Kristian Birkeland’s terrella, as pictured in an article about his use of the models at Sphæra, the newsletter of the Museum of the History of Science, Oxford:
Birkeland’s largest experiment was carried out in 1913 in a large vacuum chamber of 1,000 litres capacity with terrellas of 24 and 36 cm in diameter. This apparatus became very well known for its ability to recreate Aurora effects and in Norway its fame is such that it is depicted on the Norwegian 200 kroner banknote.
That banknote is one of the most attractive I’ve seen from any country. Sadly, as this excerpt of Lucy Jago’s excellent book The Northern Lights recounts, Birkeland’s theoretical explanation of the aurora, based on observational work in the far north of Norway during long, cold winters failed to convince the influential British scientific establishment:
Arthur Schuster, a Fellow of the Royal Society and a prominent scientist in the field of terrestrial magnetism, dismissed Birkeland’s huge volume with a terse comment in the Society’s Proceedings:
“Even originally well-defined pencils of cathode rays from the sun cannot reach the Earth. For Birkeland’s theories to be correct, the existence of such cathode rays is clearly presupposed to be necessary… and this assumption is untenable.” Birkeland was furious, for he knew that, if his theories were ever to be widely disseminated, it was necessary for the British scientific establishment to accept them. Over the next five years, Birkeland’s life fell apart.
It was only in the 1960s that the “cathode rays”, or what we’d now call the solar wind (a stream of charged particles, both electrons and protons) were observed and his theories about the cause of aurora were vindicated.
(inspired by Dan W’s post of a different image of a terrella)