The Royal Dublin Society

Founded as the ‘Dublin Society, for promoting husbandry and other useful arts in Ireland’, in 1731, the society was granted a royal charter in 1750. It initiated several scientific endeavours, including the establishment of the Botanic Gardens, Dublin (1796) and the Royal Veterinary College of Ireland (1895), and the appointment of several professors. Its members saw the practical application of science as a way not just of promoting knowledge but also of improving Irish agriculture and the economy more broadly.Footnote ⁴ Throughout the nineteenth century, it was one of the principal institutions in Ireland for the promotion of science to both elite and lay audiences, including a series of annual lectures in provincial towns.Footnote ⁵

However, the society's burgeoning endeavours were soon curtailed by increasing state interest in science. Its professors were transferred to the newly established Museum of Irish Industry in 1854 (this was abolished in 1867 and replaced by the Royal College of Science for Ireland) and paid by government grants. This new museum would be responsible for scientific education and, as noted by Clara Cullen, the RDS was hostile to this impingement on its traditional remit in this area.Footnote ⁶ With the passing of the Dublin Science and Art Museum Act 1877, the RDS lost much of its institutional infrastructure, including most of its library, the Natural History Museum, the Botanic Gardens, and the School of Art – the library and museum collections were to form the foundation collections of the National Library and National Museum.Footnote ⁷ Thus by 1877 the institution's traditional remit as a scientific organization had been considerably undermined.

Despite the losses associated with the 1877 Act, the society's negotiations with the government prior to its passing demonstrate much interest in continuing as a scientific institution. Its membership sought to revitalize and promote the institution as a society for the study of ‘pure science’. This provoked a protest from the Royal Irish Academy (RIA), which argued that this area was its exclusive prerogative. The RDS countered this argument by drawing up a list of 168 papers on scientific topics that it had published over the previous twenty years.Footnote ⁸ These efforts reached fruition with the granting of a new charter for the society in 1877 and a second supplementary charter in 1888 which directed that the society would continue to act for ‘the advancement of agriculture and other branches of industry, and for the advancement of Science and Art’. This provided the RDS with a mandate and through its laboratory the facilities to reimagine its role as a promotor and arbitrator of both applied and abstract science in Ireland. In 1889 it established a Committee for Science and Its Industrial Applications to expand and organize these activities.Footnote ⁹

From 1890 the Committee for Science and Its Industrial Applications regularly made grants available for the promotion of scientific research, an example being a grant of thirty pounds in 1898 to the anthropologist A.C. Haddon to aid his expedition to the Torres Straits and Borneo.Footnote ¹⁰ Toby Barnard has highlighted the role that the granting of ‘premiums’ – financial rewards – had in promoting the society in the eighteenth century.Footnote ¹¹ Thus the RDS was following a tried and tested tactic to promote itself – in this case as a centre of scientific enquiry – as well as providing much-needed resources for Irish scientists. It was within this context of enhanced financial and institutional support that radioactivity was received.

Radioactivity

The early history of radioactivity has received much scholarly attention in recent years.Footnote ¹² However, much of this literature is focused on the main centres of research and less attention has been given to the impact of this new science on the organization of science in more peripheral regions.Footnote ¹³ Jeff Hughes has argued that with the advent of the atomic bomb, subsequent post-war narratives of radioactive research have been shaped by ‘a linear, teleological, “internalist” sequence of theoretical developments and associated “significant” experimental discoveries through which nuclear history could be given shape and meaning’.Footnote ¹⁴ Scholars have rethought how they approach the history of radioactivity by placing scientific practices in their wider social, cultural and material contexts, and also demonstrated the impact of radioactivity on broader scientific debates.Footnote ¹⁵ It is important, however, to recognize that these teleological narratives have also excluded peripheral centres of research which ‘failed’ to contribute to the development of nuclear science.

