Double seam of a can and modem: what they have in common

1. Step 1. Double seam of a can — is part of — Tin can. A sealed seam between the lid and the bottom.
2. Step 2. Tin can — is made of — Tin. Tinplate.
3. Step 3. Tin — is material for — Phonograph. The recording is on tin foil.
4. Step 4. Phonograph — was inspired by — Electrical telegraph. Edison came to the phonograph while working on recording telegraph and telephone signals.
5. Step 5. Electrical telegraph — evolved into — Telephone. The telephone grew out of attempts to send several signals over telegraph lines (the “harmonic telegraph”).
6. Step 6. Telephone — is used in — Modem. It works over a telephone line.

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