Arabic astronomy from Regiomontanus’ work. This is, however, rather minor compared to what several expert think is the most important influence that Regiomontanus had on Copernicus.


Nicolaus Copernicus portrait from Town Hall in Toruń – 1580 Source: Wikimedia Commons

According to ancient Greek cosmology the planets orbit the earth with uniform circular motion. Any extended observation of the planets show that this is not the case and it was the job of the astronomers to construct geometrical model, which corrected the visible deviation from the cosmological norm; these deviations are known as the anomalies. Ptolemaeus had basically two geometrical tools to describe planetary orbits. With the eccentric deferent the centre of the circle that describes the orbit, the deferent, is not in the same position as the earth, i.e. the earth is not at the centre of the planets orbit. The alternative is the epicycle-deferent model in which the planet is carried around an epicycle, which is itself carried around the deferent. The mathematician Apollonius (late 3rdcentury–early 2ndcentury BCE) had shown that the two models were in fact mathematically equivalent; meaning any motion that could be described with the one model could equally well be described with the other.

Ptolemaeus, however, argued in the Almagest that whereas the retrograde motion (the so-called second anomaly, when the planet appears to reverse its orbital direction for a period of time) of the outer planets could be described with either model that of the inner planets (Venus and Mercury) could only be described with the epicycle-deferent model. In Book XII of the Epitome, Regiomontanus proved that the second anomaly of the inner planets could also be described with the eccentric deferent model. Without going into detail this seems to have led Copernicus directly to his heliocentric system for the inner planets, which he then extended to the outer ones.

Thinking hypothetically, if George had not written his translation of and commentary on the Almagest, then Bessarion would not has asked Peuerbach to write the Epitomeand Regiomontanus might never have provided Copernicus with that vital clue.

Regiomontanus wrote a second book inspired by George’s work. His Defensio Theonis contra Georgium Trapezuntium is a vast rambling mathematical work centred on a defence of Theon of Alexandria against what he saw as George’s unfair treatment of him. He accused George as having both misrepresenting Theon and plagiarising him. This work has never been published but Regiomontanus’ antagonism against George was known at the time. The Defensio was announced in Regiomontanus’ prospect and also in works published by Erhard Ratdolt. This situation led to a rather strange claim made by Pierre Gassendi. In the 1650s Gassendi published a collective biography of the great astronomers Brahe, Copernicus, Regiomontanus etc. in which he claimed that Regiomontanus was murdered in Rome by two of George’s sons in 1476. George had many vocal critics, none of whom were murdered and sensible historians think that Regiomontanus died in one of the epidemics that regularly swept Rome.


[1]Michael H. Shank, Regiomontanus and Astronomical Controversy in the Background of Copernicus, pp. 79-109 in Rivka Feldhay and F. Jamil Ragep eds., Before Copernicus: The Cultures and Contexts of Scientific Learning in the Fifteenth Century, McGill-Queen’s University Press, Montreal& Kingston, London, Chicago, 2017, p. 90

This blog post owes much to the above paper and to Michael H. Shank, The Almagest, Politics, and Apocalypticism in the Conflict between George of Trebizond and Cardinal Bessarion, in Almagest International Journal for the History of Scientific Ideas, Volume 8, Issue 2, 2017, pp. 49-83


Filed under Early Scientific Publishing, History of Astronomy, History of science, Renaissance Science, Uncategorized

Science, War and Pestilence

In my recent blog post about the Renaissance polymath Wilhelm Schickard I wrote the following paragraph about the demise of him and his family, killed by plague brought into his home by invading soldiers in the Thirty Years War.


Wilhelm Schickard, artist unknown Source: Wikimedia Commons

The last years of Schickard’s life were filled with tragedy. Following the death of Gustav Adolf in the Thirty Years War in 1632, the Protestant land of Württemberg was invaded by Catholic troops. Along with chaos and destruction, the invading army also brought the plague. Schickard’s wife had born nine children of which four, three girls and a boy, were still living in 1634. Within a sort time the plague claimed his wife and his three daughters leaving just Schickard and his son alive. The invading troops treated Schickard with respect because they wished to exploit his cartographical knowledge and abilities. In 1635 his sister became homeless and she and her three daughters moved into his home. Shortly thereafter they too became ill and one after another died. Initially Schickard fled with his son to escape the plague but unable to abandon his work he soon returned home and he also died on 23 October 1635, just 43 years old, followed one day later by his son.

The fate of Schickard and his family made me, as a historian of science, once again brutally aware that the people that I, and other STEM historians, research and write about are not just producers of theories, theorems, hypotheses and discoveries living in some sort of Platonic space of Ideals but real people living working and often suffering in in a very real and frequently hostile world. Many of the scholars that form the subject of my own main interests in the history of science and mathematics suffered disruption, displacement and even death during the turmoil that engulfed Europe during the religious wars of the seventeenth century. In the following I’ll sketch some of those life-disturbing incidents suffered by those scholars, without any pretention to being exhaustive.

Johannes Kepler (1571–1630) spent large parts of his life coping with the disruptions caused by the reformation and counter-reformation.


