Newsletter, November 2017
ISSN 1756-168X (Print) ISSN 2516-3353 (Online) Newsletter
No. 35 November 2017
Published by the History of Physics Group of the Institute of Physics (UK & Ireland)
ISSN 1756-168X
IOP History of Physics Newsletter November 2017
Contents
Editorial 2
Meeting Reports Chairman’s Report 3 Rutherford’s chemists - abstracts 5 ‘60 Years on from ZETA’ by Chris Warrick 10
Letters to the editor 13
Obituary John W Warren by Stuart Leadstone 15
Features Anti-matter or anti-substance? by John W Warren 16
A Laboratory in the Clouds - Horace-Bénédict de Saussure
by Peter Tyson 18
On Prof. W.H.Bragg’s December 1914 Letter to the Vice-
Chancellor of the University of Leeds
by Chris Hammond 34
Book Reviews Crystal Clear - Autobiographies of Sir Lawrence and Lady Bragg
by Peter Ford 54
Forthcoming Meetings 69
Committee and contacts 70
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2
Editorial
A big ‘Thank you’!
Around 45 people attended the Bristol meeting on the History of Particle Colliders, in April. It was a joint meeting between the History of Physics Group, the High Energy Physics Group, and the Particle Accelerators and Beams Group. With a joint membership of around 2000, that works out at well under 3% - and that was a good turnout. The Rutherford’s Chemists meeting held in Glasgow attracted probably a similar percentage - not very high you might think. But time and travel costs to attend come at a premium so any means by which the content of our meetings may be promulgated - reports in our newsletter and in those of the other groups - is a very worthwhile task.
Better still, though, is the publication of the talks themselves - however, not only worthwhile but a considerable undertaking for the speakers concerned. I am very pleased, therefore, to say that the group will be publishing a special issue next month comprising some of the talks given at both these meetings.
I am also very pleased to report that the meeting on the history of units held last year at the National Physical Laboratory, Teddington, is to be recollected in a book, ‘Precise Dimensions - a History of Units from 1791 to 2018’ published by the IOPP. It includes most of the talks given with the bonus of two other contributors writing on the mole and the candela.
It seems very appropriate here, to extend my heartfelt thanks to all our contributors - from the largest articles to the smallest - all are the very lifeblood of this newsletter and indeed the group as a whole.
Thank you!
Malcolm Cooper
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Chairman’s Report
Four meetings were scheduled for 2017; they have covered a wide range of areas of physics and have been co-hosted by a number of other organisations, both other groups of the IOP and those from further afield.
The first, on the History of Particle Colliders, was organised by Vince Smith and held in Bristol in April; it was a joint meeting between the History of Physics Group, the High Energy Physics Group, and the Particle Accelerators and Beams Group, with further sponsorship from the School of Physics at the University of Bristol. It focussed on the historical and political aspects of the design, construction and operation of the machines.
The first talk, by Giulia Pancheri of Frascati, discussed the work of the Austrian Bruno Touschek, who built a 15 MeV betatron with the Norwegian Rolf Widerøe during World War II, and was responsible for the first electron-positron storage ring in 1961. Philip Bryant from CERN then spoke on the CERN Interacting Storage ring and its legacy. In the afternoon, Peter Kalmus from Queen Mary spoke on The CERN proton- antiproton collider project, Sir Chris Llewellyn Smith on the genesis of the Large Hadron Collider, and Brian Foster from Oxford on future energy- frontier colliders.
The second meeting was held at Birmingham in June, and was a fairly short joint meeting of the History of Physics, Nuclear Physics, Nuclear Industry and Plasma Physics Groups of the IOP on Developments in Nuclear Fusion: 60 Years on from ZETA. From the strictly historical point of view, probably the most interesting talk was the first, given by Chris Warrick, Head of Communications at UKAEA, on ZETA itself and the subsequent developments in nuclear fusion. Kate Lancaster from York University gave a current account of inertial confinement fusion, while David Kingham from Tokamak Energy and Ian Chapman for the UKAEA gave fascinating account of the present work on tokamaks in the private and public sectors respectively.
In July there was a meeting on Rutherford’s Chemists organised in Glasgow by Neil Todd in conjunction with the Royal Society of Chemistry. During the meeting it might be suggested that a theme developed that the reputations of some of ‘Rutherford’s Chemists’ – in particular Frederick Soddy and William Ramsay, despite their Nobel Prizes - had suffered at the hands, not so much of Rutherford as of Rutherford’s biographers.
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The first talk, given by Pierre Radvanyi from Orsay, presented a study of the work of Marie and Pierre Curie, including the discovery of polonium and radium, and their studies of radioactivity. The rest of the first day was devoted to accounts of the work of Soddy. Linda Richards from Oregon State University presented a wide-ranging account of his ideas. This included a discussion not only of his scientific work, first with Rutherford and then with Ramsay and later on his own, on radioactivity, in particular covering the ‘displacement law’ and the identification of isotopes, but also his later social, political and economic ideas. David Sanderson from Glasgow presented a general account of Soddy’s work at Glasgow University between 1904 and 1914, during which much of his work on radioactivity was performed. Finally, at the evening reception, John Faithfull of the Hunterian Museum in Glasgow gave a talk on Soddy artefacts at the museum.
The next day, Finlay Stuart of the Scottish Universities Environmental Research Centre presented an account of the work of William Ramsay, in particular his Nobel Prizewinning discovery of the noble gases, and Neil Todd described the results of his radiological survey and gamma ray analysis of the laboratory notebooks of Soddy and Ramsay. Then in the final session, Ted Davis discussed the work of Bertram Boltwood, in particular his ideas on radio dating, and Dieter Hoffmann from Berlin described the work of Otto Hahn and also presented Siegfried Niese’s paper on Georg von Hevesy.
The last meeting of 2017, jointly sponsored with the Medical Physics and Magnetic Resonance Groups, was scheduled to be held in Nottingham in September. Unfortunately because of other meetings in magnetic resonance scheduled for the same day, the meeting was postponed until April 2018. It will be in memory of Sir Peter Mansfield, winner of the Nobel Prize for Medicine in 2003 for his invention of Magnetic Resonance Imaging (MRI), who died earlier this year. It will include talks on the history of Nuclear Magnetic Resonance (NMR) and MRI in Britain, and also a number of talks on the recent developments in MRI.
Andrew Whitaker
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Meetings
Rutherford’s Chemists, Glasgow, 15th/16th July, 2017
A two-day meeting, co-sponsored by the Institute of Physics and Royal Society of Chemistry, to celebrate the centenary of the second scientific revolution and a unique collaboration between physics and chemistry.
Pierre Radvanyi, Institut de physique nucléaire, Orsay, France.
Marie and Pierre Curie and the discovery of radioactivity
Prompted by the discovery of X rays by W.C. Röntgen, H. Becquerel investigated whether a very phosphorescent uranium salt did also emit X rays. In these experiments, in March 1896, Becquerel discovered what he called “uranic rays”. In the Fall of 1897, Marie Curie Sklodowska wished to prepare a PhD in science at the Sorbonne university (she would become the first woman in Paris to obtain such a degree). She decided to investigate if other chemical elements did also emit such “uranic rays”. Her husband Pierre Curie constructed the necessary apparatus. She looked also at uranium minerals and found surprisingly that these were more active than pure uranium. Marie and Pierre continued their searches together. In July 1898 they discovered polonium and in December 1898 radium, using a new physico- chemical method. The denomination “radio-activity” was introduced for the first time by Marie Curie. A number of questions were immediately raised by these discoveries. What were the properties of the rays emitted? Where does their energy come from? At this point at first E. Rutherford alone, then E. Rutherford and F. Soddy, joined in the quest to answer these questions. In the following years, Marie wished to separate pure radium and measure its atomic weight, which she succeeded in doing in 1910. Pierre devoted himself to its physical properties, and launched the first medical applications of radioactivity. He died early in a street accident in 1906.
Linda Richards, Oregon State University, Corvallis, USA.
Frederick Soddy - Transmutation in science and society
It is fitting Sir Ernest Rutherford and Frederick Soddy first met in a public debate over atomic matter, because Soddy was consumed by what mattered most about atomic energy, for good or ill. While it was Rutherford who received fame for the two men’s 1901-3 collaboration on disintegration theory, Soddy reached far beyond chemical and physical science to frame transmutation as a new kind of alchemy for
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6 mankind. Soddy felt imbued with a special responsibility, having been given a glimpse of how the atomic and chemical structure of the universe was determined. Unlike Rutherford, Soddy correctly anticipated (or perhaps he actually inspired?) a public concern that nuclear forces placed society at the precipice of abundance or destruction. Soddy began to abandon his nuclear research by 1919 and turned to the underpinnings of social structure, in the hopes of intervening in the economy in order to protect human rights and to end war. What mattered most to Soddy about atomic matter went far beyond chemistry and directed Soddy's trajectory into economics. Today Soddy is being resurrected as a de-growth economist with his anti-nuclear war clarion call. Similar in some ways to Linus Pauling’s ideas about the responsibility of the scientist, Soddy’s life can be a discursive rhetorical tool to help decipher the relationship between science and society.
David Sanderson, University of Glasgow, Glasgow, UK.
Frederick Soddy - The Glasgow years
Frederick Soddy was born in Eastbourne in 1877 and educated in Eastbourne College. After a year in Aberyswyth, he studied Chemistry in Merton College, Oxford graduating with first class honours in 1899. Travelling to Canada he was appointed demonstrator in Chemistry at McGill University (1900-1903), where, working in collaboration with Rutherford he developed the transmutation theory of radioactive decay. In London at UCL with William Ramsay (1903-1904) he showed that Helium was produced from the radioactive decay or radium. Following a Commonwealth Universities lecture tour of Australia, he moved to Glasgow as Lecturer in Inorganic Chemistry and Radioactivity. His time in Glasgow (1904- 1914) was highly productive and happy. He published 24 papers comprising original research and annual reviews of radioactivity for the Chemical Society. He was an eloquent lecturer, giving vividly illustrated public lectures on radioactivity, but also speaking publicly on broader scientific and social questions. During this period the nature of the radioactive decay series, displacement laws, the re-organisation of the periodic table of the elements from atomic mass to atomic number, were clarified. The concept of the isotope, for which Soddy received the 1921 Nobel Prize for Chemistry was cemented, and the term introduced to the scientific vocabulary in 1913. Soddy returned to Glasgow to lecture to student societies in the early 1950’s, and his contributions have been commemorated in the University by events in 1953, 1958, 1963, and in the isotope centenary year in 2013. This presentation will look at some of the Glasgow legacy of Frederick Soddy, including items from the so-called Soddy Box, and also his work on the atomic weight of lead derived from the decay of thorium.
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Finlay Stuart, Isotope Geosciences Unit, SUERC, East Kilbride, UK.
Sir William Ramsay: Chemical nobility
William Ramsay was born in Glasgow in 1852, and grew up in the shadow of the University. Although destined for a career in the church his interest in chemistry, developed while convalescing with broken leg acquired playing football, led to entry to University of Glasgow aged 14. After a Ph.D. in organic chemistry at University of Tubingen with Fittig, he returned to Glasgow University as assistant to the Professor of Chemistry in 1874. In 1880 he took a Chair in Chemistry at University College, Bristol. Here he established himself as one of the leading physical chemists of his generation as well as an expert in the design and use of apparatus for handling minute volumes of gases. In 1887 he was appointed head of general Chemistry at University College London, where he worked until his death in 1916. A meeting with the physicist R.W. Strutt (Lord Rayleigh) at the Royal Society in 1894 proved pivotal in Ramsay’s career. Within a year he had showed that sequential removal of N from air produced a progressively denser gas, eventually leading to the isolation of the inert gas argon, and the recognition that Mendeleev’s Periodic Table needed an extra column for the inert gases. Subsequent work led to the discovery of helium. In Summer 1898 his team undertook the mammoth effort of fractional distillation of 120 tons of liquified air, sequentially isolating and identifying the remaining noble gases; Ne, Kr and Xe. At the turn of the century Rutherford and Soddy discovered that Th produced minute quantities of a radioactive, inert gas. In 1903 he invited Soddy to UCL where they refined analysis techniques, then went on to demonstrate that He is a product of the spontaneous disintegration of radioactive substances - incontrovertible proof of the transmutation of elements. In late 1910 Ramsay’s group measured the atomic weight of Rn, completing column 8 of the Periodic Table.
Neil Todd, University of Exeter, Exeter, UK.
Radioactive contamination in the notebooks of F Soddy and W Ramsay
An account is given of a radiological survey and gamma ray analysis of the laboratory notebooks of Sir William Ramsay, held at the University College London archives, and of Frederick Soddy held in the Bodleian Library at Oxford. The Ramsay notebooks had previously been surveyed and four such notebooks were identified as being contaminated and held in a box separated from other material. Within the Soddy papers 46 notebooks were surveyed. The notebooks were initially scanned for residual radioactivity with a sensitive Geiger counter and the activities recorded. Selected items from both sets were further analysed by means of a NaI gamma-ray spectrometer for the purpose of radioisotope identification. Both the Ramsay and Soddy notebooks show significant contamination from the summer of
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1903 when they were working together at UCL on the production of helium from radium. Both also show later significant (>100 cps) contamination events, Soddy’s in 1905 and Ramsay in 1910. Within the Soddy papers documents which were not used to record experimental laboratory data did not show any contamination, with one exception (some press cuttings from the Times from 1903). The gamma-ray analysis indicated that all of the contamination was due to radium (Ra226). In conjunction with radiological data from buildings and apparatus, these data, as well as data from other surveys, it is argued, provide an insight into some key events in the history of science. Of particular interest is the transfer of technology developed by Ramsay and Soddy for manipulation of radium emanation to the Rutherford school at Manchester and the propensity for these methods to give rise to radioactive contamination.
Edward Davis, University of Cambridge, Cambridge, UK.
Bertram Borden Boltwood (1870 – 1927) - Radiometric dating and the age of the Earth
Extensive correspondence between Boltwood (at Yale) and Rutherford (at Manchester) started in 1904 and continued for twenty years. The letters reveal much about the man known to his friends as “Bolty’. He was clearly a very accomplished radiochemist and, as such, could supply Rutherford with experimental information and chemical insights that physicists were unable to. In addition, he is revealed as a kind and generous man, albeit with a wicked sense of humour. Historically he is known for his discovery of ionium, an element that was later shown to be an isotope of thorium (Th230). He is also credited with recognising that lead was the stable endpoint of uranium decay, which led him to suggest an important way of dating rocks by measuring the amount of lead they contained. Initial estimates for the age of the Earth based on this idea were on the scale of billions of years, in contrast to the millions of years proposed earlier by Lord Kelvin. Current values of the Earth’s age are obtained using an advanced version of this method involving measurements of the ratios of radiogenic lead isotopes in ocean sediments and basalts. Further investigation reveals that Boltwood’s contributions to science were considerably greater than these two achievements alone. I shall endeavour to identify these, as well as providing insights into his character, which might throw light on why his life ended so tragically.
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Dieter Hoffmann, Max Planck Institute, Berlin, Germany.
Otto Hahn – From new (radio)Elements to new Energy.
