| Year | 1920 |
| Date | 15-Jan |
| Volume | 42 |
| Issue | 977 |
| Page | 51 |
| Category | Electronic |
| Part | 3 |
| Title | Wireless Notes |
| Author | A.V.Ballhatchet |
| Notes | Condensers. Variable condenser with air dielectric, components of a built-up condenser, outline of fixed vane, relative positions of vanes for various capacities, condenser built up of plates of semi-circular or trough cross section |