FIG. 
. AMBIENS MUSCLE .... aa ae ‘i ane 
63. 
LIST OF ILLUSTRATIONS 
_ DIAGRAM ILLUSTRATING THE VELOCITY OF THE WING’S 
DESCENT. 4 « « ales ode ae é p . 
. DIAGRAM, ILLUSTRATING COMBINED ACTION OF WINGS 
. PARALLELOGRAM OF FORCES 
. BOAT SAILING AT AN ANGLE TO THE WIND—DIAGRAM . 
. DIAGRAM ILLUSTRATING THE ACTION OF THE AIR UPON 
THE WING. 4 4 * ye ea 
DIAGRAM EXPLANATORY OF THE AMOUNT OF SUPPORT 
AFFORDED BY THE AIR TO A BIRD IN MOTION ... 
. BIRDS GLIDING: (a) TERN WITH WINGS PARTLY FLEXED ; 
(4) GULL WITH WINGS OUTSTRETCHED ... . 
. A PAPER Toy ILLUSTRATIVE OF GLIDING FLIGHT .. 
. WING, SHOWING ELasTic LIGAMENTS AND THE MUSCLE 
THAT ROTATES THE SECONDARY FEATHERS Be oa 
. PRIMARY WING-FEATHER OF HERON, SHOWING NARROW 
OuTER WEB 
HUMERUS, SHOWING ATTACHMENT OF IMPORTANT FLIGHT- 
MUSCLES . . eae i 
. GULLS FLYING, SHOWING VARIOUS POSITIONS OF WING 
Do. Do. DO. 
GULLS FLYING. aot 0% 
. FIGURE DESCRIBED BY TIP OF CRoW’s WING 
. GULL FLYING—TO ILLUSTRATE THE QUESTION OF TRA- 
JECTORY. . a8 . see ae . a 
. BREASTBONE OF (a) FRIGATE BirbD, (6) Duck .... 
FLIGHT IN TROOPS... Bg ; ‘ F r 
. DIAGRAM TO ILLUSTRATE FLIGHT AT RIGHT ANGLES TO 
THE WIND . . ele 
. P1GEoNS FLYING—TO SHOW THE USE OF THE BASTARD 
WING... le. 
AN EGG AND ITS CONTENTS ..... +. i ie Sie 
Embryo CHICK, SIXTY-EIGHT Hours OLD. 
xix 
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