Page - 159 - in Maximilian Hell (1720–92) - And the Ends of Jesuit Science in Enlightenment Europe

159The 1761 Transit of Venus and Hell’s Transition to Fame The three main sources of error mentioned above were also the “weapons” with which astronomers challenged each other in the debates ensuing after the 1761 transit. In order to bring all the data into harmony, it was necessary to consider some features of various observations doubtful. The longitude might have been erroneously determined, the clocks wrongly adjusted, or the practi- cal skills of the observer(s) insufficient. Given the ambition, publicity, and the sheer amount of money invested in the project, it may well be that such assess- ments aroused a certain degree of anger among those whose observations were deemed unreliable. The discussion of the even more complex 1769 Venus transit ventures in Chapter 7 will give occasion to reflect in greater detail on what this enterprise reveals about the nature of eighteenth-century scientific culture, especially the notions and practices of sociability that governed it. For now, it suffices to point out that, judging from the tone of the main papers on the solar parallax published in the aftermath of 1761, it seems to be an exag- geration to describe this as a “quarrel between French and British astrono- mers.”61  Quite the contrary: the astronomers involved were generally careful to use polite language when discussing their colleagues’ observations and calcu- lations. This strategy was a prudent one: most astronomical datasets are use- less when not compared with other observations.62 Cutting off correspon- dence by giving offense risked a loss of access to precious material for future research, especially as the next transit was approaching within just a few years. Halley’s predictions included ones relating to the expected precision of the calculations to be made. He famously anticipated that his method would result in a calculation of the solar distance with a margin of error of no more than 0.2 percent.63 However, given the sources of error listed above, it is small wonder that computations of the solar parallax based on all the 1761 observations 61 For contemporary claims about a “(scientific) quarrel” between British and French as- tronomers occasioned by the 1761 transit, see Christian Mayer, Ad Augustissimam Rus- siarum omnium Catharinam ii: Alexiewnam Imperatricem expositio de transitu Veneris ante discum Solis d. 23 Maii, 1769 […] (St. Petersburg: Academia Scientiarum, 1769), pref- ace, [v]; Maximilian Hell, “De parallaxi Solis ex observationibus transitus Veneris anno 1769,” Ephemerides 1773 (1772), 1–116, here 113–14. 62 For more on this aspect of early modern astronomy, see, e.g., Sven Widmalm, “A Com- merce of Letters: Astronomical Communication in the 18th Century,” Science Studies 5 (1992): 43–58; Peter Brosche, “Korrespondierende Beobachtungen,” in Wissenschaftskom- munikation in Europa im 18. und 19. Jahrhundert: Beiträge der Tagung vom 5. und 6. Dezem- ber 2008 an der Akademie gemeinnütziger Wissenschaften zu Erfurt, ed. Ingrid Kästner (Aachen: Shaker Verlag, 2009), 95–99. 63 Halley, “Methodus singularis,” 460.