Portrait of Johannes Kepler. Source: Wikimedia Commons

In his youth he came to Graz as a Lutheran Protestant teacher in a prominently Catholic district. During the counter-reformation this couldn’t last and it didn’t; the Protestants were ordered to convert or to leave. Initially Kepler, the district mathematicus, was granted an exception due to his successful astrological prognostica but in the end he too was forced to leave losing much of his wealth in the process. In Prague he was in a similar situation as Protestant Imperial Mathematicus to a Catholic Emperor. This time it was civil strive, as Rudolf II was deposed by his brother Matthias, which caused Kepler to leave Prague to become district mathematicus in Linz. Here once again he was a Lutheran in a predominantly Catholic district, which caused Kepler much stress. In 1625 Linz was besieged for two months by a peasants uprising. The printing press that Kepler had founded to print and published his own works was burnt to the ground with much of his work. The last years of Kepler’s life were spent wandering from town to town in Southern Germany and Austria never again finding a truly safe haven. Ironically he spent much of this time serving as court astronomer to Wallenstein the deposed Catholic commander in chief.

Even Galileo (1564–1642) can be considered to have suffered under the religious conflicts, although in Northern Italy he was outside of the immediate war zone. His problems in 1616 were certainly exacerbated by the fact that the conflicts between the Protestants and Catholics were reaching a highpoint just two years before the start of the Thirty Years War. In the 1630s Galileo’s situation was certainly worsened by the fact that he was perceived, as a Medici courtier, to be on the wrong side in the political struggle between the two great Catholic powers, France and Spain, to control the Papacy.


Galileo Galilei portrait by Domenico Tintoretto Source: Wikimedia Commons

Perhaps the most obvious victim of the religious conflicts of the times was Pierre de la Ramée (Petrus Ramus) (1515–1572), who had a much bigger influence of the evolution of modern science than is usually acknowledged.


Source: Wikimedia Commons

A convert to Calvinism in 1562 he was initially forced to flee Paris, where he was Regius Professor at the Collège de France, and his house was pillaged and his library burnt in his absence. He spent two years wandering around Europe before returning to Paris. In 1572 he was murdered, one of the most famous victims, during the St. Bartholomew’s Day massacre, when a Catholic mob rose up against the Huguenots. It is not known how many Huguenots died during this slaughter but estimates range between five and thirty thousand.

The Calvinists in Geneva were responsible in 1553 for the immolation of the Spanish mathematicus and physicus Michael Servetus (1509 or 1511–1553)  (Span. Miguel Serveto) for his heterodox religious views. Although the Catholics and Lutherans would probably all have done the job if the Calvinists hadn’t.


Miguel Servet, (Villanueva de Sigena 1511- Genevra 1553) Spanish theologian & physicus Source: Wikimedia Commons

In England, the Keplerian astronomer William Gascoigne (1612–1642) died fighting on the royalist side at the Battle of Marston Moor during the English Civil War, which can also be viewed to a large extent as one of the European religious wars.


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

On the royalist side, which lost the battle, William and Charles Cavendish, both actively engaged supporters of the new sciences evolving at the time, were forced to flee to France, where they met up with natural philosopher Kenelm Digby (1603–1685) and Margaret Lucas (1623–1673), the future Lady William Cavendish and notorious female natural philosopher, two further Civil War refugees. In this later case these English refugees, although displaced by war, became part of an exhilarating philosophical scene in Paris, which featured Descartes, Mersenne, Gassendi and another English exile, Thomas Hobbes.


Margaret Cavendish: Segment from Frontispiece for several of her books in the 1650s and 1660s. Source: Wikimedia Commons

Do not misinterpret the above as in anyway supporting the unsubstantiated hypothesis of a conflict between religion and science. In each case, those I have listed suffered because of their religious affiliations or political views not because of their science. In fact it is interesting that during these times of intense religious strife, scientific scholars very often reached across religious and political boundaries to cooperate with each other, to share data, discuss discoveries and generally aid each other in their work.

Following the death of the Italian astronomer, Giovanni Antonio Magini (1555–1617) the Jesuits offered his chair for mathematics in Bologna to the Lutheran Johannes Kepler, with the assurance that he would not have to convert. When the Lutheran Protestant Georg Joachim Rheticus (1514–1574), professor for mathematics in Wittenberg, centre of the Reformation, visited the Catholic cathedral cannon Nicolaus Copernicus (1473–1543) in Warmia, Dantiscus (1485–1548), the Bishop of Warmia and a counter-reformation hardliner, greeted him with warmth and honour as a scholar. Christoph Clavius (1538–1612), Jesuit professor of mathematics at the Collegio Romano, corresponded with scientific scholars from all religious persuasions exchanging scientific news. One of his successors, Athanasius Kircher (1602–1680), collected astronomical data from other Jesuits from all over the world and then redistributed it to astronomers throughout Europe, both Catholic and Protestant.

In all of our #histSTM studies we should never lose sight of the fact that those we are researching are first and foremost human beings, who, to quote Shakespeare, suffer the slings and arrows of outrageous fortune, whilst trying to complete their own scientific investigations.








Filed under History of science

The Galileo Circus is in town

The ‘sensational’ #histSTM news of last week was that a new ‘lost’/‘hidden’ Galileo letter has been discovered in the Royal Society archives. As some people have pointed out, as it was archived and catalogued it wasn’t exactly ‘lost’ or ‘hidden’, but that is not what I am going to write about here. As the Internet’s resident Galileo deflator, I have been asked numerous times in the last few days what I think is the significance of this find and my answer has been, not a lot. I have decided to explain why I think this but before I do so we need a bit of background for those not informed about the intricate details of Galileo’s biography.


