| FIG. | | PAGE |
| 1. | Diagram showing the reduction of the projected horizontal area, | 2 |
| 2. | Professor Langley’s experiments, | 5 |
| 3. | Eagles balancing themselves on an ascending current of air, | 14 |
| 4. | Air currents observed in Mid-Atlantic, | 16 |
| 5. | Glassy streaks in the Bay of Antibes, | 17 |
| 6. | Air currents observed in the Mediterranean, | 18 |
| 7. | The circulation of air produced by a difference in temperature, | 27 |
| 8. | Kite flying, | 29 |
| 9. | Group of screws and other objects used in my experiments, | 32 |
| 10. | Some of the principal screws experimented with, | 32 |
| 11. | The three best screws, | 33 |
| 12. | Apparatus for testing the thrust of screws, | 34 |
| 13. | Apparatus for testing the direction of air currents, | 35 |
| 14. | The ends of screw blades, | 36 |
| 15. | The manner of building up the large screws, | 39 |
| 16. | A fabric-covered screw, | 40 |
| 17. | The hub and one of the blades of the screw on the Farman machine, | 42 |
| 18. | Section of screw blades having radial edges, | 43 |
| 19. | Form of the blade of a screw made of sheet metal, | 44 |
| 20. | New form of hub, | 45 |
| 21. | Small apparatus for testing fabrics for aeroplanes, | 50 |
| 22. | Apparatus for testing the lifting effect of aeroplanes and condensers, | 51 |
| 23. | Apparatus for testing aeroplanes, condensers, &c., | 52 |
| 24. | Cross-sections of bars of wood, | 53 |
| 25. | Sections of bars of wood, | 54 |
| 26. | A flat aeroplane placed at different angles, | 55 |
| 27. | Group of aeroplanes used in experimental research, | 56 |
| 28. | An 8-inch aeroplane which did very well, | 57 |
| 29. | Resistance due to placing objects in close proximity to each other, | 58 |
| 30. | Cross-section of condenser tube made in the form of Philipps’ sustainers, | 60 |
| 31. | The grouping of condenser tubes made in the form of Philipps’ sustainers, | 61 |
| 32. | Machine with a rotating arm, | 63 |
| 33. | A screw and fabric-covered aeroplane in position for testing, | 64 |
ARTIFICIAL AND NATURAL FLIGHT.
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