Chapter I: Appendix: 245

INDEX 247

LIST OF ILLUSTRATIONS

A Huge Lamp _Frontispiece_

FACING PAGE

First Effect of the Dynamite 16

A Fine Crop 24

Apple-tree planted by Spade 48

Machine-made Ice 72

A Cold Store 80

Dassen Island Lighthouse 88

Measuring Heat 128

The Telewriter 184

A Miners' Rescue Team 208

Pneumatic Hammer Drill 216

An Artificial Coal Mine 224

Sectional view of a 60-pounder Gun 232

Rifles of different Nations 240

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

MARVELS OF SCIENTIFIC

INVENTION