When was it proposed that electricity and magnetism were distinct effects by scientists William Gilbert ?
Michael Faraday wrote in the preface to his " Experimental Researches " , relative to the question of whether metallic contact is productive of a part of the electricity of the voltaic pile : " I see no reason as yet to alter the opinion I have given ; ... but the point itself is of such great importance that I intend at the first opportunity renewing the inquiry , and , if I can , rendering the proofs either on the one side or the other , undeniable to all .