Inventor's Secret

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Across
  1. 4. Small inventions
  2. 5. A 3 dimensional round shape or tube
  3. 6. To fall over or fail
  4. 9. Something that makes light
Down
  1. 1. Making explosive or sizzling sounds
  2. 2. A strange sound trains make
  3. 3. Train engines
  4. 7. Documents showing proof of invention
  5. 8. A device that plays sounds