Isaac Newton: The Last Lone Genius?

The Friday before last, with much advanced publicity, the BBC broadcast a new documentary film biography of Isaac Newton with the title The Last Magician. This phrase is part of a famous quote by John Maynard Keynes, “not the first scientist but the last magician”, describing his feeling upon reading the Newtonian alchemical manuscripts that he acquired at the auction of the Portsmouth family Newton papers in 1936.  This of course together with the advanced advertising for the programme signalled that we were due for a fresh dose of “did you know that Newton was a secret alchemist?” A phenomenon that Rebekah “Becky” Higgitt has blogged on informatively in the past.

Based on quotes from Newton’s own writings and correspondence as well of those of his contemporaries the programme was in its basics factually correct. As usual for BBC historical documentaries it was well-produced and excellently filmed and thus pleasant to watch. The basic structure was the direct quotes being spoken by actors in costume and commented upon by five more or less experts. These were the historians of science Rob Iliffe head of the Newton Papers editing project and a genuine Newton expert, Patricia Fara author of an excellent book on the changing image of Newton down the centuries and Lisa Jardine expert on Renaissance history of science, as well as popular science writer James Gleick author of a competent popular Newton biography and astrophysicist turned novelist Stuart Clark.

Given all of these preconditions it should have been an excellent hours entertainment for a historian of science like myself, unfortunately it turned out to be a major disappointment for two reasons. The programme deliberately created two principle impressions that were and are fundamentally wrong.

The first of these turned up in the pre-programme publicity but also featured prominently fairly early in the documentary in what seems at first glance to be a fairly harmless statement:

By the age of 21, he had rejected 2,000 years of scientific orthodoxy…

This brief phrase contains two claims one implicit and one explicit. The implicit claim is how wonderful Newton was to take such a bold step when he was only 21 years old. Anyone who has spent anytime at all looking at the history of mathematics knows that mathematicians tend to be very precocious. Pascal wrote the paper that gained him entry to the top flight of seventeenth century mathematics at the age of sixteen. In the nineteenth century the teenage William Rowan Hamilton was trotted out in public like a circus pony to display his brilliance. The stories are legion and there is absolutely nothing unusual in Newton intellectual development it’s par for the course for a highly talented mathematician.

As Becky put it very succinctly in a tweet what they are actually saying here is that there had been no science since Aristotle, which is of course complete rubbish. The scientific orthodoxy of the day, which was by the way on the verge of disappearing, of which more shortly, came into being in the thirteenth century when Albertus Magnus and his pupil Thomas Aquinas created a synthesis of Catholic theology and Aristotle’s philosophy with the addition of Ptolemaic geocentric astronomy. This synthesis is known as Scholastic or Aristotelian physics or natural philosophy. However as Edward Grant, one of the leading experts on medieval science, points out Aristotelian philosophy is not Aristotle’s philosophy. It is also important to note that Aristotelian philosophy was never carved in stone but in fact changed and developed continuously over the next four hundred years. Examples of major changes are the work of the Oxford Calculatores and the Paris Physicists in the fourteenth century. The Aristotelian physics of the fifteenth century is a very different beast to that of the thirteenth century. The geocentric astronomy produced in the middle of the fifteenth century by Peuerbach and Regiomontanus differed substantially from that of the first Ptolemaic translations of the twelfth century.

Added to all this change and development the first seeds of what would become modern science began to poke their slender stems out of the substrate of scientific innovation around the beginning of the fifteenth century. By 1661 when Newton went up to university Keplerian heliocentric astronomy had become the new orthodoxy and Aristotelian physics was being pushed out by the new physics developed by mathematicians such as Tartaglia and Benedetti in the sixteenth century and Stevin, Galileo, Borelli, Descartes, Pascal, Huygens and others in the seventeenth. One should bear in mind that the Leopoldina, the Accademia del Cimento, the Royal Society and the Acadédemie des Sciences all institutions dedicated to the propagation and development of the new science were founded in 1652, 1657, 1660 and 1666 respectively. The young Newton did not like some Carrollian hero draw his Vorpal Blade to slay the Jabberwock of ancient Greek science but like any bright young academic would do jumped on the band wagon of modern science that was speeding full speed ahead into the future.

We now turn to what I see as the most serious failing of the documentary expressed in the question posed in the title of this post. For the best part of an hour the documentary banged on about Newton’s solitude, his isolation his lone path to the secrets of nature. We were presented with the ultimate lone genius of the history of science. It went so far that the only other contemporary researchers mentioned by name were Descartes in passing and Hooke purely in a negative light. The way that the programme was structured created a totally false impression of Newton’s scientific endeavours.

We actually know very little about Newton’s time as a student though it is safe to say that he was more the type to curl up in front of the fire with a good book on a Friday evening than to go to the latest rave at which ever student hostelry was in that term. As a fellow we know that he communicated and worked together with other scholars such as Isaac Barrow so to talk of total solitude as the documentary did is wrong. After he emerged from obscurity at the beginning of the 1670s with his reflecting telescope and his famous paper on the phenomenon of colours he was in no way isolated. Even if Cambridge was somewhat off the beaten track in those days Newton corresponded with other scholars in Britain and also abroad as can easily be seen in his voluminous correspondence as edited by Turnbull. He was also often visited by other mathematical scholars such as Halley or John Collins. When he left Cambridge to go to London he became positively gregarious. Maintaining a town house with his niece Catherine Barton, a renowned social beauty, as his housekeeper where he received and entertained visitors. At the Royal Mint, which he attended daily, he was surrounded by a large staff. After 1703 he presided over the weekly meetings of the Royal Society and on other evenings surrounded by his acolytes he held court in one or other of the then fashionable London coffee bars.

More important for me was the totally false impression created by the documentary of Newton’s mathematical and scientific work. Anyone being introduced to Newton for the first time would come away with the impression that he revolutionised mathematics, physics and astronomy in a superhuman solo endeavour completely isolated from the rest of the late seventeenth century intellectual world.

We got presented with Newton in 1666 creating a completely new branch of mathematics, he only actually started it then and it took a number of years to develop. At no point was any other mathematician mentioned. The fact that Newton either, directly or indirectly, knew of and built on the previous work in this field of Kepler, Cavalieri, Fermat, Pascal, Descartes, van Schooten, Barrow and others was quietly swept under the carpet. Even worse no mention what so ever of Leibniz who independently developed the same mathematics almost at the same time from the same sources. This of course led eventually to the most notorious priority dispute in the history of science involving many of the leading mathematicians of Europe.

The same thing occurred with the presentation of his work in optics, no mention of Kepler, Schiener, Descartes, Grimaldi, Gregory, Hooke, Huygens or anybody for that matter. Isaac apparently did it all alone in isolation.

This form of presentation continued with his greatest work the Principia. We got each of the famous laws of motion presented individually but no hint of the fact that the first was taken from Beeckman by way of Descartes, the second from Huygens and the third from his readings in alchemy. We were told that he derived the law of gravity from his three laws but no mention was made of the fact that the concept of the law of gravity was common, much discussed intellectual property in academic circles at the time. No mention of the contributions made to the substance of the Principia by the work of Kepler, Galileo, Cassini, Halley and above all Flamsteed. We had the strange spectacle of Hooke famous accusation of Newton having stolen his law of gravity and plagiarised him delivered in a passionate speech to the Royal Society in 1660 but no mention what so ever that Hooke’s accusation had more than a little substance. Hooke and Newton had corresponded on the subject in the early 1680s and Hooke had already formulated a concept of universal gravity before Newton. This correspondence was with certainty one of the spurs that led Newton to write the Principia although Hook’s claims as to the extent of his contribution are wildly exaggerated.

