Stirrup and electrical telegraph: what they have in common

1. Step 1. Stirrup — evolved from — Saddle. The stirrup added a foot support to the saddle.
2. Step 2. Saddle — is made of — Leather. A saddle is made of leather.
3. Step 3. Leather — is material for — Drum. The drumhead is stretched hide.
4. Step 4. Drum — has part — Diaphragm. A diaphragm.
5. Step 5. Diaphragm — is part of — Phonograph. A diaphragm with a needle.
6. Step 6. Phonograph — was inspired by — Electrical telegraph. Edison came to the phonograph while working on recording telegraph and telephone signals.

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