DIAGRAMS
| fig. | page | |
| 1. | Principle of Galvanometer | [30] |
| 2. | String Galvanometer | [31] |
| 3. | Duddell Thermo-Galvanometer | [39] |
| 4. | Construction of a Voltmeter | [64] |
| 5. | The Working of a Refrigerating Machine | [70] |
| 6. | Hertz's Machine | [155] |
| 7. | Hertz "Detector" | [156] |
| 8. 9. 10. | Wireless Waves | [158] |
| 11. | A Wireless Antenna | [164] |
| 12. | Poulsen's Machine | [166] |
| 13. 14. | How Pictures are sent by Wire | [177] |
| 15. | Message received by Telewriter | [189] |