Armillary rings and rope: what they have in common

1. Step 1. Armillary rings — is part of — Armillary sphere. The equator, ecliptic and meridian.
2. Step 2. Armillary sphere — has part — Axle. The celestial axis.
3. Step 3. Axle — is part of — Yo-yo. The axis between the discs.
4. Step 4. Yo-yo — has part — Rope. A thread.

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