Otto Hahn came in 1905 as a young postdoc to Rutherford in Montreal, after a very sucessfull year at the institute of William Ramsay. There he had discovered a new radioactive element, the Radiothorium. This discovery, which were doubt by Rutherford and in particular by Boltwood, was the entre billet for Rutherfords laboratory in Monteral and the starting point of a very successful career as a radiochemist, which lead to the discovery of more radiolements – among them Radioactinium, which he discovered during his stay in Montreal. These discoveries not only gave reason of scientific acceptance and for a live long friendship by Rutherford, but it has also qualified Hahn as an excellent radiochemist. His high competence in the field enabeld him to carry out decades later the revolutionary experiments of nuclear fission during the winter 1938/39. Was Hahn one of the oldest chemists, who has joined Rutherford, so the physicochemist Paul Harteck belong to the very last one, who came in 1933 as a postdoc from Berlin to Rutherford. His aim was to learn there nuclear physics, following his conviction, that „the foreseeable future nuclear physics should open interesting and fundamental fields for a physical chemist.“
Siegfried Niese, Wilsdruff (Germany), Radiation Protection, Analytics & Disposal Inc.
Georg de Hevesy – Radioactivity and X-Rays in Manchester
The Nobel laureate Georg de Hevesy (1885-1966) studied physics and chemistry in Budapest, Berlin, and Freiburg where he defended his PhD thesis on the electrolysis of sodium hydroxide, followed by three years as assistant in Zurich and Karlsruhe, because he had planned to contribute to the development of a modern industry in Hungary. In 1912 he spent one year in Manchester to learn in Rutherford´s institute something about radioactivity. At the very creative atmosphere he learned new techniques and ideas, became interest in research work, and found friends like Moseley and Born. The year in Manchester was fundamental for his long successful scientific life with important discoveries physics, chemistry, geology, physiology and medicine. After training in radioactivity by Rutherford ´s assistant Geiger he determined the solubility of very short-lived actinium-emanation in liquids and the valences of radio-elements. When Rutherford asked him to separate RaD (210Pb) from inactive lead, like other chemist before, Hevesy was not successful, and he concluded that this radioactive element can be used as an indicator for the non- separable inactive lead in chemical processes, which in 1913 he demonstrated during a short stay in with Paneth in Vienna. Later he applied the indicator methods in physical chemistry and after the discovery of artificial radio-nuclides in biology, physiology and medicine.
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‘60 Years on from ZETA’ by Chris Warrick (UKAEA)
(from a seminar on nuclear fusion held on 14 June 2017 at the University of Birmingham.)
Report by Chris O’Leary for the Nuclear Industry Group Newsletter
Chris gave a wide-ranging, historical perspective on fusion research, starting with a discussion of the fusion processes of our nearest star, the sun. He then discussed the development of nuclear fusion research in the early twentieth century, taking-in the work on the Cockcroft-Walton accelerator at Cambridge in the 1930s; the ‘pinch’ experimental work by Peter Thonemann (who, incidentally, celebrated his 100th birthday on 3rd June this year) at the Clarendon Laboratory in Oxford and that of George Thomson and Alan Ware at Imperial College in the 1940s. This led to the work at Atomic Energy Research Establishment (AERE) Harwell.
The fusion research at Harwell took place in ‘Hangar 7’ (it had been an RAF airfield) and was classified due to the parallel research into its application to weapons; this is the location where ZETA began construction. There was ongoing dialogue with the US and a sharing of information on each other’s efforts at this time.
Chris spoke about the huge interest generated by the visit of Soviet Premier Nikita Krushcev and the famous nuclear physicist Igor Kurchatov in 1956 to Harwell, noting that Blackwell’s bookshop in Oxford changed its signage to Russian in celebration of the event and permission had to be given at the Prime Ministerial level by Churchill! There was much public focus on the UK’s energy research programmes at this time, not just for ZETA.
During the visit, Kurchatov spoke openly about the Soviet fusion programme and, from this, it was clear that they were at least level with UK and US efforts; he was keen to discuss their research and share what they were doing with the British researchers. The visit helped to declassify the work in the UK pertaining to controlled fusion research which was moved to another near-by site at Culham. It also led to a team of five scientists from Culham spending a six-month period in the Russian fusion research facility near Moscow, to help set up laser deflection apparatus. This mandated five Russians spending the same period in the UK.
Chris remarked on the large number people smoking pipes in the shots of ZETA and researchers, contrasting it with today’s health and safety
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11 regulations.
Chris highlighted the lack of diagnostic capability for ZETA and its counterparts, and how this made it far more difficult for the scientists working on the system compared to their modern counterparts, who can use high performance computers and full instrumentation.
Chris showed a video titled ‘Taming the H Bomb (1958)’ from the British Pathé News site at: http://www.britishpathe.com/search/query/zeta/recordcategories/Science++ Technology
As an aside, he noted that the Manchester Science Museum has exhibits from the ZETA programme.
Chris went on to discuss some alternative approaches, such as the Princeton Stellerator 8 built by Lyman Spitzer in the 1950s, and the work at Lawrence Livermore National Laboratory ‘magnetic mirrors’. He later compared the tokamak, which are “easy to build but a beast to operate”, to stellerators, for which the opposite is true.
An IAEA conference, ‘Atoms for Peace’ was held in 1965 at the opening of the Culham Laboratory, during which Spitzer discussed the drawbacks of the various approaches, and the drawbacks with each. The most promising work seemed to be that of Lev Artsimovich from the USSR – who described encouraging results from a so-called ‘Toroidálʹnaya kámera s magnítnymi katúškami’ or Tokamak. The toroidal field was much (by a factor of 500) larger than in classical ‘pinch’ devices.
Experiments on tokamaks took place throughout the 1960s and 1970s, and the decision was eventually made by the European Commission to construct a European tokamak called Joint European Torus, or JET, that would be 100 times bigger than existing devices; one of the major drivers for this being the 1970s oil crisis. The design work was carried out at Culham by an international team but the choice of site and director (of a different nationality) took many years and reached a high political level.
The choice was eventually between Culham and a site near Garching in Germany; Chris drew a connection between the decision to site JET at Culham and the help the UK gave to the German government, via the SAS,
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12 in solving the Lufthansa Flight 181 hijacking by ‘Popular Front for the Liberation of Palestine’ in 1977.
In discussing the construction of JET, Chris mentioned the construction workers claims that they saw ghosts on the old airfield. He also discussed the major differences between JET and the US Tokamak Fusion Test Reactor (TFTR) experiment at Princeton. The European design used a D- shaped toroid whereas the US adopted a spherical design; Chris discussed why the former was seen as being superior.
Chris also discussed the ‘fortuitous’ discovery of H-mode by Fritz Wagner in 1982 at Garching; this was to have a big impact on the development of fusion research.
Chris concluded his talk by noting that there are more than 50 tokamaks operating worldwide. The next generation experiment, the International Thermonuclear Experimental Reactor or ITER, was conceived as early as 1985, but site selection did not take place until 2006, with first plasma expected in 2025.
In the question and answer session at the end of Chris’ talk, Professor John Allen, of the University of Oxford, noted that he had been present for the Krushcev & Kurchatov visit, and sought to clear up a misunderstanding about the publicity surrounding the claims that fusion had taken place. He noted that the experimental team did not claim a thermonuclear reaction had taken place, adding that British newspapers encouraged John Cockcroft to confirm fusion had taken place, who eventually stated he was 90% certain fusion had taken place. Other papers took this story up – there was incredible press interest and even a BBC outside broadcast at the laboratory, possibly due to the impact the work could have on the nation’s morale. Chris wondered if there had also been pressure from the US to publish, in light of the recent Sputnik success enjoyed by the Russians.
Professor Allen further noted that, for the Kurchatov lecture, he and the other scientists were instructed by Mr Fry, the Division head, that: "You must not, by your questions, give him any idea of what you are working on, or what you are thinking about doing next".
My thanks to the Nuclear Industry Group for permission to reproduce this report - Editor
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Letters
December 2016*
Dear Sir,
After reading your piece in the History of Physics Group newsletter December 2016, I was particularly interested in your mention of how teaching the history of physics / science can assist in various way of the learning of the subject itself.
I am a 29 year old student, studying with the Open University. Whilst the OU is not as prestigious as many brick built Universities, it does give an opportunity with the time to discover more, to delve into the why rather than just the how. Whilst this is down to the individuals’ desire, the indulgence in the history of science has certainly benefitted me in my quest for understanding and knowledge.
So with your mention of some of your colleagues believing it ‘vital’ and ‘not simply adding a little light relief’ I am in full support of the comments, where learning the history of the subject has enabled the understanding of the current theories. In particular when it comes to both the science and mathematics, the history and story as to why a particular methodology was introduced can give an obvious expectation of the result, thus when an unexpected result is achieved it makes it ever more interesting. I believe the commonly known story that agrees with this is Newton’s apple; would people outside science view gravity in the same way if there wasn’t a story about a clever man in a picturesque setting and a falling apple?
An interesting question though would be to view your comments alternatively and say ‘where would we be if we ignored the history of science?’
To understand the history of science is to understand the conduct, convention and in many ways the expectations placed upon one to support science as a discipline. It is not about how much you know, rather about the processing of information. Would science as a general discipline descend into chaos if we forgot the past? Probably not, though would science lose the corner stone of what is being sought and why? Perhaps.
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Whilst I believe that which you mentioned is indisputable, the big questions for me would be, do we take our roles in preserving the history of both physics and science seriously enough? And, in the busy cosmopolitan world we live in, is there a distinct decrease in time to understand all of a subject, rather than that which will ‘just get you through’?
It is left for me to wish you a very happy Christmas and best wishes towards a great Newsletter.
Yours faithfully, Owen Murphy,
Astronomy and Planetary Sciences student, Buckinghamshire.
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* Unfortunately this letter just missed the 2016 issue of the newsletter but I’m sure we may take his Christmas wishes as good for this year as well!
Editor
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Disclaimer
The History of Physics Group Newsletter expresses the views of the Editor or the named contributors, and not necessarily those of the Group nor of the Institute of Physics as a whole. Whilst every effort is made to ensure accuracy, information must be checked before use is made of it which could involve financial or other loss. The Editor would like to be told of any errors as soon as they are noted, please.
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John William Warren (1923 – 2016)
[Photo courtesy of Evening News June 1971]
Members of the History of Physics Group who were active in teaching physics at undergraduate or senior-secondary level during the period from the mid-sixties to the mid-nineties are very likely to have encountered the critical writings of Dr John Warren. In addition to two books: The Teaching of Physics (Butterworths 1965) and Understanding Force (John Murray 1979) he made over 50 contributions to the journal Physics Education. He subjected the traditional teaching of many topics in physics, as purveyed in text-books and examination papers, to a relentless scrutiny. This provoked considerable reaction but, to his disappointment, did not result in significant reform. Readers who wish to know more about the background to John Warren’s life and work may like to consult the following article in which I have attempted to do justice to his life-time’s mission to “restore truth and coherence to science education”:
“The Quest for Rigour in Physics — the life and legacy of John William Warren”
On-line version (including a supplement listing his articles and letters) available at: https://doi.org/10.1088/1361-6552/aa6cff and also in the July 2017 issue of Physics Education.
Stuart Leadstone, Banchory, Kincardineshire
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Features
Anti-matter or anti-substance?
by John W Warren
Axioms
1 That radiation transfers mass, linear momentum, energy and angular momentum. 2 That the conservation laws for the above physical quantities are strictly obeyed. 3 That inertial mass and gravitational mass are identical.
The Dirac Theory
This theory was initially applied to the electron. The number of electrons is assumed to be constant for all time, i.e. it is what is now called a fermion. The theory required that there must be an anti-particle to the electron having positive electric charge: this was subsequently named a positron. Experiments showing the production and so-called “annihilation” of electron/positron pairs are well established. The positron is shown to have positive charge because its tracks in magnetic and electric fields have the opposite sense of curvature to those of the electron. The mass is clearly positive because otherwise the combination of negative charge and negative mass would give tracks of the same sense of curvature as the electron. The threshold frequency of radiation required to produce an electron/positron pair shows the mass of the positron to be equal in magnitude to that of the electron. The frequency of the radiation emitted in pair-annihilation confirms this. Similar results were later found for the proton and anti- proton pair. According to one interpretation of the theory of negative beta-decay this process can be considered to be an example of pair-production, the anti- neutrino being the uncharged anti-particle to the electron.
n p e ν Similarly, for positive beta-decay, the particle emitted is the neutrino, and the positron can be regarded as the charged anti-particle of the neutrino.
p n e ν
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Two related processes which may be classified as charge transfer are as follows:
1. In electron capture a proton in the nucleus takes a negative charge from an electron in the atom, becoming a neutron, and the electron becomes a neutrino. p e n ν
2. In the Cowan-Reines experiment (1956) an anti-neutrino takes a positive charge from a proton, becoming a positron, whilst the proton becomes a neutron. ν p e n
Anti-particles
The Dirac theory requires that the mass of an anti-particle is the same in both magnitude and sign as that of the associated particle. In order to conserve particle number (lepton or baryon, as the case may be) an anti- particle must be counted as minus a particle.
Matter and Substance
According to the S.I. the amount of matter in a body is expressed by its mass, the base unit being the kilogram. The amount of substance in a sample on the other hand is expressed by the number of elementary entities of which the sample is composed, the base unit being the mole. The term anti-matter carries the inescapable connotation of opposite (i.e. negative) mass. The term is therefore inappropriate. On the other hand, in a sample consisting of equal numbers of particles and anti-particles, the total number of particles is zero. If the particle component is regarded as substance then the anti-particle component is strictly anti-substance, not anti-matter.
Gravity
It is clear that gravity is fundamentally different from electromagnetic and nuclear interactions because the “interaction charge”, namely mass, exists in only one form. One should therefore be circumspect regarding attempts to develop theories of gravity similar to those for the other interactions, e.g. unified field theories.
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A Laboratory in the Clouds - Horace-Bénédict de Saussure (1740 - 1799)
by Peter Tyson
Horace-Bénédict de Saussure, ‘Voyages dans les Alpes’ 1796
Mont Blanc was first climbed in August 1786 by Michel-Gabriel Paccard and Jacques Balmat. The former, the local doctor, noted in his journal simply, 'Our journey to Mont Blanc - Arrived 6:23 pm, left 6:57, stayed 34 min'. Paccard was a serious amateur scientist and, doubtless to his companion's consternation so late in the day, at 18½º F and 3800m above civilisation, busied himself with practical science. Of the greatest importance, he made a scratch on the tube of a simple mercury barometer, indicating a mercury level of (what is now) 254mm. In fact, it was largely to do this that he had wanted to climb the mountain. Happily the pair returned to Chamonix safe and relatively sound the following day. So, why the barometer?
A century earlier, Edmund Halley had written,
'Now upon these principles, to determine the hight of the Mercury at any assigned hight in the Air, and e contra having the height of the Mercury given, to find the hight of the place where the Barometer stands, are
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Problems not more difficult than Curious; and which I thus resolve.'
Mariotte had noted that there would be 'changes within Barometers in places at different heights, like at the bottom and top of a tall tower, or of a mountain'. Sinclair, Boyle and Pascal had tested this by experiment. Halley derived an exponential law for the decay of pressure in the atmosphere and gave a table in which the barometer reading was the independent variable. Later, he took a barometer up Snowdon – despite the 'Horrours of the Neighbouring Precipices' – but used Caswell's earlier readings to calculate a height of 1288 yards.1 It is not the place here to discuss the other parameters but all the scientists were aware that this would be an approximation. Despite the fact that the portable barometer dates back to 1695, some early explorers still filled their barometers in situ, but when Deluc fitted a tap the mercury could be retained in transit and the true mountain barometer was born.
