The experiments of Oersted gave rise at once to much speculation as to the nature of the action between electric currents and magnets, and also to considerable experimental and mathematical research. As had been the case for many thousand years in other endeavors, speculation accomplished little, but experimental research accomplished much. By this time mathematics had been highly developed, not only as an abstract science but also as an aid to physical and chemical research. The man who attacked the problem in the most scientific manner was Ampère, who in consequence solved it in the following year, after a series of mathematically conducted experiments of the utmost originality and inductiveness. As a result in 1820, he showed that all the actions and reactions of magnets could be performed by coils of wire through which electric currents were passing, even if there was no iron within the coils:--but that they were more powerful, if iron were within. From this and kindred facts, which he developed by experiment--(especially the fact that electric currents act and react on each other as magnets do), he established a new science to which he gave the name electro-dynamics. In recognition of his contributions to electricity, the name given many years later to the unit of electric current was ampère. In the following years, while pursuing a series of investigations into the new science, Faraday invented the first electro-magnetic machines. In the first machine, a magnet floating in mercury was made to revolve continuously around a central conducting wire through which an electric current was passing; in the second a conductor was made to revolve continuously around a fixed magnet; in a third machine, a magnet so mounted on a longitudinal axis that an electric current could be made to pass from one pole half way to the other pole, and then out, would revolve continuously as long as the electric current was made to pass. Faraday invented the first machines that converted the energy of the electric current into mechanical motion; though Oersted was the first who merely effected the conversion. It can hardly be said that Oersted invented a machine; but Faraday certainly did.