Galileo Galilei portrait by Domenico Tintoretto Source: Wikimedia Commons

After the publication of his Sidereus Nuncius, Galileo was not only appointed court philosophicus and mathematicus the Cosimo De’ Medici but became almost over night the most notorious mathematical scholar in Europe. He was feted by the Northern Italian high society both secular and clerical and was definitely a celebrity. His role in the Medici household was not that dissimilar to that of a court jester. He was required to entertain the Grand Duke and his guests after dinner with his erudition and his wit. Oft opponents would be invited to dine and Galileo was expected to dispute with them over philosophical or scientific topics. In this role he acquitted himself extremely well but his growing fame and notoriety meant that he was collecting a solid body of enemies. On the subject of science contra religion his newly won high-powered friends and admirers advised him to tread carefully and to proceed with caution. Amongst those, who thus advised him, was Cardinal Maffeo Barberini an admirer and the future Pope Urban VIII.


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

In 1613, in Galileo’s absence, at an evening round at the Medicean table the philosopher Cosimo Boscaglia stated that he thought that the telescopic discoveries were valid, however the Copernican hypothesis contradicted Holy Scripture. Galileo’s former student Benedetto Castelli, now a professor for mathematics and a Benedictine Abbott, defended Galileo’s standpoint under intensive questioning from Grand Duchess Christina, Cosimo’s mother and Galileo’s first patron in the Medici family. Castelli reported all of this to Galileo in a letter and in reply Galileo wrote a long essay, now known as the Letter to Castelli, in which he attacked the Church’s interpretation of the various Bible passages that stood in contradiction to the heliocentric hypothesis and generally pleaded for freedom of expression for science, or rather for Galileo.


Benedetto Castelli artist unknown Source: Wikimedia Commons

Before I go on I think it is necessary to restate something that people discussing the situation tend to forget or ignore. In the early seventeenth century the concepts of freedom of thought, freedom of speech and freedom of expression simply did not exist anywhere in Europe neither under secular or religious jurisdiction, no matter which church was involved. This was something that Galileo was well aware of but apparently in his hubris he thought his newly found fame would protect him from censure, he was wrong. A second point that also tends to get ignored is that when Galileo decided to go into full frontal attack with the Church on scriptural interpretation it was the middle of the Counter Reformation. The Reformation and the Counter Reformation centred on the question, who is allowed to interpret Holy Scripture. The Lutherans said anybody who could read, although they later changed their minds on that, whereas the Catholic Church said only the Church theologian were entitled to. Here was Galileo a mere mathematicus, the lowest of the low in the Renaissance intellectual hierarchy, telling the theologians, the pinnacle of the Renaissance intellectual pyramid, how to interpret the Bible, not a wise move. Not only did Galileo go out on a limb but he did so with his very best polemic and invective and if there was something in which Galileo was unrivalled at it was writing polemic and invective.

As was the custom in those days, and as Galileo certainly intended, copies were made of his letter and passed around for other to read and admire. It was almost inevitable that copies would land in the hands of his enemies and they were not in any way thrilled by Galileo’s attack on the Church.  In 1615 Niccolò Lorini, a Dominican, submitted a copy of Galileo’s letter to the Inquisition in Rome:

All our Fathers of the devout Convent of St. Mark feel that the letter contains many statements which seem presumptuous or suspect, as when it states that the words of Holy Scripture do not mean what they say; that in discussions about natural phenomena the authority of Scripture should rank last… [the followers of Galileo] were taking it upon themselves to expound the Holy Scripture according to their private lights and in a manner different from the common interpretation of the Fathers of the Church…

— Letter from Lorini to Cardinal Sfrondato, Inquisitor in Rome, 1615. Quoted in Jerome Langford, Galileo, Science and the Church1998, pp. 56-57 (Borrowed from Wikipedia)

Galileo, now realising that he might have not made the most intelligent move in his life, began to back peddle and claimed that the submitted document was not the letter that he had written but had been manipulated by his enemies to make it look worse than it really was. He also issued a new version of the letter that was indeed much milder than the version submitted to the Inquisition by Lorini. Things took their inevitable course. Galileo’s letter was lumped together with the Epistle concerning the mobility of the earth by Paolo Antonio Foscarini, which provoked the famous Foscarini Letter from Robert Bellarmino, which was also addressed to Galileo. The Inquisition decided that Copernicus’ theory was both scientifically and theologically unacceptable and Galileo had his famous meeting with Bellarmino, who explained that heliocentricity could not be taught as factual.

In this situation many, in fact the majority, see Galileo, as a champion for free speech and for the ascendency of science over religion, launching a brave attack on the bastions of the Church. I think it would be more honest to regard his actions as foolhardy, driven by hubris. One the one hand he thought that his celebrity was so great that he could successfully challenge the Church; he was severely mistaken. On the other he wanted to be the one feted for having ‘proved’ the heliocentric hypothesis. This is amply shown by the fact that as things started to turn pear-shaped he rushed off to Rome and tried to convince his admirers amongst the Church hierarchy of the validity of his theory of the tides, which would form the fourth and concluding day of his Dialogo. His hubris prevented him recognising just how flawed that infamous theory was. In 1615 he found no takers. It is interesting to note in terms of Galileo’s personality that at best he developed the theory of tides together with Paolo Sarpi and at worst it was actually Sarpi’s theory and he ‘borrowed’ it without in either case giving Sarpi any credit for the theory.

