| Answer | Crossword Clue |
|---|---|
| opeidoscopes | OPEIDOSCOPE, an instrument for illustrating sound by means of light |
| opeidoscope | an instrument for illustrating sound by means of light |
| nephelometers | An instrument for measuring the size and concentration of particles suspended in a liquid or gas, esp. by means of the light they scatter |
| nephelometer | An instrument for measuring the size and concentration of particles suspended in a liquid or gas, esp. by means of the light they scatter |
| telephone | an instrument for reproducing sound at a distance, esp by means of electricity / to contact someone by telephone |
| kaleidophone | an instrument for demonstrating sound waves by lines of light |
| kaleidophones | KALEIDOPHONE, an instrument for demonstrating sound waves by lines of light |
