Leyden jar
He didn't understand why this jar stored so efficiently, but he send a scrambled description to some associates in Berlin, and one copy was sent on to von Klein's old university associate Andreas Cunaeus where it ended up in the hands of Pieter van Musschenbroek, who was the University of Leyden's main physics professor. He worked out that the storage capacity was vastly improved only if the flask was held in the hand, and his letter to scientist in France gave the jar the name "Leyden jar".