What the historian has to decide is was Galileo telling the truth and had his enemies in the Church manipulated his original letter or was he lying and was the letter submitted by Lorini the original document? Those who have written the numerous Galileo hagiographies believe that their hero was telling the truth. Others who are more sceptical about the Tuscan mathematicus don’t see him as a paragon of virtue but in this instance think that he was telling the truth and his Church enemies were out to get him. I, however, and I know that I am not alone in this opinion, think that he was lying and that the Lorini letter is in fact the original. Up till now there has been no proof either way, so you pays your money and you makes your choice.

The newly ‘discovered’ document is the proverbial smoking gun. It appears that it is the Letter to Castelli in the Lorini version with the ‘corrections’ to the later milder version all written in Galileo’s own hand. If the document is genuine, and I assume it is, then Galileo was without a shadow of a doubt lying. This of course provokes the question as to why I thought, without evidence, that he was indeed lying. The answer is very simple. As the old sergeant says in cheesy English criminal stories, “the lad had form, didn’t he?”


The original letter in which Galileo argued against the doctrine of the Roman Catholic Church has been rediscovered in London. Credit: The Royal Society

We start with Galileo’s claim that he constructed a telescope purely having heard of one based on his knowledge of optics. Modern research suggests very strongly that he had in fact both seen and handled a telescope before he constructed his own one. He also sold ‘his telescope’ to the Senate of Venice for a very high price, knowing full well that within a short time the city would be flooded with telescopes from other sources. Galileo had something of the character of the proverbial used car salesman. In his dispute with Christoph Scheiner about the nature of sunspots, Galileo kept changing the date he claimed to have first observed sunspots to guarantee his priority. Of course, both Galileo and Scheiner were unaware that Harriot had observed sunspots before both of them and Johannes Fabricius had already published on them. In 1607, charged Baldessar Capra with having plagiarised the instruction manual for his sector. At the time he exonerated Simon Marius who had been Capra’s mathematics teacher. However in 1623 in his Il Saggiatore he now falsely accused Marius of being responsible for the plagiarism along with accusing him again falsely of having plagiarised the Sidereus Nuncius in his Mundus Iovialis. In Il Saggiatore he also accused Scheiner falsely of having plagiarised his work on sunspots. To make the situation worse he quoted Scheiner’s work on sunspots as his own in the Dialogo. The main text of Il Saggiatore concerns his dispute with Grassi on the nature of comets. Here he brings his famous ‘the book of nature is written in the language of geometry’ quote implying that his point of view is mathematical/scientific whereas that of Grassi, a Jesuit, is not. Exactly the opposite is true. Grassi’s view that comets are supralunar was formed on the basis of empirical observations and mathematical calculations, whereas Galileo’s basically Aristotelian view was nothing but unsubstantiated and false speculation. In the Dialogo, the two world systems that Galileo compares are the geocentric system of Ptolemaeus and the heliocentric system of Copernicus. However when Galileo wrote his book the Ptolemaic system had already been refuted, as Galileo well knew having contributed to that refutation, and the Copernican system had long been superseded by the elliptical system of Kepler, which was regarded as a competing model. The world system being discussed as rivals at the time were a Tychonic model with diurnal rotation and Kepler’s elliptical heliocentric model both of which Galileo simply ignores. These are just some of the crassest examples of Galileo conscious dishonesty in his work. So believing that he lied about the Castelli letter is not an unreasonable assumption.

However, all in all, whether he lied or didn’t lie at this point in time doesn’t actually make that much difference. Whether his attack on Catholic theology was more or less vitriolic doesn’t actually play an important role is what happened. The important point is that he had the gall to launch that attack at all in such an undiplomatic manner. All that Galileo achieved by his ill thought out, impulsive actions was to delay quite substantially the Church’s inevitable acceptance of heliocentricity. Before somebody turns up in the comments saying it took them two hundred years to accept it, that acceptance already existed informally before the end of the seventeenth century and formally in 1758.







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

The telescope – claims and counterclaims

Sometime between the 25thand 29thof September 410 years ago Hans Lipperhey, a spectacle maker from Middelburg in Zeeland, gave the earliest known public demonstration of the telescope to Maurits of Nausau and assembled company at a peace conference in Den Hague.


Source: Wikimedia Commons

His demonstration was recorded in a French newsletter, AMBASSADES DV ROY DE SIAM ENVOYE’ A L’ECELence du Prince Maurice, arriué à la Haye le 10. Septemb. 1608., recording the visit of the ambassador of the King of Siam (Thailand), who was also present at the demonstration.

A few days before the departure of Spinola from The Hague a spectacle-maker from Middelburg, a humble man, very religious & pious, offered His Excellency certain glasses as a present, by which one is able to trace & observe clearly objects at a distance of three or four miles, as if there is a distance as little as one hundred footsteps. From the tower of The Hague with the said glasses one can observe clearly the clock on the tower of Delft, & the windows of the Church of Leiden, despite the fact that one of the said towns is at a distance of one & a half hours and the other one at three and a half hours walking distance. The States-General were already well informed about this and sent them to His Excellency to show, adding that with these glasses one could observe the impostures of the enemy. Spinola also saw them with great astonishment & told Prince Hendrik; from this moment on I will not be safe anymore, because you can observe me from afar. Whereupon the said Prince answered: we will prohibit our people to shoot at you. The craftsman who has manufactured the said glasses has received three hundred écu & he will receive more on condition that he will tell nobody about the said proficiency, which he promised with most pleasure as he doesn’t want the enemy will be able to use this, 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]