The ability to match studies on meteorology, botany and notably gravitation with height, or to perform surveys with a height datum remote from habitation and the sea, were important factors in the growth of mountain exploration. And if the learned men of Oxford were surrounded by somewhat modest hills, those in Geneva were spoiled in having the entire range of the Alps at no great distance, although in the early days the char à banc (a type of cart) could not be expected to take you all the way. In good weather, they could find a viewpoint from which they could see in the distance, peering over the top of the lower ranges, the shining glaciers of the Mont Blanc massif. So it was that the imagination of Horace-Bénédict de Saussure was fired during his youth, and at the age of twenty he walked from his home in Geneva to the little-known village of Chamonix to see for himself. He was not disappointed: he gazed up at the summit of Mont Blanc, and decided he must go there. Over the years, Saussure would build up a reputation as a consummate scientist and was granted a professorship. Not only did he design his own equipment, he started to venture out into the Alps with it, making numerous extended journeys amongst the mountains, and often up them.2
An early mountain to be climbed was the Buet, which lies not far from Mont Blanc. Whilst much lower – at 3 096m as compared with 4 810m -
1 Phil. Trans. 16 p104 and 19 p582 resp. 2 Described in the 4- or 8-volume Voyages dans les Alpes, 1796; section number in footnotes refer to this work.
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20 it still carried permanent snow to some way beneath its summit. It was first climbed in 1770 via a difficult route by the brothers Deluc, although we may never have known about this since, in a passage which makes a mountaineer's blood go cold, Deluc wrote:
"After spending some time looking around us, our attention turned to ourselves when we discovered that we were only supported by a large mass of snow [a cornice] above a fearful drop. Our first reaction was a fast retreat but, having reflected, we realised that the addition of our weight to this prodigious mass of snow, which had been held there surely for centuries, was negligible for breaking it, so we stopped worrying and turned back to the view."
The climb was a significant mountaineering achievement in itself but Jean- André had wanted to make the ascent to investigate not only the barometric pressure but also the boiling point of water which, Fahrenheit had observed, increased with the ambient pressure. An easier route was found a few years later and Saussure climbed the mountain twice to have a good look at Mont Blanc, for which the Buet is a magnificent vantage point. On his second ascent in 1778,3 partly due to the snow conditions his group made slow going and even the guides, used to working high, started to feel the altitude at 1400-1500 toises.4 Their leader devotes many pages to a discussion of this topic.5 In spite of his fatigue, he spent a busy two hours on the snowcap. Fellow scientist Marc-Auguste Pictet set up his Ramsden sextant and measured the angle of elevation of Mont Blanc. An allowance was made for atmospheric refraction, calculated to be 43½ seconds of arc and which had to be subtracted from the observed 4°21'30" elevation. For a horizontal distance of 65 443 French feet, a height difference of 4974 feet could be deduced. 109 feet were then added to adjust for the curvature of the Earth. A barometric height for the Buet of 8345 feet above the lake of Geneva (~193 toises) finally gave a height for Mont Blanc equivalent to 2426 toises above sea level.
3 2 §562. 4 1 toise = 1.949m (and for reference:) = 6 French feet; 1 foot = 12 F inches; 1 inch = 12 F lines. [0 - 80ºR] ~ [0 - 100ºC]. Putting the science in context, this all predates the metric system and theories of heat, electricity, geology, glaciers and gases were all very much in their infancy. Lavoisier defined elements the year that Saussure climbed Mont Blanc. 5 Conceding 'some readers may already, perhaps, have found this digression on physiology too long' - a salutary note to authors.
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The news in 1786 that an ascent of Mont Blanc was practicable quickly reached Saussure. He rushed to the mountain but was thwarted in making an attempt himself by the weather. The following year, with 18 guides and porters carrying a great deal of scientific equipment, and by now aged 47, he stood on its summit after a further struggle with the thin air.6 In a not atypical reaction for mountaineers, he says, 'the cost of the victory, gave me a kind of irritation. At the moment I reached the highest point... I trod it with a kind of anger rather than with pleasure', adding, 'After all, my aim was not only to reach the summit, it was mainly to make the observations and perform the experiments which, alone, gave the expedition any value'. Nobody, however, even amongst scientists, could remain unmoved and it was not long before he was entranced by the magnificence of his surroundings. But there was work to be done: Guides put up the tent and his small table for boiling water measurements and he managed to spend four and a half hours on his experiments - tasks which he felt he could have managed in three lower down.
The all-important reading on the barometer was found to be 16,, 0,, 14, 4 or 14.4 16 inches 0 /16 lines. A correction for the temperature of the mercury due to Deluc was applied - but because he had never imagined that anyone would work at such a height, some estimation was necessary... A simultaneous barometer reading was being taken in Geneva, and an allowance was made for the discrepancy between the two barometers. The height difference was deduced from the algorithm, 'subtract the common logs of the barometric heights and then multiply by 10 000 to get the height difference in toises'. The rationale is that, for an exponential, the ratio of two pressures would translate to a difference in logs, but the simple constant was due to entirely fortuitous quirk of the units.7 As Saussure writes it:
Geneve 27,, 2,, 10, 85 == 5226, 85 sixteenths, of which the log is [3.]7182400 Mont-B. 16,, 0,, 14, 4 == 3086, 4 [3.]4894522 Difference in toises . . . . . 2287,878
6 7 §1991. Pressure down to about sixty percent of that at home. 7 Note also that, in subtracting logs for a ratio of barometric heights. units are arbitrary. A single comma is a decimal point.
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It followed that Mont Blanc was 2480 toises above sea level. (He emphasised that, at this point, the calculation takes no account of the temperatures in the intervening air column.) 8
Parallel with the estimation of height on the basis of air pressure, the relation between the boiling point of water and barometric height had reached some refinement, thanks largely to Deluc. The apparatus was less fragile than a barometer – and later mountaineers would realise the possibilities of a cuppa. I shall leave it to Saussure to relate this experiment:
"To this end, Mr. Paul made for me a neat piece of apparatus in which the thermometer was armed with a micrometer,9 so that I could distinguish thousandths of a degree. Since Mr. Deluc had found so much trouble in burning charcoal on the Buet due to the rarefied air I had no reason to expect any more success on the summit of Mont-Blanc. So, to overcome this difficulty, a lamp burning alcohol was made for me on the principle of Mr. Argand's. It had a large diameter, and the water was boiled in a vessel mounted on the top of a sheet metal chimney. I checked several times that my thermometer went up to exactly 80 degrees [Réaumur 10] in the boiling water when the barometer was at 27 inches. I then took the apparatus to the coast, where the barometer showed 28 inches 7 lines & 82 160ths of a line and the water boiled at 81º, 299. Now, on the summit of Mont-Blanc, the barometer stood at 16 inches, 0 lines, & 144 160ths of a line and the water boiled at only 68º, 993, giving a temperature difference of 12º, 306. According to Mr. de Luc's formula the difference would be 12, 405. The discrepancy, barely a tenth of a degree over a range of 12 inches 6 lines on the barometer, shows that his formula offers an accuracy as high as one could possible wish."
The humidity was measured by means of a hair hygrometer, a type which Saussure had invented. Having seen how a human hair tends to stretch when it gets wet, he devised a mechanism to greatly magnify the extension: 'The best way is to attach one of the ends of the hair to a fixed point, and to attach the other to the circumference of a small cylinder or shaft, which carries a light needle at one end.
8 7 §2003. In 1784 Saussure had watched an ascent of Montgolfier balloon in Lyon and must have considered the possibilities... 9 7 §2011. Probably an attached sliding scale (cf vernier) similar to the old engineers' diagonal scale, and viewed through lenses. 10 Incidentally, another mountain explorer, Martel, used the centigrade temperature scale before Cristin's publication of it.
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This indicates movement of the shaft on a dial. The hair is tensioned by means of a counterweight of 2 to 4 grains suspended by a fine silk thread wound around the axle in the opposite direction'.11 The simple instrument did not have a linear scale, though in principle that used later on the Col du Géant was graduated from 0 (dry) to 100 (saturation).
Air and snow temperatures were recorded and a thermometer whose bulb had been blackened, using carbon black dissolved in gum arabic syrup, was exposed to solar radiation as a crude actinometer.12 A compass bearing on the church in Chamonix and a later reverse bearing established no discernible difference in magnetic declination. As to 'atmospheric electricity', what we now understand as electric potential was investigated by means of an electrometer in which two pith balls, suspended on threads inside a case, repelled.13 The atmosphere was charged positively but the balls gave a much smaller deflection than the scientist expected right on the edge of a steep slope, something he felt must be 'explained by the dryness of the air which, reducing the conducting force, did not allow the penetration of the electric fluid from above'.
11 A similar hygrometer was constructed in 1782, before Saussure published, by Richer using silkworm gut. Obs. Phys. 2, p349. 12 The difference between sun and shade temperature has been frequently used to indicate total radiation, and blackening the bulb of one of a pair of identical thermometers renders the experiment more sensitive. Without standardisation readings cannot even be compared between different instruments. Presumably Saussure was aware of this, hence the heliothermometer. 13 3 §784 Based on a design by Cavallo, Phil. Trans. 70, and functioning much as the enduring gold leaf electroscope.
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The experiments were being conducted at what Saussure believed to be the highest point in the 'Old Continent',14 so the activity continued only as long as the party dared remain on the summit. Finally, it was judged wise to start the descent. That night, in a tent on the glacier and sheltered by a rock from avalanche danger, Saussure reflected with true satisfaction on what he had achieved after so many years of dreaming. And, even on his descent from Mont Blanc, decided it wasn't enough: There and then he decided to organise a more protracted stay, if not quite as high, at least in a spot suitable for establishing a reasonable camp.
He already knew where, and by early June of 1788, he had assembled another team. The Col du Géant 15 is a high glacier pass over the middle of the Mont Blanc massif. The plan was for a longer stay, particularly in order to study any variations of the properties of the environment over the course of a day or more, research which, to have any validity, would entail working for some time in the same place. He took two small canvas tents but had also had a rough stone hut built in advance. The ascent was complicated by a section which was heavily crevassed, but the Col was reached, almost without incident.16 Here, Saussure had a shock: It was somewhat lower than he had hoped, the hut was small and low, and it had been half-filled with snow which had had blown in through the cracks between the stones. Nor was the area greatly suitable for tents, even if the views were superb. Sending most of the personnel back to Chamonix, Saussure kept four of the best guides, along with his valet(!), and Théodore, his son of 20 who was to help with the experiments.17 Whilst the others set about making camp on some rocks, Saussure fell upon his instruments but, he says,
"I was mortified to find that both barometers were out of commission; the dryness of the air since we left Chamonix had shrunk the corks in the taps which kept in the mercury and both had lost some of their thread. However, no air had got in and I proceded to cure one by reversing the process which had caused the problem and, by keeping the instrument continually wrapped in wet cloths, got the cork to expand again."
14 Saussure was familiar with the French academicians' expedition to the Andes, to measure an arc of the meridian which helped to establish that the Earth was the oblate spheroid Newton had predicted and contributed to the first definition of the metre. 15 Formerly the Tacul, renamed by Saussure. Reached from Chamonix only in 1786 after a long interval due to many crevasses. 16 7 §2029. 17 Théodore ('Saussure le fils'), 1767 – 1845, would go on to distinguish himself in the fields of plant chemistry and physiology.
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The following day the guides were predicting a change in the weather (and country folk still beat computers). Sure enough that night a storm of indescribable violence hit the camp, the wind reaching into the cabin as if the walls were not there, so Saussure moved to a tent. The guides had to hold down the poles to prevent its being carried away.
"Around seven in the morning, all this was joined by hail and lightning which continued relentlessly; one bolt struck so close that we distinctly heard a spark slide crackling down the wet fabric of the tent, right behind where my son was sleeping. The air was so charged that, when I held the point of the electrometer outside the tent the balls diverged as far as the threads would let them.18 On most strikes the electricity changed sign."
The storm abated by about midday, so Saussure and his son started work and set into a daily routine, taking shifts to enable observations to continue throughout the night. Unsurprisingly, furs were barely enough protection from the intense cold, especially when the wind rose in the evenings. The small charcoal stoves could not be lit in the tents, and in the cabin burned feebly, even when forced with bellows. At such times, says Saussure, they felt less strongly about being no higher than they were.
Théodore took sightings on the sun and determined latitude but was unable to add longitude because the watch intended for this had also ceased to function properly early in the ascent, so they fell back on the triangulation of known objects. Since a major objective was to compare various formulae, a height independent of the barometer was needed and their cabin was found by the same means to be 1223 toises above Chamonix. Taking a mean of 85 barometer readings gave a pressure of (wait for it) 18 inches 11 5688 630 lines /16000 line at an air temperature of 3 degrees /1000 and at 288 Chamonix 17 degrees /1000 . The height difference from Trembley's formula was 1207 toises, 16 toises lower than that triangulated.
Since a mean could be calculated over the stay on the Col, an obvious study was that of the temperature lapse rate. For 'ground level' Saussure notes that Chamonix lies in an enclosed valley so that, in this context, the observatory in Geneva would be a better choice. A (decimal) temperature of 17,285 ºR in Geneva, was matched with 2,201º on the Col 1555 toises higher; the previous year's figures for Mont Blanc had given Saussure, 22,6º in Geneva and -2,3º on the mountain summit, 2257 toises higher. Whilst he appreciates
18 In retrospect, like Deluc's cornice, not a clever idea. Modern mountaineers are very wary of ice axes in thunderstorms!
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26 all the complications he suggests 'one might conjecture that in summer, between 45 and 47 degrees of latitude, the mean temperature of the air decreases from sea level to the highest mountains by a hundredth of a degree per toise', in today's terms a lapse rate of 1ºC for every 156m. Unfortunately Saussure went on to use a (not unreasonable) exponential model for the thermal expansion of a gas.19
The frequent arrival of humid air as the Col du Géant became enveloped in cloud did not lend itself to a very meaningful study of atmospheric electricity, although as we have seen the instrument became as excited as the scientists during thunderstorms. But, we are told, 'Two or three days free of clouds nevertheless allowed me to check that the electricity in calm weather followed exactly the same trend at this great height as it did on the plain, that is to say it increased gradually from 4 a.m., when it was practically zero, until midday or 2 p.m. when it reached a maximum'.
Saussure was particularly interested in any diurnal changes in magnetic field and had acquired a large compass by Knight. He achieved useful results, but only after a few teething troubles:
"The needle of this compass was 23 inches 8 lines long, and its scale could, with the aid of a microscope, could be read to 20 seconds of arc. Unfortunately the 6¼ ounce weight of this needle rapidly wore down the point of the steel pivot and impaired its movement. I overcame this problem by suspending the same needle by a silk thread in Mr. Coulomb's setup, but was unable to employ, as he advised, single strands held together, without twisting, by gum arabic. The weight of the needle broke one of them after another and the needle fell to the bottom of the box. I had to resort to fishing line [horsehair?] but as it seemed a bit stiff I needed to apply Coulomb's principles to investigate the torsion. A copper bar was made of the same shape, length and weight. I suspended it from the thread and set it to perform oscillations in a box to shield it from draughts ... I did the same with the magnetised needle ... Thus the copper needle was oscillating against the torsion of the thread, the magnetised needle against this plus that exerted by the magnetic force."
The relative torsions varied inversely as the squares of the periods and experiments showed that the influence of the torsion on the compass needle
19 Perhaps due to Charles's law being abbreviated misleadingly, with 'of its volume' omitting the reference to the ice point?
