Truss and electrical telegraph: what they have in common

1. Step 1. Truss — is part of — Truss bridge. Trusses.
2. Step 2. Truss bridge — uses — Railway track. Railway bridges.
3. Step 3. Railway track — inspired — Time zones. Introduced because of railway timetables.
4. Step 4. Time zones — uses — Electrical telegraph. Synchronizing time by telegraph.

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