X 



CONTENTS. 



insects— Construction of an artificial insect which moves hori- 

 zontally—Change of plane in flight 



CHAPTER III. 



OF THE FLIGHT OF BIRDS. 

 Conformation of the bird with reference to flight— Structure of the 

 wing, its curves, its muscular apparatus— Muscular force of the 

 bird, rapidity of contraction of its muscles — Form of the bird ; 

 stable equilibrium, conditions favourable to change of plane— 

 Proportion of the surface of the wings to the weight of the body 

 in birds of diff'erent size 



CHAPTER IV. 



OF THE MOVEMENTS OF THE WING OF THE BIRD 

 DURING FLIGHT. 

 Frequency of the movements of the wing — Relative durations of its 

 rise and fall — Electrical determination — Myographical determi- 

 nation—Trajectory of the bird's wing during flight— Construc- 

 tion of the instruments which register this movement — Experi- 

 ment—Elliptical figure of the trajectory of the point of the 

 wing 



CHAPTER V. 



OF THE CHANGES IN THE PLANE OF THE BIRD'S WING 

 AT DIFFERENT POINTS IN ITS COURSE. 

 New determination of the trajectory of the wing — Description of 

 apparatus — Transmission of a movement by the traction of a 

 thread — Instrument and apparatus to suspend the bird — Experi- 

 ment on the flight of a pigeon — Analysis of the curves — 

 Description of the apparatus intended to give indications of the 

 changes in the plane of the wing during flight — Relation of 

 these changes of plane to the other movements of the wing . 2ii 



CHAPTER VI. 



RE- ACTIONS OF THE MOVEMENTS OF THE WING ON 

 THE BODY OF THE BIRD. 

 Re-actions of the movements of the wing — Vertical re-actions in 

 diff'erent species ; horizontal re-actions or changes in the 

 rapidity of flight ; simultaneous study of the two orders of 

 re-actions — Theory of the flight of the bird — Passive and active 

 parts of the wing— Reproduction of the mechanism of the flight 

 of the bird 264 