Isaac Newton did not live and work in an intellectual vacuum as was very strongly implied either deliberately or accidently through bad scripting by this documentary. He was part of a strong multi-faceted scientific community who supplied both the scaffolding and a significant part of substance of Newton’s life work in mathematics, physics and astronomy. He was in no way a lone genius but a highly significant cog in a large intellectual endeavour.

There was a time some decades back when some historians of science went so far as to decry the Principia as purely a work of synthesis with only a very small original contribution from Newton. This view was shown to be exaggerated and invalid and has been dropped but the opposite point of view implied by this documentary of the Principia as being alone the work of Newton’s genius is even more false.

Before I close there are a couple of small points from the film that I think should be mentioned. As is all too often the case we had the tired old statement that after Newton became President of the Royal Society he produced no more original scientific work. This was as always made without explicit comment but with a strong implicit negative aura. Dear people, when Isaac Newton became President of the Royal Society in 1703 he was already sixty years old. He had written and published two of the most important major scientific works in the history of mankind, his Principia and his Optics, as well as vast quantities of, largely unpublished, absolutely world-class mathematics, which he did however circulate in manuscript amongst his acolytes. What more did you expect him to do (FFS)?

I noted four major scientific/historical errors during the film, a fairly low quota; there may have been others. We of course get introduced to Newton’s reflecting telescope, the invention that first made him known to the world at large, but then we get informed that this instrument played a major role in marine navigation in the eighteenth century. Now whilst it is true that the reflecting telescope, mostly Gregorian’s and not Newtonian’s, had become the instrument of choice for astronomers by the middle of the eighteenth century they were for several good reasons not used for navigation on ships. Firstly reflecting telescopes whilst in principle smaller than refracting ones don’t telescope and so are more massive and cumbersome than the classical marine telescope. Secondly until the nineteenth century reflecting telescopes had metal mirrors made of so-called speculum metal an alloy that unfortunately was very susceptible to corrosion necessitating regular re-polishing. The salt-water atmosphere of sea voyages would have been very adverse for such mirrors requiring almost daily re-polishing and thus completely impractical.

The next error I spotted was a real howler. A voice over informed the viewer that, “for centuries light was considered the purest form of energy in the universe.” Really? Although etymologically derived from an ancient Greek word the physics concept of energy was first appeared in the nineteenth century, as did the recognition that light is a form of energy. Nuff said.

Moving along the historical time scale in the opposite direction voice over informed us the Newton’s Principia made possible the accurate prediction of comets and eclipses. Now the former is indeed true although the credit should properly go to Halley who first showed that some comets were periodical and obeyed Newton’s law of gravity. The latter is however again a real history of science howler. The Babylonians could accurately predict lunar eclipses in about the fifth century BCE and the ability to accurately predict solar eclipses was also developed in antiquity. No need to wait for Newton.

My final error is the one that as a historian of science causes me the most concern. Whilst discussing Newton’s alchemy voice over stated correctly Newton’s alchemical belief that light and matter are both products of some as yet undiscovered primal alchemical substance. The claim was immediately made that Newton had anticipated Einstein’s famous E = MC²! This claim being, to my surprise, repeated by Rob Iliffe an excellent historian of science. Now I’m not a big fan of the Kuhn/Feyerabend principle of the incommensurability of scientific theories. This says that one can’t compare scientific theories because the definitions of the concepts that they contain differ and are thus not comparable. Newton’s concept of force is not Maxwell’s concept of force for example. However I think that here we have a genuine case of incommensurability. The metaphysical concepts behind Newton’s alchemical theory and the metaphysical concepts behind Einstein’ theory of relativity are in no way comparable. It is not even comparing apples with oranges; it’s comparing apples with bicycles!

On the whole I think what was superficially a very good and certainly an excellently produced documentary failed miserably as a piece of history of science for the reasons that I have outlined above. Maybe I’m being too harsh but on the whole I don’t think so. For me the very strong emphasis of the biography of Newton as some sort of lone genius whether intended or an accidental product of ill considered scripting made this documentary next to worthless as a contribution to popular history of science.

 

 

How to murder your wife and get away with it: First become a famous successful telescope maker.

As part of my long-term project to learn about the history of (reflecting) telescopes I recently read a paper on Robert Hooke’s involvement in early attempts to grind and polish parabolic telescope mirrors. During my reading I was amused by the following comment about Richard Reeve who was the leading maker of lenses for telescopes and microscopes in London around 1660.

By this time Richard Reeve had died. His business had been disrupted in 1664 when he was arrested for killing his wife and his goods confiscated. The court proceedings were dropped when he secured a Royal pardon, but the financial cost was clearly considerable.[1]

It seems you can get away with almost anything if you make telescopes for the king.

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[1] A. C. D. Simpson, Robert Hooke and Practical Optics: Technical Support at a Scientific Frontier, in Michael Hunter & Simon Schaffer eds., Roert Hooke: New Studies, The Boydell Press, 1989, pp 33 – 61 quote p 47

It’s silly questions time again: “Was Newton a scientist or a sorcerer?

Back in May the Guardian art critic Jonathan Jones asked, “Is Leonardo da Vinci a great artist or a great scientist?” making, as I pointed out at the time, a serious category mistake. Something must be in the drinking water at the Guardian because now Stuart Clark on the Guardians Science Blogs is asking “Was Newton a scientist or a sorcerer?” making, you guessed it, a serious category mistake. As my Internet friend Tom Levenson, who is himself something of a Newton expert, pointed out on twitter Gotta stop with “Scientist and/or sorcerer” nonsense. Newton never saw himself in those terms… In fact Tom’s tweet says it all but for those not in the know, who might want to learn more, I will elaborate.

For all those at the back who haven’t been paying attention Newton cannot have been a scientist because the term was first coined by William Whewell in 1833 and did not come into common usage until around 1870. There are those who will immediately say that Newton thought like a modern scientist so it doesn’t matter if the term is anachronistic he was one, so there. The problem with this claim is that it’s based on a very limited knowledge of Newton, his life, his work and the way he thought. Put very simply Newton did not think like a modern scientist, which brings us to the second prong of Stuart Clark’s dichotomy.

Clark calls Newton a sorcerer because he was a practicing alchemist, which displays an immense ignorance of the world of seventeenth century thought on his part. A sorcerer is a practitioner of magic in fact a practitioner of black magic and that is a very, very different thing from an alchemist. What follows is a brief outline as to why Clark’s appellation is so inappropriate (with apologies to all serious historians of alchemy, astrology and natural magic for a totally inadequate explanation of these disciplines in the early modern period).

In the early modern period there are three so-called occult (occult just means hidden or concealed) sciences: astrology, natural magic and alchemy all of which found their legitimacy in the micro-cosmos macro-cosmos philosophy. This cosmology says as above so below or the world we live in is a reflection of the heavens. Astrology investigates the connections between the heavens and the earth and tries to define the heavenly or celestial influences. Both natural magic and alchemy are methods that try or at least hope to directly influence or manipulate those influences. Practitioners of all three disciplines distance themselves clearly from demonic or black magic that tries to manipulate nature through demonic powers. A sorcerer is a user of demonic magic.

Newton rejected both astrology and natural magic and is also on record as not believing in witches or ghost so I think we can safely say he also rejected demonic magic, so he definitely wasn’t a sorcerer. He was however a convinced alchemist. This was not a mild side-line or passing fantasy as some commentators on Clark’s post would like to believe, the study of alchemy was his main occupation six months of the year for about thirty years. Also this was not after he ceased doing scientific work as many sources would have you believe but parallel to his main period of scientific activity between 1666 and 1696 when he gave up academia to move to London and the Royal Mint. It is important to understand that for Newton and his fellow alchemists, which included Robert Boyle and John Locke, alchemy was an epistemic discipline that is a branch of knowledge like optics or mechanics.