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27 would affect the deflection only by 1 part in 268, too small to detect on the scale. Problem solved? Not quite. On their arrival at the Col du Géant, Saussure, needing a firm mounting, had constructed a pillar of large slabs of granite. When he started taking readings, he says, 20
"The first variations seemed a little odd, and I noticed that the entire compass moved. I decided that the pillar was not firm, so I rebuilt it more solidly. The same thing happened. I thought the ground underneath was not sound and that it was subsiding under the pillar, so I excavated down to the rock. The same happened again! I wasted a lot of time until I discovered that the rock was not part of the mountain at all, but rested on ice and that this was melting underneath it during the course of the day."
Like his observations in Chamonix and Geneva, the figures high on a mountain showed that the needle swung from east to west and back during the course of a day. Within this there were often fluctuations of smaller magnitude starting in early evening. Saussure also took a magnetometer, 'in which the force of a magnet is measured by the angular deflection it produces on a copper bar hanging vertically, to the bottom of which is attached a ball of iron', 21 but had doubts as to the physical law.
As befits someone known for his work on humidity, the scientist took advantage of the low pressure (and implicitly density) to investigate the factors which influence evaporation.22 He writes, 'To distinguish the contributions of the four different factors, heat, dryness [sic], agitation and the density of the air, I decided to start by excluding agitation and working with still air. The experiments would be done first on the mountain, then on the plain, and under a tent which was carefully closed... to get rates which were measurable in times still short enough that hygrometer and thermometer readings would not change appreciably, and so that I could repeat the experiment to separate the respective influences'. If perhaps a glorified washing line, the experiment was carefully designed. A table of results showed the difference in the mass evaporated for the differences in temperature and dryness between trials. After some maths
20 7 §2097. 21 7 §2104, 2 §458. This design was apparently his; the name of such an instrument was coined at least as early as 1773 by Blondeau (the first Voyages appeared in 1779). Saussure variously applies the idea to detect iron in mineral samples or mountains, indicate the strength of a magnet and measure the 'intensity of magnetic force'. He acknowledges much early work by others. 22 7 §2059.
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28 based on a linear model, Saussure concludes that the weighting of a change in dryness was greater than that of temperature in the ratio 4,188 to 1,386, as compared with 1,938 to 2,775 on the plain. His observations on perspiration at altitude will not be news to modern mountaineers, who drink copiously even in winter.
A parallel study employed the cooling produced by forced evaporation.23 A thermometer placed in a substance in which evaporation can take place would in principle show a drop in temperature but, aware that the process would be slow and cooling very small, Saussure sought to speed up the evaporation in such a way that it could be performed outside the lab and thus without recourse to the artificial control of temperature or humidity. He enclosed the bulb of a thermometer in a wet sponge, attached a string and whirled it around at great speed, getting a drop in temperature of 8º R or more. [Essentially the sling psychrometer, possibly the first]. However, he says, 'at first I held the string directly in my hand and the rubbing on the string as it turned against my fingers wore it away so quickly that one day it broke, the thermometer shot out at a tangent,24 rose to a great height and broke when it fell'. A suitable rotating linkage solved the problem, and he continues, 'To determine the speed of rotation I practised to find out how many revolutions I could count in a minute, in fact around 140. The bulb of the thermometer therefore travelled in this time 140 times the circumference of a circle of 5 feet in diameter, giving a speed of 36-37 feet per second'.
For comparison, each trial was preceded by a run in which the thermometer was dry. The wetted sponge (spherical, and 10-11 lines in diameter) was then brought to the temperature of the moving dry one so that only evaporation would affect it – i.e. the forced convection was common to both - and the experiment started. A similar analysis applied to that of the experiment in still air showed the great significance of maintaining the immediate surroundings of the bulb in the same state as the ambient air. Overall, the inference was that, whilst evaporation is always more pronounced on a mountain than below, the difference is less marked in a wind than it is in still air. Saussure has been credited with the invention of many instruments for measuring physical variables. Most were developments of, or variations on, earlier ones, but that used to measure the saturation of the blue of the sky
23 7 §2063. 24 Not radially – for someone who worked little with dynamics he evidently understood the First law better than many today!
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29 was probably original. He had named it his 'cyanometer',25 and his travels provided a fitting scenario because, as mountaineers had long known, the sky becomes of a deeper blue the higher you go.
Cyanometer
To get some quantitative idea of the phenomenon Saussure painted strips of paper in decreasing shades of blue, labelling them in sequence. From each strip he cut three identical squares, assembling them into three identical series, to allow simultaneous observations in different locations. The version used on the Col was graduated by allocating 1 to a blue so pale that a white circle (of standard size and at a standard distance) could just be distinguished, then progressing by 1 for the next deepest blue on the same criterion, up to 52 for black The blueness was investigated at different angles of elevation: At midday on a typical fine day, as the angle of elevation increased in 10° intervals from the horizon, 'blueness' values ran 11, 20, 31, 34, 37... after which the value stayed constant up to zenith. Blueness at zenith during the course of the day was compared with that in the valley. The figures are self-explanatory: time of day IV VI VIII IX midday II IV VI VIII mean Col du Géant 15,6 27,0 29,2 31,0 31,0 30,6 24,0 18,7 5,5 23,6 Chamonix 14,7 15,1 17,2 18,1 18,9 19.9 19,9 19.8 16,4 17,8 Anticipating work for which Tyndall is celebrated, Saussure writes that 'the colour of the sky can be considered to be a measure of the amount of vapour and suspensions in it, since it has been proved that it is otherwise quite
25 7 §2083. Paccard talked periodically to Saussure but, whilst he refers to a cyanometer himself, does not claim its invention.
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30 black... the air is not completely transparent, its elements reflect ... especially the blue rays...I say 'reflection', because ... mountains covered in snow never appear blue, through however much air they are seen ... even at 30 leagues.' 26
Also related to what would become known as scattering was the 'diaphanometer' experiment on the transparency of the air, in which a series of 16 circles whose diameters went up in geometric progression from 0,2 to 87,527 lines were viewed from an increasing distance until they disappeared, up to 1356 feet. Despite pre-testing on the plain, the procedure was found to be ineffective. Worse, relates Saussure,
'The experiment proved one of the most trying we had performed, due to the fatigue on both eyes and body in judging the disappearances and in measuring the distances at which they occurred, this against the glare from the snow of the intense sunlight and in snow up to our knees.' 27
Another such question which could not be answered without evidence in the field was, given that the air high in the mountains is relatively cold, was it indeed absorbing little heat from the rays of the sun? Saussure had investigated this in 1774. He needed to find out whether 'the direct rays of the sun would, on the summit of a high mountain, have the same efficacy as on the plain'. To this end, he says, 'I had constructed a box with half inch thick deal walls, initially measuring a foot long and nine inches in width and depth. The interior was lined with blackened cork an inch thick and the box was closed with three glass sliding doors, one above the other, leaving an inch and a half between them. Thus the sun's rays could reach a thermometer at the bottom of the box. Heated by the action of the sun, it was well insulated from the effect of the air outside, on one side by the glass and enclosed air, on the others by the layers of wood and cork'.28
Saussure had taken his 'heliothermometer' to the top of the Cramont, a modest mountain south of Mont Blanc. After allowing the temperature inside to climb slowly to 50º, he exposed the window to the direct rays of the sun for exactly an hour, during which time the temperature within rose
26 A league was notionally an hour of walking, here ~ 3 mi. Tyndall has a prominent place himself in mountaineering history. 27 7 §2089. In hindsight, shimmering of the air and diffraction through a very small pupil must have played a major part. 28 4 §932. Today we have triple glazing and the solar oven! This is all long before our overarching theory of energy.
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31 to 70º. The next day, fortuitously in identical conditions, he was able to perform the experiment near the base of the mountain. Although the ambient air was, of course, hotter, the temperature rise within the box differed by only a degree, graphically illustrating that the air through a difference in height of 777 toises made no appreciable difference to the heating effect of the sun's rays.29 When the sun drops behind the mountain, from feeling very hot we suddenly feel very cold, passing from radiative heating to convective cooling.
Eventually, after the group had spent sixteen days on the Col, the provisions ran out – strong suspicion resting on the guides, for whom the stay was uncomfortable and rather boring. As he took his departure from the col, Saussure knew he had accomplished much invaluable, and truly original, research – and here we have considered only the physics. For all the hardships and the trials, he had enjoyed his stay immensely; he was, one might justifiably say, in his element. The culmination of all his work in the mountains was to be the classic Voyages dans les Alpes, published in full in 1796. In the annals of mountaineering Saussure will be remembered for the third ascent of Mont Blanc no more than in those of science as a true pioneer of research in the field.
------
In memory of Ivor Grattan-Guinness
Bibliography and Appendix
Most of the material is that recorded in Voyages dans les Alpes, 1796. This is a massive work and the need for background and balance gives rise to shortcomings in an article of this length. I have preserved most of the old
29 Of course mountaineers vulnerable to ultra violet must consider selective absorption.
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32 notation and units as of historical interest. Other relevant works are listed below. Most are in French and to my knowledge no complete translations exist. Facsimiles can often be found online, such as at HathiTrust, and are indicated below with a dagger, † Unfortunately, digital searches are difficult due to the vagaries of language and issues with accents, italics and old s's (use f).
Any errors are most likely to do with an organic memory which is ageing faster than Voyages.
(i) References are to the 8o edition, Voyages dans les Alpes which comes in 8 volumes.† Mont Blanc summit and the Col du Géant come in Vol. 7. There is an index in Vol. 8. This gives section numbers (§) which are more useful than page numbers when referring to different formats. https://catalog.hathitrust.org/Record/008648381
(ii) The cyanometer and diaphanometer are described at length in Mémoires de l'Académie Royale des Sciences à Turin. 9 1788-1789, † pp409 and 425 resp.
(iii) The hair hygrometer is described in Saussure's Essais sur l'hygrométrie, 1783.†
(iv) Deluc's major scientific work was Recherches sur les modifications de l'atmosphère,1784 in 4 volumes.†
His ascents of the Buet are described in Relation de différents voyages dans les Alpes du Faucigny, D[eluc] et D[entand], 1776.
(v) Material on Saussure, mainly from the mountaineering viewpoint, can be found in The life of Horace Benedict de Saussure, Freshfield, 1920. † (archive.org) and The first ascent of Mont Blanc, Brown and de Beer, 1957. (vi) Halley wrote two relevant papers in Phil. Trans., († Archive of All Online Issues):
A Discourse of the Rule of the Decrease of the Height of the Mercury in the Barometer, According as Places are Elevated Above the Surface of the Earth, with an Attempt to Discover the True Reason of the Rising and Falling of the Mercury, upon Change of of Weather: 1686 16 , p104.
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A Letter from Mr. Halley of June the 7th. 97. Concerning the Torricellian Experiment Tryed on the Top of Snowdon-Hill and the Success of It: 1695 19, p582.
(vii) A good work on the history of instruments is Scientific instruments of the 17th and 18th centuries and their makers, Daumas, 1972 (first English edition).
(viii) Martel's words were: "I took also a thermometer of my own make, filled with Mercury, divided into a hundred equal Parts, from the freezing Point to boiling Water, answering to 180 Parts of Fahrenheit's thermometer beginning at 32, and ending at 212". His An account of the glacieres or ice alps in Savoy...., 1744 is rare, and versions differ. It is reproduced in The Early Mountaineers, Gribble, 1899, † (archive.org) p103. A relevant article can be found in the British Journal for the History of Science 5 #4 (Dec. 1971): An Additional Factor in the History of the Centigrade Thermometer, Bryden, pp 393-6. Note that the expedition described was in 1742.
(ix) For Théodore de Saussure, see for example Chemical Research on Plant Growth: A translation of Théodore de Saussure's Recherches chimiques sur la Végétation, Hill, 2013.
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On Prof. W.H.Bragg’s December 1914 Letter to Michael Ernest Sadler, Vice-Chancellor of the University of Leeds
Christopher Hammond University of Leeds
Summary
A seven page handwritten letter in the archives of the University of Leeds (Registry: H Physics H12), dated 16th December 1914 from William Henry Bragg, Cavendish Professor of Physics to the Vice-Chancellor, Michael Ernest Sadler, is here published in full for the first time, together with three replies or memoranda from Senior Officers of the University. The historical importance of this correspondence is that it throws new light (i) on the development of X-ray crystallography following Max Laue’s discovery of X-ray diffraction in 1912 (ii) on the problems of staffing and funding of the Physics Department of the University in the months following the outbreak of the First World War and (iii) the considerations which led to Bragg’s resignation of the Cavendish Chair in 1915. These points are addressed in the Discussion (4).
William Henry Bragg (1908) Michael Ernest Sadler (1914), by Hammer & Co., Adelaide. by George Charles Beresford. (Courtesy: The Lady Adrian) (© Copyright: National Portrait Gallery, London)
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(1) Introduction: The Background
The two-year collaboration between William Henry Bragg (WHB), Cavendish Professor of Physics in the University of Leeds and his son, William Lawrence (WLB), then a student, later Fellow, of Trinity College, Cambridge, which began in the summer of 19121 and ended when WLB enlisted in the Leicestershire Royal Horse Artillery at the outbreak of the First World War, established the new science of X-ray crystallography, the importance of which cannot be over-estimated. In 1912, the structures, or atomic arrangements in crystals, were unknown. Certainly, the evidence of external form and symmetry, together with atom-packing considerations and model-building, indicated possible structures for the elements and the simplest inorganic compounds – but of direct experimental evidence there was none. Laue’s discovery, which was communicated to WHB by Lars Vegard, a former Leeds colleague in a letter of 26 June 1912, clearly showed the existence of an internal order or pattern in the atomic arrangements in crystals. And although Laue made substantial contributions to an understanding of diffraction from crystals modelled as three-dimensional gratings, it was the Braggs, combining an elegant experimental technique (the spectrometer) with a simplicity in interpretation of the data (Bragg’s Law) who first determined these atomic arrangements. By the summer of 1914 the Braggs, in a series of papers, principally read to the Royal Society, had established, by means of X-ray diffraction, the structures of NaCl, ZnS (blende), CaF2, KI, KBr, diamond, copper, FeS2, NaNO3, CaCO3, MnCO3, (Mn, Mg)(CO3)2 and had tentatively proposed structures for quartz and sulphur2. They had the field of the determination of crystal structures entirely to themselves: their closest potential rivals were Torahiko Terada and Shoji Nishikawa in Japan. Terada independently arrived at the notion of reflection from crystal planes by observation of the movement of Laue spots as the crystal was gradually turned. Again, independently of W.L. Bragg, Nishikawa determined the structure of spinels. Terada’s and Nishikawa’s early work has been seriously underrated3. The Braggs might have been rivalled by H.G.J. Moseley, working first in Manchester and then Oxford, but largely as the result of a ‘Gentleman’s Agreement’ he chose to study the characteristic X-ray spectra of the elements.
The importance of the Braggs’ work was early recognised, resulting in invitations to WHB (but not WLB) to address a Leeds ‘Spring School’ in April 1913, the Birmingham Meeting of the British Association in
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September and most significant of all, an invitation to the Second Solvay Conference in Brussels in October, the theme of which was ‘The Structure of Matter’. This conference provided a ‘showcase’ for the Braggs’ work, and the major contribution of WLB did not go unrecognised: a postcard was sent to him in England for ‘advancing the cause of natural science’ and signed by eighteen conference members including Sommerfeld, Curie, Laue, Einstein, Lorentz, Rutherford, Langevin, Nernst and Voigt.
