Montgomery Scott was an avid reader of technical publications, both in his capacity as a chief engineer, but also as an off-hours pursuit. In 2268, James Kirk requested Scotty go on shore leave while he was engrossed in such a journal. Scott ended up being confined to quarters after the leave, and was glad to get back to his reading.
A clearer view of Scotty's journal page was acquired by Greg Jein and published in a 1975fanzine called T-Negative. According to his research, the image also was used on stage in "Space Seed", but wasn't visible in that episode's final cut. It is notable as the first mention of the Constitution-class of starship. According to those in the know, the image actually depicted a boiler in the studio.