So Newton was neither a scientist nor a sorcerer so what was he? We have already seen he was a committed alchemist, what else?

Newton was Lucasian Professor of Mathematics at Cambridge so it is safe to call him a mathematician. To find out what he was we can look at his two principle publications The Optics and Principia. The Optics is basically a book on geometrical optics, which was then still a sub-discipline of mathematics, in fact Newton in his roll as professor lectured on optics, so this can safely be subsumed under his roll as mathematician. The Principia is actually titled Philosophiæ Naturalis Principia Mathematica or in English The Mathematical Principles of Natural Philosophy, all of which tells us that Newton was a natural philosopher. So we have mathematician and natural philosopher. However the title of his main work tells us that he was a representative of a fairly new breed of academic the mathematical natural philosopher. Newton wasn’t the first of this genus, which had slowly evolved since sometime in the High Middle Ages, Galileo, Kepler, Borelli and Huygens being other examples from the seventeenth century.

Maybe we could restate Clarks question as “Was Newton a mathematical natural philosopher or an alchemist?” but should we do so we would be again doing Newton an injustice. We are back to the reason that Newton did not think like a modern scientist. For Newton his theological studies (that I haven’t dealt with here) and his alchemical studies were an integral part of his natural philosophical investigations, in fact they were at the very heart of those investigations so to present these two aspects of his work as a dichotomy would be totally false.

In his blog post Clark quotes a footnote from Richard Westfall one of the deans of Newton studies:

“My modes of thought are so far removed from those of alchemy that I am constantly uneasy in writing on the subject … [Nevertheless] my personal preferences cannot make more than a million words he wrote in the study of alchemy disappear.”

He then goes on to quote novelist Rebecca Stott:

“Westfall admitted to wishing that he could make those million words disappear.”

This is a complete misrepresentation. It was one of Westfall’s doctoral students Betty Jo Teeter Dobbs who wrote the definitive account of Newton’s alchemical studies The Foundations of Newton’s Alchemy, or the Hunting of the Green Lyon and also the definitive account of how his alchemy fitted into his approach to knowledge The Janus Faces of Genius: The Role of Alchemy in Newton’s Thought. Both books are highly recommended for anybody who wishes to know more about Isaac the Alchemist.

For an excellent short account of the misrepresentation of Newton’s alchemical activities I recommend this post from last year by Rebekah “Becky” Higgitt at he blog Teleskopos: Newton and alchemy: a constant surprise?

Addendum: As Ian Hopkinson correctly pointed out on Twitter Newton is of course a Fig Roll.

Oh dear! More crap than you can shake a stick at.

One of the websites that I usually enjoy reading is Wonders & Marvels a collective of historians[1] who post mostly short reports on historical things, oft medical, that they have found fascinating. However, as I recently visited this delightful oasis of historical frivolity I groaned inwardly upon reading the post on Abū Alī al-Hasan ibn al-Hasan ibn al-Haytham (known simply as Ibn al Haytham or in mediaeval Europe as Alhacen or Alhazen) the mediaeval Islamic scholar by Pamela Toler that I found there. I hasten to add that Ms Toler is not solely to blame for the heap of excrement posing as history of science that she has posted there, as she was just regurgitating, probably inaccurately, what she had read in a popular book on Islamic science, about which more later.

After an opening paragraph that gives a somewhat mangled version of a part of Ibn al-Haytham’s biography Ms Toler presents us with the following paragraph:

While confined in his home, Alhazen revolutionized the study of optics and laid the foundation for the scientific method. (Move over, Sir Isaac Newton.) Before Alhazen, vision and light were questions of philosophy. Alhazen considered vision and light in terms of mathematics, physics, physiology, and even psychology. In his Book of Optics, he discussed the nature of light and color. He accurately described the mechanism of sight and the anatomy of the eye. He was concerned with reflection and refraction. He experimented with mirrors and lenses. He discovered that rainbows are caused by refraction and calculated the height of earth’s atmosphere. In his spare time, he built the first camera obscura.

Nearly every single claim in this brief paragraph is wrong and I shall now try, at least in outline, to correct some of the worst errors.

Whilst it is true that Ibn al-Haytham made a major advance in the study of optics I personally, as a gradualist, object strongly to any use of the word revolution in any of its forms when writing about the history of science. Ibn al-Haytham made an important step forward building on the work of others, his work in turn being pushed forward by others. He did not in anyway what so ever invent the scientific method. Put quite simply nobody did. (see next post!)

Before Alhazen, vision and light were questions of philosophy.

Here we start in on the real rubbish. The Islamic scholars inherited their knowledge of optics from the Greeks and to state simply that Greek optics consisted of questions of philosophy is to display a deep ignorance of the history of the subject. The Greek study of optics can be divided into three main areas: philosophical, medical and mathematical. The opinions on vision can be further categorised according to whether the rays that enable vision extrude from the eyes to the object viewed, extramission, from the object viewed to the eyes, intromission, or in both directions mixed.

Philosophical theories of vision were propagated by the Atomists, intromission, Plato, mixed, Aristotle, intromission mediumistic, and the Stoics also mixed. The mathematical theories laid the basis of geometrical optics, and were propagated by Euclid, Hero of Alexandria and Ptolemaeus, all three supporting an intromission extramission theory although it is not clear if this is purely instrumental in order to facilitate simpler calculations. The principle medical theory transmitted to the Islamic scientists was that of Galen who combined a surprisingly accurate physiological knowledge of the eye with a Stoic philosophy of vision. It is not necessary for our purposes to go into greater details. It should be pointed out that all the theories except that of the atomists involved the presence and active involvement of light although the visual rays were not simply light rays.

Ibn al-Haytham argued philosophically very strongly against extramission and for intromission whilst at the same time demonstrating that an intromission theory could successfully be combined with the geometric optics of Euclid. At the same time he integrated the theory of al-Kindi that light reflects in all directions from all points of a viewed object arguing that only light rays are involved in vision. His theory of vision was thus a clever synthesis of several different theories into a coherent whole and thus a major advance in the understanding of optics.

He accurately described the mechanism of sight and the anatomy of the eye.

Ibn al-Haytham adopted Galen’s description of the anatomy of the eye and added nothing to it. His theory of vision was defective in that he like Galen believed that vision takes place in the lens of the eye and not as Kepler correctly surmised on the retina. Because of this major defect in his theory Ibn al-Haytham was forced to develop an erroneous theory that only rays falling perpendicularly onto the lens of the eye were perceived. Otherwise the eye would perceive multiple images of the object. In reality the lens focusing all the rays no matter from which angle creates just one image on the retina.

He experimented with mirrors and lenses

Ibn al-Haytham describes a limited number of experiments to demonstrate that light in propgated in straight lines, something that nobody had doubted since Euclid at the latest. To what extent these were actual experiments or just thought experiments is disputed amongst the experts.

In his spare time, he built the first camera obscura.

The principle of the camera obscura was already known to Aristotle and even earlier to the Chinese scholar Mo-Ti in the fifth century BCE who referred to it as the locked treasure room.

Ms Toler discovered her enthusiasm for Ibn al-Haytham as she tells us through reading a popular book on Islamic science.

Modern physicist Jim al-Khalili, in his excellent The House of Wisdom: How Arabic Science Saved Ancient Knowledge and Gave Us the Renaissance, calls Alhazen the greatest physicist of the medieval world, and possibly the greatest in the 2000 years between Archimedes and Sir Isaac Newton. His Book of Optics was first translated into Latin in the late twelfth or early thirteen century. It had an enormous impact on the work of western scientists from Roger Bacon (c. 1214-1292) to Isaac Newton (1642-1727).

