To-day, the aerodrome is the rendezvous of those who fly, or build machines, or seek to learn the art; while the general public, thronging the stands on racing days, learns more of aviation in an hour than it would in a month by merely reading of flights that have been made. All day, from the moment it grows light until the final dusk, there is activity upon the aerodrome. Machines are brought out and tested; pilots arrive from other flying grounds; there is a hum of activity in the workshops; and in regular batches, with this instructor and that, are pupils taught to handle a craft in flight. It is, to those who have only a vague knowledge of aviation, a surprise indeed to spend a day at an aerodrome. They imagine that the industry is no more than haphazard; that a few machines are built--mostly in small workshops, and that there is neither method nor organisation in their making. And then, perhaps, they are taken through a modern factory, and hold such views no more. By the work of trained men, who have become highly skilled in their art, are the parts of a flying machine built and assembled; and no sooner is one machine wheeled from the shops and takes the air, than another is being made ready. Governments give orders for large batches of craft; aeroplanes of new types are built and tested. And, in all departments of the factory, the output of work is constant and well ordered. First, of course, the machine is designed; and those in the drawing office are specially trained men. The planning of an aeroplane is a matter of no simplicity. First of all there is to be considered what may be termed the main feature of the machine; whether, that is to say, it is to be built for speed, for weight-lifting, or for aerial touring. For high-speed flying it will need small sustaining wings; for weight-lifting, its area must be large; while in aerial touring there is need for a medium-paced, highly reliable craft, which will ascend quickly or plane slowly to earth. The characteristic of the machine determined, there are other problems to be studied--such, for example, as the placing of the engine and propeller, the position of the body containing the pilot and passenger, and the arrangement of the control surfaces. And, above all, the craft must be built strongly. No matter how well a machine may fly, or how skilled its pilot, there is peril should its structure have a weakness, or some hidden defect. For months, perhaps, in the early days of aviation, a faulty machine would fly; and then some day, subjected to an abnormal strain, a wing or a tail would break, and the airman would fall to his death. Should an aeroplane dive suddenly, there may be a tremendous strain upon its planes; and in a violent wind, while its motor is thrusting it through the gusts, it is sustaining shocks and jars which may be of tremendous force. It is not, indeed, the ordinary wear of flying that a designer needs to guard