This was not however the first written account of Lipperhey’s new invention. The Councillors of Zeeland had given him a letter of introduction, dated 25 September, to the States-General in Den Hague, it begins:

The bearer of this, who claims to have a certain device, by means of which all things at a great distance can be seen as if they were nearby, by looking through glasses which he claims to be a new invention, would like to communicate the same to His Excellency [Prince Maurits]. Your Honour will please recommend him to His Excellency, and, as the occasion arises, be helpful to him according to what you think of the device…[2]

On 2 October 1608, Lipperhey submitted an application for a patent for his device to the States-General, from here on things, which had looked so promising for our humble spectacle-maker from Middelburg started to turn decidedly pear shaped.


Hans Lipperhey’s unsuccessfully patent request Source: Wikimedia Commons

On 14 October 1608, an, until now, unidentified young man offered to sell a telescope to the Councillors of Zeeland, who dutifully informed the States-General of this new development. On 15 October the States-General received a letter from Jacob Adriaenszoon (after 1571–1628) called Metius, a spectacle-maker from Alkmaar also requesting a patent for his instrument on which he had been working for two years and which, so he claimed, was a least as good as the instrument from Middelburg. Given these developments, telescopes were apparently available on every street corner, the States-General denied Lipperhey his desired patent but they did commission him to make six pairs of binoculars for a total of 900 guilders, a very large sum. Interestingly they demanded that the lenses be made of rock crystal rather than glass, because of the poor quality of the glass lenses, something that would remain a problem for telescope makers throughout the seventeenth century.

The problem with who actually invented the telescope does not end there. In his Mundus Jovialis, published in 1614, Simon Marius, one of the earliest telescopic astronomers, recounts how his patron Johan Philip Fuchs von Bimbach was offered a telescope at the Autumn Frankfurt Fair in 1608.


Engraved image of Simon Marius (1573-1624), from his book Mundus Iovialis, 1614 Source: Houghton Library via Wikimedia Commons

He didn’t purchase the proffered instrument because one of the lenses was cracked and the asking price was apparently too high. In many accounts of the invention of the telescope, this story is used as an illustration of how fast the new invention spread after Lipperhey’s unveiling in Den Hague. However, there is a major problem here; the Autumn Fair in Frankfurt in 1608 took place before Lipperhey’s demonstration. We have yet another unclear source for the ‘first telescope’.


Hans Philipp Fuchs von Bimbach Source: Wikimedia Commons

Up till 2008 it had become common practice to claim that the seller in Frankfurt and the unknown young man in Middelburg were one and the same and identified as Zacharias Janssen (1585-pre. 1632) and that he and not Lipperhey was the true inventor of the telescope and for good measure also the microscope.  How this all came about is almost Byzantine.


Zacharias Janssen Source: Wikimedia Commons

In 1655, the French scholar Pierre Borel (c. 1620–1671) published the first full history of the invention of the telescope, De vero telescopii inventore.


De vero telescopii inventore 1665 Title page Source

In his book he followed the account of the Dutch Ambassador to France, Willem Boreel (1591–1668). Born in Middelburg, Boreel had memories of having met the inventor of the telescope in 1610. Not sure of his memory forty-five years later he wrote to a local magistrate in Middelburg to investigate the matter. The magistrate interviewed a then unknown spectacle-maker Johannes Zachariassen, the son of Zacharias Janssen. Johannes claimed that his father and his grandfather had invented the microscope and telescope in 1590. Johannes would also tell a similar story to Isaac Beeckman, when he was teaching him lens grinding, also claiming that he and his father had also invented the long, i.e. astronomical, telescope in 1618. Boreel confirmed Johannes account as agreeing with his memories and Borel’s account that Zacharias Janssen and not Hans Lipperhey was the true inventor of the telescope.


Portrait of Pierre Borel by Jacques Pauthe Source: Wikimedia Commons

The last of Johannes’ claims is easily disposed of because it was Johannes Kepler, who first described the astronomical telescope in his Dioptrice in 1611. As to the other claim in 1590 Johannes’ grandfather was already dead and his father Zacharias was a mere four or five years old. These objections were simply swept aside over the years and Janssen’s invention simply moved forward to 1604 another date claimed by Johannes. However modern research by Huib Zuidervaart into the life of Zacharias Janssen have shown the first contact that he had with lens grinding or spectacle-making was when he became guardian the children of another spectacle-maker ‘Lowys Lowyssen, geseyt Henricxen brilmakers’. There is no other evidence that Zacharias was ever a spectacle-maker.[3]

The unknown youth in Middelburg and the telescope seller in Frankfurt remain unknown and probably forever unknowable.

News of the wonderful new invention spread really fast throughout Europe with telescopes on sale as novelties in Paris by the early summer 1609. The enthusiasm with which the new invention was greeted and the speed with which it spread throughout Europe rather puts the lie to all the competing theories that the telescope was already invented by (insert your favourite candidate) at some date before Lipperhey’s first demonstration. If it had been, we would certainly have heard about it. As far as we know, the first astronomer to make observations with the new instrument was Thomas Harriot, who drew a sketch of the moon observed with a six-power telescope dated 26 July 1609 os (5 August ns).


