Before the summer of 1740 had passed, rumours began making quiet rounds in Parisian salons concerning an imminent anonymous pamphlet. Only four copies were eventually printed, but its title, Lettre d’un horloger anglais à un astronome de Pékin (1740), captured immediate attention. Written in the form of a satire, the pamphlet addressed the ongoing debate over the shape of the Earth, a controversy that had split the Parisian scientific community into two factions. One camp consisted of the ambitious young academician Pierre-Louis Moreau de Maupertuis (1698–1759) and his followers, who had returned from the Lapland expedition in August 1737, bearing measurements that supported Newton’s theory of an oblate Earth (i.e. flattened at the poles). On the other side stood the Cassinis, veteran astronomers who, based on decades of domestic geodesy, adamantly defended a prolate Earth (i.e. a spheroid elongated along the polar diameter). The dispute over the Lapland result had been going on for three years, attracting attention throughout the learned world and among the wider public. As with two earlier anonymous pamphlets, Maupertuis’s authorship of this text was immediately apparent – it reads as his final counterattack: a cynical look at the ‘anachronistic’ objections from the Cassini camp and at the ‘belated’ rehabilitation of Cassini de Thury.Footnote 1 But perhaps the most striking aspect is the apparent disconnect between the content and the title of the pamphlet. Although astute Parisian readers may have identified the ‘English clockmaker’ as George Graham – maker of the zenith sector, crucial to Maupertuis’s arsenal – who was the ‘astronomer in Peking’?Footnote 2 What was his role in the polemic?
Such a title emerged from a discussion in the salon of the Marquis d’Argenson rather than from an arbitrary conceit on Maupertuis’s part.Footnote 3 In fact, those who followed the debate closely would have immediately understood Maupertuis’s metaphor and marvelled at the irony behind his conceit. François-Marie d’Arouet (better known by his pen name Voltaire, 1694–1778) and Emilie Le Tonnelier de Breteuil, Marquise du Châtelet (1706–49), two of the most prominent supporters of Maupertuis, can provide some clues. In a letter to Jean-Baptiste-Nicolas Formont (1694–1758) in December 1737, Voltaire noted that ‘the Cassinists have risen up against Maupertuis’ and in any case ‘do not want the Earth to be flattened at the poles’; he later added that ‘the agreement reached between French mathematicians and the Chinese’ was a ‘strong reason for believing in an elongated Earth’.Footnote 4 Several days later, du Châtelet expressed her frustration in a letter to her ally Francesco Algarotti (1712–64), noting that ‘senior academicians’ in the Académie des sciences were now allied with the Jesuits, who had ‘discovered the Earth elongated in China’. She complained that the Cassini faction had thus convinced most Parisians that ‘Maupertuis did not know what he was talking about’, greatly undermining his reputation.Footnote 5
The references to a ‘French mathematician’ and a ‘senior academician’ allied with the Jesuits unmistakably point to Jean-Jacques Dortous de Mairan (1678–1771), then known in Parisian salons by the nickname ‘le Chinois’, who was also aligned with another renowned ‘China specialist’, Nicolas Fréret (1688–1749) of the Académie des inscriptions et belles-lettres.Footnote 6 Mairan and Fréret corresponded throughout the 1730s with the French missionary astronomer Antoine Gaubil (1689–1759) in Beijing and his local superior Dominique Parrenin (1665–1741).Footnote 7 Fréret had encountered, in the ‘preface’ to the Jesuit Description … de la Chine (1735), edited by Jean-Baptiste Du Halde, the assertion that the Kangxi-era cartography (1708–17) revealed ‘some inequality’ in the length of different ‘degrees’, and so sought further information from Beijing in an effort to support the Cassini position.Footnote 8 In fact, even Maupertuis himself recognized the potential influence of the Jesuits: before leaving for Lapland, he had Fréret send carefully selected materials to Beijing, hoping for an evaluative judgement.Footnote 9 Upon Maupertuis’s return to Paris, the rumours circulating in salons and cafes that Chinese cartography had ‘generally confirm[ed] the measurement of M. Cassini’ alarmed him deeply.Footnote 10 The evidence from what was then considered the largest empire was seen as undermining the importance of Maupertuis’s Lapland expedition, whose ‘small-scale’ observations seemed insignificant in comparison.Footnote 11 As these rumours were denounced by du Châtelet as ‘persecution’ by the Cassinists, Maupertuis was forced to counterattack in public.Footnote 12 This found immediate expression in his several public lectures promoting the northern expedition; introducing the English Graham sector, previously unknown to the French; and employing emotional appeals to the audience.Footnote 13 Subsequently, Maupertuis orchestrated an anonymous authorial ruse in the Republic of Letters, circulating a pamphlet designed to be mistaken for Mairan’s work in order to humiliate him.
The title Maupertuis chose for his final pamphlet probably served as an ironic allusion to this important chapter, even carrying a subtle self-deprecating undertone, implying that both sides’ secret weapons originated outside France. Whereas this layered meaning would have been immediately apparent to contemporary readers, it has attracted little attention in existing studies of the polemic. It has rarely been considered that Jesuit-mediated information from China might have played any role in the controversy.Footnote 14 This absence is not incidental but reflects a long-standing tendency to regard the Jesuits as obstacles rather than contributors to the development of modern science.Footnote 15 Recent scholarship has begun to revise this picture.Footnote 16 Beyond recognizing the Jesuits’ role in European intellectual life – particularly in the development of mathematical education – historians have increasingly turned to the Jesuits’ China mission, emphasizing the role of European intermediaries who mobilized, selected and reframed missionary knowledge for use in intra-European debates.Footnote 17 Such studies have shown that information circulating from China did not enter European discussions in a neutral form, but was shaped through processes of appropriation and reinterpretation, often serving specific argumentative ends.
