Altimeter and hollerith tabulator: what they have in common

1. Step 1. Altimeter — evolved from — Barometer. An altimeter is a barometer with an altitude scale.
2. Step 2. Barometer — is part of — Weather station. A barometer.
3. Step 3. Weather station — is used in — Weather forecast. Observations.
4. Step 4. Weather forecast — uses — Electrical telegraph. Collecting reports by telegraph.
5. Step 5. Electrical telegraph — has part — Relay. Relays boosted the signal on long lines.
6. Step 6. Relay — is part of — Hollerith tabulator. Relays controlled the sorting box.

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