Churn lid with hole and gyroscope: what they have in common

1. Step 1. Churn lid with hole — is part of — Butter churn. It lets the dasher’s shaft through.
2. Step 2. Butter churn — uses — Lever. A dasher.
3. Step 3. Lever — is used in — Optical telegraph. The arms were moved by a system of levers and rods.
4. Step 4. Optical telegraph — uses — Telescope. Signals were read through a telescope.
5. Step 5. Telescope — includes — Space telescope. A space telescope is a telescope above the atmosphere, so air does not blur the view.
6. Step 6. Space telescope — has part — Gyroscope. Pointing gyroscopes.

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