Set of six original standard resistance coils, representing the B.A. unit of resistance and multiples of it, constructed for the British Association Committee for Electrical Standards Set of six original standard resistance coils 1870
Set of nine original standard resistance coils, representing the B.A. unit of resistance, constructed in 1864 for the British Association Committee on Electrical Standards, and " Chart showing the variation of the resistances of the standard ohms" Set of nine original standard resistance coils 1864