WHB’s burgeoning reputation led to invitations to visit Canada and the United States in the late Summer/Autumn of 1914 (accepted) and the offer of appointments at Edinburgh University, King’s College and University College London (declined). At the same time it was becoming apparent in the Autumn of 1914 that the war would ‘not be over by Christmas’ but would be prolonged and that the country would need to muster its scientific resources in its defence. In view of the deteriorating situation, and also as a direct result of a telegram from Sadler, WHB curtailed his visit to the USA. It is against this scientific and historical background that the importance of WHB’s letter of 16th December to Sadler should be assessed.
Michael Ernest Sadler, 1861-1943, was born in Barnsley. He went to school at Rugby (where he became Head Boy of School House) and in 1880 to Trinity College, Oxford, as a classical scholar. He was elected President of the Oxford Union in 1882. At Oxford he came under the influence of John Ruskin which served to establish his life-long interest in, and concern for, secondary educational reform. His pioneering work as Secretary to the Oxford Extension Delegacy led, in 1903, to his appointment to a newly- established Chair at Manchester University in the History and Administration of Education. He was appointed to the Vice-Chancellorship of Leeds University in 1911, a post he held until 1923, except for a two-year period, 1917-19, when he was a member of the Calcutta University Commission and for which work he received a knighthood. In 1923 he returned to Oxford as Master of University College.
Sadler’s tenure at Leeds was a difficult one. In 1913 he provoked the hostility of the local trade union movement by allowing students to help maintain social services during a strike and in the war years when, in accordance with his liberal views, he refused to participate in anti-German propaganda. But despite the unfavourable economic situation, he oversaw a substantial increase in student numbers.
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At Leeds, Sadler built up a substantial and important private collection of paintings and sculpture and supported and encouraged the ‘avant garde’ artists of his day. Most significant of all, and an enduring legacy for the University, was his commissioning of a War Memorial from Eric Gill, which portrays ‘Christ Driving the Money Lenders out of the Temple’. This caused an outcry at its unveiling in 1923 and indeed the portrayal is still regarded as contentious. It is now displayed in the foyer of the Michael Sadler Building in the University.
The letter, and the three accompanying replies, or memoranda, were discovered by John Jenkin in the Leeds University Archives (H: Physics H12) whilst researching his 2008 biography on William and Lawrence Bragg1. An extract was included in the published book (p. 357). A complete transcript of the seven page handwritten letter and the three memoranda was prepared by the author and again an extract of WHB’s letter was published in 20161. The letter, and the three memoranda, are published here for the first time.
(2) Text of letter from William Henry Bragg, Cavendish Professor of Physics4 to the Vice Chancellor of the University of Leeds, Michael Ernest Sadler
The page numbers of the original handwritten letter on quarto sheets are indicated in the square brackets.
[p.1] The University Dec 16/14 My dear Vice Chancellor
Since we discussed for a few moments a day or two ago the possibility of increasing the output of research from the Physics Department I have been considering the question very earnestly, and have come to the conclusion that I had better set down in writing some account of our present position in respect to research. There is a special reason for doing this just now, because the position is of peculiar interest.
As you know we have been busy with a new development of physical science concerned mainly with X-rays and with crystals. As regards X- rays, a powerful method of analysis has been devised which is providing a
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38 new insight into X-ray theory, and through that, into the general theory of radiation. The practical applications are likely to be of no less importance than the theoretical. As regards the crystals, studied necessarily at the same time as the X-rays, a whole new crystallography has been founded which is wider and far more fundamental than the old. The new work bears also on most important chemical principles, on geology, on mineralogy and generally in fact it is of the widest application. To speak frankly, I doubt if any other new development in physics of equal interest has risen since the indication of radioactivity, and before that of X-rays and wireless telegraphy.
The beginnings of the new work were made by Dr Laue of Zurich5 in a certain brilliant experiment, the details of which were published in June 1912.
[p.2]
The complexity of the experiment and especially of the mathematical form of Laue’s explanation would however have hindered indefinitely the progress of the new work, had it not been for the theoretical investigation of my son, W.L. Bragg, first published in the Proceedings of the Cambridge Philosophical Society, November 1912. My son showed that there was a far simpler method of considering and interpreting Laue’s experiment: a method which was at the same time suggestive of further progress. As we have had a considerable experience of X-ray work, in the University of Leeds we were able to follow up these suggestions and some remarkable discoveries were made immediately. The further development of the subject has been the work of the past two years. We have built five of the new instruments (X-ray spectrometers)6 required for the work, one of which was taken by my son to Cambridge and set up in the Cavendish Laboratory: he has got excellent results from it but has been obliged to give it up for the present as he has a commission in the army. The other four are set up in our own laboratory. No one else has done any work on the new lines in England, with the exception of Mr Moseley7 in Manchester, who commenced to develop my son’s suggestions at about the same time as we did. His success was only partial at first, but afterwards he made use of some of our discoveries and did brilliant work on the spectra of X-rays, which has excited worldwide interest and throws a new light on fundamental points of chemistry, and also on the question of atomic structure. His work could really have been done here, but we had not the men nor
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[p.3] the implements to work out all the possible lines of development at one time. We were fully occupied with the crystallographical and other sides. Abroad, the amount of effective work has been very small. The new science, for indeed it may so be called, has so far been worked out by ourselves in Leeds, by my son who has worked sometimes in Cambridge sometimes in our own laboratory, and by Moseley at Manchester and afterwards Oxford.
The instruments are now being made for sale by W.G. Pye & Co. of Cambridge8: two have already been sent to America. A book on the subject is to appear very shortly9. My invitation to America was largely due to a wish to hear about the new subject: and I was unable to comply with half the further requests to lecture at different universities in the States and in Canada. I lectured at the Sorbonne in Paris last Easter and was to have lectured to the German Physical Society in Hanover last September.
I mention all these points in order to make clear the special nature of the position which we occupy. It is really very strong. At present we have the field almost to ourselves but presently of course there will be a large addition to the number of workers.
We are pushing on with several lines of investigation: including some which are very difficult and may not be productive immediately. But we take the difficult cases because it seems right that we, who have had most experience, should be the ones to attack them.
[p.4]
Besides myself these are working in the laboratory, Mr Porter10, Mr Quarmby11 and Dr Woeljar12. Mr Porter’s work has been largely interrupted by military training but he has now been told that he cannot be accepted as an officer for medical reasons: his heart is not quite strong enough. He will probably return now to the research work: unless indeed he accepts a very alluring offer to join a commercial concern as a research worker. Mr Quarmby is a student of last year and promises well, but has not had much experience yet. Dr Woeljar is a very clever student who has come over from Amsterdam to acquire experience in the new work: he is likely to stay over Christmas and perhaps longer unless his finances break down under the strain of present conditions.
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Mr Peirce13 who was working with us, as an 1851 scholar from Sydney, New South Wales, has got a commission in the army, and so also has our demonstrator Mr Nuttall14. Both these were good workers.
The special instruments we have used and are using have been built in our own workshops. If we had not spent the money on the workshops, and had not engaged the services of Jenkinson15, who is a first class instrument fitter, we could have done nothing.
The point is therefore, how can we best use our present advantage? We must get out of it all we can before the rush of better equipped laboratories and larger staffs deprives us of our lead. Our lead is certainly a fairly long one, and we ought to do a great deal before we are overhauled: unless anything untoward happens.
We can of course increase our staff: but this would undoubtedly be expensive if we were to
[p.5] engage assistants. A good research assistant would cost from £100 to £150 a year, depending on the quality of the man. Such a man would not be of much use to us as a personal assistant, because it happens that I cannot work comfortably except by myself. He would simply be an additional independent worker and would be valuable in that way. In normal times one might expect research students to come without pay, as Dr Woeljar has done already. But the war has interfered and will continue to do so. Two Russians were expected next year: and I feel sure there would have been others. We have indeed lost through the war both Peirce and Nuttall. If there were plenty of money and we could play a bold game, it would be splendid to engage a first class young man, preferably of reputation, just as Manchester has recently engaged Dr Bohr of Copenhagen16. I do not know what Bohr gets as a salary, perhaps £250 a year. I do not imagine however that it is worthwhile to discuss such possibilities.
We might do a good deal immediately by rendering the services of the present staff more effective. After all, we have the experience and can do more than newcomers if we get the time. Now there is a quantity of routine clerical work in the laboratory which takes much of the demonstrators time, and mine also. Nor is it effectively done at present: from sheer lack of time. It includes the keeping of the laboratory records, the filing and entering of
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41 reports of students’ progress, the weekly printing of tutorial papers, and of standard answers, the keeping of catalogues, of laboratory accounts, writing
[p.6] letters, typing MS of papers, distribution of printed papers to other laboratories and so forth. Many of these services are woefully behindhand now, and we are torn between the desire to do the clerical work of the laboratory efficiently and the desire to go on with the research work. I do think we might have a junior clerk to ourselves, as I find most physical laboratories do; an intelligent young typist could do quite well and would keep us out of the mess I am afraid we often get into. It would be very much better for the students: and would make us more efficient in the laboratory. At present the relief could be especially great because we have lost not only Peirce and Nuttall, but also our very efficient lecture assistant who has joined the Leeds City Battalion.
Lastly, we must not, if possible, let ourselves suffer from lack of material. We make our own special instruments but we use also older instruments of standard patterns which go to complete the equipment. Our stock is not quite sufficient: we want about £100 worth now: and have [word omitted] in hand. The more workers we have, the more apparatus we want of course. If we had plenty of money I could put together a first class equipment which should include the new powerful X-ray tubes manufactured in the General Electric Co: in this way we should greatly extend the compass of our work. That could take £300. At present it seems more likely that this extension of the work will be done by some who have this equipment and are buying our spectrometer. At Cornell University I saw an equipment which had cost more than twice as much as the sum just named.
To sum up, we have a splendid position just now, and we must try to keep it. The workers
[p.7] we have should not suffer from lack of tools; at present we want to spend about £100, but we could spend many times that sum with great advantage were it available.
We could save the present workers time and make our department run more smoothly and efficiently if we had our own clerk.
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Were there plenty of money we could add to our staff; and the best way would be to engage a young man of ability who is interested in modern physics.
There is one other line of research which should be discussed. The problem of the electrification of fabrics during manufacture is of interest scientifically and of practical importance to this district. Enough has been done to show that much more could be done with profit. No other university could do it more suitably as it takes in textile work on the one hand and our own special work on X-rays and ionisation on the other. It would take the whole time of a good experimenter. In this case it would be directly profitable to engage a research worker at a cost of perhaps £120 or £150 a year. We have tried to get on to this work two or three times: but it is too exacting for those of us who have other work in hand.
Yours very sincerely
WH Bragg
(3) Memoranda in Reply from Three Senior University Officers
The University Archives do not include an acknowledgement or reply from Sadler, but it is clear that he immediately forwarded the letter to the Pro- Chancellor, A.G. Lupton, the Chairman of the Finance Committee, H.J. Bowring and the University Secretary, A.E. Wheeler.
Arthur Greenhow Lupton, the first Pro-Chancellor of the University, was a member of a long-established Leeds family – the cloth making firm of Wm. Lupton & Co. dating back to 1773. He was awarded the Degree of Hon. LLD in 1910 in recognition of his public service – but at the time his greatest service lay concealed. In order to provide for the University’s growth, and so as not to excite the interest of speculators, he privately purchased land and property for the University – purchases which were not disclosed until 1922.
H.J. Bowring was Chairman of the Finance Committee from 1902 (prior to the University’s Royal Charter in 1904) until 1921. At the time (1920s) when a relocation of the University to a more salubrious site on the outskirts of Leeds (Weetwood) was being mooted, he urged the view that it was
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‘more important to buy less romantic, slummy property adjoining the cemetery’ (now St George’s Field, part of the University campus).
Archibald Edward Wheeler was Sadler’s private secretary 1911-12 and in 1912 was appointed to the new office of Secretary to the University. The office was changed to that of Registrar in 1919, an office which Wheeler held with distinction until 1945.
Memorandum from Arthur G. Lupton, Pro-Chancellor of the University
18 December 1914 Dear Sadler
This is a very interesting paper of Bragg’s and I am inclined to think he has chosen a wise moment to suggest the need of more assistance in one way or another.
We have always said that personality of the teachers is much more important than spending money on Buildings. If it can in any way be managed I should be inclined to give him the typist he asks for, and in regard to that would not a woman typist etc. give a more reliable and higher standard of person than a youth.
As to the whole question of the Department, your suggestion of considering the whole position of the Electrical Department also is of much importance
Sincerely yours
Arthur Lupton
William Lupton & Co. Whitehall Mills Leeds (also at Cliffe Mills, Pudsey)
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Memorandum from H.J. Bowring, Chairman of the Finance Committee
20 December 1914 Dear Sadler
I was most interested in Braggs letter which you handed to me the other day and should very much like him to have facilities for enhancing his research. If I remember rightly some of his difficulties are due to his assistants undertaking military duties and in that case we might perhaps find the means of helping him out of the extra savings we have just made in connection with the payment of salaries of the ‘university militant’. However I will try to have a word with you on the subject if I may in the course of the next day or two. I return the Pro-chancellor’s letter.
Yours sincerely
H.J. Bowring Blackwood Moor Allerton Leeds
Memorandum from Archibald Edward Wheeler, University Secretary
Professor Bragg’s memorandum of research work
Vice-Chancellor
I have read with great interest Professor Bragg’s important memorandum and venture to think the University would be wise to do at once a good deal more than he modestly asks. The future of the University, it seems to me, depends on its being pre-eminent in at least some branches of its work. At present our Physics Department is leading the world, and it is unlikely that we shall ever get a better chance than this of drawing attention to the University. Looked at from the purely material point of view of increasing our fee and grant income, it would be a good speculation, I am sure, to spend money liberally on Professor Bragg’s Department. I therefore venture to make the following suggestions:-
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1. The appointment of a ‘first class young man’ at (say) £250 a year (see Bragg pp. 3 & 4). As this appointment is made more necessary by the absence of Mr Nuttall, the salary may be provided, for the present, out of the savings on the salaries of those who are on military service.
2. The appointment of a research worker at £120 or £150 a year (see Bragg pp. 4 & 5). I do not know whether it would be possible to combine this appointment with the one desired by Mr Perkin: perhaps it is not reasonable to hope that the two types of work could be done by a single worker. Alternatively, is it possible that the Clothworkers’ Company would be so interested as to be willing to provide funds in addition to the large contribution they already make to the Textile and Dyeing Departments?
3. The appointment of a woman clerk at (say) £1 to 25/- a week.
4. A liberal grant for apparatus from the Research and Apparatus funds, the balance unassigned being as follows:- £ Apparatus: Arts & Science 205 Technology 155
Research: 193
Some part of these amounts should be kept in hand for other needs that may arise during the present year.
The first three of these proposals if proceeded with should be considered by the Board of Faculty and the Senate; the fourth by the Apparatus and Research Committee.
A.E.W. 22/12/14
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(4) Discussion
(i) The letter underlines the importance of instrumentation in scientific research – an importance clearly recognised by WHB in his generous acknowledgement of the contribution of Jenkinson. As he records on [p.4] of his letter ‘if we had not spent the money in the workshops, and had not engaged the services of Jenkinson, who is a first class instrument fitter we could have done nothing’ [my italics]. The contribution of the engineer, craftsman or mechanic in providing the necessary instrumentation for scientific research is, I think, seriously underrated by historians of science. Of all the five spectrometers made by Jenkinson (and Watts) in the Physics Workshop in the period from the winter of 1912-13 to December 1914 perhaps only one survives – that in the Museum of the Royal Institution in London. The spectrometer in the Physics Museum in the University of Leeds is a later (commercial) model manufactured by W.G. Pye & Co.