The increasing importance of scientific research and teaching in the nineteenth century was demonstrated by greater state support for these activities.Footnote ¹⁶ In tandem with this was the growth of laboratory research in higher-education institutions across the United Kingdom. By the beginning of the twentieth century, the Cavendish Laboratory still maintained a dominant position as the centre of excellence for physics research in the British Isles. However, the prominence of physics was increasing. Other research laboratories expanded or opened across the United Kingdom – most significantly for radioactivity research was Ernest Rutherford's elevation to the chair of physics at the University of Manchester. Rutherford's radioactive research at Manchester and his rise to prominence demonstrate the considerable benefits to his own and these institutions’ national and international standing. Indeed, it has been noted that ‘the leadership of innovation in physics was shifting from Cambridge to Manchester’ in this period. His subsequent return to the Cavendish demonstrates how radioactivity had impacted his career.Footnote ¹⁷

In Ireland reformers saw science and non-denominational education as a route to economic improvement and a method of defusing sectarian tension. The growth of Irish mechanics' institutes in the nineteenth century is a sign of the popularity of scientific instruction. These institutes formed strong bonds with the temperance movement. Scientific education and temperance were seen as two parts of the same quest to improve the lot of the Irish artisan.Footnote ¹⁸ Traditionally, science education had been based in Trinity College Dublin and the RDS – both dominated by the Anglo-Irish elite. Thus the state's increasing concern and interference in scientific education threatened to break this monopoly.Footnote ¹⁹ However, the RDS mounted a vigorous rearguard action against this encroachment and radioactivity was a central plank in these endeavours. Its predominately Protestant and wealthy membership were in a position, through their own resources and social standing, to act for the preservation of the society's scientific credentials.

Numerous studies have demonstrated the importance of local factors in the growth and activities of scientific institutions. Steven Shapin has highlighted that ‘their failure to survive or to contribute to the advance of scientific knowledge does not diminish their historical significance’.Footnote ²⁰ Elizabeth Neswald's research on the Galway Mechanics' Institute shows that such Irish institutes shared many characteristics with their British counterparts, but their development must be understood within a local context. Indeed, Neswald highlights the strong connection between self-improvement, scientific knowledge and education, and national improvement, some seeing this as a route toward national independence.Footnote ²¹ The predominantly Protestant, landowning, elite membership of the RDS must have viewed these connections with concern.

Thus the RDS's scientific activities were an integral part of its members’ self-fashioning as civic-minded, educated and cultured members of society, who regarded themselves as the country's natural leaders. Consequently, the retention of science as an integral part of the society's activities was an essential part of this group's efforts to retain its social position within, and relevance to, Irish society. It was within this context that radium was to play a central role as a nexus for the maintenance of an experimental and philanthropic culture that permeated much of the RDS's scientific output at the beginning of the twentieth century. This in turn demonstrates the important role that sociability played in the promotion of science in Ireland in this period.

Radiation and Ireland

In November 1895 Wilhelm Röntgen, while experimenting with cathode rays, discovered a new type of ray which had the ability to pass through matter. In January of the following year, Röntgen shared his revelation, which he called ‘X-rays’, with the world and word of the new discovery quickly spread.Footnote ²² Lawrence Badash has highlighted that no other discovery in the period aroused as much professional and public interest and Röntgen's experiments were quickly repeated around the world.Footnote ²³ Ireland was not immune to the widespread interest in this new marvel and by 16 January the Irish Examiner was reporting on these new and mysterious rays. The potential uses of X-rays, for example in surgery, were quickly realized and others swiftly began replicating Röntgen's experiments.Footnote ²⁴ The nature of this new form of ‘light’ generated much curiosity from both Irish scientists and the public.Footnote ²⁵

Interest in the X-ray phenomenon was demonstrated at a presentation on the topic delivered to the RDS on 18 March 1896 by Richard J. Moss.Footnote ²⁶ While Moss had little to add to existing knowledge of these rays, his lecture attracted a large crowd and provoked much discussion. In addition, Professor William Fletcher (W.F.) Barrett (chairman of the proceedings) ‘exhibited Röntgen photographs of a needle in a woman's hand’.Footnote ²⁷ Luis A. Campos has demonstrated that such public lectures were based in the tradition of showmanship as much as education and firmly connected to earlier exhibitions of electricity.Footnote ²⁸ Barrett, who had used telephones to display electricity in action, is a prime example of the continuation of this tradition in Ireland.Footnote ²⁹ Using this ‘shadowgraph’ the needle was successfully removed by a Dr M. Causland (22 March 1896). This was the third – recorded – successful use of the new discovery in surgery in Ireland and Röntgen rays were soon regularly used in both surgery and dentistry.Footnote ³⁰

While the new rays were not only exciting and useful, there was also a growing awareness of the dangers that they presented. The ‘Röntgen rays were particularly apt to cause the worst kind of sunburn’, and overexposure, it was warned, could lead to fingernails being shed.Footnote ³¹ In November 1896 the Evening Herald stated that anyone ‘who has taken any interest in the wonderful development of the X rays, knows that those who are constantly subjected to them run the risk of injury’.Footnote ³² Hence the potential short-term dangers, as well as the benefits, of these new rays were known about soon after their discovery.