Harriot’s sketch of the moon 1609

Following on to his encounter with a telescope at the Frankfurt Fair, Fuchs von Bimbach together with Simon Marius obtained, with some difficulty, suitable lenses and the two of them constructed their own telescope. Simon Marius began his own astronomical observations sometime also in 1609. Galileo Galilei heard of the telescope through his friend Paolo Sarpi and it is now thought that his claim that he devised the construction of his telescope purely on the basis of having heard of it is not true and that he had in fact seen and handled a telescope before he began his own efforts at construction.


Galileo Galilei. Portrait by Ottavio Leoni Marucelliana Source: Wikimedia Commons

Galilei/ Fernrohre / Aufnahme

Galileo’s telescopes Source: Wikimedia Commons

Galileo, ever on the look out to make a quick buck and further his career, first marketed ‘his invention’ to the civil authorities, demonstrating a six-power telescope to the aristocrats of Venice 21 August 1609. On the 24thof the month he presented said telescope formally to the Doge and Senate of Venice. The following day the authorities granted him a lifetime contract as professor of mathematics at the university with the extraordinary salary of 1,000 florins p.a. with however the condition that he would never receive another pay rise. The Senate was apparently more than somewhat miffed when they discovered that the telescope was not the invention of their talented mathematics professor but was readily available on every street corner in Europe to knockdown prices. Galileo repaid their generosity by beginning plans to leave Venice and return to Florence.

We don’t know for certain when Galileo began his astronomical observations but we do know that he was an exceptionally talented observer and was soon viewing the skies on clear nights with a twenty-power instrument of his own construction. On 7 January 1610 he knew he had hit the jackpot when he first observed three of the moons of Jupiter. Simon Marius made the same discovery one day later on 8 January. More accurately he realised he had hit the jackpot only a couple of days later when it became clear that what he had discovered were satellites and not fixed stars. Marius waited four years before he published his discovery, Galileo didn’t! He immediately changed from Italian to Latin in his observing blog log and began making plans to publish his telescopic observation before he could be beaten to the gun by some unknown rival.

He decided to dedicate his planned publication to Cosimo II De’ Medici Fourth Grand Duke of Tuscany and started negotiations with the Tuscan Court over which names/names they would prefer for the newly discovered moons. In the end the term Medicean Stars was decided upon and Galileo’s Sidereus Nuncius was published with a preface dated forth day before the Ides of March 1610, that’s 12 March in modern money.


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

Seldom has a book hit the streets with such an impact. It truly marks the beginning of a new epoch in the history of astronomy and a new phase in the life of its author. Galileo got what he was angling for, he was appointed court mathematicus and philosophicus to the court in Florence and given a professorship at the university without teaching obligations but with a salary of 1,000 florins p.a.

The very poor quality of the glass available to make lenses and the errors in grinding and polishing made it very difficult for observers to see anything at all through the early telescopes, a problem that would continue to plague telescope users throughout the seventeenth century. There were as many claims made for discoveries that didn’t exist as for real ones.  All of this made it difficult for others to confirm Galileo’s spectacular claims. In the end the Jesuit astronomers of the Collegio Romano in Rome were able with much effort and many setbacks to confirm all of his discoveries. In 1611 he made a triumphant tour of Rome, which included a celebration banquet put on by the Jesuits at the Collegio. At a second banquet put on by Prince Frederico Cesi, founder and President of the Accademia dei Lincae of which Galileo would become a member, the telescope first received its name, in Greek teleskopos.

Another central problem in the first months of telescopic astronomical observation was that there existed no scientific explanation of how or why the telescope functions. This allowed critics to reject the discoveries as imaginary artefacts produced by the instrument itself. The man who came to the rescue was Johannes Kepler. Already in 1604 in his Ad Vitellionem Paralipomena Astronomiae pars optica, Kepler had published the first explanation of how lenses focus light rays and how eyeglasses work to compensate for short and long sightedness so he already had a head start on explaining how the telescope functions.

Francesco Maurolico (1494–1575) had covered much of the same ground in his Theoremata de lumine et umbra earlier than Kepler but this work was only published posthumously in 1611, so the priority goes to Kepler.


Source: Wikimedia Common


In 1611 Kepler published his very quickly written Diotrice, in which he covered the path of light rays through single lenses and then through lens combinations. In this extraordinary work he covers the Dutch or Galilean telescope, convex objective–concave eyepiece, the astronomical or Keplerian telescope, convex objective–convex eyepiece, the terrestrial telescope, convex objective–convex eyepiece–convex–field–lens to invert image, and finally for good measure the telephoto lens! Galileo’s response to this masterpiece in the history of geometrical optics was that it was unreadable!


Source: Wikimedia Commons

One small footnote to the whole who–invented–what story is that Kepler attributed the invention of the telescope to Giambattista della Porta (1535?–1615).


Giambattista della Porta Source: Wikimedia Commons

Della Porta did indeed describe the magnifying effect of the lens combination of the Dutch telescope in his Magiae Naturalis(various editions 1558 to 1589).

With a concave you shall see small things afar off, very clearly; with a convex, things neerer to be greater, but more obscurely: if you know how to fit them both together, you shall see both things afar off, and things neer hand, both greater and clearly.

He provided a primitive sketch in a letter to Prince Cesi in 1609.

