Just an anecdote, but I've got a Thacher's Cylindrical Slide Rule, manufactured around 1914 (based on SN). For comparison with the one in the article, the Thac

Just an anecdote, but I've got a Thacher's Cylindrical Slide Rule, manufactured around 1914 (based on SN). For comparison with the one in the article, the Thacher rule has a scale length of 18m (59 feet). I found it on the scrap pile when an old building on my university was being renovated. It didn't have a university inventory serial number on it, so they weren't allowed to surplus it and had to toss it. I was in utter shock that it was going to get tossed, so took it. The building it was in was built in 1913, originally to hold the School of Mines for Oregon State University, so I imagine it used to belong to a professor or researcher there when the School was quite new. I've never actually used it, but perhaps some day can find a the original manual to learn how. If you 'Unwrap' a Thacher's it ends up being the equivalent of a regular slide rule that's 59 feet / 18 meters long. Here's one in a collection with a picture and some background... https://americanhistory.si.edu/collections/search/object/nmah_1131290 https://americanhistory.si.edu/collections/search/object/nma...