In addition to their medical uses, there were many hucksters trying to promote inventions based, supposedly, on X-rays. Hopes of the rays’ ability to restore sight were but one of many promises. Another example was the Röntgen pill, which, it was claimed, having been bombarded with X-rays, would be useful in medical diagnostics. The Connaught Telegraph glibly warned its readers not to consume too many, because if two or three were taken at a time ‘a policeman might mistake him for a conflagration, and call out the fire brigade’.Footnote ³³

Röntgen's discovery was one of many in the area of radiation in the late nineteenth and early twentieth centuries. In 1896 Henri Becquerel, while investigating whether phosphorescent minerals produced X-rays, discovered that uranium salts emit radiation, and by 1897 it had been established that this radiation carried an electrical charge. Throughout this period Irish scientists kept well abreast of such developments.Footnote ³⁴

Becquerel's discovery prompted the work of Pierre and Marie Curie, who discovered radium in 1898 by separating it (and polonium) from pitchblende, a uranium ore.Footnote ³⁵ Due to Marie Curie's efforts this discovery spawned a ‘radium economy’ where the production and manufacturing of radium were intertwined with laboratory research. For scientists such as Curie the radium economy was not about financial gain but rather about securing a steady supply of radioactive material. Even with the use of industrial methods, it would take the processing of tonnes of pitchblende before the Curies possessed a tenth of a gram of radium chloride in 1902.Footnote ³⁶

This new element provoked much interest and by 1902 radium bromide was commercially available. This accessibility was a boon to scientists and led to a massive increase in research into this new science.Footnote ³⁷ The fact that little was known about radium and the strange radiations that it produced meant that it was fertile ground for those hoping to advance their careers. In addition, the requirement of expensive high-tech apparatus was not a feature of this period. Thus scientists made valuable discoveries with the most rudimentary, and often home-made, equipment.Footnote ³⁸

Knowledge and interest in this new science quickly spread; in the United Kingdom, the Royal Society was to establish a Radium Committee on 10 December 1903. Its function was to acquire radium for scientific research. The impetus for its formation was likely a lecture, by the Curies, at the Royal Institute, London, in June of that year. The Royal Society did not receive its first supply of radium until December 1906, although some individuals had access to small quantities of radium prior to this.Footnote ³⁹

Irish scientists were also interested in this new element and in 1903 Gerald Molloy and John Alexander McClelland – both members of the RDS as well as university lecturers –petitioned the RDS's Committee for Science and Its Industrial Applications to purchase a supply of radium for scientific research.Footnote ⁴⁰ McCelland, following postgraduate studies at Trinity College, Cambridge, during which he gained research experience at the Cavendish Laboratory, returned to Ireland as professor of physics at University College Dublin (UCD) in 1900. McClelland is a prime example of the post-1895 ‘out-of-Cambridge’ recruits who not only contributed to the development of the school but also brought the cutting-edge research and methodologies of the Cavendish home. McClelland was one of a plethora of graduates appointed to chairs of physics across the United Kingdom and the empire.Footnote ⁴¹ Despite this appointment he had limited resources with which to continue his scientific research. UCD's chemistry laboratory was located in a shed at the back of its premises at 85–86 St Stephen's Green, Dublin, and the physics laboratory was just as cramped. Luckily, he was elected a fellow of the Royal University of Ireland in 1901.Footnote ⁴² This provided him with not only an annual salary of four hundred pounds but also access to the university's relatively well-equipped laboratories that were used for examinations (however, this access was denied to his research students).Footnote ⁴³ Thus, with experience researching radiation and now in a position to resume experimentation, it was not surprising that McClelland would seek to begin investigating one of the most promising and exciting scientific fields of this period.

