Friedrich Christoph Mayer and his theory of the aurora borealis

The eleventh volume in the series presents two articles on the aurora borealis by Friedrich Christoph Mayer (1697–1729), a mathematician at the Imperial Academy of Sciences in Saint Petersburg. The first paper, titled “De Luce Boreali” (On the Northern Light), was presented during a session at the newly founded Academy in October 1726. It was printed two years later (1728) in the very first volume of its official periodical, the Commentarii Academiae Scientiarum Imperialis Petropolitanae. The second paper, also bearing the title “De Luce Boreali”, constitutes the author’s ‘second thoughts’ on the matter. It was presented during a session in October 1728 but was not printed until after Mayer’s death, in the fifth volume of the Commentarii (1735). Both papers are included in facsimile in this issue of Aurorae Borealis Studia Classica. 
Eric Chassefière, member of the Histoire des sciences astronomiques team of the SYRTE laboratory at the Observatoire de Paris, has written an introduction to Mayer’s life and works with a special emphasis on his theory of the aurora borealis. In his introduction, Chassefière also recounts how Mayer’s theory was received by other eighteenth-century savants.


Aurorae Borealis Studia Classica
Vol. XI The articles De Luce Boreali (1728 & 1735) by Friedrich Christoph Mayer with an introduction by Eric Chassefière Aurorae Borealis Studia Classica (Classic Studies of the Northern Lights) is a series of digitized texts, with biographical introductions and content summaries, edited by Per Pippin Aspaas and published by Septentrio Academic Publishing, University of Tromsø -The Arctic University of Norway (UiT). The texts as such are already in the public domain; all further content is open-access except when stated otherwise.
The eleventh volume in the series presents two articles on the aurora borealis by Friedrich Christoph Mayer (1697-1729), a mathematician at the Imperial Academy of Sciences in Saint Petersburg. The first paper, titled "De Luce Boreali" (On the Northern Light), was presented during a session at the newly founded Academy in October 1726. It was printed two years later (1728) in the very first volume of its official periodical, the Commentarii Academiae Scientiarum Imperialis Petropolitanae. The second paper, also bearing the title "De Luce Boreali", constitutes the author's 'second thoughts' on the matter. It was presented during a session in October 1728 but was not printed until after Mayer's death, in the fifth volume of the Commentarii (1735).
Eric Chassefière, member of the Histoire des sciences astronomiques team of the SYRTE laboratory at the Observatoire de Paris, has written an introduction to Mayer's life and works with a special emphasis on his theory of the aurora borealis. In his introduction, Chassefière also recounts how Mayer's theory was received by other eighteenth-century savants. defined discipline, the following year. He is recognized in the new academy as a specialist in "mathesis", i.e. "the foundation of knowledge", a rationalist project inherited from Descartes and Leibniz based on the fact that it should be possible to understand the universe on the basis of a small number of simple laws, the universal order thus proving to be accessible to reason.
During the four years he spent at the Academy, up until his premature death in 1729, Mayer worked with the French astronomer Joseph-Nicolas Delisle, who was in charge of the Imperial Observatory. Among other things, he composed a calendar, the first and only for a long time not to include astrological elements. It is also known that from the time of Leonhard Euler's arrival in 1727, Mayer helped the Basel mathematician with various problems of celestial mechanics applied to the determination of the sun's orbit, the movement of the planets and the calculation of lunar eclipses. In addition, he worked with two other Basel mathematicians, Jakob Hermann and Daniel Bernoulli, on a theory of the moon based on Delisle's extensive programme of astronomical observation, which included the occultations of stars and planets by the moon, as well as lunar and solar eclipses. This work gave rise to several publications by Mayer in the first volumes of the Commentarii Academiae Scientiarum Imperialis Petropolitanae, the official journal of the Academy.
One of Mayer's most outstanding subjects of study was the observation of and theory regarding the aurora borealis. Delisle states that Mayer observed many auroras during the first year of his stay in Russia as part of his meteorological observation work, and that he published in the first volume of the Commentarii a collection of his observations, accompanied by "his thoughts on the cause of this phenomenon, & the first foundations of his system, which he strove to perfect until his death three years later". Delisle is rather negative about Mayer's observational skills, judging that the latter did not take the trouble to write down the details of his auroral observations, often indicating only the day. 1 In his article "De Luce Boreali" (On the Northern Light) in volume 1 of the Commentarii published in 1728, Mayer analyses the different observed types of aurora borealis and concludes that "it is obvious that this matter [the auroral matter] has all the characteristics of the clouds and thus occupies the same position as them and is the same distance from the Earth" (p. 358). 2 He suggests that auroral jets "are issued from the reflection of the light that is present in the small luminous clouds [that form the auroral matter], […] while these small clouds project beams upwards onto the flat surface of the very tenuous vapours that overlook them, through which light is subsequently reflected in the form of beams" (p. 362). Regarding the physical cause of the auroral light, he attributes it to "flammable exhalations [sulphur, nitre, salts]", which, "with the aid of heat, mingle and merge with the watery vapours and are then separated from them when the cold arrives, at the moment when the watery vapours gather faster than the flammable exhalations" (p. 364). He proposes a cycle of ignition-extinction where the heat generated by the ignition causes the exhalations to mix with the vapours, which then separate again when the air cools down, re-concentrating the exhalations and provoking a new ignition, explicitly referring to Wolff's theory of the 'imperfect thunderstorm' (p. 364). For Mayer, the auroral light is similar to that of a small flash of lightning, as Wolff advocated.
On the strength of his knowledge of mathematics, at the end of his first article Mayer proposes a trigonometric method for estimating the height of the auroral arc from a single point of observation. This method met with great success in the community of astronomers and mathematicians of the time. Mayer further elaborated the theory in his second article titled "De Aurora Boreali", presented during a session at the Academy in 1728 and ultimately published in volume 5 of the Commentarii in 1735, five years after his death. In this article, Mayer modifies some of the claims in his first article on the subject, revisiting his method for estimating the height of the aurora on pp. 127-130. Mayer, although not believing in his observations, seems to have had a great level of confidence in his aurora borealis system, inherited from Wolff, at least enough to publish it in the Commentarii. Is his abandonment of the observation of the aurora a consequence of his philosophical conceptions, which would have given pre-eminence to reason over experience, or is it simply the result of a mind naturally more turned towards the imagination than towards the real world? We lack the evidence to answer this question. 4