Cast iron lamp post and piston pump: what they have in common

1. Step 1. Cast iron lamp post — is part of — Gas lamp. A cast-iron post.
2. Step 2. Gas lamp — has part — Valve. A gas supply valve.
3. Step 3. Valve — includes — Check valve. A kind of valve.
4. Step 4. Check valve — is part of — Piston pump. Check valves direct the flow.

Open Evothings