If you attended school between the 1950s and the 1970s, you must remember those moments when the teacher distributed copies of tests or work sheets. Where I grew up we called such copies "dittos." Churned out by a mimeograph, fresh dittos were damp and limp with a heady gluelike aroma and distinct purplish ink.

Thomas Edison is credited with inventing the first mimeograph copying system. But the true precursor of the technology I knew in grade school (and that businesses used for much of the 20th century) came from Alfred Blake Dick. Dick, whose company licensed Edison’s technology, invented the mimeo stencil and marketed the first commercial mimeograph in 1887. Once text is cut (or typed) into the stencil, the stencil is wrapped and fastened around a cylinder. Rotating the cylinder forces ink through the stencil and onto individual sheets of paper served up from a tray.

Kathleen Roberts of Raynham, Mass., used the gamut of copying technology during her 47-year teaching career, from carbon paper in 1937 to a hand-cranked mimeograph by the 1950s, to a stain- and odor-free copier when she retired in 1982. Pouring ink into the mimeograph "was like taking a bath," Roberts recalls. But the machine was a real time-saver, so purple hands were just part of the job.

The advent of inexpensive copiers killed the mimeograph. That’s too bad. While photocopies, webpages and e-mail are efficient ways to distribute learning materials, I doubt they’ll prove as evocative of childhood as the lowly mimeograph and its pungent dittos.