| Year | 1922 |
| Date | 25-May |
| Volume | 46 |
| Issue | 1,100 |
| Page | 514 |
| Category | Radio Engineering |
| Part | |
| Title | Thermionic Shadows |
| Author | Captain H. de A.Donisthorpe |
| Notes | Illustrating Edison's experiment, showing various thermionic shadows, circuit for producing a magnetic field within the triode's bulb |