In order to do this McClelland needed to engage with the emerging radium economy. Following its discovery, demand for radium had been insatiable. Its production was an arduous task which involved strenuous physical labour to separate minuscule amounts of radium from tonnes of pitchblende ore. To extract adequate quantities of the element this process needed to take place at an industrial level. The Curies are a perfect example of the strategies adopted to accumulate radium. Marie Curie sought to connect the development of radioactive research to the foundation and expansion of a radioactive industry. Thus Curie's research was aided not only by state grants but also by access to radium afforded to her by her close association with the developing radium industry. However, despite the nascent stirrings of a radium industry, access to the element was limited. Adding to difficulties with production, the Austrian government banned export of uranium ore from the St Joachimsthal mine for industrial use in 1903. While Curie could overcome such difficulties due to her prominent place as the discoverer of radium, others were not so fortunate.Footnote ⁴⁴

In the US, physicists were to turn to industry to solve their funding problems, as Jon Agar has demonstrated, and the option to engage in commercial work was also open to physics professors in Britain.Footnote ⁴⁵ However, this was not possible for Irish scientists. A lack of an electrical or radium industry meant that there was little recourse to this avenue of funding. In addition, this abstract research held out little appeal to the state. Instead the RDS and its traditional philanthropic role in the promotion of science was essential for the acquisition of radium.

Irish scientists could not refine radium, and thus the only option open to them was its purchase on the international market. On 10 November 1903 the RDS Science Committee voted the sum of thirty pounds for the purchase of radium. While the radium remained the property of the society, it would be ‘placed at the service’ of Molloy and McClelland for a period of six months. On 26 November the RDS took its first delivery of radium when it received two tubes, each containing five milligrams of radium bromide, at a total cost of fifteen pounds. This was followed by a further fifty milligrams in January 1904, at a cost of thirty pounds.Footnote ⁴⁶

The radium bromide's arrival in November 1903 provided a catalyst for an array of experiments and presentations on the subjects of radium and radioactivity. Experimenters were soon attempting to ascertain the properties of radium and its potential effects on organic matter. In December 1903, H.H. Dixon read a paper at the RDS outlining experiments that he and J.T. Wigham had undertaken to investigate the possible biological impacts of radium.Footnote ⁴⁷ Dixon's experiments had two purposes: he sought first to investigate the impact of radium on the growth of plants, and second to investigate the ‘inhibitory’ effect of radium bromide on various bacteria.

Using seedlings, Dixon established that while plants were not radiotropic, exposure to radium did stunt plant growth.Footnote ⁴⁸ Despite this, there was no indication that it caused abnormal or pathological effects. While the experiments provided little of worth to those seeking to utilize radium, they do point to some important perceptions concerning radioactivity. These included the notion that radium, which had the ability to emit its own energy without any external stimulus, could be a tool for the infusion of some type of life force into organic matter. Such debates were global and possession of radium allowed Irish scientists to engage with these, in turn demonstrating the importance of the RDS in the promotion of science in early twentieth-century Ireland. Thus, by providing access to radium, it had provided a useful tool in its efforts to reinvigorate itself as a centre of scientific enquiry.Footnote ⁴⁹ In a second set of experiments Dixon investigated the element's effect on the bacteria that cause anthrax and typhus, two diseases which had serious impacts for farmers and the general public respectively. This demonstrates another popular trope concerning radioactivity in the science's formative years: that it could become an important therapeutic tool.Footnote ⁵⁰

McClelland quickly utilized the radioactive source provided by RDS funding. In a 1904 publication he revealed a method of testing the electrical capacities of radioactive substances using a quadrant electrometer, a relatively simple piece of equipment, thus demonstrating considerable awareness of developments in the science.Footnote ⁵¹ Given that an International Radium Standard was not set until 1912, when twenty milligrams of radium was placed at the International Office of Weights and Measurements, such experiments were a necessary part of scientists’ ongoing efforts to measure and standardize radioactivity (this would be an essential part of any potential radiotherapy).Footnote ⁵² While a relatively simple experiment, this did provide Irish scientists with a method of checking radioactivity using the limited equipment available. The lack of proper facilities to carry out research into radioactivity was noted by Professor Johnson Symington.Footnote ⁵³ He stated that Rutherford would have found ‘no laboratory in Ireland’ with ‘the equipment necessary for the conduct of his experimental work’.Footnote ⁵⁴ Thus, with limited facilities and funds available, the RDS provided Irish scientists with important resources with which to pursue their work. These grants and the promise of publication in one of its scientific journals made the RDS an important arbiter of scientific knowledge in Ireland.

