On connecting one of the two electrodes to one of the poles of an electrostatic generator the sphere begins rotating slowly in the direction in which the two electrodes are pointed; this is caused by the fact that the cylindrical part of the electrode polarizes the strip of the celluloid sphere nearest to it, thus creating asymmetry; the attraction by the small ball makes the celluloid sphere rotate in the direction leading to the small ball along the electrode.
On connecting the two electrodes to the poles of an electrostatic generator, owing to their concordant action, the celluloid sphere begins rotating so fast that it appears to be uniform in colour. If the two electrodes are pointed in opposite directions, on connecting them to the electrostatic generator the celluloid sphere does not rotate.