CONTENTS
I. Preliminary Notions 1
II. Historical Considerations 13
III. On the Hertzian Waves 25
IV. Constructional Details 65
V. Recent Improvements in Wireless Telegraphy 119
Appendix 128
INDEX TO SECTIONS
1. Knowledge essential 1
2. What Electricity is 1
3. General Laws of Electricity 5
4. Two Conditions ever present 6
5. Transference 6
6. Induction 8
7. Electrical Strain 11
8. Magnetism an aspect of Electricity 11
9. Action of Charged Conductor 13
10. Lateral Discharge 15
11. Iron-filings affected by Discharge 19
12. Syntony, or 'Tuning' 22
13. Guarini's Discovery 24
14. The Hertzian Waves 25
15. Waves compared 25
16. Leyden Jar Discharges 30
17. Coherence 34
18. Practical Applications 38
19. Effect of Light on Discharge 44
20. Identity of Electricity and Light 60
21. Chunder Bose's Experiments 51
22. Hertzian Waves and Photography
23. Hertzian Waves and Nikola Tesla 53
23a. Application to Telephone 59
23b. Abbb Michel's System 119
23c. Collins's System 123
24. Desire of making Apparatus 65
25. The Induction Coil 65
26. The Wheatstone Commutator 80
27. The Tapping-Key 85
28. The Wimshurst Machine 86
29. The Transmitter 94
30. The Receiver .96
31. The Coherer 101
32. The Bell and Decoherer 109
33. The Batteries required 110
34. Instruction for putting together 111
35. To use the Apparatus 116
36. Condenser, where applied 118
37. Recent Improvements 119
Aerials, 120
Liquid Aerial, 123
Blake Detector, 123
Magnetic Detector, 124
Electrolytic Coherer, 125
Marconi Coherer, 126
Italian Navy Coherer, 126
Lodge-Muirhead Coherer, 127
LIST OF ILLUSTRATIONS
1. Lateral Discharge 16
2. Induction Discharge 17
3. Preece's System 19
4. Kinging Bell by a Discharge 22
5. Preece's System : another form 30
6. Syntonic Jars 32
7. Hertz's Oscillator and Resonator 35
8. The Branly Tube 38
9. Marconi's Original Arrangement 41
10. Miller's Decoherer 43
11. General Arrangement of Receiver 44
12. Hertz's Device to show effect of Light 45
13. Oliver Lodge's Arrangement 47
14. Ch under Bose's Explosion Experiment 53
15. Tesla's Hertzian Wave Boat: plan 54
16. Tesla's Transmitter and Boat : elevation 55
17. Tesla's Boat : section 57
17a. Popoffs Wireless Telephone 61
17b. Popoffs Radio Conductor 63
18. Coil Base 67
19. Section of Condenser .69
20. Finished Condenser 70
21. Bobbin-Winder 73
22. Contact-Breaker 78
23. Completed Coil : section 80
24. Commutator, Roller of 83
25. Commutator, Wheatstone's 84
26. Tapping-Key 86
27. Wimshurst Machine 94
28. Lodge's Transmitter 96
29. Bracket for Armature 99
30. Completed Relay 101
31. Simple Coherer 105
32. Frame for Multilocnlar Coherer 106
33. Multilocular Polytonic Coherer 108
34. Bell with Decoherer 110
35. Receiver, completed 116
36. Michel's "Earth" go and return System 128
37. Armorl's Electro-Capillary Relay 130

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