Whoops; here's the second image with white bg and no alpha channel so the text is actually visible

My vote is for the ball-and-disk integrators that were used in Kelvin's harmonic analyser to compute the tides, and in US naval vessels during WWII to compute distance traveled over variable velocities. Absolutely ingenious design.

Permian synapsids are so goddamn cool, I'm so glad kids are being given these opportunities to learn about them instead of just pretending like dinosaurs are the only extinct animals that ever existed