Drais’s running machine and sickle: what they have in common

1. Step 1. Drais’s running machine — evolved into — Michaux velocipede. Michaux added pedals to the front wheel.
2. Step 2. Michaux velocipede — has part — Crank. Cranks on the wheel axle.
3. Step 3. Crank — is part of — Reaper. A crank moves the knife.
4. Step 4. Reaper — evolved from — Sickle. Mechanical reaping.

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