By pure chance I stumbled across a video of a public lecture that Jim al-Khalili gave earlier this year on the subject of his book. I’m not going to give a detailed analysis of this lecture as it contains enough errors to keep me in blog posts for at least a year. He seems to be of the opinion that because he is a physicist and was born in Baghdad that this qualifies him to write a book about the history of Islamic science. In the lecture he proudly tells us that he devoted all of eighteen months of his research time to researching this book. A. Mark Smith took fourteen years to research and write his annotated translation of the first three books of the Latin edition of Ibn al-Haytham’s Book of Optics but he is a mere historian and not a physicist. In his lecture al-Khahili gives a clear and explicit commitment to a Whig interpretation of the history of science and strong implied commitment to the great man theory; both of these have been rejected by real historians of science long ago.

A typical example of al-Khalili’s arrogant ignorance occurs in his lecture when he talks about the first use of place value decimal fractions in Arabic mathematics. First of all he apparently doesn’t know the difference between the decimal point and decimal fractions. He also doesn’t appear to know that the Babylonians were using place value fractions, albeit sexagesimal not decimal, a thousand years earlier. He then goes on to say that The Chinese developed decimal fractions about the same time as Arabic mathematicians “but we don’t know as much about them”! I hope he doesn’t make this statement within reach of the Needham Research Insitute. Al-Khalili appears to confuse his own ignorance of the history of science with the general state of the art.

Returning to the blog post we have the following statement:

Jim al-Khalili […] calls Alhazen the greatest physicist of the medieval world, and possibly the greatest in the 2000 years between Archimedes and Sir Isaac Newton.

None of the three scholars named above was a physicist in the modern sense of the word and as I’ve said in the past there is no such thing as “the greatest”.  Even if we ignore these criticisms al-Khalili’s statement would be a hopeless exaggeration. A much more sensible assessment of Ibn al-Haytham’s achievements is given by somebody who knows what he is talking about, historian of optics David C. Lindberg[2]:

Alhazen was undoubtedly the most significant figure in the history of optics between antiquity and the seventeenth century.

There is a substantial difference between the two claims most important, historically, Ibn al-Haytham’s influence stops with the new model of optics developed by Kepler.

As far as I can see without having read his book al-Khalili is a typical example of a scientist thinking because I’m an expert in my subject I can also write about its history without doing the groundwork. Writing history requires a different form of expertise to doing modern science and writing about the history of science requires a wide range of expertise that cannot be thrown together in ones spare time in eighteenth months if one is trying to write a survey of the scientific activity of a major culture over a period of something approaching a thousand years. To do so without first acquiring the necessary expertise results not in history but in a collection of anecdotes and clichés most of them inaccurate and many simply false.

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[1] What is the collective noun for historians? A heap? A huddle? A hysteria? I somehow feel it should be alliterative.

[2] This quote is taken from David C. Lindberg, Theories of Vision from al-Kindi to Kepler, which is a good source for anybody wishing to fill in on the history of optics that I only sketch above.

Reflecting the heavens

In the past I have written about the problems of deciding who actually invented the reflecting telescope and also about John Hadley the man who, about fifty years after Newton had made the first functioning reflecting telescope, finally succeeded in manufacturing them. Today I want to look at the greatest maker of reflecting telescopes in the eighteenth century, James Short who was born on 21 June 1710 (NS).

James Short

The orphaned son of a wright Short was destined for the Manse when he entered Edinburgh University in 1726 to study classics and divinity but fate in the form of mathematics professor Colin MacLaurin had another future in store for him. Inspired by MacLaurin’s lectures Short abandoned divinity for mathematics and astronomy. Recognising the young man’s talents MacLaurin allowed him to use his own rooms at the university as a workshop. Short began experimenting with the construction of reflecting telescopes in 1732.

After initial failures to construct mirrors of silvered glass Short perfected Newton’s metal mirror alloy, speculum, and began producing parabolic telescope mirrors. Whereas Hadley had gone for the relatively simply Newtonian telescope design with a parabolic main mirror and a plain secondary mirror

 A Newtonian Telescope

Short started making the much more complex telescopes according to the design of fellow Scotsman, James Gregory, with a parabolic main mirror and an ellipsoidal secondary mirror.

A Gregorian Telescope

Short perfected the art of grinding and polishing these difficult shapes and as this knowledge provided the source of his not inconsiderable success as a telescope maker he never revealed how he was able to do so. By 1734 he was manufacturing telescopes in several different sizes and according to MacLaurin they were far superior to those of his rivals. In 1735 MacLaurin informed the Royal Society in London of his achievements who then tested some of Short’s telescopes in 1736. In the same year Short was engage by the Queen to instruct her younger son William, Duke of Cumberland in mathematics. Shorts royal pupil would go on to become notorious as “Butcher Cumberland” following the Battle of Culloden. In 1737 Short was elected as a fellow of the Royal Society. Also in 1737 Short became a founding member along with MacLaurin of the Philosophical Society of Edinburgh. Short had manufactured 180 telescopes in Scotland before he left to set up shop in London in April 1738. He left Scotland already established as a leading instrument maker and as a wealthy man.

A Short Reflector

Short quickly became established in London, then the leading European centre for the manufacture of scientific instruments, or as they were known then, philosophical instruments. Short was on friendly terms with all of the leading London instrument makers but in one thing he differed strongly from all his friends and competitors. Whereas Shorts friends all had specialities, John Bird for example was famous for his wall quadrants, George Graham for his clocks and John Dollond for his refracting telescopes, all of them ran large workshops in which they and their employees produced a wide range of instruments of many types; Short however only produced reflecting telescopes and with few exceptions they were all Gregorians. Short was a specialist and although his instruments were on average twice as expensive as those of his rivals he became the leading European maker of reflecting telescopes. His largest, and most expensive, instrument was an eighteen-inch aperture reflector for the King of Spain, which cost £1200. To put this into perspective an assistant astronomer at the Royal Observatory in Greenwich earned £30 p.a. at this time. Short also constructed a large reflector for the observatory in Uppsala, which brought him the rare distinction of a foreign membership of the Swedish Royal Academy of Science in 1758. Despite his financial success Short obviously valued such honours and titles because he applied for and received an MA degree from the University of St. Andrews in 1753.

Short was not just a maker of telescopes but also a respected astronomer who regularly published reports of his observations in the Philosophical Transactions of the Royal Society. He also calculated the size of the astronomical unit based on the results of many of the observations of the transit of Venus of 1761, many of these observations being made with Short’s own instruments. These calculations led to a bitter dispute with the French astronomer Alexandre Guy Pingé (1711 – 1796) whose results differed substantially from those calculated by Short. Short accused Pingré of having messed up his observations and Pingré countered by accusing Short of having screwed up his calculations. The dispute rumbled on in varies journals and pamphlets until Short’s death in 1768. In the end history would prove Short half right. Pingré’s observations had been good but his determination of the longitude of his observation position was wrong. Short was also heavily involved in the preparations for the 1769 Venus transit supplying telescopes for many of the European expeditions, including the instruments used by Green and Cook on Tahiti but did not live to witness the event himself.