The Royal Dublin Society's publications

The purchase of radium and the possibility of publication meant that the RDS was to be one of the primary Irish institutions for the dissemination of research into radioactivity. The society provided many opportunities for this. In addition to its publications, from 1836 the society ran regular ‘evening scientific meetings’. These consisted of lectures on a wide variety of topics ranging from time signals to X-rays.Footnote ⁵⁵ The purpose of these meetings was ‘the reading and discussion of scientific papers’, which provided entertainment and elucidation to members of the RDS but also served as important opportunities to disseminate emerging knowledge.Footnote ⁵⁶ John Joly (a polymath, elected fellow of the Royal Society (of London) in 1892, a prominent member of the RDS, and professor of geology at Trinity College Dublin) noted that presenting such papers provided a forum where research and findings were ‘listened to’ and in return would receive ‘friendly and useful criticism’.Footnote ⁵⁷

The importance of the RDS as a venue for the dissemination of scientific research must be understood in the context of the limited nature of such opportunities in Ireland. The existing universities were small, as were their science departments. Thus academics were reliant on several learned societies for collaboration and the pursuit of scientific rigour through peer review. Two important Irish bodies that provided scientific credibility in nineteenth- and early twentieth-century Ireland were the RIA and the RDS.Footnote ⁵⁸ Consequently, the acceptance of presentations at the RDS was a method of validating one's scientific research, subjecting it to the rigour of open discussion amongst one's scientific and social peers, as well as disseminating knowledge.

Presentations deemed of sufficient quality would be chosen for publication in one of the society's scientific journals – the Scientific Proceedings of the Royal Dublin Society and the Scientific Transactions of the Royal Dublin Society. These had been relaunched by Richard J. Moss and George Johnstone Stoney in 1877 (in 1909 the Transactions were discontinued, with the Proceedings remaining as the society's only scientific journal).Footnote ⁵⁹ Negotiations with the government had resulted in a substantial grant to aid these publications and they were seen as essential to the society's efforts to promote science. These funds allowed the RDS to print copious amounts of extremely high-quality illustrations and the journal was noted for its speed of publication. Thus the new journals provided a valuable facility for Irish scientists.Footnote ⁶⁰

As a stipulation for those presenting at its scientific meetings, the RDS got first refusal on the subsequent publication of the paper.Footnote ⁶¹ Thus, while the provision of resources and publication opportunities offered much to scientists and greatly aided their scientific endeavours, these efforts in turn helped sustain the society in a period when its remit as a scientific institution was under increasing threat from the state. Such journals provided many of the limited opportunities for the publication of scientific research in Ireland (the journals of the Royal Irish Academy also represented a valuable outlet) and their importance as a tool for the dissemination of this research cannot be overemphasized.Footnote ⁶² Papers chosen for publication would be quickly published and placed for sale in Ireland and the rest of the UK, but their reach extended beyond this. Through an array of reciprocal arrangements these journals were exchanged with learned societies and research groups throughout the globe (these numbered 375 in 1899 and 474 in 1915, and reached 567 by 1953). A sample of the institutions receiving these journals gives some small indication of its reach: the Surveyor General, Natal; the Museum of São Paulo, Brazil; the Connecticut Academy; the South African Museum; the Yerkes Observatory; and the American Mathematical Society.Footnote ⁶³ As can be seen, publication in the society's journals meant dissemination of one's research on a global scale. This only added to the importance of such publications to scientists, such as McClelland, far from the main centres of research into radioactivity. Thus presentations at the RDS's scientific meetings should not be seen as merely a recreational and local activity for its members but rather as an important opportunity to disseminate research findings and participate in a global discourse around this emerging science.

