A circular time-base giving radial deflections, for use with the cathode-ray oscillograph

In the study of electromotive forces varying with time, the electromotive force under examination is caused to modulate similarly and simultaneously two voltages which are applied in quadrature to the deflecting plates of a cathode-ray oscillograph. The resultant screen-image on the oscillograph consists of a circular time-base, on which are superposed radial deflections delineating the wave-form and the time relation ships of the applied electromotive forces.