Hook and eye and archimedes’ screw: what they have in common

1. Step 1. Hook and eye — evolved into — Zip. Judson started with a chain of hooks.
2. Step 2. Zip — has part — Wedge. The slider works like a wedge, bringing the teeth together and pushing them apart.
3. Step 3. Wedge — is used in — Knife. The blade cuts like a wedge.
4. Step 4. Knife — is part of — Meat grinder. A cross-shaped blade.
5. Step 5. Meat grinder — has part — Auger. An auger.
6. Step 6. Auger — evolved from — Archimedes’ screw. The Archimedes’ screw as a conveyor.

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