The importance and impact of the RDS's publications is illustrated in McClelland's nomination certificate for the Royal Society. In recognizing McClelland's contribution to the field of radioactivity a large portion of the publications cited are those in RDS journals, thus demonstrating their reach, impact and importance. The certificate also states that ‘the line of work opened up in these papers has been taken up by many investigators’, further demonstrating the international reach of Irish research. This, combined with the calibre of the proposers, including J.J. Thomson, Ernest Rutherford, C.T.R. Wilson, H.A. Wilson, R.J. Strutt, S. Young, John Joly, J.S. Townsend and E.T. Whittaker, demonstrates that provincial scientific centres could make contributions to scientific discourse in the early twentieth century.Footnote ⁶⁴

The RDS as scientific arbiter

The importance of these scientific publications also highlights the role of the society as an arbiter of science. Research into radioactivity was literally rewriting the laws of nature and what shape the new laws would take. Even certainty that the pronouncements of scientists regarding their findings were accurate was not always a given. The transmutation of radium, initially into radium emanation (radon) but eventually lead, was often compared to the alchemical quest to change lead into gold. Scientists were – initially at least – concerned that such comparisons would undermine the credibility of their findings.Footnote ⁶⁵ It was in this context that institutions such as the RDS provided legitimacy and authority to their proclamations.

Much of this early research was reliant on human observation. Apparatus, such as calcium sulphide screens, could demonstrate the presence of radiation through phosphorescence. However, such experimentation relied on human eyesight and interpretation. For this reason, the repeatability of a scientific experiment was essential for its credibility. A paper in 1904 on N-rays by Felix Edward (F.E.) Hackett (presented to the RDS by McClelland) is a good illustration of the difficulties these experimenters faced.Footnote ⁶⁶ The discovery of N-rays was announced by René Blondlot in 1903, as a result of his attempts to polarize X-rays. Blondlot claimed that N-rays were emitted from living and inert objects, yet there was much contemporary disagreement regarding their existence.Footnote ⁶⁷ In 1904 the Revue scientifique had examined Blondlot's claims and found that the rays did not exist. Hackett begins his paper by highlighting the disagreements about the existence of N-rays and the point that experiments to observe N-rays were, in many cases, not repeatable. He states that this was due to ‘the effects being so small that they cannot be observed without special training’. Thus it was not the experiment or thesis that was at fault but the experimenter. Indeed, Hackett's article goes on to highlight that difficulties in seeing N-rays were due to the human eye and the nature of phosphorescent screens.Footnote ⁶⁸

In his experiment, Hackett notes that ‘substances under strain were found the most suitable sources of N-rays. Wood or cork compressed, tempered steel, and unannealed glass were used for this purpose. As other more intense sources emit heat in addition to N-rays. Their use could not be satisfactory’. Hackett claims that ‘when a source of N-rays was brought up behind the screen, the pattern came out more clearly’. Thus for him there was no doubt about the existence of N-rays; rather the fault was that ‘an ordinary person without any previous training found great difficulty in detecting small changes’, and ‘it was not surprising, then, that so many have failed to see the effects’.Footnote ⁶⁹ This acclamation of trained scientists was similar to Blondlot's own pronouncements. According to Irving M. Klotz, the relative ease with which N-rays were accepted was a product of the context in which they were ‘discovered’. The discovery of an array of ‘rays’ since 1895 and the contested debate around their existence meant that scientists and the general public were much more open to the possibility of discovering more.Footnote ⁷⁰

While N-rays were subsequently proven to be non-existent, the rays rather being a product of the human eye, Hackett's paper demonstrates the difficulties with proclamations of scientific truth and that experimental data is the product of human interpretation. As such, scientific institutions such as the RDS were essential in providing authority to the pronouncements of scientists. Mary Jo Nye has argued that French acceptance of N-rays was a symptom of worries about the loss of national prestige in the area of science.Footnote ⁷¹ Such concerns on a national and institutional level could explain the acceptance of Hackett's N-ray paper by the RDS. Additionally, such experiments connected the RDS to an international network of scientific discourse where repeatability of experiments was essential for the validation of their accuracy. As the case of N-rays demonstrates, scientific knowledge was not blindly received, but rather assimilated, experimented upon and reassembled in a local context.

