CONTENTS. 



vii' 



PROCxRESSION ON AKD IN THE WATER. 



PAGE 



Swimming of the Fish, Whale, Porpoise, etc., . . .66 



Swimming of the Seal, Sea-Bear, and Walrus, . . ,74 



Swimming of Man, . . . . , .78 



Swimming of the Turtle, Triton, Crocodile, etc., . , 89 



Flight under water, ...... 90 



DiflPerence between sub-aquatic and aerial flight, . . 92 



Flight of the Flying-fish ; the kite-like action of the wings, . 98 



PEOGKESSION IN OR THROUGH THE AIR. 



The wing a lever of the third order, , . . .103 



Weight necessary to flight, . . • . ,110 



Weight contributes to horizontal flight, . . .112 



Weight, momentum and power to a certain extent synonymous 



inflight, . . . . . . .114 



Air-cells in insects and birds not necessary to flight, . . 115 



How balancing is eff'ected in flight, . . . .118 



Rapidity of wing movements partly accounted for, , ,120 

 The wing area variable and in excess, . . . . 124 



The wing area decreases as the size and weight of the volant 



animal increases, . . . . . .132 



Wings, their form, etc. All wings screws, structurally and 



functionally, . . . . . .136 



The wing, during its action, reverses its planes, and descril^es 



a figure-of-8 track in space, .... 140 



The wing, when advancin*;; with the body, describes a looped 



and waved track, . . . . . .143 



The margins of the wing, thrown into opposite curves during 



extension and flexion, ..... 146 

 The tip of the bat and bird's wing describes an ellipse, . 147 



The wing capable of change of form in all its parts, . . 147 



The wing during its vibration produces a cross pulsation, . 148 

 Compound rotation of the wing, . . . .149 



The wing vibrates unequally with reference to a given line, . 150 

 Points wherein the screws formed by the wings diff'er from 



those in common use, . . . . .151 



