Apparatus for applying printed matter to the rear sides of webs of photographic paper in a copying machine has an upright frame for a vertically reciprocable housing which is lifted by a first rotary electromagnet and retained in raised position and thereupon released by a second rotary electromagnet. The housing is movable up and down with several modules each of which contains a wheel having at its periphery a set of symbols. Selected symbols can be moved to positions at the lowermost points of the respective wheels by remotely controlled electromagnets so that such selected symbols face a ribbon which is located above the rear side of a web of photographic paper. The modules are movable downwardly in the housing against the opposition of separate springs and the frame carries a projection which intercepts the housing, after the housing is released by the second electromagnet and while the housing descends by gravity, before the selected symbols can press the ribbon against the web of photographic paper. When the housing is intercepted, the modules therein descend due to inertia and against the opposition of the respective springs whereby the selected symbols press the adjacent portions of the ribbon against the rear side of the web. The housing is lifted by the first electromagnet in automatic response to completion of an exposure in the copying machine.