South-pointing spoon (Chinese compass) and watt steam engine: what they have in common

1. Step 1. South-pointing spoon (Chinese compass) — evolved into — Compass. A magnetic pointer.
2. Step 2. Compass — evolved into — Gyrocompass. A compass without a magnet.
3. Step 3. Gyrocompass — is part of — Ironclad. Steel ships distort a magnetic compass.
4. Step 4. Ironclad — has part — Watt steam engine. Steam engines.

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