Engineering Wonders of the World
Volume III

INTRODUCTION. 3 of aerial invasion and warfare in the clouds. The military side of aerial navigation has been, we venture to think, too widely emphasized. The locomotive has played a most important part in modern warfare, yet its mission has been mainly peaceful. Similarly, though the airship, like the submarine boat in another element, will be employed in war time on account of the moral effect produced by its possible presence, it will justify itself far more fully as a means of maintaining communication in many part 5 of the world whither roads and railway have not yet penetrated. Consider what an aerial postal service would mean to people living on the outskirts of civilization, in districts where pioneers are at present painfully feeling their way. In the following chapters we are concerned, not with questions of the future, but with the past and present progress of aeronautics. We shall review the principles and prob- lems of mechanical flight, and give attention to the most successful aeroplanes of to-day. The aeronautical engine, upon the development of which has depended so largely that of human flight, is treated in a separate article. The second main section is devoted to the airship or dirigfble balloon. Things are moving so fast, metaphorically as well as literally, in the field of aeronautics that we cannot hope to keep here quite abreast of the latest developments. Even while these articles pass through the press fresh triumphs will doubtless be won. The letter- press and illustrations will, however, have a value, even where they do not refer to principles rather than applications, as embodying a record of the early chapters in the history of the most fascinating, as it is the most recent, of engineering wonders.