Building on this line of inquiry, this article recovers the episode alluded to in Maupertuis’s title by focusing on the processes through which information from China was recast as credible evidence in the Parisian debate over the Earth’s figure. It starts by examining the origins of such evidence, namely the circulation of Chinese information through transcontinental networks. How did the two Parisian pro-Cassini savants, Mairan and Fréret, differing in social standing, institutional position and scholarly expertise, form their alliance, and how did they forge connections with the French missionaries across continents? Their collaboration took shape not through formal institutional channels, but through what Lux and Cook have termed ‘weak ties’: informal, personal connections sustained by private correspondence, acquaintance networks and sociability in salons and cafes.Footnote 18 These decentralized links, operating beyond official structures, enabled the circulation of Chinese information across vast distances at a time when, under Louis XV, the institutional connections between the Académie des sciences and the Jesuits in China had markedly weakened from their Louis XIV-era strength, and when the Académie des inscriptions had never maintained such strong ties.Footnote 19
Yet the significance of these connections lay not simply in the circulation of Chinese information, but also in the uses to which it was put. Without institutional mandates, why did Mairan and Fréret establish private ties with missionaries in distant China and go further by bringing Jesuit information to bear on the Maupertuis–Cassini dispute? This article argues that such information was mobilized primarily for polemical purposes. In practice, information obtained from Beijing was then strategically reinterpreted and introduced into Parisian discussions in ways that could support the Cassini position. It was through such deployment that Chinese information was transformed into evidence capable of intervening in the controversy, most clearly in the Parisian public sphere. As recent scholarship has shown, scientific disputes in Paris during the first half of the eighteenth century increasingly unfolded beyond the confines of the academies, extending into salons, cafes and pamphlets – and it was in these informal public spaces that private exchanges became resources in public debate, allowing ‘weak ties’ to play their crucial role.Footnote 20 Within these settings, the credibility of evidence depended not only on geodetic results per se but also on the provenance of information, its argumentative presentation and its circulation through informal networks. The appeal to Chinese information would prove effective in this context. As noted by du Châtelet and Voltaire, such ‘Chinese evidence’ generated a sensation in Paris, and in turn it intensified the polemic and ultimately prompted Maupertuis’s public counterattack.
At the same time, the ways in which such evidence was constructed and contested were closely bound up with the academic politics of the Parisian learned world – understood as a field shaped not only by personal agendas and institutional allegiances, but also by the actors’ keen awareness of knowledge–power dynamics such as factional rivalries. The underlying motivations behind the deployment of such Chinese evidence in public debate can thus be further discerned in the ways in which Parisian mediators situated themselves within the interplay of these factors. Fréret’s involvement reflected both his reliance on Jesuit materials for his scholarly work and his efforts to position himself within elite intellectual networks. Mairan, for his part, drew on his reputation and standing within the académie to lend public authority to claims that aligned with the Cassini camp. Their ability to mobilize the missionaries rested on the latter’s eagerness to re-establish ‘strong ties’ with the académie through the mediation of Mairan and Fréret during the Jansenist-induced politico-religious crisis. Likewise, Maupertuis’s response was shaped not only by disagreement over evidence but also by concerns over reputation and career advancement. In this sense, the controversy concerned not only the origins and construction of evidence but also the underlying driving forces that shaped how such evidence was forged and contested in the public arena.Footnote 21
This article therefore argues that the forging of ‘evidence from China’ in the Maupertuis–Cassini dispute depended on both the circulation of information across Eurasian networks and the academic politics that shaped its use. It first examines the origins of such evidence, tracing how Fréret and Mairan forged connections with Gaubil and Parrenin in Beijing and mobilized cartographic information through private correspondence. It then analyses how such information was transformed into credible evidence through reinterpretation and public deployment in salons and cafes, before tracing Maupertuis’s public counterattack. Finally, it explores the motivations underlying these interventions, showing how personal agendas, institutional affiliations and struggles over reputation informed the ways in which evidence was mobilized and contested. By bringing the Eurasian entanglements of the dispute to the fore, this article enriches our understanding of a classic intra-European controversy and offers a case study for understanding how credible evidence was constructed and contested in the eighteenth-century public sphere.
Origins of evidence
The private correspondence between Fréret, historian of the Académie des inscriptions, and the missionary–astronomer Gaubil in Beijing began with Fréret’s turn to Chinese astronomical chronology. Fréret’s early, classical approach to chronology was shaken by Newton in the late 1720s.Footnote 22 Newton’s draft Abrégé radically compressed Greek antiquity by five centuries by using astronomical observations recorded in Hipparchus’ Commentary.Footnote 23 As this threatened Catholic historiography, the Jesuit theologian René-Joseph de Tournemine – who had secured Fréret’s release from the Bastille in 1714 – tasked him with drafting a refutation.Footnote 24 As the Jesuit librarian Etienne Souciet and the astronomer Edmond Halley entered the dispute, it escalated from an internal Jesuit affair into a Franco-British clash.Footnote 25 The outcome humiliated the French: their critiques were technically dismantled by Halley. Fréret attributed their failure to unfamiliarity with the English ‘novel [astronomical] methods’; the defeat convinced him that chronology required astronomical calculations, not just philology.Footnote 26 Fréret then turned to Chinese astronomical chronology to counter Newton, who had dismissed China’s antiquity and placed Chinese history far later than the Flood (2349 BCE).Footnote 27
