Plaster cast and optical telegraph: what they have in common

1. Step 1. Plaster cast — has part — Bandage. A bandage base.
2. Step 2. Bandage — is part of — First aid kit. Bandages.
3. Step 3. First aid kit — is made of — Tin. A tin box.
4. Step 4. Tin — is material for — Phonograph. The recording is on tin foil.
5. Step 5. Phonograph — was inspired by — Electrical telegraph. Edison came to the phonograph while working on recording telegraph and telephone signals.
6. Step 6. Electrical telegraph — evolved from — Optical telegraph. The electrical telegraph replaced semaphore lines.

Open Evothings