| Year | 1921 |
| Date | 29-Dec |
| Volume | 45 |
| Issue | 1,079 |
| Page | 578 |
| Category | Radio Engineering |
| Part | |
| Title | An Acoustic Oscillator Capacity Bridge |
| Author | Captain H. de A.Donisthorpe |
| Notes | Diagram of connections, acoustic oscillator, amended circuit, two alternative circuits |