Aware of his own ‘limited familiarity with astronomical calculations’, Fréret had attempted to collaborate with French missionary–astronomers in China to address his technical shortcomings in Chinese chronology.Footnote 28 It was in this context that Gaubil’s work captured his attention. Beginning in 1729, Gaubil’s manuscript Histoire appeared in Paris as part of the Observations (1729–32), edited by Souciet.Footnote 29 These works included highly sophisticated technical calculations aimed at establishing the reliability of Chinese antiquity. Reading Gaubil’s work in 1732, Fréret recognized its decisive value for his own research and promptly drafted his first letter. Introducing himself as ‘an enthusiast of Chinese antiquities’ inspired by Gaubil’s ‘excellent work on Chinese astronomy’, Fréret asked for Gaubil’s friendship and proposed that they collaborate on Chinese astronomical chronology.Footnote 30
As their correspondence continued, Fréret came increasingly to appreciate the value of Gaubil’s expertise.Footnote 31 Writing to Father Prémare, Fréret claimed that by combining Chinese ancient literature with ‘Father Gaubil’s work’, he could then ‘construct … a system of Chinese chronology.’Footnote 32 Fréret believed that only by integrating Gaubil’s calculations could the accuracy of ancient celestial records be verified – precisely where his own skills fell short.Footnote 33 Benefiting from these exchanges, Fréret later articulated his method at the Académie des inscriptions: one must compare ‘the dates of these [astronomical] phenomena in the annals with those provided by the calculation of the tables’, which necessarily required consulting ‘Gaubil’s chronological notes’.Footnote 34 Through this synthesis, Fréret concluded that ‘the reign of [emperor] Yao [堯]’ commenced in ‘2205 BC.’Footnote 35 It then further confirmed Chinese antiquity reaching back to the era of Fuxi [伏羲] (‘2500 BC’) – older than Newton had allowed.Footnote 36
While chronology had first brought Fréret into contact with Gaubil, by 1735, as the debate over the Earth’s shape intensified in Paris, Fréret quickly recognized the additional value of his correspondence with Gaubil – that Chinese data might provide independent evidence for the Cassini side. He appended a postscript to one of his letters, introducing this ‘fashionable issue’ that had ‘divided our astronomers’ and preoccupied Parisian academic circles, and proceeded to invite Gaubil to take part.Footnote 37 In the original Paris edition of Du Halde’s Description, Fréret had just encountered information directly pertinent to the polemic. The ‘preface’ documented how Jean-Baptiste Régis (1664–1738) and Pierre Jartoux (1669–1720), during the Kangxi-era cartography, had shown ‘some inequality in the degrees’ between 41° and 47° in north-eastern China.Footnote 38 Seizing on this finding, Fréret urged Gaubil to collaborate with his colleagues in China to examine ‘as rigorously as possible … the ratio’ between ‘the degrees of latitude’ measured in southern and northern China, as well as ‘the ratio of the degrees of longitude to the degrees of latitude’ in each region. Although Du Halde’s ‘preface’ had revealed a ‘variation’, Fréret emphasized that Régis had failed to ‘indicate how great it is, nor does he even say whether the degrees increase or decrease as one approaches towards the pole’ – the very key to the matter.Footnote 39
At the same time as Fréret corresponded with Gaubil, the senior mathematical physicist at the Académie des sciences, Dortous de Mairan, also established private communication with Gaubil’s superior in Beijing, Parrenin. From the beginning of their cross-continent communication in 1728, Mairan and Parrenin engaged in extensive analyses of physics (iron, ice), mathematics (binary numeral systems), chronology and cultures (population, subsistence) in both China and Europe – a multidisciplinary dialogue stemming partly from Mairan’s personal interest in Eastern science and partly from his need to gather material for his own research in mathematics and physics.Footnote 40 This was exemplified by his keen interest in Chinese auroral observations and the perceived affinity between ancient Chinese mathematics and Leibniz’s binary system. Many of these dialogues were preserved as part of the Jesuits’ propaganda for Europeans in volumes of the Lettres édifiantes et curieuses, edited by Du Halde. In Paris, these Far Eastern sciences and culture became fodder for Mairan’s salon conversations, where he occasionally displayed ancient Chinese books sent to him by Parrenin, a practice that earned him the nickname ‘le Chinois’. Meanwhile, in Beijing, missionaries who had access to Parrenin’s shared correspondence came to regard Mairan as a reliable and prominent figure of the académie, even expressing hope that he might become ‘a cardinal’ to further advance the interests of the Society of Jesus.Footnote 41
Echoing Fréret’s mobilization of Gaubil, Mairan also included a brief aside on the Earth’s-figure controversy in his correspondence with Parrenin. He proposed an alternative solution that aligned with his own research: inviting Gaubil to conduct ‘pendulum experiments’ in various regions of China, an undertaking he considered ‘perfectly suited to an astronomer’.Footnote 42 In 1672, while conducting pendulum experiments at the French colony of Cayenne, Jean Richer confirmed that his carefully calibrated pendulum clock from Paris was running slow and losing 2′ 28″ per day.Footnote 43 Newton and Huygens both explained this discrepancy by treating the Earth as a fluid in hydrostatic equilibrium. Newton attributed it to weaker effective gravity at the equator – centrifugal force plus reduced gravitational pull from oblateness – yielding an oblate spheroid, while Huygens, drawing on voyage data from the East Indian Company, concluded that centrifugal force alone sufficed and obtained a (less markedly) oblate figure using a different gravity law.
