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Well, thanks to a link provided by another youtuber, I have found the answer which is much stranger than expected. It's an early scientific device used to determine the frequencies of sounds. It is an early siren invented by Frenchman Cagniard de la Tour in 1819. These instruments were used to determine frequencies of sound by associating specific tones with revolutions per second of the rotating disc. De la Tour is credited with many other discoveries in physics in addition to inventing (and naming) the siren. Here's a good article for further reading:
https://civil-defense-sirens.fandom.com/wiki/De_la_Tour%27s_Siren