Measuring Electricity It is important to remember that no method of measuring electricity existed in 1831, when Faraday entered upon the great period of his electrical researches. The galvanometer, the outcome of Schweig-ger's invention of the ‘multiplier’ in 1820, was not yet the indispensable instrument it afterwards became; it was not until 1833, in a footnote to his Third Series of Experimental Researches, that Faraday referred to “the great and general value of the galvanometer as an actual measure of the electricity passing through it”. The relation between the three quantities we now call current, electromotive force and resistance, upon which modern methods of measuring the electricity in a circuit depend, had been established by G. S. Ohm in 1827; but his work was neglected at first. His paper, “Die Galvanische Kette”, was mathematical, and written in German, circumstances which explain why Faraday apparently had no knowledge of it.
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