The Spectacle of Science: An Experiment in 1744 Concerning the Aurora Borealis

Peas and Aquavit

Figure 1.

The illustration to the article on artificial aurora in the Proceedings of the Royal Swedish Academy of Sciences in 1744. Reprinted from Kungl. Vetenskapsakademiens Handlingar 6 (1744), plate III.

In 1744 a short article, little more than a page in length, was published in the Kungliga Vetenskapsakademiens Handlingar (Proceedings of the Royal Swedish Academy of Sciences, abbreviated KVAH in the following); it was entitled “Experimentum aurorae borealis artificialis.” ¹ The article was illustrated with a copperplate (Figure 1) and described an attempt to reproduce in the laboratory the luminous phenomena that are characteristic of the aurora borealis. The experiment proceeded as follows: Through a hole “as large as a large pea” ² a ray of sunlight was admitted into a darkened room to strike a prism; which was so angled that the refracted ray passed just above the surface of a glass filled to the brim with “common grain spirit”:

And then one observes with wonderment on the screen a northern light so natural that nothing can be more similar, and as the surface of the aquavit is quickly warmed by the colored sunbeam and in consequence evaporates, so one perceives most wondrous movements on the screen, on which flashing beams shoot suddenly up and then transform into colored veils, endlessly changing position between themselves, the one against the other; to speak briefly, one sees all the phenomena that the natural northern lights display and as changeable as the same.

These unending changes and the fact that it is never twice the same, just like the northern light, arises in part from the greater or lesser evaporation of the aquavit, and in part from the movement of the sunbeam, in that it moves with the sun and falls now above, now below the actual surface of the liquor. ³

The author concludes by saying that because of the continuous change in the movement of the light across the screen one never tires of watching this experiment, and also that it is the “very most beautiful thing that can be arranged in a dark room.” ⁴

The first conclusion that we can draw from this little article is based on an examination of our own reaction. A modern reader is inclined to smile at the experiment, particularly when Sweden’s national beverage, “common grain spirit,” represents the vital medium. Our reaction of indulgent amusement when confronted with the experimental methods of earlier times, may often lead us to overlook their contemporary significance. The cumulative nature of technical knowledge ensures that we are more or less familiar with most of the subjects. To us they seem trivial, and we are therefore apt to notice concrete details that our own values cause us to find picturesque and amusing, such as, in this case, the fact that the diameter of the aperture was stated to be “as large as a large pea.” We have difficulty in differentiating between what was new and what was part of the established technology of the period in the list of apparatus, and we therefore tend to miss important innovations. It all seems rather obvious, and we find it mildly amusing.

Our condescending attitude stems from our modern knowledge of natural phenomena and their causes. Today even a layperson— any member of “the educated public,” and not just the geocosmic physicist—may consider that he or she knows that the aurora originates from the interaction of charged elementary particles from space with the upper atmosphere in the regions around the earth’s magnetic poles. If we happen in addition to know our history of science, we are also aware that the English astronomer Edmund Halley declared as early as 1716 that the aurora was of a magnetic nature, and that this was confirmed by the Swede Anders Celsius and his assistant Olof Hiorter in 1747. The short Swedish essay— published a quarter of a century after Halley’s theory—thus becomes a cul-de-sac branching from the main road of knowledge, giving us all the...