(ii) There can be little doubt that the young men whom WHB names in his letter he hoped would provide the initial core of his research group – a hope of course dashed by the war and the deaths, in France, of three members of the Physics Department – S.E. Peirce, F. Quarmby and A.E. Watts – as well as his own younger son, Robert. Of all those named only Nuttall remained up and until the appointment of Richard Whiddington to the Cavendish Chair in 1919. WHB does not mention the established members of staff of the Physics Department (established, that is, before his own appointment): A.O. Allen (who was appointed Acting Head, 1915-19) and S.A. Shorter (who was approaching retirement). But surprisingly he does not mention Norman Campbell, Fellow of Trinity College, Cambridge and a distinguished scientist in his own right. Campbell greatly admired WHB’s work; he came to Leeds in 1910 and was appointed Honorary Fellow for Research in Physics, an (unpaid) post which he resigned in 1916 to go to the National Physical Laboratory. And although none of his many publications were authored jointly, Campbell acknowledges the inspiration he gained from WHB.
The University Officers were clearly far-sighted men. Wheeler may only have had a layman’s understanding of the scientific content of WHB’s work, but he clearly recognised its importance both scientifically and with respect to the University ‘At present our Physics Department is leading the world’. He also recognised WHB’s innate reticence ‘The University would be wise to do at once a good deal more than he modestly asks’. These views are echoed by Lupton ‘We have always said that the personality of
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47 the teachers is much more important than spending money on buildings’ – views which were doubtless shared by Sadler himself. They were followed, in the early months of 1915, by material support from the University, largely in accordance with Wheeler’s recommendations and which would presumably have been a factor in WHB’s refusal of the offer of the Quain Chair in Physics at University College (10 March 1915). But later that month (possibly the result of his ground-breaking Bakerian Lecture to the Royal Society), University College increased its offer which WHB accepted.
(iii) The grounds upon which he did so were explained in a letter to Arthur Smithells17, Professor of Chemistry and a close friend. Although reluctant to leave Leeds, WHB realised, that in the continuation of the war, the Royal Society would need to take on the role of an Advisory Body to the Government and that in order to be closely involved in this endeavour he would need to be in London, in the centre of things. There is no evidence of dissatisfaction or any personal difficulties at the University – indeed the contrary. In a letter to Sadler written two years later (March 10 1917) from the Admiralty Experimental Station18 at Parkeston Quay, Harwich, WHB requests the loan of a lathe from the Physics workshop, ending his letter with the words ‘The University has been so exceedingly good already that I have the greatest reluctance in proffering any further request’. Further, both he and Gwendoline had established friendships at Leeds which were to continue throughout their lives. This makes WLB’s comment, in a letter to his mother, supporting his father’s move from ‘that deadly Leeds University atmosphere’ so inexplicable19.
A further, and perhaps more significant factor in WHB’s decision to leave Leeds stems from his very keen sense of responsibility: in particular his feeling that, despite his great scientific success and the prestige that he had brought to the University (culminating in the award of the Nobel Prize for Physics, jointly with WLB in 1915), he had failed to fulfil all the duties expected of a Professor of Physics. The Yorkshire College of Science, out of which the University had grown, owed its origin in 1874 to supply the need for technical education to support local industries in the face of increasing foreign competition. WHB recognised the importance of such work, particularly in support of the textile industry, but, as he expresses in the last sentence of his letter ‘We have tried to get on with this two or three times, but it is too exacting for those of us who have other work in hand’. Such concerns are also expressed in his letter to Arthur Smithells17 with respect to the physical problems associated with the textile trade. He says ‘I
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48 would make a shot at it myself but I am not so well equipped as many younger men and should have to give up my own research work’.
In 1928 WHB was able to recommend W.T. Astbury, one of his own research workers at the Royal Institution, for the post of lecturer in Textile Physics and Director of the Textile Physics Laboratory at the University of Leeds – an appointment that had an enormous impact on the scientific development of the textile industry. In doing so perhaps WHB felt that he was assuaging his conscience and that he was fulfilling, in some degree, his obligations to the University.
(5) Endnotes and References
1 The collaboration between WHB and WLB, and the events which led up to it, have been described in several biographical accounts – most recently: John Jenkin (2008) William and Lawrence Bragg, Father and Son – the most extraordinary collaboration in science. Oxford University Press, Oxford. John Meurig Thomas (2012) William Lawrence Bragg: The Pioneer of X-ray Crystallography and his Pervasive Influence. Angewandte Chemie Int. Ed., 51 p12946-12958 André Authier (2013) Early Days of X-ray Crystallography. International Union of Crystallography/Oxford University Press, Oxford. Christopher Hammond (2016) ‘Whin Brow’: the house at which the new science of X-ray crystallography began. Crystallography Reviews 22 p220-227.
2 These crystal structures were published in the following papers: W.H. Bragg and W.L. Bragg (1913) The Reflection of X-rays by Crystals I. Proc. Roy. Soc. A88 p424-438. [Proposed structure for NaCl, Bragg’s law expressed as nλ = 2dsinθ for the first time.] W.L. Bragg (1913) The Structure of some Crystals as Indicated by their Diffraction of X-rays. Proc. Roy. Soc. A89 p248-277. [Determination of crystal structures of NaCl, ZnS (blende), CaF2, KI, KBr.] W.L. Bragg and W.H. Bragg (1913) The Structure of the Diamond. Proc. Roy. Soc. A89 p277-291. [Also comparison of the structures of diamond and ZnS (blende).] W.L. Bragg (1914) The Analysis of Crystals in the X-ray Spectrometer. Proc. Roy. Soc. A89 p468-489. [Analysis of NaCl, ZnS (blende), CaF2,
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FeS2, NaNO3, CaCO3, MnCO3, FeCO3, (Ca, Mg)(CO3)2. Estimates of single-parameter shifts of S atoms in FeS2 and O atoms in CO3/NO3 ‘rings’ from intensity measurements.] W.H. Bragg (1914) The X-ray Spectra given by Crystals of Sulphur and Quartz. Proc. Roy. Soc. A89 p575-580. [Incomplete solutions.] W.L. Bragg (1914) The Crystalline Structure of Copper. Phil. Mag. Series 6 28 p355-360.
3 Prof Shigeru Ohba of Keio University has brought my attention to the early work and papers of Torahiko Terada. In a paper of 1913 On the Transmission of X-rays through Crystals (Proc. Tokyo Math-Phys. Soc 7 (1913) 60-70) he describes the elliptical pattern of spots on a Laue photograph as ‘formed by pencils of rays ‘reflected’ from a number of planes intersecting one another in the crystallographic axis’ and that the positions of the spots ‘may be explained by simple reflection from different netplanes in the crystal’. In the same way he explains the elongated shapes of the spots – but also is careful to note that by ‘reflected’ nothing more is meant than the geometrical relation to the incident beam. However, Terada acknowledges the prior claim of WLB in formulating the law of reflection – he received WLB’s seminal paper, The Diffraction of Short Electromagnetic Waves by a Crystal, read to the Cambridge Philosophical Society on November 11th 1912 and published in 1913 (Proc. Cam. Phil. Soc. 7 43-57), after he had read his own paper. Terada went on to apply X-ray diffraction techniques to study the Deformation of Rocksalt Crystal (Proc. Tokyo Math-Phys. Soc 7 (1914) 290-291) and the Molecular Structure of Common Alum (Proc. Tokyo Math-Phys. Soc 7 (1914) 292-296). Further X-ray work was undertaken by Shoji Nishikawa who studied fibrous, lamellar and powdered specimens and then sheets of rolled metals. Independently of WLB he analysed the Structure of some Crystals of the Spinel Group (Proc. Tokyo Math-Phys. Soc. 8 (1915) p199-209).
4 The Cavendish Chair in Physics in the University of Leeds is named in memory of Lord Frederick Cavendish, first president of the Yorkshire College, who was assassinated in Phoenix Park, Dublin in 1882. The Cavendish Laboratory in Cambridge is named after an earlier member of the Cavendish family, Henry Cavendish (1731-1810), the reclusive and eccentric scientist, who’s fortune of over a million pounds sterling provided the endowment to the laboratory in 1871.
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5 The ‘certain brilliant experiment’ was made at the University of Munich at which Laue was a ‘privatdozent’. He was subsequently (1912) appointed to a Chair in Theoretical Physics at the University of Zurich, a Chair which he resigned in July 1914 for a Chair at Frankfurt-am-Main. Clearly, W.H. Bragg was unaware of Laue’s return to Germany.
6 Both W.H. and W.L. Bragg referred to the diffraction/reflection peaks as spectra and the instrument as a spectrometer. They are now referred to as diffraction or reflection peaks and the instrument a diffractometer.
7 Henry Gwynn Jeffreys Moseley was educated at Eton (King’s Scholar) and Trinity College, Oxford (Millard Scholar). After graduating in Natural Sciences in 1910 he was appointed Lecturer in Physics at Manchester University to work on radioactivity under Ernest Rutherford. However, encouraged by W.H. Bragg, he chose to study the characteristic X-ray emission spectra of the elements using crystal diffraction, continuing the work on his return to Oxford in 1913. His work established the relationship between the wavelengths of the spectral lines and (what is now called) atomic number Z and led to major improvements in Mendeleev’s periodic table. At the outbreak of the war, Moseley enlisted in the Army and was commissioned in the Royal Engineers. His life and promising career were cut short by a sniper’s bullet at Gallipoli in August 1915, at the age of 27.
8 William George Pye trained as an instrument maker and joined the staff of the Cavendish Laboratory in 1880. In 1896 he formed, together with his wife, his own company, W.G. Pye & Co., for the manufacture of precision scientific instruments for schools and Universities. He first worked part-time with the Cavendish and, after 1899, full-time. By 1914 the company had expanded with a work force of 14 people.
9 X-rays and Crystal Structure, first published by G. Bell & Sons Ltd. In 1915. The final (4th) edition was published in 1924. The book was then expanded to become Volume 1 of The Crystalline State: A General Survey by Sir Lawrence Bragg, first published in 1933 and last reprinted in 1962. It remains a classic introductory text and is only marginally out of date.
10 H.L. Porter, BSc (London) [not to be confused with A.B. Porter whose development of Abbe theory was made use of by WLB in his work on
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the optical simulation of X-ray diffraction] joined the Physics Department in the academic year 1910-11 as a Demonstrator. He collaborated with WHB on the ionisation of materials by X-rays; work which was jointly published in Proc. Roy, Soc. In 1911.
11 Frederick Quarmby graduated from the University of Leeds in July 1914 with a BSc degree. In 1915 he enlisted in the Duke of Wellington’s (West Riding) Regiment as a Second Lieutenant. He was killed in September 1916 near Thiepval in the Battle of the Somme at the age of 24. His name, F, Quarmby, is recorded in the University Roll of Honour in the Parkinson Court.
12 Dr Ad Maas of the Boerhaave Museum identifies Dr Woeljar as Herman Robert Woltjer who was awarded his PhD in 1914 for a thesis with Pieter Zeeman on ‘magnetic splitting and temperature’. He then continued research on low temperature magnetism with Kamerlingh Onnes at Leiden. He presumably visited Leeds prior to taking up the Leiden appointment but it is not known whether he intended to carry out any collaborative research with WHB. Certainly, none of his research, either before or after the Leeds visit, involved X-ray diffraction techniques.
13 Sydney Ernest Peirce was awarded the BSc degree from Sydney University in 1913 and on the strength of published research on the ionisation caused by X-rays was, in the same year, awarded an 1851 Exhibition Scholarship. During his short time in Leeds he carried out research on the absorption of X-rays, work which was published jointly with WHB in Phil. Mag. In 1914. In the same year he was commissioned as second Lieutenant in the King’s Own Yorkshire Light Infantry and was awarded the Military Cross in 1915. He was killed in France in December 1915 at the age of 20. His name, S.E. Peirce, is recorded in the University Roll of Honour in the Parkinson Court.
14 John Mitchell Nuttall came to Leeds in 1912 from Rutherford’s Laboratory at Manchester University where, together with Hans Wilhelm Geiger, he established the relationship between the rate of decay of radioactivity and the energies of the emitted α-particles (The Geiger-Nuttall Rule). He became Captain in the Royal Engineers and in 1921 returned to Manchester in 1921 as Assistant Director of the Physics Laboratories.
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15 Charles H. Jenkinson was a skilled instrument fitter. Prior to joining WHB at Leeds he was a foreman with the Cambridge Scientific Instrument Company – the Company founded in 1881 by Horace Darwin (Charles Darwin’s youngest son) and Albert George Dew- Smith. His value to WHB was such that he remained with WHB to the end of his working life. The University Annual Reports 1912-14 also list A.E. Watts as a mechanic (presumably Jenkinson’s assistant) in the Physics Department. In 1915 Albert Edward Watts is recorded as being on Active Service, like Peirce, as second Lieutenant in the King's Own Yorkshire Light Infantry. He was killed in France in September 1916 and his name, A.E. Watts, is recorded in the Roll of Honour in the Parkinson Court.
16 Rutherford’s engagement was a two-year Readership (in succession to G.C. Darwin whose tenure had expired) at a salary of £200. Bohr’s reputation at this time rested upon a ‘trilogy’ of papers, written in Copenhagen and Manchester, which were to lead to the award of the Nobel Prize for Physics in 1922. On his return to Copenhagen in 1916 Bohr took up the newly-established Chair in Theoretical Physics and founded the Institute which now bears his name.
17 Letter: W.H. Bragg to A. Smithells (draft) 26 March 1915. In the Bragg Archive at the Royal Institution. Quoted by Jenkin1, p358.
18 WHB took up the Quain Chair at University College at the commencement of the new academic year (September 1915) but his work there was forestalled by his appointment to a Government Panel concerned with submarine acoustic detection methods. In April 1916 he was seconded to be Resident Director of Civilian Scientists at the Naval Research Station at Hawkcraig in the Firth of Forth. Collaboration with the Naval Staff there proved to be difficult and within a year he moved to the newly-established Admiralty Research Station at Harwich, returning to University College at the end of the war.
19 Letter, early 1915 from WLB to Gwendoline Bragg. In the Bragg Archive at the Royal Institution. Quoted by Jenkin1, p369.
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(6) Acknowledgements
I wish to thank Prof. Sir John Meurig Thomas F.R.S. for alerting me to the historical importance of the correspondence reported in this paper and The Lady Adrian and the Head of Special Collections, University of Leeds, for giving permission for its publication.
In the preparation of this paper, I have greatly benefitted from the constructive advice and helpful comments of John Jenkin, Lucy Adrian and Sir John Meurig Thomas. Finally, I wish to thank Nick Brewster, University Archivist, for his help in the preparation of the transcript, the staff of Special Collections in the University of Leeds for help in searching out historical material, Dr Ad Maas of the Boerhaave Museum, Amsterdam, for identifying Dr Woeljar and Professor Shigeru Ohba of Keio University, Japan for alerting me to the contributions of Torahiko Terada and Shoji Nishikawa in the early analysis of X-ray diffraction by crystals.
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Book review
Crystal Clear – The Autobiographies of Sir Lawrence and Lady Bragg.
