Category Archives: History of Technology

Renaissance Heavy Metal

One of the most fascinating and spectacularly illustrated Renaissance books on science and technology is De re metallica by Georgius Agricola (1494–1555). Translated into English the author’s name sounds like a figure from a game of happy families, George the farmer. In fact, this is his name in German, Georg Pawer, in modern German Bauer, which means farmer or peasant or the pawn in chess. Agricola was, however, anything but a peasant; he was an extraordinary Renaissance polymath, who is regarded as one of the founders of modern mineralogy and geology.


Georg Bauer was born in Glauchau on 24 March 1494, the second of seven children, to Gregor Bauer (born between 1518 and 1532) a wealthy cloth merchant and dyer. He was initially educated at the Latin school in Zwickau and attended the University of Leipzig, where he studied theology, philosophy and philology from 1514 to 1517. From 1518 to 1522 he worked as deputy director and then as director of schools in Zwickau. In 1520 he published his first book, a Latin grammar. The academic year 1522-23 he worked as a lecturer at the University of Leipzig. From 1523 to 1526 he studied medicine, philosophy and the sciences at various Northern Italian university graduating with a doctorate in medicine. In Venice he worked for a time for the Manutius publishing house on their edition of the works of Galen.

From 1527 to 1533 Agricola worked as town physician in St. Joachimsthal*, today Jáchymov in the Czech Republic. In those days Joachimsthal was a major silver mining area and it is here that Agricola’s interest in mining was ignited.


Silver mining in Joachimsthal (1548) Source: Wikimedia Commons

In 1530 he issued his first book on mining, Bermannus sive de re metallica, published by the Froben publishing house in Basel. It covered the search for metal ores, the mining methods, the legal framework for mining claims, the transport and processing of the ores. Bermannus refers to Lorenz Bermann, an educated miner, who was the principle source of his information. The book contains an introductory letter from Erasmus, who worked as a copyeditor for Froben during his years in Basel.

In 1533 he published a book on Greek and Roman weights and measures, De mensuris et ponderibus libri V, also published Froben in Basel.


From 1533 to his death in 1555 he was town physician in Chemnitz. He was also district historian for the Saxon aristocratic dynasty. From 1546 onwards he was a member of the town council and served as mayor in 1546, 1547, 1551 and 1553. In Chemnitz he also wrote a book on the plague, De peste libri tres, his only medical book,  as ever published by Froben in 1554.


Source: Internet Archive

Having established himself as an expert on mining with the Bermannus, Agricola devoted more than twenty years to studying and writing about all aspects of mining and the production of metals. He wrote and published a series of six books on the subject between 1546 and 1550, all of them published by Froben.

De ortu et causis subterraneorum libri V, Basel 1546

The origin of material within the earth

De natura eorum, quae effluunt ex terra, Basel 1546

The nature of the material extruded out of the earth

De veteribus et novis metallis libri II, Basel 1546

Ore mining in antiquity and in modern times

De natura fossilium libri X, Basel 1546

The nature of fossils whereby fossils means anything found in the earth and is as much a textbook of mineralogy

De animantibus subterraneis liber, Basel 1549

The living underground

De precio metallorum et monetis liber III, 1550

On precious metals and coins

At the same time he devoted twenty years to composing and writing his magnum opus De re metallica, which was published posthumously in 1556 by Froben in Basel, who took six years to print the book due to the large number of very detailed woodcut prints with which the book is illustrated. These illustrations form an incredible visual record of Renaissance industrial activity. They are also an impressive record of late medieval technology. Agricola’s pictures say much more than a thousand words.

De re metallicahas twelve books or as we would say chapters. What distinguishes Agricola’s work from all previous writings on mineralogy and geology is the extent to which they are based on empirical observation rather than philosophical speculation. Naturally this cannot go very far as it would be several hundred years before the chemistry was developed necessary to really analyse mineralogical and geological specimens but Agricola’s work was a major leap forward towards a modern scientific analysis of metal production.


