Digital projector and r-7 rocket: what they have in common

1. Step 1. Digital projector — evolved from — Film projector. Digital projection.
2. Step 2. Film projector — evolved from — Magic lantern. Projecting images from a transparent medium.
3. Step 3. Magic lantern — uses — Oil lamp. The light source is an oil lamp.
4. Step 4. Oil lamp — evolved into — Kerosene lamp. A development of the oil lamp.
5. Step 5. Kerosene lamp — uses — Kerosene. The fuel.
6. Step 6. Kerosene — is material for — R-7 rocket. The fuel is kerosene.

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