Photocopying invented.

Before xerography, making copies was tedious and chancy. Carbon copies, hectographs, and mimeographs, the methods used in the mid-twentieth century, required special care and materials. Expensive photostats were needed to copy a preexisting document. Scholars took copious notes from research materials by hand. In the 1950’s, an office copier, the Thermo-Fax, was introduced, which used rolled, heavy paper and made dark, fading copies.