"Random-Ish Straight But Not Paralel Lines Next To My Office Building… What’s Happening Here?"

Answer: "You probably live in the UK, where planning authorities often require developers to do "evaluation trial trenching" to make sure there are no important archaeological artifacts that might be destroyed by excavation. If the trial trenches turn up anything interesting, a more serious archaeological dig may be required before building can begin."
Pretty sure you are wrong.... the black/blue pages in those are thin. photo looks more like an album.
Better... er... what? That would depend on the specific function of the slide rule. I used these in an engineering drawing office early 70's
#56... That is what is left after removing a metal screen that was painted at one time
came with firearm accesories... Probably a wick for old gun.
But the two things can look more or less identical.