Sighting vanes and refrigerator: what they have in common

1. Step 1. Sighting vanes — is part of — Quadrant. A sight for the celestial body.
2. Step 2. Quadrant — has part — Plumb bob. A plumb line shows the vertical.
3. Step 3. Plumb bob — is made of — Stone. The bob of a plumb line is stone or copper.
4. Step 4. Stone — is material for — Ice house. Ice houses were built of stone and sunk into the ground.
5. Step 5. Ice house — evolved into — Refrigerator. The refrigerator replaced natural ice.

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