y'lii CONTENTS. 



PAGE 



The wing at all times thoroughly under control, . ,154 

 The natural wing when elevated and depressed must move for- 

 wards, ....... 156 



The wing ascends when the body descends, and vice versd, . 159 

 The wing acts upon yielding fulcra, . . . .165 



The wing acts as a true kite both during the down and up 



strokes, ....... 165 



Where the kite formed by the wing differs from the boy's kite, 166 

 The angles formed by the wing during its vibrations, . • 167 



The body and wings move in opposite curves, . • • 168 



The Wings of Insects, Bats, and Birds. 



Elytra or wing cases and membranous wings ; their shape and 



uses, . . . . . . .170 



♦ The Wings of Bats. 



The bones of the wing of the bat ; the spiral configuration of 



their articular surfaces, , , , . .176 



The Wings of Birds. 



The bones of the wing of the bird ; their articular surfaces, 



movements, etc., . . . . . .178 



Traces of design in the wing of the bird ; the arrangement of 



the primary, secondary, and tertiary feathers, etc., . 180 



The wing of the bird not always opened up to the same extent 



in the up stroke, . . . . . .182 



Flexion of the wing necessary to the flight of birds, . ,183 

 Consideration of the forces which propel the wings of insects, . 186 

 Speed attained by insects, . . . . .188 



Consideration of the forces which propel the wings of b^s and 



birds, . . . . . . .189 



Lax condition of the shoulder- joint in bats and birds, . 190 



The wing flexed and partly elevated by the action of elastic 

 ligaments ; the nature and position of said ligaments in 

 the Pheasant, Snipe, Crested Crane, Swan, etc., . . 191 