Short was also involved in the British efforts to determine longitude at sea serving on the parliamentary committee to organise the sea trials of John Harrison’s H4 conducted by Charles Green and Nevil Maskelyne in 1763. Short was a close fried of Harrison’s a friendship that supposedly cost him the job of Astronomer Royal. Harrison appears to have suffered from some form of dyslexia or dysgraphia and had great difficulties formulating written applications for grants etc. Short is known to have helped him write his petitions to the Board of Longitude. In 1763 an anonymous printed pamphlet appeared in London praising Harrison’s achievements and criticising his treatment by the Board. Rumour had it that Short was the author of the pamphlet, a rumour that purportedly led Short’s patron Lord Morton, then President of the Royal Society, to oppose Short’s candidature for the position at Greenwich in 1764, although he acknowledge his superior qualifications for the job. Short’s criticisms of the quality of the Greenwich observations also probably played a role in the story.

Short’s restriction of his workshop to only making Gregorian telescopes was not his only unusual practice as an instrument maker. Usually the instrument makers made all of the parts for their instruments, lenses or mirrors, cases, and stands in the case of telescopes, in their own workshops; Short did not. Short only made the mirrors for his telescopes himself, farming the rest of the work out to other craftsmen and then assembling the finished product before selling it to the customer. His workshop practices were also fairly revolutionary. He is thought to be one of the first telescope mirror makers to use optical methods to control the grinding and polishing of his mirror. Using beams of light reflected from the surface being worked to control the curvature. He also produced his mirrors in batches and then paired main and secondary mirrors out of the batches to find the best combinations turning the mirrors as well around their central axis to find the best positions for optimal magnification. Once this had been determined he marked the mirrors so that it was possible to dissemble and reassemble the telescope without loss of quality. This careful personal attention to detail was the key to Short’s immense commercial success.

Having outlined Short’s working methods I would like to correct an error in Jenny Uglow’s excellent Lunar Men:The Friends Who Made the Future. In 1755 the nineteen year old James Watt, he of steam engine fame, travelled down from Scotland to London to learn the trade of philosophical instrument maker. He carried with him a letter of recommendation to James Short written by Dr Robert Dick, professor of natural philosophy at Glasgow College. Uglow claims that Short refused to help Watt and turned him away. This is not true. With his very narrow specialisation Short could not offer Watt the type of general apprenticeship that he was looking for. He did however pass him on to another philosophical instrument maker, John Morgan, who could and did give Watt what he was looking for.

Short was in the habit of carefully numbering the instruments that he made so we know that he manufactured at least 1370 telescopes before he died leaving a fortune of £20 000. One great irony of Short’s highly successful career is that although he made so many high quality telescopes that travelled all over the world and of which many still exist today, no major astronomical discoveries were made with a Short.

The story of a problem

Some days ago mathematician John D Cook of the Endeavour blog posted the following mathematical problem from the 15^th century.

In 1471, Johannes Müller asked where you should stand so that a vertical bar appears longest.

To be more precise, suppose a vertical bar is hanging so that the top of the bar is a distance a above your eye level and the bottom is a distance b above your eye level. Let x be the horizontal distance to the bar. For what value of x does the bar appear longest?

Note that the apparent length of the bar is determined by the size of the angle between your lines of sight to the top and bottom of the bar.

 At the same time he sent me an email asking if I knew whether Müller had solved the problem himself and if so what his solution was. Now Johannes Müller is nowadays much better known as Regiomontanus and although I am considered something of an expert for the life and work of Franconia’s greatest 15^th century mathematicus I had to honestly answer John’s enquiry with a resounding no, I don’t know. Although well aware of Regiomontanus’ prowess as a mathematician I have always been more interested in his activities as an astrologer, his achievements with his teacher Peuerbach in setting the astronomical revolution in motion and his activities as the world’s first scientific printer publisher. However I was intrigued by John’s question, which as he pointed out seemed to require a solution using calculus a couple of hundred years before it was invented, and set about finding the answer. My first step was to order all the relevant literature that I could find from the university library and through inter-library loan and as I type there is a literally one metre high stack of books next to my computer all of which are dedicated to the life and work of Herr Müller or contain papers on the same. Where to look? (Any reader wishing to know more details about Regiomontanus’ life should follow the links to earlier posts where they will find most of the details)

Now the only mathematical, as opposed to astronomical, book that Regiomontanus wrote was his trigonometry textbook, which was published posthumously about sixty years after his death,[1] so where to look for mathematical problems of the type posted by John Cook? The answer is to be found in his correspondence. During the four years that he spent in Italy, 1461 – 1465 in the entourage of Cardinal Bessarion Regiomontanus made the acquaintance of many of Italy’s leading mathematicians with whom he then corresponded when he moved on. Parts of his correspondence with Paolo dal Pozzo Toscanelli (1397 – 1482) doctor of medicine and Florence’s leading mathematician, the Ferrara professor of mathematics and court astrologer to Leonello d’Este, Marquis of Ferrara, Giovanni Bianchinni, and Jacob of Speier court astrologer to the Duke of Urbino still exist. Toscanelli and Bianchini had also been friends of Peuerbach. In these letters Regiomontanus challenges his correspondents to proffer solutions to long lists of complex and challenging mathematical problems. Such challenges were fairly common throughout the Early Modern Period. The most well know examples being the various challenges involving Tartaglia and the solutions of the cubic and bi-quadratic algebraic equations. Even at the end of the 17^th century the various mathematicians involved in the invention of the calculus challenged each other to solve difficult problems to prove their prowess in the new discipline. Most famous is the so-called brachistochrone problem posed by Johann Bernoulli, which according to his niece, Catherine Barton, Isaac Newton solved between supper and going to bed. Although his solution was submitted anonymously Bernoulli recognised it as Newton’s remarking, “as the lion is recognised from his print, but back to Johannes Müller. John’s problem is not in the surviving Italian letters so what now.

There is one more letter written by Regiomontanus containing a list of thirty-eight problems and it is here that the original of John’s problem can be found. After several years in Hungary Regiomontanus settled in Nürnberg in 1471 with the intention of reforming the whole of astronomy. Now even he realised that he would not be able to achieve this task alone and so he cast around for potential partners. His first choice fell on the Erfurt University professor of mathematics Christian Roder and it is the letter that he wrote in 1471 trying to win Roder for his project that contains the problem. The original problem is slightly different to the one John posted and reads as follows:

A ten-foot pole hangs vertically so that its lower end is four feet off the floor. Find the point on the floor from which the stick appears longest, or, as there are infinitely many such points that lie on a circle, find the diameter of the circle.[2]

Apart from being a somewhat tricky mathematical problem it is also interesting in that it is actually a problem out of the geometrical optic. The solution invokes Euclid’s fourth postulate of geometrical optics:

That things seen under a larger angle appear larger, those under a smaller angle smaller, and those under equal angles equal.[3]

The first lectures that Regiomontanus held as a freshly baked Magister Artium at the University of Vienna at the tender age of 21 were on geometrical optics a standard course in the scholastic university since Robert Grosseteste had made the metaphysics of light the central pillar of his natural philosophy in the 13^th century.

Unfortunately Regiomontanus does not offer us a solution to his problem but the addition of the information that the point lies on a circle, which must be tangential to the floor lead almost automatically to the solution offered by Pat Bellew and lvps1000vm at Endeavour, which is also the solution that was reconstructed for the problem at the end of the nineteenth century independently by both of the German historians of mathematics Moritz Cantor[4] and Sigmund Günther.[5] All of the surviving letters between Regiomontanus and Jacob of Speier, Bianchini and Roder were edited and published in the original Latin by Maximilian Curtze.[6]

 

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[1] Ioanis de Regio Monte, De triangulus omnimodis, ed. Johannes Schöner, Johannes Petreius, Nürnberg, 1533

[2] Quoted from Ernst Zinner, Regiomontanus: His Life and Work, trans. Ezra Brown, North-Holland, Amsterdam etc., 1990 p. 106

[3] Quoted from David C. Lindberg, Theories of Vision: From al-Kindi to Kepler, University of Chicago Press,  Chicago, 1976, p. 12

[4] Moritz Cantor, Vorlesung über Geschichte der Mathematik, Zweite Band Von Jahre 1200 bis zum Jahre 1668, 2 Aufl. 1900, Johnson Reprint Corp, New York, 1965, p. 283

[5] Sigmund Günther, Geschichte der Mathematik, 1. Teil, Leipzig, 1908, pp. 302f.

