Young's most illustrious successor in the Royal Institution, Michael Faraday, devoted himself calmly but unflinchingly to research work, in the conviction that no discovery, however remote in its nature, from the subject of daily observation, could with reason be declared wholly inapplicable to the benefit of mankind. After discovering in 1831 that electric currents could be produced by the relative motion of magnets and coils of wire, a discovery which is the basis of all the electric engineering of our day, Faraday constructed several experimental machines embodying this principle, and then turned away abruptly from the work, saying, "I had rather been desirous of discovering new facts and new relations dependent on magneto-electric induction than of exalting the force of those already obtained, being assured that the latter would find their full development hereafter." Our own Joseph Henry, whose sterling merit is universally recognized, beautifully said in this connection: "He who loves truth for its own sake feels that its highest claims are lowered by being continually summoned to the bar of immediate and palpable utility." Oersted seems to have shared the opinion largely held by the scientific men of his day, that electricity is mainly a magnetic phenomenon. Ampère, for one, did not think so, as is evident from the beautiful theory which he devised to explain the magnetism of a bar by minute electric currents flowing round each individual molecule of the iron. To the French physicist, magnetism was purely an electrical phenomenon. [Illustration: FIG. 25 Ampère's molecular currents] Though propounded more than eighty years ago, this theory is still in harmony with all facts and phenomena in the domain of magnetism known to-day. It is important to remember, when thinking of this physical theory, that the Amperian currents in question are confined to the molecule, and that they do not flow from one molecule to another. Critics have urged against the theory that the molecules must be heated by the circulation of these elementary currents, to which objection it has been replied that, as we know nothing of the nature of the molecule, we cannot say that it offers any resistance to the current; and, therefore, we cannot affirm that there is any development of heat due to the circulation of these elementary currents.