The Slide Rule
That IBM ad at the end is priceless on so many levels.  
(What did that massive computer do? How many female engineers do you count... etc,)Thanks for the article. My grandfather was an accountant who preferred the slide rule to a calculator. I grew up with slide rules around me, and never could understand the logic.Another tool lost in the past generation is the Abacus (here is a great story with Feynman[1]) and I would love more info as to how those compared in logic or use, if anyone can shed insight.[1]: https://www.ee.ryerson.ca/~elf/abacus/feynman.html