Book I: Discusses the industry of mining and ore smelting

Book II: Discusses ancient mines, finding minerals and metals and the divining rod

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Book III: Discusses mineral veins and seams and plotting with the compass

Book IV: Discusses the determination of mine boundaries and mine organisation

Book V: Discusses the principles of mining, the metals, ancient mining and mine surveying

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Book VI: Discusses mining tools and equipment, hoists and pumps, ventilation and miners’ diseases

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Book VII: Discusses assaying ores and metals and the touchstone

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Book VIII: Discusses preparing ores for roasting, crushing and washing and recovering gold by mercury

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Book IX: Discusses ores and furnaces for smelting copper, iron and mercury and the use of bellows

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Book X: Discusses the recovery of precious metals from base metals as well as separating gold and silver by acid

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Book XI: Discusses the recovery of silver from copper by liquidation as well as refining copper

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Book XII: Discusses salts, solvents, precipitates, bitumen and glass

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Agricola’s wonderfully illustrated volume became the standard reference work on metal mining and production for about the next two hundred years. The original Latin edition appeared in Basel in 1556 and was followed by a German translation in 1557, which was in many aspects defective but remained unchanged in two further editions. There were further Latin editions published in 1561, 1621, and 1657 and German ones in 1580, and 1621, with an improved German translation in 1928 and 1953. There was an Italian translation published in 1563.

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Of peculiar interest is the English translation. This was first published in 1912 in London, the work of American mining engineer Herbert Hoover (1874–1964) and his wife the geologist Lou Henry (1874–1944). A second edition was published in 1950. Hoover is, of course, better know as the 31stPresident of the USA, who was elected in 1928 and served from 1929–1933.


Herbert Hoover in his 30s while a mining engineer Source: Wikimedia Commons


Lou Henry, circa 1930 Source: Wikimedia Commons

Agricola’s tome also represents an important development in the history of trades and professions. Before De re metallicaknowledge of trades and crafts was past from master to apprentice verbally and kept secret from those outside of guild, often on pain of punishment. Agricola’s book is one of the first to present the methods and secrets of a profession in codified written form for everyone to read, a major change in the tradition of knowledge transfer.

*A trivial but interesting link exists between St. Joachimsthal and the green back. A silver coin was produced in St. Joachimsthal, which was known as the Joachimsthaler. This got shortened in German to thaler, which mutated in Dutch to daalder or daler and from there in English to dollar.

All illustrations from De re metallica are taken from Bern Dibner, Agricola on Metals, Burndy Library, 1958






Filed under Early Scientific Publishing, History of Technology, Mediaeval Science, Renaissance 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

Apples & Pears – comparing print technologies


On Facebook I recently stumbled across a link to a piece on 3 Quarks Daily, which in turn was only a lede for a short essay on the London Review of Books entitled, The Oldest Printed Book in the World. This is an article about the Chinese Dunhuang Diamond Sūtra


Frontispiece of the Chinese Diamond Sūtra, the oldest known dated printed book in the world. The colophon, at the inner end, reads: Reverently [caused to be] made for universal free distribution by Wang Jie on behalf of his two parents on the 13th of the 4th moon of the 9th year of Xiantong [i.e. 11th May, CE 868 ] Source: British Library via Wikimedia Commons

 from the ninth century explaining its origin and how it came to be housed in the British Library. The article contains the following sentence:

A colophon at the end of the Dunhuang Diamond Sūtra scroll dates it to 868, nearly six centuries before the first Gutenberg Bible.

Although not stated explicitly the intention of this sentence seems to be, the Chinese invented book printing six hundred years before the Europeans. Although on a very superficial level this is true it is actually a case of comparing apples with pears, as the two books in question are printed with very different reproduction technologies. The Dunhuang Diamond Sūtra is a woodblock print, whereas the Gutenberg Bible is printed with movable type.


