| Year | 1919 |
| Date | 24-Apr |
| Volume | 40 |
| Issue | 939 |
| Page | 298 |
| Category | Electrical |
| Part | |
| Title | A G.P.O.-Type Telegraph Sounder |
| Author | D.J.S. |
| Notes | The complete sounder, elevation & plan of the Morse sounder, details of armature bar & section of core riveted to yoke |