Time is such an amazing, reflective concept.

History of timekeeping devices.

History of navigation.

History of longitude.

[via Disney Research]

Part 1 features the logical progression of engineering mechanisms developed to accomplish The Cycle of Operation:

1. chambering
2. locking
3. firing
4. unlocking
5. extraction
6. ejection
7. cocking
8. feeding

Part 2 and Part 3 build upon this basic model, ending with a fully functional firearm.

If you liked these videos, check out this other one about differential steering.

[via MetaFilter]

Skip to about 2 minutes to avoid the intro.

A commenter recommended Feynman explaining the alternative to a differential drive that trains employ.

I’ve been forgetting “via”s, which I suppose isn’t fair: [via reddit]