1. THE METHOD OF DEVELOPING A CONTINUOUS-TONE ELECTROSTATIC LATENT IMAGE ON A SURFACE, WHEREIN SAID IMAGE COMPRISES ELECTROSTATIC CHARGES OF ONE POLARITY VARIOUSLY DISTRIBUTED ON SAID SURFACE TO PROVIDE POTENTIALS WHICH DIFFER FOR DIFFERENT AREAS OF SAID SURFACE, THE LOW POTENTIAL AREAS CORRESPONDING TO IMAGE HIGH LIGHTS, THE INTERMEDIATE POTENTIAL AREAS CORRESPONDING TO MIDDLE TONES AND THE HIGH POTENTIAL AREAS CORRESPONDING TO SHADOWS AND DARK TONES, WHICH METHOD COMRISES EFFECTING A PLURALITY OF STEPS OF PARTIAL DEVELOPMENT OF SAID IMAGE BY CLOSELY SPACING A CONDUCTOR IN FROMT OF SAID SURFACE AND INTRODUCING AN AIR SUSPENSION OF A FINELY-DIVIDED MATERIAL BETWEEN SAID CONDUCTOR AND SAID SURFACE, AT LEAST ONE OF SAID STEPS BEING PERFORMED WITH SAID CONDUCTOR HELD AT HIGH-LIGHT POTENTIAL AND OTHER OF SAID STEPS BEING PERFORMED WITH SAID CONDUCTOR HELD AT INTERMEDIATE POTENTIALS, SAID FINELY-DIVIDED MATERIAL BEING CHARGED TO A POLARITY OPPOSITE TO THAT OF SAID IMAGE.