Fascinating. Here's a crappy amateur video of one in action at the Gamla Pershyttans mining museum in Sweden, anybody got a better example? https://www.youtub

Fascinating. Here's a crappy amateur video of one in action at the Gamla Pershyttans mining museum in Sweden, anybody got a better example? https://www.youtube.com/watch?v=ycN8nR9SD4w https://www.youtube.com/watch?v=ycN8nR9SD4w