In stark contrast, the mathematical physicist Mairan, in the 1720s, sought to reconcile Jacques Cassini’s prolate Earth model with existing data. He argued that pendulum measurements could be made consistent with an elongated Earth by assuming a specific, non-Newtonian variation of pesanteur with latitude.Footnote 44 Hence Mairan sought to use pendulum variation experiments conducted in Beijing – comparing their results with his pro-Cassini hypothesis – as an empirical test that could strengthen his earlier work.Footnote 45 As he told Parrenin, ‘the question of the Earth’s figure, and that of the different intensities of gravity at various points on its surface … owe their origin only to the question of the length of the pendulum’.Footnote 46 Moreover, ‘such an experiment is … rather necessary, after the great undertaking of the map of the Chinese Empire’.Footnote 47
To this end, Fréret and Mairan, each driven by their own agendas, mobilized their respective correspondents on different grounds. In fact, all communications with missionaries in Beijing during this period were shared and jointly advanced by Fréret and Mairan.Footnote 48 They formed a coalition in support of the Cassinist position regarding the Earth’s figure. Their collaboration rested initially on institutional ties, but more importantly on personal networks. Fréret’s timely access to the latest developments in the controversy came entirely through Mairan. The two académies had, since the time of Louis XIV, engaged in regular exchanges to foster disciplinary development, and during this period, Fréret and Mairan served as institutional representatives at annual meetings – the debate over the Earth’s figure occupied a significant portion of their discussions in the 1730s.Footnote 49
More importantly, they moved in overlapping circles of elite Parisian salons. Both had been habitués of the renowned salons of Mme Lambert and Mme Tencin in the 1720s, where they engaged in discussions on the most fashionable topics of science, art, culture and politics. They also frequented Madame du Boccage’s gatherings as well as the ‘Jesuit salon’ hosted by Mme Tencin, where Tournemine was particularly active. Most importantly, they were the two foremost ‘China experts’ within these salons. Whenever either received a letter from Gaubil or Parrenin, Fréret made a point of visiting Mairan’s residence at the Louvre to ‘discuss the Chinese thesis’.Footnote 50 All these overlapping networks provided the fertile ground upon which the two scholars’ friendship and collaboration flourished. It was through these intertwined ties that Fréret and Mairan forged their alliance and maintained privileged access to the missionaries in Beijing, securing a steady flow of information that would soon prove instrumental in the public arena for undermining their opponent.
Forging evidence
Fréret and Mairan had mobilized their correspondents, yet the decisive evidence they expected from Beijing did not materialize. Gaubil informed Fréret that ‘the degrees decreased from south to north, and between 41° and 47° they had noticed a decrease of 258 Chinese feet’.Footnote 51 However, the evidential force of this finding was limited because it could not be placed on the same methodological footing as an established French meridian measurement. Since the time of Jean-Dominique Cassini and Jean Picard, French geodesy had been rooted in a rigorous methodological tradition: using triangulation to determine geometrically the terrestrial distance corresponding to a meridian arc, while simultaneously conducting precise stellar observations at the end points to establish the associated difference in latitude. The Kangxi survey, by contrast, was a decade-long imperial mapping programme rather than a dedicated meridian-arc survey; its regional operations combined astronomical observations, trigonometrical calculations, and estimates from route distances in varying ways. In the six-degree measurement at issue, Régis and Jartoux measured successive ground intervals with divided ropes and made astronomical observations of latitude with a mobile quadrant. Gaubil, who had not participated in the survey, obtained the result from Régis and supplemented it with a general account of the circumstances in which the mapping had been carried out. He explained that the accompanying officials pressed for rapid results and did not give the missionaries sufficient time for the further observations they wished to add.Footnote 52 Gaubil therefore stated that, on the basis of the information available from the Kangxi survey, he could not provide a decisive answer to the question of the Earth’s figure.
In Gaubil’s assessment, any attempt to verify the measurements anew faced insurmountable obstacles. For one thing, ‘the emperor flatly rejected’ Jartoux’s proposal to re-examine the ‘variation of degrees’.Footnote 53 In addition, the French missionaries had no power in the Imperial Astronomical Bureau: the Peking Observatory, re-established shortly after Ferdinand Verbiest’s proposal in 1668, was maintained predominantly by the Portuguese.Footnote 54 Beyond these limitations, the instruments in Beijing proved insufficient to meet the académie’s standards of accuracy, leaving him helpless.Footnote 55 Similarly, Mairan never received a reply from Parrenin regarding the Earth’s figure either – by then, Parrenin was already gravely ill; only after Parrenin’s death in 1741 did Gaubil finally reply, ‘I do not believe that anyone here can give you anything very decisive on the question of the figure of the earth.’Footnote 56
However, Fréret and Mairan did not relinquish their pursuit; instead, they resorted to a more strategic course of action. Armed with the details, Fréret conceded that such cartographic data were ‘inadequate’. Yet he still counted on Gaubil to provide useful information through new measurements that might correct the figures. Fréret wrote, ‘These observations made on a large scale, although with less good instruments, always deserve in general more credence than those which have been made only on a small scale, like that of our northern astronomers’.Footnote 57 But just as this letter was sent, the situation fundamentally changed – Maupertuis returned triumphantly in August 1737, vigorously advocating for an oblate Earth. In fact, it was precisely this change that prompted Fréret (and Mairan) to take further action. Sensing the growing urgency, Fréret abandoned any wait for Gaubil’s reply and promptly reversed his stance. Having earlier dismissed the data as ‘inadequate’ – a decrease of 258 feet between 41° and 47° – he now hastily concluded that ‘since by this measurement the length of the degree decreases as one goes from the equator to the poles, this generally confirms M. Cassini’s measurement’.Footnote 58 Without delay, he informed Gaubil’s superior, Parrenin, of this conclusion.
If Fréret adopted a hasty, opportunistic strategy – repurposing information from his private correspondence with Gaubil into evidence in support of the Cassini faction – then Mairan was the figure behind the scenes who gave this process real traction in the public arena, even though he himself may well have held deep doubts about the reliability of Chinese information. Indeed, Gaubil’s reluctance to conduct the pendulum experiments for Mairan may be attributed not only to the instrument damage and the Chinese emperor’s repression, but also to Gaubil’s awareness of Mairan’s scepticism. Mairan’s correspondence with Parrenin on China had been selectively distorted for European readers by Du Halde in the Lettres édifiantes et curieuses. These redactions – which omitted Mairan’s sceptical remarks, including his admission that ‘the various claims I read about it [China] … left me … vacillating between admiration and doubt’ – led Europeans to perceive Mairan as an uncritical Sinophile.Footnote 59
However, Mairan’s engagement with Chinese science was in fact marked by deep scepticism and a selective approach to Chinese materials. This scepticism was most evident in his treatment of Chinese astronomy and chronology. During the 1730s, he had read and been partly persuaded by the critiques of Jean-Dominique Cassini and Foucquet, both of whom, unlike Gaubil, dismissed Chinese astronomical records as fundamentally unreliable.Footnote 60 In Mairan’s own words, ‘What could one expect from such [Chinese] people who truly believed that the heavens were round, but who made the Earth square, in the middle of which they persuaded themselves for certain that their empire was situated?’Footnote 61 He openly confided to Parrenin his scathing assessment that the Chinese were profoundly ignorant of astronomy, being more ‘infatuated’ with ‘judicial astrology’.Footnote 62 While he considered Chinese astronomical observations sufficiently valuable to warrant consultation, he denied that Chinese astronomers possessed the theoretical and demonstrative capacities necessary to interpret them correctly.
