Transferring scientific discovery to the public: The intramercurial planet Vulcan in 1860

1. Introduction

Astronomers and historians often refer to the discovery of Neptune in 1846 as a triumph of Newtonian celestial mechanics. The irregularities of the orbit of Uranus led French mathematician Urbain Le Verrier (1811–1877) to correctly predict the location of a hitherto undiscovered planet. John Couch Adams independently made similar calculations in Cambridge, England, but failed to convince the Greenwich observatory to search for it. This discovery and subsequent quarrels between the French and British over its credit were sensational headlines in contemporary newspapers. By discovering a planet at the tip of a pen, scientists showed feats of intelligence and caught the imagination of the public.

Another absorbing but often underrated episode in nineteenth-century science (Baum and Sheehan, 1997; Fontenrose, 1973; Levenson, 2015) was the search for the hypothetical planet ‘Vulcan’ (not to be confused with the fictional homeworld of Mr Spock in Star Trek!). Like Uranus, the anomalous orbit of Mercury, which was inconsistent with theory, had long troubled astronomers. To solve the mystery, Le Verrier claimed that an undiscovered planet – or at least a mass of asteroids – stood between Mercury and the Sun. For a brief time, astronomers thought they had found this hypothetical planet and officially named it ‘Vulcan’, after the Roman god of fire. The breaking news of Le Verrier’s triumph once again became a sensation.

In hindsight, Vulcan is an error or an obsolete folly, like aether and epicycles. The planet does not exist. Le Verrier stuck up for Newtonian mechanics and hence created Vulcan, which was debunked by a later ‘better’ theory. The initial sensation and eventual failure of Vulcan is often interpreted as ‘a conceptual shift of historical significance’ (Baum and Sheehan, 1997: vii). However, the Vulcan affair is more than an abstract conceptual shift. It reveals a complex network of knowledge production and circulation behind the historical scenes. Involved in the wider construction of the discovery were not only elite and amateur astronomers, but also journalists, writers and lecturers. These actors and their audiences were crucial to construct the image of science in public, yet most of the time they are ignored in accounts of this episode.

Following the work of historians of science taking their lead from the sociology of scientific knowledge (e.g. Shapin and Schaffer, 1985), in this article, the making of scientific knowledge is conceptualized as a form of communicative action. This concept is captured in James Secord’s (2004) phrase ‘knowledge in transit’. It is not merely about circulation or transmission of knowledge, but directs historians of science to look at the dynamics shaping knowledge – changes, compromises or even mutations – as it is transferred. The material forms of knowledge transfer, from three-dimensional models to pamphlets and engravings, are all key media to understand science as practice (Secord, 2004: 665). The turn to studying ‘knowledge in transit’ follows reflections on the history of science popularization and science in popular culture (Cooter and Pumfrey, 1994). Recognition of the plurality of sites, genres and signifiers of scientific activity has already proved scholarly fruitful (Bowler, 2009; Lightman, 2007).

2. Le Verrier’s planet and a doctor’s spotting

A poster (Figure 1) advertising a Lenten astronomical lecture in April 1860 in London, 3 months after the discovery of Vulcan made for sensational news in France, shows how the discovery was adopted for a public lecture in a theatre in Britain. The poster encapsulates transits of knowledge across different boundaries: between countries, contexts and media.

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Figure 1.

Poster advertising C.H. Adams’ lecture in Princess’ Theatre, 2 April 1860. Inventory number: S. 1702-1995. © Victoria and Albert Museum, London.

The perihelion of Mercury’s orbit has a slight advance – 43 arc seconds per century – making Mercury’s orbit inconsistent with theoretical calculations. This puzzle, known as perturbations, had bothered astronomers for quite some time. In 1859, Urbain Le Verrier, the director of the Paris Observatory and the grand homme powerfully dominating the directions of French astronomical research, set out to tackle the problem.

As a virtuoso on Newtonian mechanics, Le Verrier tried to repeat his success at finding Neptune. The cause of Mercury’s perturbated orbit, he surmised, was a hitherto unknown mass, either a planet or a group of asteroids, standing between Mercury and the Sun. Le Verrier spelled out the hypothesis in a letter to his colleague Hervé Faye and published it in Comptes rendus, the institutional journal of the French Academy of Science, on 12 September 1859. In the letter, Le Verrier launched an appeal to astronomers to seek out the new ‘planet’.

Coming from the director of the Paris Observatory and the discoverer of Neptune, the appeal could not be ignored. The hypothesis stirred great interest among astronomers on both sides of the Channel. Le Verrier’s letter was translated into English and published in November (MNRAS, 1859), causing alarm in Britain, for it was a forcible reminder of ‘the period preceding the discovery of Neptune’, as noted by the Monthly Notices of the Royal Astronomical Society editor. The British could not get rid of the shadow of the bitter rivalry with the French.