First page of the first volume: The Epistle of St. Jerome from the University of Texas copy. Source: Ransom Center of the University of Texas at Austin via Wikimedia Commons

For woodblock printing the image to be printed is carved into a woodblock or rather the parts that are not to be printed are cut away with a knife or chisel. This is then inked and pressed onto the sheet of material, cloth or paper, to be printed. The used block produced by this difficult process can only be used to print this one page. With moveable type the individual pieces of type, or sorts, are composed into the image to be printed, inked and pressed into the sheet of material to be printed. When finished the sorts can be reused to compose a new page and so on. Once cut a set of woodblocks can only be used to print the same book over and over again. A full set of type can be continually reconfigured to print literally thousand of different books. This difference is important and the six hundred year gap throws up some very important and intriguing historical questions.


A case of cast metal type pieces and typeset matter in a composing stick Source: Wikimedia Commons

Central to these is the question of technological transfer. Woodblock printing was developed in East Asia sometime before the third century CE. The oldest fragments of printed cloth date to 220 CE. The oldest woodblock prints on paper date to the late seventh century CE. And as stated above to oldest extant woodblock printed book the Dunhuang Diamond Sūtra dates to 868 CE. Although the Chinese invention of paper arrived in Spain via the Islamic Empire in the late eleventh century CE and crossed the Alps into Northern Europe in the late fourteenth century CE, woodblock printing does not appear to have accompanied it. Strangely European books printed with woodblocks, block books, apparently only appeared after Gutenberg had introduced printing with movable type in the second half of the fifteenth century. There are a very limited number of such books mostly dating from the 1460s and 1470s and printed in the Netherlands of Southern Germany.


Block book – Biblia Pauperum (“Bible of the Poor”) Netherlands 1460s/70s Source: Wikimedia Commons

Gutenberg was by no means the first to use moveable type. Around 1040 CE a Chinese inventor, Bi Sheng (990–1051) invented a form of moveable type with the pieces of type made of ceramics. Beyond a short description of his invention nothing more is known about it and nothing he might have printed has survived. This was followed in East Asia by various other forms of moveable type carved from wood or made of various metals. The oldest book printed with wooden movable type was Records of Jingde County printed by Wang Zhen in 1298. In 1313 he published an account of his invention A method of making moveable wooden types for printing books.


A revolving typecase for wooden type in China, from Wang Zhen’s book published in 1313 Source: Wikimedia Commons

The oldest known book printed with metal moveable type is the two volume Jikji, a collection of excerpts from the analects of revered Buddhist monks, printed with metal type in Korea in 1377; that is at least seventy years before Gutenberg’s famous Bible. However, whereas 49 copies of Gutenberg’s Bible still exist, of which 21 are complete, only one copy of the second volume of the Jikji is still extant.


Korean movable type from 1377 used for the Jikji Source: Wikimedia Commons


Jikji or “Selected Teachings of Buddhist Sages and Seon Masters”, published in 1377, Korea during the Goryeo Dynasty. Source: Wikimedia Commons

Even within Europe Gutenberg was not the first to use moveable type, with several people experimenting with varying system. However Gutenberg was the first to produce anything functional and in reality his greatest inventions were not so much moveable type as the printing press (he converted a wine press) and printing ink or to put it another way he didn’t just invent moveable type but the whole printing process.


Replica of the Gutenberg press at the International Printing Museum in Carson, California Source: Wikimedia Commons

Although extensive effort has been invested into the research on the topic, no evidence has been found of a technology transfer from East Asia to Europe and it is thought that Gutenberg’s was an independent (re)invention.

Although my account is itself only a sketch of the development of printing, both woodblock and moveable type ( I don’t even touch upon book (re)production before woodblock printing or after moveable type), my main argument is that the London Review of Books article in just making its invalid comparison between the Dunhuang Diamond Sūtra and Gutenberg’s Bible creates an inadequate and distorted impression of a long and complex historical process; an impression that uninformed readers will take away with them. A mythical historical meme has been created “the first printed book is the Dunhuang Diamond Sūtra and not the Gutenberg Bible” to replace the Eurocentric myth that Gutenberg invented movable type printing and his Bible is the earliest printed book. If writing short popular historical pieces for the general public we should avoid simplistic descriptions and thereby the risk of creating myths rather than transmitting real knowledge.



