LIST OF ILLUSTRATIONS 



xix 



FIG. PAGE 



45. Ambiens Muscle 169 



46. Diagram illustrating the Velocity of the Wing's 



Descent 177 



47. Diagram illustrating Combined Action of Wings 180 



48. Parallelogram of Forces 181 



49. Boat sailing at an Angle to the Wind — Diagram . 182 



50. Diagram illustrating the Action of the Air upon 



the Wing 183 



51. Diagram explanatory of the Amount of Support 



afforded by the Air to a Bird in Motion . . . 187 



52. Birds Gliding : (a) Tern with Wings partly flexed ; 



(6) Gull with Wings outstretched 191 



53. A Paper Toy illustrative of Gliding Flight . . . 192 



54. Wing, showing Elastic Ligaments and the Muscle 



that rotates the Secondary Feathers 199 



55. Primary Wing-feather of Heron, showing Narrow 



Outer Web 203 



56. Humerus, showing Attachment of Important Flight- 



muscles 204 



57. Gulls Flying, showing various Positions of Wing 218 



58. Do. do. do. 218 



59. Gulls Flying 219 



60. Figure described by Tip of Crow's Wing 221 



61. Gull Flying— to illustrate the Question of Tra- 



jectory 224 



62. Breastbone of (a) Frigate Bird, {&) Duck 225 



63. Flight in Troops • 230 



64. Diagram to illustrate Flight at Right Angles to 



the Wind 241 



65. Pigeons Flying — to show the Use of the Bastard 



Wing 254 



66. An Egg and its Contents 277 



67. Embryo Chick, Sixty-eight Hours Old 280 