Edited by A.M. Glazer & Patience Thomson
OUP 2015 ISBN-13: 978-0198744306 448pp £35
Essay review by Peter Ford
The world of physics is full of names: Newton’s Laws; Faraday’s Cage; Young’s Interference; Maxwell’s Equations; Rayleigh Scattering; Planck’s Constant; Heisenberg’s Uncertainty Principle; Schrodinger’s Cat; The Pauli Exclusion Principle; The Dirac Delta Function. The list goes on and on.
One of the most important is Bragg’s Law enunciated by Lawrence Bragg late in 1912. It relates to a beam of X-rays striking a crystal which results in interference of the rays reflected at different lattice planes of the crystal producing a characteristic X-ray diffraction pattern. Analysis of these patterns has proved to be instrumental in determining the structure of the crystal. The first structure to be determined was that of common salt (NaCl) carried out by Lawrence Bragg and shortly afterwards, together with his father William Henry Bragg, they determined the structure of diamond. Subsequently, the technique of X-ray analysis has been developed by a large number of people and used to determine the structure of ever more complicated molecules. Probably the most famous of these was the determination of the crystal structure of DNA by Crick and Watson in 1953, which is widely regarded as one of the most important scientific achievements in the second half of the twentieth century.
This work was carried out in Bragg’s own MRC Laboratory at Cambridge.
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The book “Crystal Clear” is the previously unpublished Autobiographies of Sir Lawrence and Lady Bragg. It has been edited by Mike Glazer, Emeritus Professor of Physics at Oxford University, a distinguished crystallographer, and Patience Thomson, the younger daughter of Sir Lawrence and Lady Bragg. It is a fascinating account of the lives of two remarkable people with very different personalities, temperaments and abilities who married to form a truly class act. Through their devotion and commitment to each other and in their very different roles they played an important part in British Society over many years. It is appropriate that this book was published in 2015 since it marks the centenary of the award of the Nobel Prize in Physics made jointly to Lawrence Bragg and his father, William Henry Bragg, the only occasion that a Nobel Prize has ever been jointly awarded to a father and son. Lawrence Bragg was the youngest person, at twenty five years of age, to obtain a Nobel Prize in any discipline for the following ninety nine years until he was upstaged by Malala Youzafsai in 2014, who at the age of seventeen was awarded the Nobel Prize for Peace.
In his Foreword to the book, Mike Glazer gives a brief account of the history of X-rays leading to the discovery of Bragg’s Law. He also recounts how the book came into existence. It was some years ago when he was invited to a conference in Madrid to talk about the two Braggs, that he made contact with Lady Heath (Margaret), the elder daughter of Lawrence Bragg who lent him the family photograph album and the unpublished autobiography of Sir Lawrence Bragg. Later he also obtained the unpublished autobiography of his wife Alice Bragg. Rightly he felt that these two autobiographies deserved to be read by a wide audience and the resulting book reflects their lives played out during much of the twentieth century, a time of momentous change.
The book opens with an interesting and novel introduction by their younger daughter, Patience Thomson, and is titled “Meet my Mother and Father.” Patience writes “My mother was beautiful – not just pretty, but beautiful” and “Her great strength was her social confidence and personality. She was the life and soul of parties, people fell for her and she made deep and enduring friendships”. These two aspects of her character, combined with an excellent education and her complete integrity, account for much of her success and help to explain her considerable achievements in life such as becoming Mayor of Cambridge in 1945 and later Chair of the National Marriage Guidance Council. Patience Thomson describes her father as follows: “Dad was not part of the Establishment. He had not been to public or grammar school and had no English friends from schooldays….; he was
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56 a colonial from Australia. ….. He delegated administration whenever he could. He was not clubbable and did not particularly relish dinners at the High Table in Trinity ……. Modest and self-deprecating my father was quick to acknowledge mistakes and quick to apologise, but could still get very angry, so much so that he would go red in the face and start to stammer”.
Early years
In his Autobiography William Lawrence Bragg describes growing up in Australia. He was born in Adelaide in 1890, which at that time was still a fairly undeveloped country. His father, William Henry Bragg, had been asked to go out to Adelaide to become the Professor of Physics and Mathematics at the University there shortly after graduating from Trinity College, Cambridge. Lawrence Bragg describes his young life and early schooling and recalls that he was great friends with his next door neighbour Eric Gill, who was of the same age and later became one of the leading sculptors in Britain following in his father’s footsteps. Lawrence Bragg’s grandfather was Sir Charles Todd who set up the Overland Telegraph Link between Adelaide and Darwin. In addition to being Postmaster General, he was Astronomer Royal for South Australia. Lawrence spent a lot of time in his company and this must have helped develop his interest in science. In 1897 his family returned to England for a year and we have an interesting account of this visit through the eyes of a seven year old. On his return to Adelaide he continued his schooling at St Peter’s College, the premier Church of England School in South Australia and then entered Adelaide University at the age of fifteen. He obtained a first class Honours Degree in Mathematics at the age of eighteen and also studied physics. Academically he was outstanding but he was also shy and gauche and a lot younger than his fellow students which meant that he had difficulty fitting in with them.
In January 1904 the Australian Association for the Advancement of Science met in New Zealand and William Henry Bragg, Lawrence’s father, gave the presidential address in the mathematics-physics section. Up to that time, William Bragg had never done research but preparing for this lecture stimulated him to carry out some experiments on the passage of particles through matter. He proved to be an outstanding experimentalist and produced some classic work on the penetration of matter by alpha rays and on the secondary beta rays. His investigations made, between 1904 and 1908, were highly regarded in the physics community and led to him being invited to take the chair of Physics at Leeds University.
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They arrived back in England early in 1909 and later that year Lawrence Bragg went up to Trinity College, Cambridge taking Part 1 in Mathematics in his first year and then Part II switching to Physics obtaining his degree again with first class honours in 1912. C.T.R. Wilson of cloud chamber fame was his main lecturer and, though he had an appalling lecturing style, the content was excellent and he taught him most of the physics that he learnt especially optics, which was to prove so crucial in his explanation of the diffraction of X-rays by crystals. During his time at Trinity College he made a group of friends who did much to draw Lawrence Bragg out of his shell and mature and develop him. In particular he formed a friendship with Cecil Hopkinson who was studying engineering at Trinity and came from a distinguished family of engineers. Cecil loved adventure and hardship and did much to broaden his horizons such as introducing him to skiing and boating both of which he loved and continued throughout his life.
Father and Son
Lawrence Bragg began research at the Cavendish Laboratory under J.J. Thomson. It was not a satisfactory experience since there was inadequate supervision and poor facilities, such as the lack of a first rate workshop, which meant that students had to construct most of their own apparatus which were often too crude to produce meaningful data. It was a frustrating time for him. His breakthrough came when the German scientist von Laue published his paper on the diffraction of X-rays by zinc-blende and other crystals. Lawrence discussed these results with his father William Henry Bragg while they were on holiday together on the Yorkshire coast. On his return to Leeds, Lawrence set up an experiment in his father’s laboratory to understand the nature of the spots observed on von Laue’s photographs. It was a short while later back at Cambridge that it suddenly occurred to him that the spots observed by von Laue were due to the reflection of X-ray pulses by sheets of atoms in the crystal. He presented his ideas at a meeting of the Cambridge Philosophical Society in November 1912 and wrote a paper for the Proceedings of the Society entitled “The Diffraction of Short Electromagnetic Waves by a Crystal”, which appeared early in 1913.
Following on from his ideas he was able to determine the crystal structure of common salt (NaCl), which he published in the Proceedings of the Royal Society in 1913. The structure consisted of alternating atoms of sodium and chlorine arranged on a lattice. It is difficult today to appreciate how novel Bragg’s structure appeared at the time. Several elderly but eminent chemists were incensed that there were no NaCl molecules and were critical
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58 of the whole approach of X-ray analysis to determining molecular structure developed by Bragg. The equipment available to Lawrence Bragg at the Cavendish Laboratory was extremely primitive and so he was fortunate to be able to combine forces with his father at Leeds, who had access to a first class workshop, to have built a state of the art X-ray spectrometer. This enabled Lawrence rapidly to obtain data on the structure of several crystals and he wrote a seminal paper jointly with his father on the crystal structure of diamond, which appeared in the Proceedings of the Royal Society in1913.
William Henry Bragg, being by now a senior and highly respected scientist, presented a lot of the new results at the British Association, the Solvay Conference outside Brussels and in lectures he gave in Britain and also the United States. This did produce a certain amount of tension between father and son although on every possible occasion William Bragg emphasised the outstanding contributions made by his son. In addition, they thought in very similar ways and so it was often difficult to determine who had originally come up with an idea or suggestion.
The First World War
The flow of research came to an abrupt end with the outbreak of the First World War, which came out of the blue in August 1914. A series of interlocking treaties between European countries and the murder of Archduke Ferdinand, heir to the Austrian throne, at Sarajevo, precipitated this devastating event which rapidly became out of control. Initially Lawrence Bragg was in a mounted horse infantry unit which, used tactics which had been developed during the Boer War. A year later in 1915 he transferred to heading a sound ranging unit, which was developing techniques to determine the positioning of enemy guns on the Western Front. This was difficult to achieve, a major problem being able to distinguish between the sonic boom of the shell, which was released with an initial velocity greater than that of sound, and the low frequency sound made by the actual gun, which the sound ranging equipment was trying to pin-point. The development work was carried out in-situ on the Western Front and involved some excellent applied physics. The First World War was the first occasion that science was used in the pursuit of warfare.
It was while they were testing out their sound ranging equipment south of Ypres, that Lawrence Bragg heard that he and his father had jointly been awarded the 1915 Nobel Prize for Physics. He was billeted in the house of
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59 a kindly priest who celebrated the award with him by going to his cellar and breaking open a bottle of Lachryma Christi.
The First World War caused a devastating loss of life with a huge number of talented people being killed from which Britain perhaps has never fully recovered. Lawrence Bragg’s younger brother Bob was killed at Gallipoli as was Henry Moseley, a scientist set for a glorious career in physics and who had already discovered Atomic Numbers and whose name had been put forward for the Nobel Prize in Physics in 1914. In addition, Bragg’s great friend, Cecil Hopkinson, died in 1917 from wounds that he had received some time earlier.
Manchester and Marriage
After his discharge from the army, Lawrence Bragg spent a short time back at Trinity College, Cambridge before being invited to take over Rutherford’s chair at Manchester University on his appointment as head of the Cavendish Laboratory, Cambridge. The Manchester chair was a prestigious position for Bragg but one for which he felt that he was singularly ill prepared.
During the short period at Cambridge, between being discharged from the War and leaving for Manchester, Lawrence met Alice Hopkinson, a cousin of his close friend Cecil Hopkinson. She was reading History at Newnham College and was well known as a lively and highly attractive young lady. Lawrence did propose marriage to her while he was at Cambridge, but this was declined it appears on the grounds that she was having too good a time and did not wish to tie herself down. In 1921, two years after arriving at Manchester University, Lawrence Bragg was elected a Fellow of the Royal Society and among the many congratulations that he received was a handwritten letter from Alice. Shortly afterwards they re-met and became engaged. Alice Hopkinson and Lawrence Bragg were married on 20th December 1921, at Great St Mary’s Church in Cambridge.
Bragg described Manchester as a “dreadfully dirty and ugly place with a vile climate, foggy and drizzly”. Initially, it was very difficult, mainly because he had had no previous experience at working and lecturing at a University in a more junior level. Many of the students at Manchester had returned from War service and were frequently older and much brasher than Bragg and quite a handful to control. Gradually things improved as he became more experienced at running a large and important department and
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60 he was able to build up an excellent teaching and research team, which specialised in a wide variety of studies using X-rays.
An important member of his department was Charles Darwin, grandson of the Charles Darwin of evolution fame, who had been at Manchester during Rutherford’s day. Before the First World War he had produced two seminal papers on the theory of X-ray diffraction and much of their subsequent analysis was based on these two papers. Darwin’s work enabled Bragg’s team to determine the structure of a large number of increasingly complicated materials such as the silicates and bring some order into understanding the mineral kingdom.
Another key member of the Manchester staff was Reginald James who was a fascinating person. He had volunteered to take part as a physicist in Ernest Shackelton’s 1914 expedition to the Antarctic. Their ship was trapped in an ice sheet and was crushed and sank, leaving the party stranded on an ice floe which was slowly drifting north. Using some ingenious astronomical observations, he was able to determine their position and decide when the party was nearest to Elephant Island which they reached by travelling in an open boat. Shackelton then made an epic boat journey to South Georgia to summon help and a few months later the whole party was rescued by a steam ship from Elephant Island. James worked closely with Bragg on the sound ranging work during the First World War and followed him to Manchester as a lecturer. He played an important role in building up the “Manchester School” of X- ray analysis after the War and co-authored a seminal review paper with Bragg and Darwin on the structure of a variety of complicated materials. James and his co-workers made measurements of thermal vibrations leading to a direct measurement of the zero-point energy. Eventually James left Manchester to become Head of the Physics Department at the University of Capetown.
During his time at Manchester, Bragg made several foreign trips. In 1922 he visited Stockholm to receive the Nobel Prize for Physics, which he and his father had been jointly awarded in 1915, but the award ceremony had been delayed due to the First World War. In 1927, he went to Italy for the celebration of the centenary of the death of Alessandro Volta during which Mussolini charmed the ladies by his presence. But America beckoned and Bragg spent roughly six months as the guest of the Massachusetts Institute of Technology. This was a valuable experience and allowed him to work with a variety of students some of whom came to Manchester to carry out research. Bragg built up a formidable experimental
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61 research team mainly specialising in all aspects of crystallography. This was strengthened by some outstanding theoreticians. In addition to Charles Darwin, there was Hans Bethe, Douglas Hartree, Nevill Mott and Rudolph Peierls.
In the summer of 1937, Lawrence Bragg was invited to become Director of the National Physical Laboratory (NPL) in Teddington, Middlesex. It had been founded in 1900 with the aim to “bring scientific knowledge to bear practically upon our everyday industrial and commercial life”, something which it continues to follow to this day. Bragg was delighted about the appointment, particularly since it meant that his wife and family would be able to come to southern England away from the rather grim area of Manchester with its bleak northern climate. The NPL was housed in the beautiful and historic Bushy House which Queen Victoria had made available for that purpose. However, it was to be a very short term appointment since that year Lord Rutherford, Head of the Cavendish Laboratory at Cambridge, died rather suddenly. Bragg was encouraged to apply for the vacant position and was duly appointed.
Cambridge
He arrived in Cambridge in October 1938 at a difficult time. War with Germany was again looming despite the Prime Minister Neville Chamberlain bringing back from Munich a paper assuring us all that it was “Peace in our Time”. By the summer of 1939, war appeared imminent. John Cockcroft, who was later to share the 1951 Nobel Prize for Physics with Ernest Walton for their artificial splitting of the atom, had been appointed to the Jacksonian Chair having previously been head of the Mond Low-Temperature Laboratory. He had devised a scheme to make physicists available should war break out by producing a “Register of Scientists”. This produced little interests among the heads of the army, navy and air force research departments. The only people who seemed to show interest was the radar research establishment and as a result many clever young physicists became interested in radar and were involved in its development during the war. The use of radar was very important during the pursuance of the war. A major breakthrough was the development of the powerful cavity magnetron at Birmingham University, which enabled radar to be installed into aircraft and this was decisive in the submarine war over the Atlantic.
