facing page 21 11. Connections of complete transmitting apparatus 23 12. Drawing of ordinary type of spark-gap 27 13. Synchronous rotating spark-gap 28 14. Non-synchronous rotating spark-gap 28 15. Connections for complete wireless photographic station 30 16. Connections of Professor Korn's apparatus 31 17. Connections of Poulsen's photographic recorder 33 18. Author's photographic receiver 38 19. Enlarged drawing of cone 39 20. End view of Author's photographic receiver 39 21. Connections of decohering apparatus 41 22. Connections for complete photographic receiver 42

23. Arrangement of Einthoven galvanometer

45 24. Einthoven galvanometer arranged for receiving 46 25. Connection of telephone relay 49 26. Drawing of Author's improved photographic receiver 51 27. Diagram giving ratio of vibrating arm 51 28. Arrangement of polarisation receiver 53 29. Arrangement of kathode-ray receiver 54 30. Connections of electrolytic receiver 56 31. Drawing of improved stylus for receiving 58 32. Drawing of Hughes telegraph governor 66 33. Arrangement of simple speed regulator 68 34. Diagram of connections of simple speed regulator 68 35. Author's arrangement for complete radio-photographic station 77 36. Drawing of transmitting machine and circuit breaker 78 37. Drawing of special transmitting stylus showing adjusting arrangements 79 37a. End view of transmitting stylus 79 38. Connections of new type of relay designed by the Author 80 39. Arrangement of mercury containers and dipping rods for