Outboard motor and elevator: what they have in common

1. Step 1. Outboard motor — has part — Propeller. A propeller.
2. Step 2. Propeller — is part of — Screw steamship. A propeller.
3. Step 3. Screw steamship — is made of — Wrought iron. The hulls of screw steamships were iron.
4. Step 4. Wrought iron — is material for — Elevator safety brake. The safety catches are wrought iron.
5. Step 5. Elevator safety brake — is part of — Elevator. Otis’s safety brakes.

Open Evothings