Bronze steam boiler and zip: what they have in common

1. Step 1. Bronze steam boiler — is part of — Heron’s aeolipile. A vessel of boiling water.
2. Step 2. Heron’s aeolipile — is made of — Bronze. The aeolipile is a bronze ball.
3. Step 3. Bronze — is material for — Hook and eye. Medieval fasteners were bronze.
4. Step 4. Hook and eye — evolved into — Zip. Judson started with a chain of hooks.

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