# Who introduced concept of capacitance matrix

We know of two ways of representing voltage-charge relations of an assembly of conductors: $$V_j=\sum P_iq_i$$ and $$Q_j=\sum C_iv_i$$ Who introduced these equations for the first time and though one can be modified to other, yet which one of them was first to be introduced (in Maxwell's treatise, he first mention the former equation and then the latter) ?