[6] Maximilian Curtze, Urkunden zur Geschichte der Mathematik in Mittelalter und der Renaissance, B.G. Teubner, Leipzig, 1902, pp 185 – 336.

James Gregory did not invent the reflecting telescope.

Yesterday, 6^th November, was supposedly the birthday of the 17^th century Scottish mathematician James Gregory; his exact birthdate appears not to be known. My Internet friend Pat Ballew of the excellent history of maths Pat’s Blog posted the following tweet on twitter, “1638 James Gregory born Scottish mathematician, astronomer and inventor of the reflecting telescope.” This statement is fundamentally wrong concerning the reflecting telescope in the same way that statements about Gregory’s contemporaries Isaac Newton or Laurent Cassegrain as the inventor of the reflecting telescope are wrong. Now the three most common forms of the reflecting telescope are the Gregory, the Cassegrain and the Newtonian, named after James, Laurent and Isaac respectively, so why do I say that the claims about them as inventors are wrong? The answer is very simple and lies in the use of the definite article. Neither Newton nor Gregory nor Cassegrain invented the reflecting telescope all of them invented a reflecting telescope, a small but important difference.

Now it might be argued that the one who was first is entitled to say that he invented the reflecting telescope but even this would not be correct. Gregory published his design for his reflecting telescope in 1663 but failed in his attempts to produce a working model of his device. Newton produced the earliest known function model of a reflecting telescope in about 1668, presented one to the Royal Society in 1671, which led to his election to that august body and published a paper describing his design in the Philosophical Transactions of the Royal Society in 1672. In the same year Jean-Baptiste Denys published a letter in a French journal claiming that Cassegrain was the first to design a reflecting telescope much to the annoyance of Newton. All three designs were distinctively different and Newton’s was the only one of which a working model existed, although it would be more that fifty years before John Hadley succeeded in producing working copies of Newton’s telescope and would then go on to do the same for the Gregorian. It would be quite late in the 18^th century before working models of the Cassegrain were produced.

Now one could argue for Newton as the inventor of the reflecting telescope as he produced the first functioning example of one but there is no denying that Gregory and possibly Cassegrain preceded him with the concept of the reflecting telescope. However if one were to take the concept rather than the realisation as criterion then none of our 17^th century trio would take the laurels, as the concept has a long history stretching back to at least the 1^st century CE.

The earliest known presentation of the optical principle of the reflecting telescope can be found in the catoptrics of the 1^st century Alexandrian mathematician, engineer and inventor Hero. He clearly demonstrates the fact that a concave parabolic mirror focuses parallel rays reflected from its surface at a point, creating an image. In our times one can see Hero reflecting telescopes on the roofs and balconies of numerous buildings in all of the towns and cities of the world in the form of television satellite dishes. This telescopic property of parabolic mirrors was well known to Leonardo who discusses it in one of his unpublished manuscripts. In the early 17^th century, after the introduction of the refracting or lens telescope, the Jesuit mathematician and friend of Galileo Niccolò Zucchi constructed a simple reflecting telescope with a bronze mirror in 1616 but was unable to construct and polish his mirror accurately enough to produce a usable image. In fact Zucchi’s failure illustrates the major problem in the construction of reflecting telescopes. Mistakes in the curvature or surface of the mirror distort the image to the point of uselessness with a factor of six greater than similar errors in the polishing of lenses. It is a mark of Newton’s abilities as a technician and craftsman that he succeeded in constructing and polishing a functioning mirror. Around 1640 Marin Mersenne also published several designs for reflecting telescopes but never tried to realise them, probably because he was aware of the technical problems involved.

I hope you can see from my very brief outline of the history of the reflecting telescope that claiming one individual as the inventor is to say the least problematic, not least because one first has to decide if the originator of the concept or the producer of the first working model is actually the be considered the inventor, and as a historian it is preferable to refer to the originator of one or other of the various models as an inventor of the reflecting telescope.

Upon reflection: The Hadley brothers.

This is not a post about a circus act, a Canadian punk band or a boy band from Tulsa, Oklahoma.  John (1682 – 1744), George (1685 – 1768) and Henry Hadley (1697 – 1771) were three mathematical inclined gentleman scholars active in England in the first half of the 18^th century. This is really a post about John but as he states quite clearly in his publications that George and Henry were actively involved in the realisation of his two major contributions to the histories of science and technology I thought it only fair that they should also be mentioned at least at the beginning of this article. In reading up for this piece I also discovered that George made a major contribution to the history of meteorology, which I will briefly sketch at the end.

The three were the sons of a wealthy landowner George Hadley who owned properties throughout the Home Counties as well as a town house in Bloomsbury Square in London although it appears that the family seat was in East Barnet in Hertfordshire of which county George senior was a deputy-lieutenant and in 1691 High Sheriff.

John Hadley

John, the first born, was according to his father born, “16 April 1682, just half an hour past nine, before noon, Sunday, Easter-day; christened the 21^st, by Dr. Sharp Dean, of Norwich; sponsors, Sir Harry Fitzjames, John Huxley, Esq., and Lady Fitzjames.” (Sharp would later become Archbishop of York). This should give a flavour of the circles in which John moved. Nothing is known about his education and he appears not to have attended university. According to the Newtonian physicist Desagulier he invented and was granted a patent for some sort of water lift for mill wheels sometime between 1700 and 1710. In 1717 he was elected to the Royal Society and attracted notice by commenting in the Philosophical Transactions on the work of Bianchini and Maclaurin, which shows that he had a high level of mathematical knowledge. It was in 1721, however, that he made the first of two technological contributions that were to establish his fame.

 Isaac, John and the Reflecting Telescope.

It is wrong to state, as is often claimed, that Isaac Newton invented the reflecting telescope. The basic principle behind this instrument, that a concave parabolic mirror focuses parallel beams of light falling onto its surface at a single point, thus forming an image, can already be found in the catoptrics of Hero of Alexandria in the 1^st century CE and the same phenomenon is discussed in the works of Leonardo da Vinci. The Jesuit astronomer Niccolò Zucchi, a contemporary and friend of Galileo attempted to build one in 1616 and the Scottish mathematician and physicist James Gregory published the design of what is now known as the Gregorian telescope in 1663. Between the attempts of Zucchi and Gregory the polymath Marin Mersenne also published designs of several different models of reflecting telescope. Both Zucchi and Gregory stumbled over the difficulties of grinding and polishing a mirror for their telescopes; Mersenne apparently aware of the problems didn’t even try. It is six times more difficult to grind and polish a telescope mirror than a telescope lens and the errors produced in this procedure meant that the instruments of both Zucchi and Gregory were useless. It was Isaac Newton who in about 1666 first succeeded in producing a functioning reflecting telescope, which became his entry ticket to the Royal Society and the world of science. Newton’s telescope was very small, scarcely more than a toy, although it had a magnification factor of forty, and for the reflecting telescope to become practical it was necessary for somebody to scale up the mirror and telescope, all attempts to do so failed miserably; enter John Hadley.

