Page - 226 - in Maximilian Hell (1720–92) - And the Ends of Jesuit Science in Enlightenment Europe

Chapter 5226 and the 1793 volumes of the Ephemerides, respectively. For centuries, the au- rora had been one of the most intriguing riddles of the atmosphere, capable of spellbinding the general populace and scientific circles alike. Major theories of the eighteenth century included sulfurous emissions from volcanoes of the far- thest north; reflections of the rays of the sun illuminating frozen particles in the upper atmosphere from underneath the horizon; discharges in the sky, ei- ther of a magnetic or electric nature (no theory of electromagnetism existed as yet); and a host of others.55 In his treatise, Hell refers to all the major theories in existence, refuting them one after the other. Notably, Hell dismisses a pos- sible correlation between the northern lights and magnetism as well as elec- tricity. Instead, the aurora borealis is described by him as a “purely optical phenomenon.” Hell had brought a kind of electric machine with him to Vardø to see wheth- er there might be some way to measure the electricity involved in auroral out- breaks. Details regarding the instrument are not known, except that it was of English origin and had been borrowed from the senior district stipendiary of Christiania, the above-mentioned von Storm, an avid book collector who also took an interest in scientific experimentation. While in Vardø, Hell tested von Storm’s electric machine in the period from October to January.56 He found nothing, which is not surprising considering the extreme distance of the phe- nomena (it is now known that the average auroral outbreak takes place more than eighty kilometers above the surface of the Earth). As mentioned, Hell also had magnetic needles at his disposal, and in late April he set up a magnetic observatory to measure the fluctuations of the compass needle several times a day. He did experience some disturbances similar to those that had been re- ported by Anders Celsius (1701–44) and others. But when he looked up into the sky, there was no northern light in sight. What he did see, in the foggy condi- tions of the Vardø climate, was a variety of other optical phenomena, like rain- bows, halos around the moon, and so-called parhelia, or “mock suns,” all of which are purely optical illusions, which can sometimes resemble the aurora borealis. Accordingly, Hell vigorously rejected any connection between the 55 See, e.g., J. Morton Briggs, “Aurora and Enlightenment: Eighteenth-Century Explanations of the Aurora Borealis,” Isis 58, no. 4 (1967): 491–503; Wilfried Schröder, Das Phänomen des Polarlichts (Darmstadt: Wissenschaftliche Buchgesellschaft, 1984); Per Pippin Aspaas, “The Auroral Zone versus the Zone of Learning: A Brief History of Early Modern Theories on the Aurora Borealis,” in Travels in the North, ed. Silje Gaupseth, Marie-Theres Feder- hofer, and Per Pippin Aspaas (Hannover: Wehrhahn Verlag, 2013), 113–36. 56 Hell, “Aurorae borealis theoria nova,” 8–9. Sajnovics, travel diary, proofread version (wus), on July 16, 1768.