The world is literally kept from coming apart by screws and bolts, and yet we don’t often give a thought to these mechanisms. Part of that is probably because we’ve gotten so good at making ...

The Italian polymath Leonardo da Vinci drew his design for an "aerial screw" in the late 1480s, while he was employed as a military engineer by Ludovico Sforza, Duke of Milan from 1494 to 1499. The ...