20 Greatest Non-Medical Mechanical Inventions

1. The Plough
2. The Spear
3. Wheel
4. Levers
5. Working sewage system
6. The Clock
7. Writing
8. Printing Press
9. Radio
10. Telephone
11. Computers
12. Modern Irrigation
13. Automobiles
14. Sailing Ships
15. Airplanes
16. The Compass
17. Conveyor Belts
18. Television
19. Nuclear Reactors
20. The Drill