Filed under Early Scientific Publishing, History of Technology, 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

Today in something is wrong on the Internet

When I was growing up one of the most widespread #histSTM myths, along with the claim that people in the Middle Ages believed the world was flat and Stone Age people lived in holes in the ground, was that Galileo Galilei invented the telescope. This myth actually has an interesting history that goes all the way back to the publication of the Sidereus Nuncius. Some of Galileo’s critics misinterpreting what he had written asserted that he was claiming to have invented the telescope, an assertion that Galileo strongly denied in a latter publication. Whatever, as I said when I was growing up it was common knowledge that Galileo had invented the telescope. During the 1960s and 1970s as history of science slowly crept out of its niche and became more public and more popular this myth was at some point put out of its misery and buried discretely, where, I thought, nobody would find it again. I was wrong.

When I wrote my essay on the origins of the reflecting telescope for the online journal AEON, my editor, Corey Powell, who is himself a first class science writer and an excellent editor, asked me to provide a list of reference books to help speed up the process of fact checking my essay. I was more than happy to oblige, as even more embarrassing than a fact checker finding a factual error in what I had written, and yes even I make mistakes, would be a reader finding a real clangour after my essay had been published. As it turned out I hadn’t made any mistakes or if I did nobody has noticed yet. Imagine my surprise when I read an essay published two days ago on AEON that stated Galileo had invented the telescope. Hadn’t it been fact checked? Or if so, didn’t the fact checker know that this was a myth?

The essay in question is titled Forging Islamic Science and was written by Nir Shafir and edited by Sally Davies. The offending claim was at the beginning of the second paragraph:

Besides the colours being a bit too vivid, and the brushstrokes a little too clean, what perturbed me were the telescopes. The telescope was known in the Middle East after Galileo invented it in the 17th century, but almost no illustrations or miniatures ever depicted such an object.

I tweeted the following to both the author’s and AEON’s Twitter accounts:

If the author is complaining about forgers getting historical details wrong he really shouldn’t write, “The telescope was known in the Middle East after Galileo invented it in the 17th century…”

The author obviously didn’t understand my criticism and tweeted back:

There are references to the use of telescopes for terrestrial observations, mainly military, in the Ottoman Empire, such as in evliya çelebi.

I replied:

Galileo did not invent the telescope! He wasn’t even the first astronomer to use one for astronomical observations!

Whereupon Sally Davies chimed in with the following:

Thank you for drawing this to our attention! A bit of ambiguity here; we have tweaked the wording to say he ‘developed’ the telescope.

Sorry but no ambiguity whatsoever, Galileo did not in anyway invent the telescope and as I will explain shortly ‘developed’ is just as bad.

Today the author re-entered the fray with the following:

Thank you for bringing this up. It’s always good to get the minor details right.

The invention of the telescope is one of the most significant moments in the whole history of science and technology, so attributing its invention to the completely false person is hardly a minor detail!

About that ‘developed’. A more recent myth, which has grown up around Galileo and his use of the telescope, is that he did something special in some sort of way to turn this relatively new invention into a scientific instrument usable for astronomical observations. He didn’t. The telescope that Galileo used to discover the Moons of Jupiter differed in no way either scientifically or technologically from the one that Hans Lipperhey demonstrated to the assembled prominence at the peace conference in Den Hague sometime between the 25thand 29thof September 1608. Lipperhey’s invention was even pointed at the night sky, “and 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]

