Backstrap loom and optical telegraph: what they have in common

1. Step 1. Backstrap loom — uses — Plant fibre. Cloth is woven from threads spun from fibres.
2. Step 2. Plant fibre — is material for — Hygrometer. Humidity was shown by a fibre that changed length.
3. Step 3. Hygrometer — is part of — Weather station. A hygrometer.
4. Step 4. Weather station — is used in — Weather forecast. Observations.
5. Step 5. Weather forecast — uses — Electrical telegraph. Collecting reports by telegraph.
6. Step 6. Electrical telegraph — evolved from — Optical telegraph. The electrical telegraph replaced semaphore lines.

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