Scientists associated with the RDS were to make many such investigations, interrogating existing scientific claims and contributing to emerging knowledge. One example was the concept of transmutation. Irish scientists such as McClelland were well aware of the latest development in such theories and he had integrated them into his teaching.Footnote ⁷² He was to investigate this phenomenon, presenting a paper, ‘On the emanation given off by radium’, on 12 January 1903. The content of this emanation (radon) was extremely important for providing proof of transmutation. John Finnegan highlighted this to the Belfast Natural History and Philosophical Society in 1904. The previous summer Ramsay had discovered that with the decay of radium emanation, helium was produced. This seemed to support Rutherford's speculation that radium was ‘being constantly transformed into helium’ (although Rutherford thought that these were alpha particles).Footnote ⁷³ Finnegan stated that ‘assuming the truth of these laboratory results, we find ourselves in presence of quite startling phenomena’; thus Ramsay's findings would have to be ‘confirmed’.Footnote ⁷⁴ During his investigation, McClelland confirmed Rutherford's theory that radium emanation (radon) had no charge, hence endorsing an important part of the theory of radioactive transformation. In the process he not only relied on his method of testing activity using a quadrant electrometer but also developed expertise in drawing off radium emanation from radium.Footnote ⁷⁵ Interest in transmutation was further demonstrated by a presentation to the RDS by Richard J. Moss, the RDS's chemical analyst and registrar, ‘On the state in which helium exists in pitchblende’.Footnote ⁷⁶

McClelland followed up on these experiments throughout the 1900s, building up his own, and the RDS's institutional, knowledge of radium and its isotopes in the process. Hence McClelland's experiments should not be seen as the recreational pursuits of a provincial scientist but rather as an integral part of a broad scientific discourse in which truth claims were not taken at face value but subjected to the test of repeatability. This gave scientific investigation meaning to the society's members. Through it, they were demonstrating their own status as members of a scientific and cultural elite.

McClelland made a number of contributions to the society's lecture series and journals on a range of topics related to radioactivity. These included investigations of the nature of the gamma rays emitted by radium and of secondary radiation and its implications for understanding atomic structure. In studying gamma rays he sought to understand whether they were electromagnetic radiation, similar to X-rays, or charged particles, as were alpha and beta radiation. He was able to do this using his electrometer technique. In examining secondary radiation, McClelland used fifty milligrams of partially screened radium to send a ‘pencil’ of beta and gamma rays to a plate, in order to investigate the amount of secondary radiation that various substances produced. Again, using his electrometer technique, McClelland gained much insight into the penetrating powers of these rays and their role in the production of secondary radiation. These experiments also allowed him to theorize that ‘the impact of the β-rays produces a disturbance sufficient to cause the disintegration of the atom in substances which, in the normal state, are in stable equilibrium’.Footnote ⁷⁷

Secondary radiation was an important subject of investigation for the membership of the RDS, and by the end of the 1900s it had built up a considerable body of knowledge about this topic.Footnote ⁷⁸ Central to this research was the finding that secondary radiation was an entirely atomic phenomenon. Given the experimental nature of the science this was cutting-edge research and mimicked much that was happening elsewhere in Europe. Thus the research of scientists associated with the RDS in the 1903–1909 period was primarily concerned with secondary radiation and, through that, atomic structure. They had established that the amount of secondary radiation released was directly proportional to atomic mass. However, they could not deduce the mechanisms by which subatomic particles were released.Footnote ⁷⁹

McClelland's work with radioactivity brought him much recognition. He was elected secretary of the RIA in 1906 and a fellow of the Royal Society in 1909, and awarded a Boyle Medal from the RDS in 1917.Footnote ⁸⁰ This was the society's highest award for scientific excellence and it was conferred for his contribution to Irish science, primarily for research that dealt ‘(a) with ionisation as resulting from addition of electrons to gaseous molecules or to aggregates of such: and (b) with the more recently discovered forms of radiation associated pre-eminently with radioactivity’. McClelland's decision to investigate radioactivity had certainly proved a worthwhile one. By 1917 the membership of the RDS considered him a ‘pioneer in investigating the nature of the radiations associated with radio-activity’.Footnote ⁸¹

