Cylinder seal and electric fan: what they have in common

1. Step 1. Cylinder seal — works like — Gutenberg printing press. An analogy: both a seal and a press reproduce a pre-carved pattern.
2. Step 2. Gutenberg printing press — has part — Screw press. Gutenberg adapted the screw press known from pressing grapes.
3. Step 3. Screw press — uses — Screw. The force is produced by turning a screw.
4. Step 4. Screw — is used in — Propeller. A propeller “screws” itself into the water, like an Archimedes’ screw.
5. Step 5. Propeller — is part of — Electric fan. The blades.

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