As in nature, all is ebb and tide, all is wave motion, so it seems that in all branches of industry, alternating currents - electric wave motion - will have the sway.
When a coil is operated with currents of very high frequency, beautiful brush effects may be produced, even if the coil be of comparatively small dimensions. The experimenter may vary them in many ways, and, if it were nothing else, they afford a pleasing sight.