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VISUAL READ OUT RECORDERS AND ACCESSORY APPARATUS THEREFOR-NAMELY, FACSIMILE TRANSMITTERS AND RECORDERS, GRAPHIC RECORDING INSTRUMENTS ACTUATED BY AN ELECTRIC INPUT SIGNAL, DENSITOMETERS AS FOR RAPIDLY SCANNING MICROFILM FOR DETERMINING THE ABSOLUE DENSITY OF BOTH BACKGROUND AND FINE LINES, AND RECORDING PAPER TO BE USED WITH SAID RECORDERS