Abstract: Apparatus for developing latent images of X-rayed objects on dielectric receptor sheets has a carrier which advances receptor sheets along a circular path about a horizontal axis. A tank with an open top is installed below the six o'clock position of the carrier and contains a horizontal developing electrode having narrow elongated channels extending in parallelism with the axis of the carrier. A pump draws liquid developer from a vessel in which the tank is confined and admits the developer into the bottom zone of the tank wherein the developer rises to fill and flow above the channels of the electrode and to thereby contact the latent image of a sheet on the moving carrier. The surplus of liquid developer overflows the upper edge of the tank and returns into the vessel. The electrode is movable up and down by rotary eccentrics to thereby influence the development of latent images, especially the development of outlines of dark portions of the images.