This distinction allowed Mairan to draw selectively on Chinese information without conceding authority to Chinese astronomy itself, an attitude that also informed his use of materials supplied from Beijing in the Cassini–Maupertuis controversy. Although it was Fréret who made the assertions in favour of the Cassini faction based on Chinese land survey data, it was only through Mairan’s endorsement and promotion that such claims could be packaged as credible evidence and disseminated in the public sphere to support the Cassini faction – their credibility derived directly from Mairan’s prestigious reputation and senior standing within the académie. It was precisely this endorsement that allowed such purported evidence – whether genuinely valid or not – to wield considerable influence in salon discourse. That influence was further amplified by two factors: the two scholars’ established reputations as China experts, which lent additional credibility to their claims, and the intense fascination with Qing affairs that pervaded Parisian intellectual circles at the time.Footnote 63 Given his established presence in Parisian salons, Mairan was well placed to regale audiences with accounts of Fréret’s discoveries, gleaned from Gaubil – an outstanding French astronomer in Beijing – while the very source of those discoveries, the Kangxi-era cartography, had in fact been proposed by his own correspondent, Parrenin, Kangxi’s favourite missionary at the time.Footnote 64
Mairan’s endorsement of Chinese evidence was immediately apparent in the way the Jesuit Journal de Trévoux embellished these claims with dramatic reinterpretations, even fabricating specific details in the process. In fact, the Jesuits’ observational collaboration with the Paris Observatory and the Cassinis could be traced back to the age of Louis XIV, albeit with a subsequent decline. The journal reported that the missionary astronomers and geographers in Beijing ‘committed themselves to measuring six degrees [47°–41°] of the meridian in the vast plains of Tartary’, and that ‘by the irregularities found and rediscovered in these degrees’ these missionaries provided confirmation of Cassini’s ‘elongated’ Earth shape.Footnote 65 In this way, information first obtained through Fréret’s private correspondence was thus recast by Mairan and amplified by the Jesuits, becoming public ammunition against Maupertuis.
The pamphlet trap
When Maupertuis returned to Paris, these purported Eastern findings quickly became rhetorical weapons in salons and cafes to counter the northern result. To dispel these rumours, Maupertuis swiftly launched a counterattack. On the one hand, his public lectures promoting the northern expedition achieved remarkable success. At the Louvre on 13 November 1737, for example, Maupertuis dazzled the audience with a performance that emphasized Arctic nights, suffering in extreme weather and the marvellous Graham sector. As Réaumur wrote to Bignon, ‘If this [lecture] account had been printed … upon the arrival of these gentlemen … [those] bad rumours made in the cafes during this holiday season … would not have been made.’Footnote 66
Simultaneously, the rumours fuelled Maupertuis’s bitter hatred of Mairan, whom both du Châtelet and Voltaire saw as the chief conspirator behind the entire affair. In early 1738, an anonymous pamphlet entitled Examen désintéressé … de la Terre began circulating in salons and cafes. To implicate Mairan as the presumed author, Maupertuis deployed two masterstrokes. First, while attempting anonymity, he adopted a neutral, Cassinist-leaning and Mairan-like mild tone that perfectly fitted with Mairan’s long-cultivated persona as the ‘most enlightened’ and ‘gentle scholar’ in Parisian circles and the Republic of Letters.Footnote 67 As Montesquieu wrote to his friend Martin Folkes, ‘the author appears to be a wise and reserved man’.Footnote 68 Indeed, Mairan’s benevolent image was well documented and his sociability and moderation were widely praised: Grandjean de Fouchy described him as having ‘eyes that sparkle with intellectual vitality and a gentle temperament … impeccably gracious’; François-Joachim de Pierre de Bernis called him ‘Mairan the sage’, and Madame Geoffrin declared, ‘I adore Monsieur de Mairan.’Footnote 69
The second deployment was more ingenious: the first section of the pamphlet addressed pendulum and gravitational physics drawing on Mairan’s 1720 essay, while the second section included J.T. Desaguliers’s sharp rebuttal of Mairan in 1725. A central figure in the Earth-shape polemic since the 1720s, Mairan had defended the Cassinis’ prolate spheroid by arguing that existing pendulum measurements of effective gravity did not rule it out, a position that brought him into conflict with Newtonians, particularly with the exiled Desaguliers in England.Footnote 70 Maupertuis’s masterstroke was to make the two sections appear stylistically contrasting: the Examen maintained a moderate tone, discussing issues, while its supplement, the Examen des trois dissertations, adopted a polemical tone, quoting extensively from Desaguliers. This feigned comparison was thus a brilliant stratagem to make the readers of the Republic of Letters immediately ‘recognize’ the author’s identity for the first section, the Examen: only Mairan, so closely associated with the use of pendulum measurements in the debate and equally known for his cultivated moderation, could have appeared to readers as the author of such a re-examination.