In 1721 John Hadley succeeded where all others had failed and produced a comparatively large scale functioning Newtonian reflecting telescope, which he presented to the Royal Society whose President was of course Sir Isaac himself. This instrument was tested against the 120-foot (focal length) refracting telescope in Wanstead, a present to the Royal Society from Huygens, and found to be superior and so introduced the age of the reflecting telescope. Hadley also went on to build a functioning Gregorian telescope and more importantly was able to teach his method of grinding and polishing to the leading instrument makers of the time enabling the serial production of reflecting telescopes. Important though this breakthrough was, and it should be remembered that most of the important astronomical telescopes since then, including Hubble, have been reflecting telescopes, Hadley would go on to produce a second possibly even more important invention.

 John Hadley (almost) invented the sextant.

One of the few scientific instruments that has, largely thanks to Hollywood, become a household name is the sextant. It serves as a guarantee of authenticity in movies about the sea to have the captain or first officer of a ship shoot the sun at noon in order to establish the ships latitude.

When we see this scene on the big silver screen we know we are in the hands of real sea dogs. This ritual is of course carried out using a sextant that instantly recognisable insignia of the navigator. John Hadley is credited with the invention of the sextant in 1731. It should be pointed out that the American glazier Thomas Godfrey invented an almost identical instrument in the same year a coincidence that led both men to being accused of intellectual theft by the supporters of the other. In fact the inventions were genuinely independent of each other but because it was Hadley’s instrument that went on to change history he is given the major share of the recognition as inventor. This attribution is slightly incorrect as Hadley’s original instrument was actually an octant and not a sextant and is confusingly often referred to as Hadley’s quadrant. I shall come to the story of how Hadley’s instrument became a sextant shortly but first we need to take a sort look at the history of navigation in the couple of centuries preceding Hadley’s invention.

It is a fairly easy task to determine ones latitude by measuring the altitude, that is height above the horizon, of either the pole star or the sun and then making some routine mathematical calculations. In the European history of navigation this was not done before the 15^th century because seamen’s charts were not drawn with a latitude and longitude grid. This practice first came in after the rediscovery of Ptolemaeus’ Geographia in 1406. In fact using latitude determinations in sailing only began to become established in the 16^th century and then only very slowly. At first altitudes were determined with a Jacob’s Staff an instrument   first described by the French Jewish astronomer Levi ben Gerson in the 14^th century. This instrument had the disadvantage that the sailor doing the measuring was required to stare directly into the sun, which even with the use of a dark glass filter was not very healthy.

Using a Jacob’s Staff

In 1594 an English seaman John Davis invented the back staff, or as it was commonly know the Davis quadrant, an instrument with which the navigator stood with his back to the sun and a vane cast a shadow onto the measuring scale thus sparing the user the necessity of looking directly into the sun.

Simple Backstaff or Davis Quadrant

The next stage in the development was the invention of single reflecting instruments of which several prototypes were produced at the end of the 17^th century, by Robert Hooke amongst others in which the image of the sun was reflected onto a measuring scale with a mirror. We are now ready for Hadley’s quadrant.

Hadley’s quadrant is a so-called double reflecting instrument here a small telescope is focused on the horizon through a half mirrored glass plate the mirrored half displaying an image of the sun reflected from a second mirror pointing behind the observer thus allowing the user to observe the horizon and sun simultaneously, the principle of the sextant.

Hadley’s Octant

Hadley’s instrument was only an octant because its measuring scale was only an eighth of a circle but because the readings are doubled creating the illusion that the scale is a quarter circle the instrument became known as Hadley’s quadrant. Although I have introduced the subject by talking about altitude measurements in navigation Hadley’s quadrant was originally conceived to make a completely different navigational measurement and in fact played a pivotal role in a much more difficult task the determination of longitude.

 Hadley’s quadrant, the sextant and the lunar distance method.

Regular readers of this blog and the Board of Longitude Blog will be well aware that the most pressing problem in navigation in the 18^th century was the determination of longitude aboard ship. On land the problem had been largely solved by cartographers but their methods were not practicable on the rolling deck of a ship. Although not the only methods under consideration the two main competitors were the clock method first proposed by Gemma Frisius and the lunar distance method first proposed by Johannes Werner. Both methods depend on comparing local time with time at a known point elsewhere and then determining the time difference and thus the difference in longitude. The clock method depending on a clock carried on the ship displaying the time of the given distant point and the lunar distance method depending on accurate tables of the time of occurrence of astronomical phenomena, i.e. the distance of the moon from a given star, at the given distant point and comparing the time when the phenomena occur locally. In the 18^th century nearly everyone doubted that anyone could build a clock that would remain accurate enough under the strenuous conditions of sea travel and so nearly all the leading astronomers backed the lunar distance method. This method, however, suffered from three major problems: 1) there existed no tables of the lunar orbit accurate enough to be used for this method, 2) there existed no table to correct for a whole collection of distorting factors that I wont go into here and 3) there existed no instrument capable of determining the lunar distances to the necessary accuracy of ± 1 minute of arc (astronomical and navigational distances are determined in degrees of separation). In the middle of the 16^th century the French mathematicus Jean Rotz determined his longitude in the Atlantic Ocean west of Dieppe using a Jacob’s staff and the lunar distance method. The inherent inaccuracies of his instrument led him to an answer of 150 degrees and 30 minutes west of Dieppe, which would have had in the Pacific Ocean heading towards the International Date Line!

The solution to the problem of instrument accuracy was Hadley’s quadrant and he actually presented it to solve exactly this problem. His first instrument was subjected to a trial on the yacht Chatham under the supervision of Hadley himself, his brother George, the somewhat aged Astronomer Royal Edmond Halley and his successor the astronomer James Bradley. The instrument despite being new and the testers unskilled in its use preformed excellently and the first step had been taken along the road to the realisation of the lunar distance method. What were now necessary were accurate lunar tables and these were supplied by the German astronomer Tobias Mayer who sent them to the Board of Longitude in the 1750s. Mayer was convinced that the problem lay, not as had long been supposed in an inadequate lunar theory, but in inaccurate observations and equally inaccurate calculations both suppositions he proved right with his own diligent work. It was clear to him that for the lunar distance method to work the shipboard measurements would also have to be highly accurate and so he conceived a new measuring instrument, based on surveying instruments, called a reflecting circle. He sent drawings and a model of his new instrument along with his tables to the Board. James Bradley now Astronomer Royal recommended testing Mayer’s tables and a London instrument maker was commissioned to construct his reflecting circle.

Reflecting circle (not from Mayer)

This instrument together with the tables were tested by Captain John Campbell who found them to function well he however compared the readings of Mayer’s instrument with those made with his Hadley Quadrant. The quadrant proved to be as accurate as Mayer’s circle and because it was already established and being smaller easier to use than Mayer’s instrument it became the recommended instrument for the lunar distance method. However Campbell found some advantage in the 360° scale of the Mayer circle and so he had an instrument maker produce a double reflecting instrument with a sixth of a circle scale, as opposed to Hadley’s eighth, giving him because of the doubling effect 120° and so the sextant was born. Not long after mariners were able to determine longitude using the Campbell/Hadley sextant and Maskelyne’s simplified version of Mayer’s tables (Maskelyne simplified the calculations necessary by pre-calculating the steps between measurement and determination).

As I said at the beginning John Hadley explicitly credited his brothers George and Henry with the realisation of his two groundbreaking optical instruments so one should also give them credit along with John for these achievements. However George established his own scientific reputation in a completely different field and it is to his work that I will now briefly turn.

