Vibration motor and oil lamp: what they have in common

1. Step 1. Vibration motor — is made of — Tungsten. The eccentric weight is tungsten.
2. Step 2. Tungsten — is material for — Incandescent light bulb. A tungsten filament (since 1904–1910).
3. Step 3. Incandescent light bulb — evolved from — Oil lamp. The electric lamp replaced oil and gas lamps.

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