INTRODUCTION Lighter-than-air craft consist of three distinct types: Airships, which are by far the most important, Free Balloons, and Kite Balloons, which are attached to the ground or to a ship by a cable. They derive their appellation from the fact that when charged with hydrogen, or some other form of gas, they are lighter than the air which they displace. Of these three types the free balloon is by far the oldest and the simplest, but it is... more...