The method described is a single-phase application of the general principle discussed in an earlier paper. In one application it gives directly the relative phase-displacement between any two comparable alternating voltages as the angular position of a linear trace relative to a uniformly graduated circular scale attached to the face of a cathoderay tube. It is also possible to use a magslip, or an instrument of the ratiometer type, as an indicator in place of the cathode-ray tube.The circuit arrangements employed are founded on symmetrical-component theory, which serves both as a basis for design and also for estimating the effect of conditions which are different from those the method ideally demands. Practical tests on the instrument and its circuits, which are exceptionally simple, are discussed.