Trammell HudsonSlide rule fans: have you ever seen one with two cursors and a second sliding rule? This odd sliderule illustration was on the cover of Astounding Science Fiction, May 1951 https://archive.org/details/Astounding_v47n03_1951-05_Sam_Hall/mode/2up
slash@th My best guess is that this was done to make a longer rule more compact. I.e., you first extend the nested rule, then use that and the slider as normal.
If someone has a reference to something like this in reality, I'd be interested in seeing that.