Della Porta Telescope Sketch

Kepler assumed that the Dutch spectacle-maker, he didn’t know Lipperhey’s name, had somehow learnt of della Porta’s idea and put it into practice. It is more probable that della Porta was actually describing some sort of compound magnifying glass rather than a telescope and that Lipperhey had no idea of della Porta’s work.

Despite the confusion that surrounds the origins of the telescope, today most historians attribute the honours to Hans Lipperhey, whose demonstration set the ball rolling. We have come a long way since Lipperhey demonstrated his simple invention to Prince Maurits in Den Hague. I don’t suppose the humble spectacle–maker from Middelburg could have conceived the revolution in astronomy he set in motion on that day four hundred and ten years ago.

[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 intoEnglish 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)

[2]Taken from Fred Watson, Stargazer: the life and times of the Telescope, Da Capo Press, Cambridge MA, 2005

[3]For more details of the Dutch story of the invention of the telescope see Huib J. Zuidervaart, The ‘true inventor’ of the telescope. A survey of 400 years of debate, in The origins of the telescope, ed. Albert van Helden, Sven Dupré, Rob van Gent, Huib Zuidervaart, KNAW Press, Amsterdam, 2010


Filed under History of Astronomy, History of Optics, History of science, History of Technology, Renaissance Science, Uncategorized

The first calculating machine


Even in the world of polymath, Renaissance mathematici Wilhelm Schickard (1592–1635) sticks out for the sheer breadth of his activities. Professor of both Hebrew and mathematics at the University of Tübingen he was a multi-lingual philologist, mathematician, astronomer, optician, surveyor, geodesist, cartographer, graphic artist, woodblock cutter, copperplate engraver, printer and inventor. Born 22 April 1592 the son of the carpenter Lucas Schickard and the pastor’s daughter Margarete Gmelin he was probably destined for a life as a craftsman. However, his father died when he was only ten years old and his education was taken over by various pastor and schoolteacher uncles. Following the death of his father he was, like Kepler, from an impoverished background, like Kepler he received a stipend from the Duke of Württemburg from a scheme set up to provided pastors and teachers for the Protestant land. Like Kepler he was a student of the Tübinger Stift (hall of residence for protestant stipendiaries), where he graduated BA in 1609 and MA in 1611. He remained at the university studying theology until a suitable vacancy could be found for him. In 1613 he was considered for a church post together with another student but although he proved intellectually the superior was not chosen on grounds of his youth. In the following period he was appointed to two positions as a trainee priest. However in 1614 he returned to the Tübinger Stift as a tutor for Hebrew.


Wilhelm Schickard, artist unknown Source: Wikimedia Commons

Here we come across the duality in Schickard’s personality and abilities. Like Kepler he had already found favour, as an undergraduate, with the professor for mathematics, Michael Maestlin, who obviously recognised his mathematical talent. However, another professor recognised his talent for Hebrew and encouraged him to follow this course of studies. On his return to Tübingen he became part of the circle of scholars who would start the whole Rosicrucian movement, most notably Johann Valentin Andreae, the author of the Chymical Wedding of Christian Rosenkreutz, who also shared Schickard’s interest in astronomy and mathematics.


Johann Valentin Andreae Source: Wikimedia Commons

Although Schickard appear not to have been involved in the Rosicrucian movement, the two stayed friends and correspondents for life. Another member of the group was the lawyer Christian Besold, who would later introduce Schickard to Kepler.


Christopher Besold etching by Schickard 1618

This group was made up of the brightest scholars in Tübingen and it says a lot that they took up Schickard into their company.

In late 1614 Schickard was appointed as a deacon to the parish of Nürtingen; in the Lutheran Church a deacon is a sort of second or assistant parish pastor. His church duties left him enough time to follow his other interests and he initially produced and printed with woodblocks a manuscript on optics. In the same period he began the study of Syriac. In 1617 Kepler came to Württtemburg to defend his mother against the charge of witchcraft, in which he was ably assisted by Christian Besold, who as already mentioned introduced Schickard to the Imperial Mathematicus. Kepler was much impressed and wrote, “I came again and again to Mästlin and discussed with him all aspects of the [Rudolphine] Tables. I also met an exceptional talent in Nürtingen, a young enthusiast for mathematics, Wilhelm Schickard, an extremely diligent mechanicus and also lover of the oriental languages.” Kepler was impressed with Schickard’s abilities as an artist and printer and employed him to provide illustrations for both the Epitome Astronomiae Copernicanae and the Harmonice Mundi. The two would remain friends and correspondents for life.


3D geometrical figures from Kepler’s Hamonice Mundi by Schickard

In 1608 Schickard was offered the professorship for Hebrew at the University of Tübingen; an offer he initially rejected because it paid less than his position as deacon and a university professor had a lower social status than an on going pastor. The university decided to appoint another candidate but the Duke, whose astronomical advisor Schickard had become, insisted that the university appoint Schickard at a higher salary and also appoint him to a position as student rector, to raise his income. On these conditions Schickard accepted and on 6 August 1619 he became a university professor. Schickard subsidised his income by offering private tuition in Chaldean, Rabbinic, mathematic, mechanic, perspective drawing, architecture, fortification construction, hydraulics and optics.


