Francois Dominique Arago

The web has a lot to say about this character. The Arago experiment is in demonstration at Tekniikan Museo in Helsinki, Finland. I tried it out, and it seemed interesting. There was a magnet on top of a metallic disc. There was a pulley to rotate the metallic disc - when you would rotate the disc for a long while, the magnet that was hung slightly away from the surface of the disc, but still slightly far away from the disc, would start spinning. The finnish explanation which i wrote down said "Aragon koe. Ranskalainen fyysikko Dominique Arago havaitsi v. 1822 kokeellaan magneeteilla, että magneettineulaan ei vaikuttanut ainoastaan sähköjohdin vaan myös magneettineulan lähellä pyörivä metallilevy".

So who was this man Arago? The web has a bit to say about him:

encyclopedia britannica says:
French physicist who discovered the principle of the production of magnetism by rotation of a nonmagnetic conductor. He also devised an experiment that proved the wave theory of light and engaged with others in research that led to the discovery of the laws of light polarization. In 1820, elaborating on the work of H.C. Ørsted of Denmark, Arago showed that the passage of an electric current through a cylindrical spiral of copper wire caused it to attract iron filings as if it were a magnet and that the filings fell off when the current ceased. In 1824 he demonstrated that a rotating copper disk produced rotation in a magnetic needle suspended above it. Michael Faraday later proved these to be induction phenomena.

NNDB says:
François Arago was a French physicist and astronomer who made major contributions to the early study of electromagnetism including the phenomenon of magnetic rotation and the fact that a wire coil could be magnetized by passing electrical current through it. Along with Fresnelon he discovered the principles governing the polarization of light and established the theory of light as a wave. He also studied the velocity of sound, and made it possible to invent the polariscope. Began the studies of the velocity of light which lead to discoveries by Léon Foucault. Arago also investigated the compressibility, density, diffraction, and dispersion of gases and the various types of lightening.