In July, 1921, the United States Patent and Trademark Office granted Walter Meyner, of New York City, a patent for the radioactive pencil. Meyner’s idea was to mix ordinary graphite with “self-luminous material of the type ordinarily employed in so-called `radium paints.'”
The self-luminous pencil, or crayon, would be, Meyner told the patent office in his application, “relatively inexpensive and … entirely practical.”