A dirigible balloon.
A dirigible balloon, sometimes termed simply a dirigible, usually has its gas envelope elongated in form. It is fitted with motive power to propel it, and steering mechanism to guide it. It is distinctively the airship.
Aeroplanes are those forms of flying machines which depend for their support in the air upon the spread of surfaces which are variously called wings, sails, or planes. They are commonly driven by propellers actuated by motors. When not driven by power they are called gliders.
A biplane glider.
Aeroplanes exist in several types: the monoplane, with one spread of surface; the biplane, with two spreads, one above the other; the triplane, with three spreads, or decks; the multiplane, with more than three.
The tetrahedral plane is a structure of many small cells set one upon another.
Ornithopter is the name given to a flying machine which is operated by flapping wings.
