Spirit level and oil well: what they have in common

1. Step 1. Spirit level — uses — Universal gravitation. The bubble rises to the highest point.
2. Step 2. Universal gravitation — is used in — Pile driver. A falling weight.
3. Step 3. Pile driver — has part — Block and tackle. Lifting the weight.
4. Step 4. Block and tackle — is part of — Drilling rig. The block and tackle lifts the drill string.
5. Step 5. Drilling rig — is used in — Oil well. A well is drilled by a rig.

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