Nor has the influence of the gasoline motor been much less upon that other great class of aircraft, the dirigible balloon. After 1885, when Renard and Krebs’ airship La France made its two historic voyages from Chalais-Meudon to Paris, returning safely to its shed, under the propulsion of an electric motor, the problem of the great airship lay dormant, waiting for the discovery of adequate motive power. If the development of the dirigible balloon seems less spectacular than that of the aeroplane, it is because the latter had to be created; the dirigible, already in existence, had only to be revivified.
Confronted with these new and strange shapes in the sky, some making stately journeys of hundreds of miles, others whirring hither and thither with the speed of the whirlwind, wonder quickly gives way to the all-absorbing question: How do they fly? To answer fully and satisfactorily, it seems wise, for many readers, to recall in the succeeding chapters some principles doubtless long since forgotten.
As with every great advance in civilization, this expansion of the science of aeronautics has had its effect upon the language of the day. Terms formerly in use have become restricted in application, and other terms have been coined to convey ideas so entirely new as to find no suitable word existent in our language. It seems requisite, therefore, first to acquaint the reader with clear definitions of the more common terms that are used throughout this book.
Aeronautics is the word employed to designate the entire subject of aerial navigation. An aeronaut is a person who sails, or commands, any form of aircraft, as distinguished from a passenger.
Aviation is limited to the subject of flying by machines which are not floated in the air by gas. An aviator is an operator of such machine.
A free balloon, with parachute.
Both aviators and aeronauts are often called pilots.
A balloon is essentially an envelope or bag filled with some gaseous substance which is lighter, bulk for bulk, than the air at the surface of the earth, and which serves to float the apparatus in the air. In its usual form it is spherical, with a car or basket suspended below it. It is a captive balloon if it is attached to the ground by a cable, so that it may not rise above a certain level, nor float away in the wind. It is a free balloon if not so attached or anchored, but is allowed to drift where the wind may carry it, rising and falling at the will of the pilot.