CHAPTER III. THE FORM OR SHAPE OF FLYING MACHINES The Theory of Copying Nature. Hulls of Vessels. Man Does not Copy Nature. Principles Essential, not Forms. Nature not the Guide as to Forms. The Propeller Type. Why Specially-designed Forms Improve Natural Structures. Mechanism Devoid of Intelligence. A Machine Must Have a Substitute for Intelligence. Study of Bird Flight Useless. Shape of Supporting Surface. The Trouble Arising From Outstretched Wings. Density of the Atmosphere. Elasticity of the Air. "Air Holes." Responsibility for Accidents. The Turning Movement. Centrifugal Action: The Warping Planes. CHAPTER IV. FORE AND AFT CONTROL The Bird Type of Fore and Aft Control. Angle and Direction of Flight. Why Should the Angle of the Body Change. Changing Angle of Body not Safe. A Non-changing Body. Descending Positions by Power Control. Cutting off the Power. The Starting Movement. The Suggested Type. The Low Center of Gravity. Fore and Aft Oscillations. Application of the New Principle. Low Weight not Necessary with Synchronously- moving wings. CHAPTEB V. DIFFERENT MACHINE TYPES AND THEIR CHARACTERISTICS The Helicopter. Aeroplanes. The Monoplane. Its Advantages. Its Disadvantages. The Bi-plane. Stability in Bi-planes. The Orthopter. Nature's Type not Uniform. Theories About Flight of Birds. Instinct. The Mode of Motion. The Wing Structure. The Wing Movement. The Helicopter Motion. CHAPTER VI. THE LIFTING SURFACES OF AEROPLANES Relative Speed and Angle. Narrow Planes Most Effective. Stream Lines Along a Plane. The Center of Pressure. Air Lines on the Upper Side of a Plane. Rarefied Area. Rarefaction Produced by Motion. The Concaved Plane. The Center of Pressure. Utilizing the Rarefied Area. Changing Center of Pressure. Plane Monstrosities. The Bird Wing Structure. Torsion. The Bat's Wing. An Abnormal Shape. The Tail as a Monitor. CHAPTER VII. ABNORMAL FLYING STUNTS AND SPEEDS Lack of Improvements in Machines. Men Exploited and not Machines. Abnormal Flying of no Value. The Art of Juggling. Practical Uses the Best Test. Concaved and Convex Planes. How Momentum is a Factor in Inverted Flying. The Turning Movement. When Concaved Planes are Desirable. The Speed Mania. Uses of Flying Machines. Perfection in Machines Must Come Before Speed. The Range of its Uses. Commercial Utility. CHAPTER VIII. KITES AND GLIDERS The Dragon Kite. Its Construction. The Malay Kite. Dihedral Angle. The Common Kite. The Bow Kite. The Box Kite. The Voison Bi-plane. Lateral Stability in Kites, not Conclusive as to Planes. The Spear Kite. The Cellular Kite. Tetrahedral Kite. The Deltoid. The Dunne Flying Machine. Rotating Kite. Kite Principles. Lateral Stability in Kites. Similarity of Fore and Aft Control. Gliding Flight One of the Uses of Glider Experiments. Hints in Gliding.