You caught my eye. I have a K&E log-log duplex that I bought in 1944 for a HS Trig class. I worked in a bakery the previous summer greasing bake pans to get the money for the K&E. I was drafted into WWII and came back to school under the G.I. Bill. College expenses were paid including supplies for my engineering education. Picked up a metal(magnesium I think)Pickett&Eckel which had more functions and which I used more. I have a collection of slide rules including circular ones.
“I have a collection of slide rules including circular ones.”
Aaahhh, the good old E6B (”whiz wheel”) flight computer.