Mode of ascending, descending, turning, etc., 201 The flight of birds referable to muscular exertion and weight, 204 Lifting capacity of birds, 205 AËRONAUTICS. The balloon, 210 The inclined plane, 211 The aërial screw, 215 Artificial wings (Borelli’s views), 219 Marey’s views, 226 Chabrier’s views, 233 Straus-Durckheim’s views, 233 The Author’s views; his method of constructing and applying artificial wings, as contra-distinguished from that of Borelli, Chabrier, Durckheim, and Marey, 235 The wave wing of the Author, 236 How to construct an artificial wave wing on the insect type, 240 How to construct a wave wing which shall evade the superimposed air during the up stroke, 241 Compound wave wing of the Author, 242 How to apply artificial wings to the air, 245 As to the nature of the forces required for propelling artificial wings, 246 Necessity for supplying the roots of artificial wings with elastic structures in imitation of the muscles and elastic ligaments of flying animals, 247 The artificial wave wing can be driven at any speed--it can make its own currents or utilize existing ones, 251 Compound rotation of the artificial wave wing. The different parts of the wing travel at different speeds, 252 How the wave wing creates currents and rises upon them, and how the air assists in elevating the wing, 253 The artificial wing propelled at various degrees of speed during the down and up strokes, 255 The artificial wave wing as a propeller, 256 A new form of aërial screw, 256 The aërial wave screw operates upon water, 257 The sculling action of the wing, 231 CONCLUDING REMARKS, 258 [Illustration] LIST OF ILLUSTRATIONS. The Engravings are, with few exceptions, from Photographs, Drawings, and Designs by Mr. Charles Berjeau and the Author. Such as are not original are duly acknowledged. FRONTISPIECE. PAGE In the clutch of the enemy--(_The Graphic_). The three orders of lever--(_Bishop_), 19, 20