I saw a link to this YouTube video shared on Tom Limoncelli’s blog. It’s a 1953 US Navy instructional video about an all-mechanical fire control computer. Yes, I really mean a computer that can solve continuously changing 25-variable fire control problems using only mechanical means (gears, cams, etc.). Think about it for a minute - it’s truly mind-boggling. And really gives one an amazing appreciation for the power of a simple pocket calculator, and the amazing engineering that went into solving these problems before electronic computers. I’m usually not much of a math geek, but I watched the whole 40 minute video and was in awe of both the simple ability to use three arms and a pin to multiply numbers, and the amazingly precise engineering and machining it would take to translate various rotation inputs into landing a shell on a moving ship miles away. It’s a really good watch, and will probably leave you astonished by both how far technology has come (and what we take for granted every day), and by the fact that feats of engineering like this one worked quite well.