Graduated wooden staff and rope: what they have in common

1. Step 1. Graduated wooden staff — is part of — Jacob’s staff. A long bar with a scale.
2. Step 2. Jacob’s staff — works like — Quadrant. Two angle gauges for measuring the altitude of celestial bodies.
3. Step 3. Quadrant — has part — Plumb bob. A plumb line shows the vertical.
4. Step 4. Plumb bob — has part — Rope. A suspension fibre.

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