Balanced microscope stand and boyle’s air pump: what they have in common

1. Step 1. Balanced microscope stand — is part of — Operating microscope. It holds the optics above the field.
2. Step 2. Operating microscope — is a kind of — Microscope. A microscope.
3. Step 3. Microscope — evolved into — Electron microscope. Overcoming the limit of optics.
4. Step 4. Electron microscope — has part — Vacuum pump. A vacuum in the column.
5. Step 5. Vacuum pump — evolved into — Boyle’s air pump. An improved version of Guericke’s pump.

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