LIST OF FIGURES IN TEXT. 



Page 

 1. — Glass balls, an illustration of Sir I. Newton's experi- 

 ment . . . . . . . . . . . . . . 3 



2. — Diagram illustrating gliding . . . . . . . . 6 



3. — Parallelogram of forces . . . . . . . . . . 7 



4. — Diagram and drawing of boat tacking . . . . 8 



5. — Illustrating kite-flying . . . . . . . . . . 9 



6. — Showing the proportion of resistance to support . . 10 



7. — Further illustrating the subject of resistance and 



support . . . . . . . . . . . . . . 11 



8. — Planes set at different angles to the horizon . . . . 12 



9. — Showing the advantage of a curved surface . . 16 



10. — Two cubes 19 



11. — Showing the disadvantage of an excessive curve .. 25 



12. — Showing the shifting of the centre of pressure . . 26 



13. — Swift gliding with wings fully extended . . . . 35 



14. — House-Martin gliding with wings partly flexed . . 35 



15. — Showing the velocity with which the extremity of the 



wing moves . . . . . . . . . . . . 39 



16. — Showing how the downstroke propels as well as lifts 42 



17.— (After Marey) Gulls flying 43 



18. — Breastbones of Guillemot and Falcon . . . . . . 68 



19. — Breastbone and connected bones of Adjutant . . 69 



20.— Clavicles of Tern and Eagle 70 



21. — Humerus of Eagle . . . . . . . . . . 71 



22. — Humerus of (a) Skua ; (6) Hornbill ; (c) Sea-Eagle. 



Drawn to scale . . . . . . . . . . . . 78 



23. — Skeleton of wing of Adjutant . . . . . . . . 80 



24. — (After Alix) showing elastic ligament, anterior wing- 

 membrane, eto . . . . . . . . . . . . 82 



25. — Illustrating advance with motionless wings at right 



angles to the wind . . . . . . . . . . 131 



26. — Illustrating advance in the teeth of the wind with 



wings held rigid . . . . . . . . . . 136 



27. — Gull gliding sideways with wings held rigid . . 140 



