Alfonso San Miguel and Bernard Pallandre found the object in the reserves of the Ampère museum in Poleymieux-au-Mont-d'Or. It is the only complete and authentic version of the experiment carried out in 1915 by Albert Einstein and Wander de Haas on Ampère's molecular work.
An article on this valuable discovery for the world of physics is to be published soon in the journal Europhysics News. But there is no question of reusing it to reproduce the experience.