| Year | 1919 |
| Date | 11-Sep |
| Volume | 41 |
| Issue | 959 |
| Page | 255 |
| Category | Optical |
| Part | |
| Title | The Photophone |
| Author | R.Dunn |
| Notes | Diagram showing the principle upon which the photophone works, plan of transmitter, action of diaphragm (exaggerated), apparatus for receiving the beam, transmitting & receiving station |