The gambit succeeded spectacularly. Mairan, believing the work to be that of a covert ally, privately lavished praise on the pamphlet. His praise was eventually published in the Journal helvétique. ‘This work’, it was declared, ‘is achieving a brilliant success in Paris; there is hardly anyone, men and women alike, who has not read it … by the moderation and politeness with which it is written for both sides … there is no gentleman who cannot acknowledge it.’Footnote 71 The source of this published praise was likely the Bernoullis. Having learned that Mairan had praised Examen in a letter to Johann Bernoulli (via du Châtelet), Maupertuis demanded the correspondence and urged Nicolaus Bernoulli to publish it in the Mercure suisse. Footnote 72 This manoeuvre angered du Châtelet when she discovered that her private letters had been appropriated.Footnote 73 When confronted by both du Châtelet and Johann Bernoulli in 1740, Maupertuis flatly denied authorship: ‘Madame is mistaken! How can we attribute to him a book that was clearly written against him?’ He argued that the spelling of Mairan’s name (‘Meyran’) in the Examen did not necessarily point to his own authorship: ‘Everyone here spells Meyran’s name this way.’ He then sneered, ‘with the Earth’s oblateness now proven, doesn’t this work seem ridiculous?’Footnote 74 Although aware of the deception, Nicolaus Bernoulli played along and persistently denied Maupertuis’s authorship, having evidently been let in on the secret – as hinted by Maupertuis’s subsequent letter: ‘I believe you are quite certain, my dear friend, that I do not reveal to anyone the things of which I might have made a mystery to you’.Footnote 75
By 1741, the Parisian elites had seen through the artifice. As du Châtelet wrote to Maupertuis: ‘I found it so well established in Paris that you are the author of the Examen.’Footnote 76 Mairan’s earlier lavish praise now made him sound absurd, turning him into an academic laughingstock.Footnote 77 Maupertuis’s retaliation was complete; he gloated: even ‘the most enlightened man in the kingdom’ had mistaken satire for praise.Footnote 78
What the pamphlet retaliation revealed was, in fact, the considerable impact of the purported evidence from China on opinions in the public sphere. This influence lingered in Maupertuis’s mind, troubling him long after the affair and not only driving him to retaliate against Mairan but also leading him to seize every opportunity for ridicule, as exemplified by the title of his final pamphlet, Lettre d’un horloger anglais à un astronome de Pékin. Even in the 1740s, Maupertuis still could not resist satirizing the sheer absurdity of the attacks on his Lapland results – attacks at least partially fuelled by the purported eastern evidence. As he complained bitterly, ‘all the cafes were full of people who would have supported the Earth elongated like a cucumber if it had been necessary’.Footnote 79
The undercurrent: academic politics
Although Fréret’s deep involvement in the dispute may initially seem difficult to explain, upon closer examination it stemmed from multiple considerations – all of which reflected both his reliance on Jesuit materials and his efforts to position himself within elite intellectual networks. On the one hand, he indeed sympathized with Gaubil and the missionaries’ plight in Beijing.Footnote 80 As Fréret put it, Gaubil’s participation would prompt ‘the Ministry to pay some attention to the missionaries in China’, ultimately contributing to ‘the interests of the mission’.Footnote 81 Gaubil faced politico-religious pressures from both Beijing and Paris. In Beijing, the missionaries’ standing deteriorated sharply after the death of the Kangxi emperor (1722). Gaubil later reflected that he ‘came here at a bad time’.Footnote 82 The Yongzheng emperor, deeply hostile to foreign religions, officially banned Christianity nationwide in January 1724, permitting to remain only those missionaries deemed useful. While Parrenin and Gaubil stayed on as imperial servants and translators, most others were exiled to Canton.Footnote 83
Meanwhile, in Paris, the Jesuits faced mounting political and public pressure as the Jansenists, allied with the Parliamentarians, fiercely accused them of being ultramontanists and complicit with royal authority. According to Voltaire, the prestige and influence of the Jesuits in France were in sharp decline.Footnote 84 Gaubil was acutely aware of this: ‘The Jansenist heretics are our mortal enemies’, he fretted, noting the intense agitation against the society.Footnote 85 Gaubil knew that while the king and his ministers privately favoured the mission, they dared not publicly support the Jesuits for fear of backlash.Footnote 86 Worse, he confided to Fréret, ‘the same people who, in France, seek to destroy the Jesuits, continue to … destroy us here. Our missionaries have had to defend themselves’.Footnote 87 It was precisely in this situation that securing the support of a scientific institution appeared as a source of protection, a consideration already spelled out in a letter from Gaubil’s colleague Jean-Baptiste Jacques to Souciet: ‘We must maintain connections with the Messieurs of the Academy, and these gentlemen must be satisfied with us’; only by relying on scholarly ties could the Jesuits secure protection at court: ‘such are our true interests’.Footnote 88
Thus the Cassini–Maupertuis dispute offered Gaubil an ideal opportunity to re-establish connections with the académie, something he had long sought. Gaubil longed for the recognition once granted to Jean de Fontenay (1643–1710), the only astronomer among Louis XIV’s six mathématiciens du roi. Having collaborated with Thomas Gouye (1650–1725) as a correspondent member of the académie and published two volumes of Observations in Paris, Fontenay received praise from Jean-Dominique Cassini.Footnote 89 Under Louis XV, however, the once glorious collaboration between the Paris Observatory and the Jesuits had all but disappeared. After a perfunctory acknowledgement of Gaubil’s work in December 1730, Jacques Cassini fell silent.Footnote 90 When Gaubil sent his astronomical essays to Souciet, he repeatedly stipulated that they were not intended for publication but ‘only for Messrs. of the Observatory’, and yet the lack of response left him despondent.Footnote 91 He vented to Fréret, ‘I had recommended F. Souciet to connect with M. Cassini … I perceive great indifference in M. Cassini’.Footnote 92 Seizing the moment, Fréret framed involvement in the Earth-figure polemic as Gaubil’s best chance to rebuild connections, especially since ‘the Comte d’Maurepas … champions the sciences … nothing would be better than to let him know what he can expect from you’.Footnote 93
Although mobilizing Gaubil would facilitate Fréret’s continued access to Chinese materials, his underlying, more covert intention lay elsewhere: to position himself as a key Sino-French liaison for the Cassini faction in the polemic – a move aligned with both his personal interests and those of the Académie des inscriptions. This positioning was made possible through his association with Mairan. Despite their alliance, their standing within their respective intellectual circles was markedly different. While Mairan enjoyed a prominent position as one of the ‘Seven Sages’ of the salon of Mme Tencin, Fréret remained a mere participant.Footnote 94 The disparity in their standing was evident in events such as Mme Tencin’s personal invitation to Mairan in 1733 – an honour never extended to Fréret.Footnote 95 This hierarchy likely mirrored the institutional imbalance of power between their respective académies: The Académie des sciences’s overwhelming advantage in resources and influence during the ‘polemics between Ancients and Moderns’ completely overshadowed the Académie des inscriptions.Footnote 96 Faced with the rapid development of mathematical astronomy and the dominant position of the Académie des sciences, allying himself with prominent academicians like Mairan – and demonstrating that research from the Académie des inscriptions could complement the work of a géomètre from the Académie des sciences and contribute to important scientific conclusions, even on crucial matters such as the Earth’s figure – was perhaps an optimal strategy. It served both to protect Fréret’s own scholarly standing and to indirectly secure a space for classical studies.