Both instruments consisted of a tube with a biconvex or plano-convex objective lens at one end and a bi-concave or plano-concave eyepiece lens at the other end. The eyepiece lens also had a mask or stop to cut down the distortion caused around the edges of the lens. The only difference was in the focal lengths of the lenses used producing different magnitudes of magnification. Galileo’s use of other lenses to increase magnification was nothing special; it had been done earlier than Galileo by Thomas Harriot and at least contemporaneous if not earlier by Simon Marius. It was also done by numerous others, who constructed telescopes independently in those first few years of telescopic astronomical observation. The claims that Galileo had developed, improved, specialised, etc., etc., the telescope are merely mythological elements of the more general Galileo hagiography. Modern research has even revealed that contrary to his own claims Galileo probably did not (re)-construct the telescope purely from having heard reports about it but had almost certainly seen and handled one before he attempted to construct one himself.

Going back to the offending AEON essay, Sally Davies could have saved herself and Nir Sharfir if she had simply changed the sentence to:

The telescope was known in the Middle East after it was invented  in the late 16th early 17th century…(even I make mistakes)

What I intended to write before my brain threw a wobbly was:

The telescope was known in the Middle East after it was invented in late 1608…

 She doesn’t even need to mention Lipperhey’s name if she wants to avoid the on going debates about who really did invent the telescope.








[1]Embassies of the King of Siam Sent to His Excellency Prince Maurits, Arrived in The Hague on 10 September 1608


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

A multi-functional book for a multi-functional instrument

Probably the most talked about astronomical instrument in recent years is the so-called Antikythera Mechanism, several corroded chunks of bronze gear work found in the sea of the coast of the Greek island of Antikythera at the end of the nineteenth century.


The Antikythera mechanism (Fragment A – front); visible is the largest gear in the mechanism, approximately 140 millimetres (5.5 in) in diameter Source: Wikimedia Commons

Historian of ancient astronomy, Alexander Jones, who was a member of one of the teams investigating and interpreting the mechanism, has now written a book about it, A Portable Cosmos.[1]


I say that he has written a book but in fact it is really several books in one. The first two chapters deal with the story of the original discovery and recovery of the mechanism. They also sketch the history of the succession of investigations and interpretations of the mechanism that have taken place between its discovery and the present. The longest section of the book deals with a detailed description of the external aspects of the mechanism, its dials, scales and pointers. The penultimate chapter is an examination of the physical aspects of the mechanism, its gears and gear shafts. The final chapter, an afterword, is titled The Meaning of the Mechanism. For me, the most fascinating element of the book is that Jones in his explanations of the functions of the dials and pointers delivers up a comprehensive introduction to the histories of astronomy, astrology and cosmology of ancient Babylon and Greece, in fact I would rate it as the best such introduction that I have ever read.

Despite his very obviously high level command of the material Jones does not baffle with science but writes in a light and very accessible style and I for one found the book highly readable. Of interest is the fact that because large parts of the mechanism are missing and what is there is highly damaged there is not a general agreement under the experts, who have worked on the mechanism, about how to interpret the function or purpose of numerous aspects of it. Jones doesn’t just express his own well-informed and well-reasoned explanations but draws his readers’ attention to alternative suggestions and interpretations, explaining why he prefers his own chosen one. Having said this archaeoastronomer Doris Vickers, who recommended the book to me suggested also consulting the official Greek Antikythera Mechanism Research Project website, which has more information and other viewpoints to those of Jones.

The book has a very useful glossary of technical terms, endnotes (regular readers already know my views on endnotes contra footnotes), a comprehensive bibliography so you can read up on those interpretations that deviate from Jones’ and a good index.

To quote a cliché, if you only read one book on the Antikythera Mechanism, then it really should be this one. It kept me occupied and entertained during my recent four days in hospital and proved to be an excellent companion for that period and I would whole heartedly recommended for happier circumstances as well.

[1] Alexander Jones, A Portable Cosmos: Revealing the Antikythera Mechanism, Scientific Wonder of the Ancient World, OUP, Oxford, 2007

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Filed under Book Reviews, History of Astrology, History of Astronomy, History of Technology, Uncategorized