Ballast weights and pneumatic tube: what they have in common

1. Step 1. Ballast weights — is part of — Diving bell. It sinks the bell.
2. Step 2. Diving bell — evolved into — Diving suit. Individual equipment.
3. Step 3. Diving suit — evolved into — Aqualung. Autonomy.
4. Step 4. Aqualung — uses — Compressed air. Cylinders.
5. Step 5. Compressed air — is used in — Pneumatic tube. Air pressure.

Open Evothings