Fréret’s calculation – aligning himself with the Cassini faction and acting as a key liaison – is also evident in his strategic connections with Parisian elite networks, including the Jesuits. In fact, Fréret’s initial source of Chinese cartographic information, the 1735 original edition of the Description, was likely an intentional component of the Cassini faction’s design. The repeated delays in its publication, initially announced in 1730 but not issued until five years later, stemmed mainly from Le Mercier’s reluctance to finance such an expensive folio (144 livres).Footnote 97 At the time, publishers, rather than authors, exercised decisive control over publication; they were not neutral intermediaries but gatekeepers with distinct preferences and, above all, commercial imperatives. Publishers systematically prioritized ephemeral pamphlets over substantial scholarly volumes. As Fréret complained, they had never been ‘so frivolous! Now nothing but pamphlets are wanted’.Footnote 98 Thus the timely delivery of the first printed copies to subscribers in the summer of 1735, a critical moment, can hardly be separated from the Earth-figure polemic: the first recipients who could afford such volumes happened to be those elite Parisian scholars most invested in the dispute.Footnote 99 Among the subscribers, besides Mairan, Fontenelle, and Fréret himself, was Bishop Jean-François Foucquet, recently expelled from China and back in Paris. Upon receiving his copy, Foucquet immediately wrote to Abbé de Rothelin, claiming he had ‘once found in the ancient books of China this [Earth-figure] question decided’.Footnote 100 This explains Le Mercier’s exceptional decision to finally publish such an expensive folio in 1735, especially considering that Mairan and others were actively lobbying for its publication.Footnote 101
Meanwhile, the editors of the Journal de Trévoux, Tournemine and Claude-Joachim Thibault, may have exerted subtle pressure on the publisher – a move that reflects the complex context in which the Jesuits aligned themselves with the Cassini position. Amidst the hostile climate with the Jansenists, the journal faced increasing pressure regarding its printing privileges, exacerbated by former editor Castel’s public declaration of war against academicians like Mairan since the 1720s, which forced the académie to lodge ‘a complaint with the Duke of Mayne and Cardinal Fleury’.Footnote 102 These tensions prompted the journal’s current editors to actively seek reconciliation with Fontenelle and Mairan as a protective measure. The Description, which compiled the scientific achievements of twenty-seven Jesuit missionaries dating back to the reign of Louis XIV, including extensive astronomical and geographical observations, would thus serve as definitive proof of the society’s enduring contributions to leading scientific disciplines of the académie. This demonstration of continued scientific relevance would prove significant at a time when the Jesuits were facing institutional marginalization, having been formally excluded even from the rank of honoraire of the académie since 1728.Footnote 103 In this charged climate, Fréret was likely expected, if not explicitly tasked, by his Jesuit Parisian allies to use this 1735 publication as a polemical weapon, much as he had done earlier when commissioned by Tournemine to write the rebuttal of Newton.
If Fréret’s case reveals how informal networks and polemical actions are underpinned by academic politics, a similar dynamic operated no less forcefully in the conflict between Mairan and Maupertuis, in which factional divisions, personal reputations, and career ambitions were all at play. Despite being identified as a Cartesian stalwart, Mairan was not dogmatically opposed to Newtonian experimentalism.Footnote 104 Privately, he even admitted the possibility that the Lapland expedition might confirm Newton’s predictions. Writing to Gabriel Cramer on 31 August 1738, he conceded that if the observations from Peru agreed with those from the north, he would be willing to accept any figure of the Earth.Footnote 105 This private openness, however, never translated into public concession. Before the académie and in salons, Mairan consistently aligned himself with Fontenelle and the Cassinis, defending the Cartesian orthodoxy and the elongated-Earth hypothesis. It was precisely this public posture – as a guardian of institutional legitimacy – that disposed him to leverage Chinese evidence for polemical purposes. The Chinese cartographic data, as mediated by missionaries, could offer independent testimony to be marshalled in the public arena to support the Cartesian–Cassini position against the Newtonian challengers. Thus Mairan’s promotion of Chinese evidence in the salons was largely a strategic move embedded in his institutional role and public image.
