Sound film and hammer: what they have in common
- Step 1. Sound film — is a kind of — Cinema. Cinema.
- Step 2. Cinema — uses — Cinématographe. Cinema began with the cinématographe.
- Step 3. Cinématographe — was inspired by — Sewing machine. Louis Lumière said he came up with the intermittent film feed while watching the fabric feed of a sewing machine.
- Step 4. Sewing machine — has part — Cam. Cams drive the fabric feed.
- Step 5. Cam — is part of — Trip hammer. Cams on the shaft lift the hammer.
- Step 6. Trip hammer — evolved from — Hammer. A trip hammer is a hammer lifted and dropped by a water wheel.