Video call and autoclave: what they have in common

1. Step 1. Video call — evolved from — Telephone. A telephone with a picture.
2. Step 2. Telephone — has part — Rotary dial. A dial.
3. Step 3. Rotary dial — has part — Spring. A return spring.
4. Step 4. Spring — is part of — Safety valve. A spring-loaded valve.
5. Step 5. Safety valve — is part of — Autoclave. A safety valve releases pressure.

Open Evothings