Mop and electrical telegraph: what they have in common

1. Step 1. Mop — evolved from — Broom. A cleaning tool.
2. Step 2. Broom — is made of — Plant fibre. A broom is tied from twigs and grasses.
3. Step 3. Plant fibre — is material for — Hygrometer. Humidity was shown by a fibre that changed length.
4. Step 4. Hygrometer — is part of — Weather station. A hygrometer.
5. Step 5. Weather station — is used in — Weather forecast. Observations.
6. Step 6. Weather forecast — uses — Electrical telegraph. Collecting reports by telegraph.

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