Following a lull in publications from 1908 to 1912 McClelland returned to research work, with a new focus on atmospheric aerosols. Another interesting aspect of this later work was that the bulk of it was published in the Proceedings of the Royal Irish Academy.Footnote ⁸² (He became secretary of the RIA in 1906 and was elected a member in 1920.Footnote ⁸³) The takeover of the Royal University's laboratory facilities by University College Dublin in 1909, when the Royal University was disestablished following the founding of the National University of Ireland, provided a vastly improved situation for scientists researching at the university. McClelland soon had research students, who had previously been barred, at work in these laboratories.Footnote ⁸⁴

The bulk of Irish radioactive research was carried out between 1903 and 1909. The primitive nature of understanding concerning this new science created many opportunities for ambitious and motivated scientists. Irish scientists had similar research objectives as those in Britain. For example, many articles in the Proceedings of the Royal Society explored similar topics during the 1900s.Footnote ⁸⁵ Indeed, McClelland contributed to the journal on the subject of secondary radiation,Footnote ⁸⁶ and two of his articles on secondary radiation and the absorption of gamma rays are cited by Rutherford in his 1905 book Radio-activity, while John Joly's work was also cited on two occasion.Footnote ⁸⁷ Thus, during these formative years, Irish scientists assisted by the RDS were able to make important contributions to this emerging science. This demonstrates the success of the society's strategy of using radium to maintain its scientific relevance.

Internationally, in the subsequent years there was a sustained focus on secondary radiation; however, research centres, such as Paris, also focused on radioactive standards, preparation of radium, and its industrial and medical applications.Footnote ⁸⁸ By 1910 radioactive researchers and material were concentrated at the main research centres, such as Paris, Montreal, Berlin and Vienna, and increasing amounts of radioactive material were needed to continue research.Footnote ⁸⁹ Irish scientists had not refined radium from pitchblende and had only a small quantity of the element that the RDS had purchased with which to work. Hence, despite increasing interest in the medical applications of radioactivity, they could make little contribution to broader international research objectives. As the science progressed so did the complexity of research,Footnote ⁹⁰ and with the return of Rutherford to the UK in 1907 British researchers became increasingly interested in the use of radioactivity to investigate the atomic interior.Footnote ⁹¹ This research needed advanced equipment and resources (including new radioactive substances) which even specialist laboratories, such as the Cavendish, had difficulties acquiring.Footnote ⁹² Thus as the science advanced it became more difficult for scientists peripheral to these main research centres, with limited resources, to make valuable contributions to it.

At the RDS focus shifted to the impact of radioactivity on human understanding of the world and its age. Central to this was the work of Prof. John Joly which explored the impact of radioactivity on geological processes. Eventually it was realized that radioactivity provided a mechanism that allowed estimates of the age of the Earth to be extended considerably, which in turn had knock-on effects for other scientific theories such as evolution. While Joly's work had important implications for wider understandings of the age of the Earth, it relied on a theoretical understanding of the properties of radioactivity rather than on physical experimentation.Footnote ⁹³

John Joly and radium 1909–1914

Parallel with ongoing investigations concerning the nature of radium and radioactivity had been its application to therapeutic purposes. Joly and Dr Walter C. Stevenson,Footnote ⁹⁴ of Dr Steevens’ Hospital Dublin, began using radium bromide to treat rodent ulcers (this is a type of skin cancer) early in the twentieth century. The success of these treatments prompted Joly to request that the RDS establish a Radium Institute in Ireland, with the purpose of extracting radium emanation (radon) to treat cancer.Footnote ⁹⁵

Following a public appeal, which provided the RDS with funds (including a thousand pounds supplied by the society itself) to substantially increase its supply of radium, it established a Radium Institute in 1914.Footnote ⁹⁶ This new interest in the therapeutic uses of radium brought renewed research which focused on the production and use of radium emanation for cancer treatment. There was limited experimental physics research, such as Felix Hackett's presentation on the production of polonium from radium emanation in January 1919.Footnote ⁹⁷ It was this process that would allow scientists at the Cavendish to produce the polonium used to establish the existence of the neutron in 1932.Footnote ⁹⁸ However, the RDS was now soundly focused on the medical applications of radium. Its Radium Institute continued producing emanation until 1953, when its activities were superseded by the Cancer Association of Ireland. This provided an important outlet for the society's scientific and philanthropic energies, in turn ensuring its continued importance to Irish society.