Surprised we don’t seem to have mentioned this web site before - lots of juicy resources for slide rule history and usage.
For example, here’s something you don’t see every day, from LONG-SCALE SLIDE RULES in LIFE-SIZE IMAGES by Otto E. van Poelje:
Caption: “LOGA 15R Calculating Cylinder length 60cm, diameter 16.4cm, log(10) span 15m, divided over 60 segments of 25cm each”
Here’s the history page:
Here’s a gallery of rarities:
https://osgalleries.org/os/completegallery.cgi