Page from a manuscript on the comets of 1618 written and illustrated by Schickard for the Duke of Württemberg

The Chaldean indicates his widening range of languages, which over the years would grow to include Ethiopian, Turkish, Arabic and Persian and he even took a stab at Malay and Chinese later in life. Schickard’s language acquisition was aimed at reading and translating text and not in acquiring the languages to communicate. Over the years Schickard acquired status and offices becoming a member of the university senate in 1628 and a school supervisor for the land of Württemberg a year later.  In 1631 he succeeded his teacher Michael Mästlin as professor of mathematics retaining his chair in Hebrew. He had been offered this succession in 1618 to make the chair of Hebrew chair more attractive but nobody had thought that Mästlin, then almost 70, would live for another 12 years after Schickard’s initial appointment.


Michael Mästlin portrait 1619 the year Schickard became professor for Hebrew (artist unknown)

In 1624 Schickard set himself the task of producing a new, more accurate map of the land of Württemberg. Well read, he used the latest methods as described by Willebrord Snell in his Eratosthenes Batavus (1617).


This project took Schickard many more years than he originally conceived. In 1629 he published a pamphlet in German describing how to carry out simple geodetic surveys in the hope that others would assist him in his work. Like Sebastian Münster’s similar appeal his overture fell on deaf ears. Later he used his annual school supervision trips to carry out the necessary work.


Part of Schickard’s map of Württemberg

Schickard established himself as a mathematician-astronomer and linguist with a Europe wide reputation. As well as Kepler and Andreae he stood in regular correspondence with such leading European scholars as Hugo Grotius, Pierre Gassendi, Élie Diodati, Ismaël Boulliau, Nicolas-Claude Fabri de Peiresc, Jean-Baptiste Morin, Willem Janszoon Blaeu and many others.

The last years of Schickard’s life were filled with tragedy. Following the death of Gustav Adolf in the Thirty Years War in 1632, the Protestant land of Württemberg was invaded by Catholic troops. Along with chaos and destruction, the invading army also brought the plague. Schickard’s wife had born nine children of which four, three girls and a boy, were still living in 1634. Within a sort time the plague claimed his wife and his three daughters leaving just Schickard and his son alive. The invading troops treated Schickard with respect because they wished to exploit his cartographical knowledge and abilities. In 1635 his sister became homeless and she and her three daughters moved into his home. Shortly thereafter they too became ill and one after another died. Initially Schickard fled with his son to escape the plague but unable to abandon his work he soon returned home and he also died on 23 October 1635, just 43 years old, followed one day later by his son.

One of the great ironies of history is that although Schickard was well known and successful throughout his life, today if he is known at all, it is for something that never became public in his own lifetime. Schickard is considered to be the inventor of the first mechanical calculator, an honour that for many years was accorded to Blaise Pascal. The supporters of Schickard and Pascal still dispute who should actually be accorded this honour, as Schickard’s calculator never really saw the light of day before the 20thcentury. The story of this invention is a fascinating one.

Inspired by Kepler’s construction of his logarithm tables to simplify his astronomical calculation Schickard conceived and constructed his Rechenuhr (calculating clock) for the same purpose in 1623.

The machine could add or subtract six figure numbers and included a set of Napier’s Bones on revolving cylinders to carry out multiplications and divisions. We know from a letter that a second machine he was constructing for Kepler was destroyed in a workshop fire in 1624 and here the project seems to have died. Knowledge of this fascinating invention disappeared with the deaths of Kepler and Schickard and Pascal became credited with having invented the earliest known mechanical calculator, the Pascaline.


A Pascaline signed by Pascal in 1652 Source: Wikimedia Commons

The first mention of the Rechenuhr was in Michael Gottlieb Hansch’s Kepler biography from 1718, which contained two letters from Schickard in Latin describing his invention. The first was just an announcement that he had made his calculating machine:

Further, I have therefore recently in a mechanical way done what you have done with calculation and constructed a machine out of eleven complete and six truncated wheels, which automatically reckons together given numbers instantly: adds, subtracts, multiplies and divides. You would laugh out loud if you were here and would experience, how the position to the left, if it goes past ten or a hundred, turns entirely by itself or by subtraction takes something away.

The second is a much more detailed description, which however obviously refers to an illustration or diagram and without which is difficult or even impossible to understand.

Schickard’s priority was also noted in the Stuttgarter Zeitschrift für Vermessungswesen in 1899. In the twentieth century Franz Hammer found a sketch amongst Kepler’s papers in the Pulkowo Observatory in St Petersburg that he realised was the missing diagram to the second Schickard letter.


The Rechenuhr sketch from Pulkowow from a letter to Kepler from 24 February 1624

Returning to Württemberg he found a second sketch with explanatory notes in German amongst Schickard’s papers in the Würtemmberger State Library in Stuttgart.


Hammer made his discoveries public at a maths conference in 1957 and said that Schickard’s drawings predated Pascal’s work by twenty years. In the following years Hammer and Bruno von Freytag-Löringhoff built a replica of Schickard’s Rechenuhr based on his diagrams and notes, proving that it could have functioned as Schickard had claimed.

Schickards Rechenmaschine

Schickard’s Rechenuhr. Reconstruction by Bruno Baron von Freytag-Löringhoff and Franz Hammer

Bruno von Freytag-Löringhoff travelled around over the years holding lectures on and demonstrations of his reconstructed Schickard Rechenuhr and thus with time Schickard became acknowledged as the first to invent a mechanical calculator, recognition only coming almost 450 years after his tragic plague death.



Filed under History of Astronomy, History of Computing, History of Mathematics, History of science, History of Technology, Renaissance Science, Uncategorized