CHAPTER XIII. THE PROPELLER
Propeller Changes. Propeller Shape. The Diameter.
Pitch. Laying Out the Pitch. Pitch Rule. Laminated
Construction. Laying up a Propeller Form.
Making Wide Blades. Propeller Outline. For High
Speeds. Increasing Propeller Efficiency.

CHAPTER XIV. EXPERIMENTAL GLIDERS AND MODEL AEROPLANES
The Relation of Models to Flying Machines. Lessons
From Models. Flying Model Aeroplanes. An
Efficient Glider. The Deltoid Formation. Racing
Models. The Power for Model Aeroplanes. Making
the Propeller. Material for the Propeller. Rubber.
Propeller Shape and Size. Supporting Surfaces.

CHAPTER XV. THE AEROPLANE IN THE GREAT WAR
Balloon Observations. Changed Conditions in Warfare.
The Effort to Conceal Combatants. Smokeless
Powder. Inventions to Attack Aerial Craft. Functions
of the Aeroplane in War. Bomb-throwing Tests.
Method for Determining the Movement of a Bomb.
The Great Extent of Modern Battle Lines. The Aeroplane
Detecting the Movements of Armies. The Effective
Height for Scouting. Sizes of Objects at Great
Distances. Some Daring Feats in War. The German
Taube. How Aeroplanes Report Observations. Signal
Flags. How Used. Casualties Due to Bombs
From Aeroplanes.