Indeed, these roles and images, when intertwined with factional allegiances and personal reputations, weighed significantly in the undercurrent between Mairan and Maupertuis. In fact, Maupertuis’s public reputation had flourished even before the Lapland expedition. Maupertuis’s scholarly reputation and social networks were inextricably linked to Parisian cafe culture, particularly the Café Procope and the Café Gradot.Footnote 106 While his acquaintance with Fréret at the Procope, and subsequent recommendation to Bignon, granted him entry to the académie, his engagements at the Gradot secured his scientific renown.Footnote 107 After succeeding Antoine Houdar de la Motte as de facto leader of the Gradot circle in 1731, he transformed this cafe into a platform for challenging Cartesian academicians.Footnote 108 This young academician, who unabashedly described himself as seeking ‘honour, glory, and fortune’, found in Newton’s theory of gravitation both a conceptual framework and an opportunity for career advancement and public prominence in Paris after his trip to London.Footnote 109 He strategically connected this theory to the debate on the Earth’s figure revived in 1732, thereby gaining dual recognition. Institutionally, his proposal for the Lapland expedition earned him promotions – to sous-directeur in 1735 and directeur the following year.Footnote 110 Socially, by the early 1730s Maupertuis had effectively mobilized Newtonian attraction through his charisma and connections in cafes and salons, gradually turning these informal gatherings into Newtonian strongholds while forming alliances with Voltaire and du Châtelet.Footnote 111 Simultaneously, a new generation of young mathematicians in the académie, sympathetic to his views, were drawn to his passion and wit, attending his ‘Newtonian dinners’ after formal meetings, where they opposed the Cartesian views of senior academicians and even attacked them personally, for example by mockingly imitating Mairan’s thick Gascon accent.Footnote 112 Consequently, Maupertuis used these venues as counterweights to the senior academicians, gradually eroding his initially cordial relations with Fontenelle and Mairan.
Unsurprisingly, Maupertuis was furious when the Cassini faction pre-emptively dominated the cafe and salon discourse, resulting in ‘three-quarters’ of Parisians believing their claims about the Chinese evidence.Footnote 113 His anger concerned not only his public image and personal reputation but also his career prospects. He had believed that the success of the Lapland expedition would earn him a higher position within the académie; Mairan’s posturing now stood in the way. That position – the secretaryship of the académie – was precisely what Voltaire later revealed as the driving force behind Maupertuis’s retaliation against Mairan. ‘Those in Paris who are aware of M. de Maupertuis’s manoeuvres against M. de Mairan’, Voltaire observed, ‘would not be surprised by his behaviour toward M. Koenig and toward me’; ‘when I was received into the Académie française, he complained bitterly to me that I had not compared him, in my speech, to Plato travelling to Dionysius of Syracuse’. This insight from Voltaire stemmed from his own rift with Maupertuis, which itself originated from their rivalry over the secretaryship of the Académie des sciences – as Voltaire noted, Maupertuis ‘had schemed to strip Mairan of the position … in order to share it with me’. Only later did the disillusioned Voltaire realize that Maupertuis had coveted the post for himself alone.Footnote 114 By then, the ‘Newtonian dinners’ had disbanded, and Voltaire had turned hostile.
The pamphlet ruse against Mairan proved to be a tactical misstep – one that backfired on Maupertuis’s own career prospects. Far from consolidating his fame or securing a higher position, it left Maupertuis almost isolated in the académie after 1741. His celebrated powers of repartee could no longer offset the reputation for internecine conflict that he had acquired during the affair.Footnote 115 Réaumur publicly censured him for ‘excessive zeal’; Maupertuis only made matters worse by mocking Réaumur’s own ‘spider-studying fervour’.Footnote 116 Moreover, Fontenelle now came to regard Maupertuis’s public behaviour as an unprecedented and irreconcilable challenge to the académie’s Cartesian orthodoxy. As a staunch defender of Cartesianism, Fontenelle saw it as his task to ensure that only candidates who upheld the académie’s Cartesian orthodoxy could be considered for this important position of secretaryship, thereby safeguarding its reputation and interests.Footnote 117
Against this background, Maupertuis’s fall from professional and reputational grace in Paris was ironically the result of his own pursuit of reputation and advancement. This fall was subtly linked to his rift with Mairan, a rift that had hardened into private animosity over perceived damage to personal honour from the pamphlet retaliation. Mairan privately confessed that he never forgave Maupertuis.Footnote 118 Yet whereas Maupertuis conducted his polemics in public, Mairan responded more circuitously through the internal politics of the académie. Drawing on nearly three decades of seniority and personal connections within the institution, he did not respond openly to the pamphlet trap but instead exercised his influence over the succession to the permanent secretaryship. In 1740, when Fontenelle finally stepped down as permanent secretary, Mairan – despite his advanced age and repeated protestations of reluctance – allowed himself to be persuaded by Fontenelle to accept the post. This ensured that the administrative nerve centre of the académie remained in Cartesian hands. More critically, three years later he successfully manoeuvred to have his own protégé, Grandjean de Fouchy, appointed as his successor, rather than Maupertuis or any of his allies.Footnote 119 These appointments preserved Cartesian influence within the académie’s administration and effectively denied Maupertuis the secretaryship as a platform from which to extend his institutional authority. The Maupertuis–Mairan affair thus further reveals that the debate over the Earth’s shape was, to a significant extent, driven by academic politics – a power play in which institutional loyalties, personal rivalries and reputational stakes became inextricably entangled.
Conclusion
Who, then, was that ‘astronomer in Peking’? As this article has shown, the phrase referred not to a single figure but to a constellation of actors: Gaubil and Parrenin, the French missionaries in Beijing who supplied the cartographic information; Fréret and Mairan, the Parisian savants who mediated and redeployed the information for polemical purposes; and, more broadly, those ‘three-quarters’ of the Parisian learned public who followed these manoeuvres and whose sympathies tilted towards the Cassini camp as a result. Maupertuis’s sardonic choice of title captured, perhaps more than he intended, a defining feature of a controversy in which evidence acquired polemical force through the circulation and transformation of knowledge across Eurasia. Behind this process lay a complex web of private ties and transcontinental networks, together with the interplay of personal ambitions, public personae, institutional allegiances and factional rivalries. Such evidence was therefore forged and contested within the academic politics of the Parisian learned world. This article has thus revealed how knowledge acquired credibility and polemical force in such a context and repositions the Maupertuis–Cassini affair as a case in which global knowledge networks were actively harnessed to construct and contest evidence in the Enlightenment public arena.
Acknowledgements
I am grateful to Michael Bycroft, Marco Chan, Rob Iliffe, James Poskett and two anonymous reviewers for their careful reading and valuable comments, which greatly improved this article. I also thank the editorial team for their careful handling of the manuscript.
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