Towards the end of 1859, Le Verrier received a letter from an unknown amateur, Edmond Lescarbault (1814–1894), a country physician, claiming that he had already seen the planet from his private observatory in Orgères-en-Beauce, in March the same year. Partly due to diffidence, Lescarbault had not announced his result immediately, waiting instead until he read a journal article on Le Verrier’s work. Lescarbault’s procrastination annoyed Le Verrier. To verify the claim, Le Verrier secretly visited Lescarbault before New Year’s Eve. Details of the meeting transpired in an article by the celebrated scientific author Abbé Moigno (1804–1884) in the journal Cosmos (Baum and Sheehan, 1997: 150; MNRAS, 1860), later translated and cited in the English press. Moigno amusedly describes the drama of the country ‘lamb’ unexpectedly encountering the ‘lion’ from Paris: The poor physician, unaware of the stranger’s identity, was ‘subjected to a severe cross-examination by his unknown visitor, who pressed him hard from step to step’ (MNRAS, 1860: 98). Eventually Le Verrier was convinced. Returning to Paris, he announced the discovery at the French Academy of Sciences on 2 January 1860. Lescarbault suddenly rose from unknown country doctor to scientific celebrity and was made Chevalier de la Légion d’honneur within a month.

News of the discovery quickly spread, receiving extensive coverage in the British press by early February 1860. ¹ The intramercurial planet, along with the amusing tale of the dramatic encounter between Le Verrier and Lescarbault, became an immediate sensation. Newspaper readers could not miss such a headline story, neither did astronomical popularizers. Vulcan soon became a fresh subject in public lectures – this time securing a place in theatres.

3. Vulcan on stage

Public lectures on astronomy were a phenomenon in nineteenth-century Britain. Lent, the 6-week period before Easter in the Christian calendar, was the astronomy season (Altick, 1978: 364; Huang, 2016). As during Lent, theatres’ activity was severely restricted, they usually arranged alternative entertainments to replace regular plays. Astronomical lectures, aligning with religious sentiments of natural theology and the fashion of rational amusement, thus became a fixture.

One celebrated Lenten astronomy lecturer in early Victorian London was Charles Henry Adams (1803–1871), who regularly performed in West End theatres from 1830 to 1861. This longevity made him the target of lampoons by such satirical magazines as Punch (Huang, 2015, 2016: 57–59). To Victorian London theatre audiences, C.H. Adams was a familiar name during Lent.

As a seasoned showman, Adams could not miss the Vulcan story, making the intramercurial planet a main feature in his April 1860 lecture (Figure 1). The poster of the lecture demonstrated Adams’ grasp of the sensation. It starts in bold typeface indicating the venue (Princess’s Theatre) and time (‘One week only. This evening’). It also stresses that this event marks the lecturer’s 30th year in London. The headline in the middle section of the poster catches the eye: ‘Another great triumph in astronomical science in M. Leverrier’s [sic] splendid discovery of an Intra-Mercurial planet’. The name of the lecturer, ‘C. H. Adams’, and the iconic instrument in his repertoire, ‘Orrery’, are embossed in bold. The organization of the poster makes a passer-by notice the keywords in a glance. It shows a striking design combining the sensational headline story with the lecturer’s long-time reputation.

The exact content of C.H. Adams’ April 1860 lecture, however, is not clear. Very few accounts of the lecture are known aside from this poster. The literary magazine Athenæum just briefly mentioned it in a summary of that year’s Passion Week entertainments: ‘At the Princess’s Mr. Adams exhibited his Orrery, and delivered his usual Astronomical Lecture, including among its topics M. Leverrier’s [sic] discovery of an intramercurial planet’. ² We do not know how Adams narrated this story to the audience. Nineteenth-century Lenten lectures on astronomy usually shared a conventional programme: the shape of the Earth, the phases of the Moon, the phenomenon of tides, eclipses and the solar system were among the most common topics discussed (Huang, 2015: 149–157). Adams’ annual lectures followed these conventions too. The 1860 one should not have been different, except for the addition of Le Verrier’s triumph.

4. Epilogue and conclusion

The Vulcan mania did not last long. Le Verrier refined calculations of Vulcan’s orbit according to Lescarbault’s report and predicted transits of Vulcan across the Sun. However, most subsequent observations around the world failed to spot the planet. The existence of Vulcan was never truly verified and sceptical voices rose. Despite consistently unsuccessful observations, Le Verrier kept his faith in Vulcan to the end of his life. The elusive intramercurial planet remained an unsolved mystery until the early twentieth century, when Albert Einstein solved the anomaly of Mercury with his theory of general relativity, hence ‘destroying’ the planet.

The poster of C.H. Adams’ April 1860 lecture reminds us of the role of often ‘invisible’ contributors other than elite scientists in the construction and circulation of knowledge, such as Abbé Moigno the writer and Adams the lecturer. As Roger Cooter and Stephen Pumfrey remark, ‘our ignorance both of the low drama and the high art of science’s diffusion and modes of popular production and reproduction is staggering’ (Cooter and Pumfrey, 1994: 237). Scientists shape our understanding of the universe in observatories or at the tip of a pen, so do popularizers through various channels. Away from familiar spaces and actors of scientific knowledge production, many unknown landscapes of knowledge transfer and transformation await to be charted.