Ultraviolet und electrical telegraph: was sie gemeinsam haben
- Schritt 1. Ultraviolet — wird verwendet in — Sunglasses. A UV filter.
- Schritt 2. Sunglasses — entwickelte sich aus — Brille. Glasses with dark lenses.
- Schritt 3. Brille — entwickelte sich zu — Telescope. The first telescopes were assembled by spectacle makers.
- Schritt 4. Telescope — wird verwendet in — Optical telegraph. Signals were read through a telescope.
- Schritt 5. Optical telegraph — entwickelte sich zu — Electrical telegraph. The electrical telegraph replaced semaphore lines.