8 August 1876: The Mimeograph

Thomas Edison patented the mimeograph, a device which brought printing to the masses. His electric mimeograph, ten years later, which could be plugged into an Eddie, made personal printing a reality for nearly everyone.

In reality, Edison did not get a patent for a device we would recognize as a mimeograph (i.e. a system whereby a special typewriter is used to cut letters through waxed-paper "stencils", which are then wrapped around the drum of a (manual or electrical) machine, which forces ink out through the cut marks on the stencil).

The device Editon had patented in 1875, Edison’s Autographic Press and Electric Pen, and which was intended to be used with the 1876 invention, was however an electrical device: the user would hold a special pen (in a vertical position and write or draw on a stencil resting on a sheet of blotting paper. The top portion of the pen was a small uncovered electric motor attached by flexible wires to a nearby battery. Each time the motor’s horizontal shaft rotated, a cam attached to the shaft caused a needle inside the pen to make three vertical strokes, each one cutting a minute hole in the stencil. The pen made approximately 135 perforations a second.

Edison’s 1876 patent describes a simple hand press consisting of a flat bed with a hinged frame to which the stencil was attached. The patent explains that to print copies one places the stencil over the paper on which an impression is to be made. A felt-covered roller is used to press ink through the perforations in the stencil to the surface of the sheet below.