Rabies vaccine and davy lamp: what they have in common

1. Step 1. Rabies vaccine — is a kind of — Vaccine. A vaccine.
2. Step 2. Vaccine — uses — Syringe. Injections.
3. Step 3. Syringe — has part — Piston. A plunger.
4. Step 4. Piston — is part of — Newcomen engine. Atmospheric pressure moves the piston.
5. Step 5. Newcomen engine — uses — Coal mine. Pumping water out of mines.
6. Step 6. Coal mine — uses — Davy lamp. Protection against methane explosions.

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