Evaluation of the potential of the Wilson terminal in 33 normal young adults indicates that its potential is zero about once in every twelve. Weighting of the terminal brought its potential to zero in ⅔ of the subjects and left a very small residual (technical) error in the remainder. The vertical component of the cardiac vector is primarily responsible for the error on the Wilson terminal. A weighted terminal in which the arm resistances are 2.6 times the left leg resistance has a zero potential in 50 percent of a small group of subjects. The residual error on the weighted terminal is at most one-half of that on the Wilson terminal. The eccentric origin of the cardiac vector varies only with respiration. Ordinarily, the zero-potential plane of the antero-posterior component of the cardiac vector passes simultaneously through or just dorsal to the limb electrodes and contributes little to the negative error on the Wilson terminal.