Ion Printing: past, present, and future

In 1842 Ronalds called down lightning from the sky to generate the world's first ion print. His "Recorder of Atmospheric Electrical Events" employed a wire, supported from an elevated anchor paint, as a atmospheric charge collector. The wire was connected to a stylus which radially traversed a rotating insulating disk to form a spiral track on the surface of the disk. When the potential across the recording gap at the tip of the stylus exceeded the breakdown strength of air, a discharge occurred which formed an electrostatic latent image on the surface of the insulating disk.