 The Hadley Cell 

Unlike John who inherited the family fortune George earned his living as a lawyer but like his elder brother he was interested in things natural philosophical and like his brother, who in the meantime had become a vice president of that august body, he became a member of the Royal Society in 1735. His main interest was in meteorology and he became responsible for handling the societies meteorological correspondence. One of the open questions of the age was the cause or origin of the so-called trade winds that were so vital to trans-Atlantic sailing George provided the first largely correct answer in that the winds are a product of the temperature gradient between the equator and higher or lower latitudes and the earth’s rotation. In recognition of this important achievement in the history of meteorology the section of the globe in which the trade winds are generated is called a Hadley Cell. This is a Hadley Cell and not the Hadley Cell because as well as for the earth the Hadley Cell for Venus has also been determined something that George Hadley almost certainly never imagined.

Next time you are contemplating significant 18^th century natural philosophers alongside the Newtons and Halleys, the Watts and the Huttons, the Priestleys and the Lavoisiers spare a thought for the Hadley Brothers who also made some not insignificant contributions.

Teleskopos: How the telescope got its name

My Whewell’s Ghost sister in spirit Rebekah “Becky” Higgitt has left the safe haven of our collective history of science blog and set up shop under the sign of the “Teleskopos”. As she herself writes:

A word on the name of the blog. It is, of course, all fancy-shmancy Greek for telescope. Since I work within an historic observatory, researching its heritage and curating some of its telescopes, it seems fair enough, although I will not be sticking to history of instruments or astronomy. There will also, probably, be very little Greek science, but I liked teleskopos because it clearly shows the etymology: ‘far-seeing’. If an astronomical telescope looks back through time as it peers into space, I hope my own little ‘perspective glass’ will facilitate some sort of view on the past.

In this brief passage she manages to mention three of the names for the telescope, Greek original (to which more in a minute), English translation and the alternative English expression ‘perspective glass’. In the following I shall sketch the historical events that led up to a simple tube with two lenses acquiring the, to quote Becky, ‘fancy-shmancy’ Greek name teleskopos.

In the first historical record of the telescope, a letter of introduction for its inventor, Hans Lipperhey, from the Councillors of Zeeland to the States General in Den Hague, this wonderful invention that would revolutionise astronomy had no name and was referred to as “a certain device, by means of which all things at a very great distance can be seen as if they were nearby, by looking through glasses…” Not exactly a phrase that rolls off the tongue. In the first printed account of this new invention, a French pamphlet reporting on the visit of the Siamese Ambassador to the Court of Prince Maurice of Nassau during which the telescope was first demonstrated in public, it is just referred to as ‘lunettes’ the French for glasses leading to a possible confusion with ordinary eye glasses or spectacles.

In the early phase of its existence the new instrument acquired the Latin name perspicillum the origin of both the English perspective glass and the spyglass well known to all lovers of novels about seamen and pirates who are all equipped with their spyglasses.

The first telescopic astronomer the English polymath Thomas Harriot when corresponding with his friend and pupil Sir William Lower referred to the new Dutch invention as a perspective trunk. His German contemporary the court astronomer in Ansbach, Simon Marius, writes of an ‘instrumentum belgicum’ commonly called perspicillum. The third of Europe’s pioneering telescopic astronomers Galileo Galilei varies between instrumento, perspicillum and the Italian for glasses, occhiale.

In 1610 when Galileo first published his telescopic discoveries in his Sidereus nuncius he was a 46-year-old North Italian mathematics professor and instrument maker well on the way to obscurity. He enjoyed a good local reputation in a fairly low-grade profession, had no notable publication to his name and had made no significant academic discoveries. If his life had continued along the same lines he would probably have died a fairly insignificant Renaissance scholar but the Sidereus made him an international star over night. The honours followed in quick succession. A life-time contract in Padua with a vastly increased salary, which he dropped in favour of the position as Medici court philosopher for even more money. This was followed by a triumphal journey to Rome where he was honoured at a banquette at the Collegio Romano by the Jesuit mathematicians in 1611. On 14th April of the same year he was guest of honour at a far more prodigious banquette thrown by Prince Frederico Cesi founder and president of the Academy of the Lynxes an exclusion society dedicated to scholarly pursuits to which Galileo would be appointed as a member eleven days later. At this banquette Cesi gave the Dutch instrument that was responsible for Galileo’s rise to fame the name teleskopos, coined by one of the other guests, John Demisiani the Greek court mathematician of the Duke of Gonzaga. The name stuck and became telescopium in Kepler’s Latin, telescopio in Galileo’s Tuscan and telescope in English.

Becky has chosen a name for her blogdrenched in the history of science, a discipline in which she excels, and I wish her at least a part of the longevity and success of Lipperhey’s “certain device, by means of which all things at a very great distance can be seen as if they were nearby, by looking through glasses…”

A Croatian Polymath

I devote a certain amount of time and effort on this blog to countering the popular misconception that the Jesuits functioned as a sort of theological Sturmtruppe leading the offensive against modern science in the name of the Pope in the Early Modern Period, as I have pointed out in several earlier post exactly the opposite is true. The Jesuits as the best educated and most intellectual monastic Apostolic order in the Catholic Church actually made many significant contribution to the evolution of the modern sciences in this period and any list of the Jesuit and Jesuit trained and educated scientific researches is impressive by any standards. One of these was the leading figure in the science of the 18^th century the Croatian¹ Jesuit polymath Ruđer Josip Bošković (English: Roger Joseph Boscovich) who was born in Dubrovnik 300 years ago on 18^th May 1711.

Boscovich was an astronomer, physicist, mathematician, geodesist, philosopher, theologian, poet and diplomat whose influence on the development of the mathematical science was immense. Major conferences and exhibitions to celebrate this anniversary are planned in both in the land of his birth Croatia and Italy where he worked for most of his life.

Boscovich was initially educated in the Jesuit academy in Dubrovnik and moved to Rome where he joined the order at the age of 14. He was educated at the Collegio Romano in mathematics and physics and in 1740 became professor for mathematics at his alma mater.

Over his long life Boscovich wrote and published 70 papers on optics, astronomy, gravitation, meteorology and trigonometry as well as devising a method to strengthen the dome of St. Peter’s in Rome, which was in danger of collapsing, and contributing to the production of an accurate map of the Papal States. He observed a transit of Mercury in 1743 and in 1759 he travelled to London, via Paris, where he was made a member of the Royal Society. In 1761 he took part in an expedition to Istanbul to observe the transit of Venus but due to delays on route too late for the event. He continued his travels to Russia where he was appointed to the Russian Academy of Science in St. Petersburg.

In 1764 he was appointed professor for mathematics in Pavia and director of the observatory in Brera. In 1769 he was invited by the Royal Society to lead an expedition to observe the transit of Venus in California however a Spanish Government ban of the Jesuit Order prevented his participation. The same church political movement against the Jesuits led to his moving to Paris in 1773 where the King provided him with a substantial pension to pursue his scientific work. He returned to Italy in 1783 where he died in 1787.

Boscovich made important contributions to spherical trigonometry, geodesy, optics and astronomy but his most important work was his Theory of Natural philosophy derived to the single Law of forces which exist in Nature, which combined Leibniz’ monad theory and Newton’s Principia and developed the theory of physical force and the atom concept. This work enjoyed five editions and was read widely and was highly influential on succeeding generations of scientists.

Boscovich made important contributions to the evolution of the sciences in the 18^th century and deserves to be much better known than he is and to be more widely honoured on this his 300^th birthday.

1) I have made Boscovich a Croat but both Italy and Serbia claim him as one of theirs and for the tens years that he lived in France he was a naturalised French citizen. As usual in such cases the argument has rumbled on for most of the last 200 years; my calling him a Croat is purely practical and if any reader prefers to see him as Italian, Serbian, French or simply European please feel free to do so.