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It was in 1938, that Bragg first began his association with protein research which later produced such spectacular successes. Max Perutz, who had come to the Cavendish Laboratory as a refugee from Austria, showed him some X-ray diffraction pictures which he had obtained from haemoglobin crystals. Bragg had a hunch that this work might be significant and supported him. However, the work was soon to be put on hold. Perutz, who was Jewish, was initially interned and then moved to Canada where he worked on a fanciful and not totally unrealistic project to build a large floating ice platform in the mid-Atlantic to be used as an air base.
Just before the outbreak of war, the Cavendish laboratory was expanded by the opening of the Austin Wing the money having been supplied by the motoring magnate Lord Austin. At the outbreak of war most of the researchers at the Cavendish left for some form of war work and the laboratory was also turned over to the war effort. Queen Mary College and Bedford College were evacuated from London to Cambridge and physics teaching was carried out at the Cavendish. Bragg was based in Cambridge during the war except for a period of eight months in 1941 when he was in Canada as Scientific Liaison Officer, a period which he enjoyed and found most interesting except for the fact that he greatly missed his family. Much of his time was spent running the Cavendish but in addition, he was involved in sound ranging activities and with ASDIC, the admiralty underwater acoustic system for detecting submarines. Both of these involved quite extensive travelling around the country. One variation of the sound ranging technique, which he had been prominent in developing in the First World War, was using a novel method for the successful location of the origin of V2 rockets fired by the Nazis on England towards the end of the second war.
Difficult decisions
Peacetime proved to be a difficult period for Bragg. The two key appointments in the laboratory were that of the Jacksonian Chair which was held by Cockcroft and the Plummer Chair of Mathematical Physics, held by Ralph Fowler, Rutherford’s son in law. It was clear that Cockcroft would be appointed to the directorship of the new Atomic Energy Authority. However, until that appointment was officially created he retained his position as Jacksonian Professor. As a result, several highly suitable candidates went instead to other Universities. In the end Otto Frisch was appointed which proved very successful. By contrast, Fowler was suffering from a long and debilitating illness and again several otherwise suitable
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63 candidates had become unavailable until the position was finally filled by Douglas Hartree from Manchester. Bragg’s assistant in running the Cavendish laboratory was John Ratcliffe who carried out pioneering research work on radio waves in the ionosphere. He proved to be invaluable.
Not unsurprisingly, Bragg had great soul searching as to whether to continue research into nuclear physics, which Rutherford had pioneered so effectively. Bragg did not have expertise in this area and to have continued to work in it would have needed the building of a highly expensive particle accelerator. This in turn would require an extremely able person to run and direct operations and would also need huge funds and lots of manpower. In addition, particle accelerators were being built in Birmingham, Liverpool and Glasgow by people who had previously worked under Rutherford. In the end the decision to discontinue nuclear research at Cambridge was made and enabled Bragg to take the Cavendish Laboratory into new areas of research such as the study of biological molecules by X-rays and radio- astronomy both of which proved to be immensely fruitful.
After the war, Perutz returned to the Cavendish to continue his work on the diffraction of X-rays by haemoglobin supported by the Medical Research Council (MRC). Bragg was persuaded to see Sir Edward Mellanby, the secretary of the MRC, who agreed to fund the creation of the MRC Unit for Molecular Biology at Cambridge. This proved to be outstandingly successful and in 1962 four Nobel Prizes were awarded to workers in the unit, a unique achievement in the history of these prizes. The four people were Max Perutz and John Kendrew for their work on haemoglobin and myoglobin and Francis Crick and James Watson for their determination of the structure of DNA. The MRC Unit for Molecular Biology at Cambridge continues to this day to be a very important centre for research in this area.
The area of radio-astronomy at Cambridge was developed by Martin Ryle who, together with Anthony Hewish, developed an interferometer whereby interference fringes were produced by two aerials receiving signals from radio stars. Good resolution was achieved through the wide spacing of the aerials, which were in the form of a wire mattress standing about a foot or two above the ground and covering a space of some 150 by 20 feet. It was at the Cambridge radio-astronomy laboratory that pulsars were first discovered in 1967 by Jocelyn Bell-Burnell. In 1974 Ryle and Hewish were jointly awarded the Nobel Prize for Physics.
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By the late 1940s the Cavendish Laboratory was flourishing again. Although there was some nuclear physics being carried out under Frisch, the long shadow caused by Rutherford had largely gone away. Exciting research was now focused on radio-astronomy and molecular biology and there was also excellent work being carried out in the Mond Laboratory under Brian Pippard and David Schoenberg who were among the first people to determine the Fermi surfaces of metals. Another new and fruitful area was that of electron microscopy which was pioneered at the Cavendish by Vernon Coslett. Although Bragg himself was much occupied with running the department, he was able to lead a group engaged in the X-ray analysis of metals. Among those interested in metal physics was Egon Orowan who had come to the Cavendish from Birmingham University. He was one of the original people who put forward the theory of metal slip by the movement of dislocations. Bragg and his colleagues were able to produce an ingenious soap bubble raft, which could be made to simulate the behaviour of dislocations. Nowadays this is sometimes an undergraduate physics experiment.
It was during the early part of the 1950s that the autobiography of Lawrence Bragg ends abruptly. The likely reason is that in 1954 he was appointed to become director of the Royal Institution (RI) in London. He arrived at a very difficult time since the previous director Edward Andrade had departed following serious and acrimonious disagreements with the managers of the RI. For many years Bragg was fully occupied initially in trying to save the RI and then to build it up. In this he was remarkably successful. He was able to develop the research programme, the most prominent being the first determination of an enzyme structure by David Phillips and Louise Johnson. In addition, he introduced the now famous lecture/demonstrations to school children. Over a roughly ten year period he spoke to some two hundred thousand people. In his introduction, Mike Glazer says that he was one of these students. I was another and I well remember going to the RI to hear Sir Lawrence in the late 1950s when I was at my grammar school in North London. There must still be thousands of people still alive who were inspired by attending the RI and hearing Sir Lawrence lecture and watching a series of impressive experimental demonstrations. He finally retired in 1966 and died in 1971.
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The Lady’s perspective
The future wife of Lawrence Bragg had a very different upbringing from him. Alice Hopkinson was the daughter of a very hard working and conscientious medical doctor practicing in a suburb of Manchester. His name was Albert and he came from a large and highly talented family. One of his brothers, John, became an eminent electrical engineer and invented the Hopkinson dynamo, which at one time was in widespread use. He, along with several of his siblings, was an excellent rock climber although he came to a tragic end when in 1898, John, two daughters and a son were all killed in a mountaineering accident in the Swiss Alps. There is a plaque to this effect in Free School Lane, Cambridge, between the old Cavendish Laboratory and the Whipple Museum. John’s youngest son, Cecil, has already been mentioned as the very close friend of Lawrence Bragg and he was tragically killed at Gallipoli during the First World War. Another uncle, Alfred, was twice elected to Parliament and became Vice-Chancellor of Manchester University.
Her mother’s side of the family was also remarkably talented. Her maternal grandfather, who became Sir Philip Cunliffe-Owen, was the second Director of the South Kensington Museum before it became the Victoria and Albert Museum. Alice Hopkinson’s grandmother was German and she and Cunliffe-Owen had nine children. One of the daughters, Monica, married Harry Wills, one of seven sons of Henry Overton Wills who owned tobacco factories in Bristol. The family were great benefactors and among the beneficiaries was the University of Bristol including the H.H. Wills Physics Laboratory. Alice’s mother, Olga, was one of the last of the children. She was small and shy and rather overawed by her older brothers and sisters. Nevertheless, Olga was a talented lady being fluent in French and German and being well read in art, literature and history as well as on a more practical level having taken a teacher’s diploma in cooking. Alice Hopkinson was the middle of five children, the second eldest Eric being a very talented person who was also tragically killed in the First World War. According to Alice “we lived in an ugly house, in an ugly Manchester suburb” As a young child she went to the Lady Barn House School which was highly regarded in the city. Afterwards she went to the prestigious St Leonards at St Andrews, Scotland where she received an excellent education. At the end of it she was uncertain what to do but was advised “Go to Cambridge and read history, get a degree, then marry a man older than yourself”. Alice did precisely that.
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After leaving school, Alice Hokinson spent a year at home helping her parents who were profoundly saddened by the death of their son. The following year, just before the Armistice was signed bringing to an end the First World War, she went to Newnham College, Cambridge to study history. She seemed to have had a marvellous time. Being vivacious and attractive, Alice Hopkinson was much in demand and in addition to her studies attended balls, dances, parties, teas and other social events. Her parents had moved back to Cambridge. Her father, having spent thirty years as a medical doctor in Manchester, then spent several years as a demonstrator in the Anatomy Department at Cambridge where he was greatly liked and respected. As noted earlier it was while at Newnham that she first met Lawrence Bragg but he had to wait another couple of years before he secured her affections, after he had moved to Manchester where he had taken over the Chair in the University Physical Laboratories to replace Rutherford.
Life in Manchester was not that easy for the young Mrs Bragg. They lived in the suburb of Didsbury and each day Lawrence left shortly after breakfast and had to work very hard developing the physics department at the University. Manchester was still grey and grimy with a great deal of drizzle. However, they had a good social life frequently giving or attending dinner parties for university colleagues and friends. In addition, Alice often entertained students, visitors to the department and staff to tea as well as overnight guests. It was at their home in Didsbury that three of their four children were born, initially two boys followed by a girl. Professor and Mrs Bragg made several important travels abroad in connection with his work and wonderful holidays as a family at home.
They lived in Didsbury for ten years before moving out to Alderley Edge in Cheshire, which was much leafier and more rural than Manchester but still within an easy commute to the city. It was here that their fourth child Patience was born who is the co-editor of Crystal Clear. They had a beautiful, large house high up on a hill with commanding views over the Cheshire plains. They found an interesting new circle of friends and life here was very pleasant.
Lawrence Bragg was head of the physical laboratories at Manchester for eighteen years and although he had built up a powerful department felt the urge to move on. As mentioned earlier he was appointed to become the Director of the National Physical Laboratory at Teddington, Middlesex.
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It was while she was living at Teddington that Alice Bragg first met the formidable Dowager-Marchioness of Reading who wanted her to join up to a voluntary scheme (WVS), which she was launching on behalf of the Home Office. War with Germany again seemed imminent. Alice became one of half a million women recruited for Air Raid Precaution work (ARP). On arrival at Cambridge, Lady Reading put Alice in charge of starting the WVS in Cambridge and as a result Alice got to know a large number of town people who were not directly associated with the University. As soon as War was declared in 1939, life in Cambridge changed rapidly. Many people went off to the War and a large number of refugees came into the city to be housed temporarily. Like so many homes in Britain, the Bragg residence became an open house with all manner of people dropping in for meals, a cup of tea or living there for a short term. Lawrence and Alice Bragg agonised as to whether to send their children over to the safety of Canada but in the end decided not to. Lawrence was sent to Canada and the United States on a government mission in 1941 and was away for the best part of a year, which was very difficult for all parties. While he was away Alice was co-opted into the town’s Civil Defence Committee and shortly afterwards was invited to become a town councillor representing Newnham, the ward in which they lived. The War period was extremely taxing and difficult for almost all people in Britain. The end in 1945 was a great relief although conditions afterwards were slow to improve.
Immediately after the War, Alice was appointed Mayor of Cambridge, a role which she carried out with characteristic aplomb. The main business was taking the chair at the regular council meeting dressed in her full mayor’s regalia. These meetings could become very tedious with some councillors droning on and on. A big occasion was when she had to take the salute when the local regiment was given the Freedom of the Borough. It was also a poignant event since her brother Eric had been killed in the First World War while serving in this regiment. She opened the local Marshall’s Airport in Cambridge during which she was taken on a rather precarious flight in a Tiger Moth.
Her position as Mayor of Cambridge only lasted a year and Alice Bragg had acquitted herself extremely well. She returned to a normal life with Britain in the grips of post war austerity. Lawrence Bragg was very busy trying to build up the Cavendish Laboratory after the war. In 1951 she received a letter from the Minister of Education inviting her to join the Advisory
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Council for Education in England and shortly afterwards she received a letter from the Prime Minister, Mr Attlee, asking her to serve on the Royal Commission for Marriage and Divorce.
A few years later they moved to the Royal Institution in London, which Lawrence Bragg was charged with trying to revive. They lived in the beautiful Director’s flat at the top of the Institution. In part because of its central location, the flat was visited by numerous people, either for meals or a short stay, and as always Alice Bragg was an excellent hostess. It was while she was living in London that Alice was invited to serve on the Lord Chancellor’s Advisory Committee for Legal Aid, which she did for fourteen years. Another appointment, which meant an enormous amount to her, was chairmanship of the National Marriage Guidance Council. She went around the country getting to know local Marriage Guidance Councils. It was important work in which Lawrence supported her enthusiastically sometimes attending their Annual General Meeting. She was involved with this for nearly twenty years.
The final years
During the early 1960s the fortunes of the Royal Institution were turned around and it was recognised as a foremost science organisation within Britain. This was in no small way due to the efforts of Sir Lawrence and his introduction of the lectures for school students. However, there was concern about his health. Several times he had bad pneumonia and twice he underwent operations. In 1962 he was in hospital for five weeks. By this time Sir Lawrence had become “The Grand Old Man of Science” receiving numerous honorary doctorates. There was a big celebration in 1965 to mark the fiftieth anniversary of his Nobel Prize for Physics. In addition they had several marvellous trips abroad including to South Africa and India and in 1960 a trip round the world, which enabled him to show Alice his old haunts in Adelaide, which he had left so many years before.
In 1966, at the age of seventy six, Sir Lawrence Bragg retired from the Royal Institution. The couple went to live in a home that they had purchased some years before in Suffolk where they could garden and Lawrence could paint and go for walks and study the bird life. He died in 1971 having just finished a final book. Alice returned to live in Cambridge, where she felt that she belonged, and lived happily in a secure accommodation. She died in 1989.
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In this Essay Review I have concentrated on the scientific work of Lawrence Bragg, although it should be clear that his wife made very important contributions to British life. However, Crystal Clear describes much more than just the work and personalities of Sir Lawrence and Lady Bragg. We are given interesting insights into the four Bragg children and their development, the houses that they lived in, some of which were beautiful and interesting, their holidays and official travel and their wide circle of friends. In addition we learn about their hobbies. Lawrence Bragg was a keen hiker and bird watcher and had a great love of nature and also of sailing. He was an accomplished amateur artist and the book contains many of his sketches which add considerably to it as do the photographs many of which were supplied by Patience Thomson.
For me Crystal Clear is an excellent read. The book is greatly enhanced by the large number of footnotes giving thumbnail sketches of the many prominent scientists, politicians, administrators and other with whom they came into contact. All the profits from the sale of this book are to go towards the Royal Institution in London. Sir Lawrence would have approved.
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Forthcoming meetings
The history of Nuclear Magnetic Resonance (NMR) and MRI in Britain - now to be held in April 2018, details to follow and a meeting on Physicists of London universities - yet to be arranged.
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History of Physics Group Committee 2016/17
Chairman Professor Andrew Whitaker
Hon Secretary Dr. Vince Smith
Hon. Treasurer Dr. Chris Green
Members Mrs Kathleen Crennell Professor John Dainton Professor Edward Davis Dr. Peter Ford Dr. Jim Grozier Professor Keith MacEwen. Dr. Peter Rowlands Dr. Neil Todd Professor Denis Weaire
Newsletter Editor Mr Malcolm Cooper
IOP History of Physics Newsletter November 2017