It is probable that, as air ships develop, this general characteristic will become more marked. As aeroplanes become larger and faster they will therefore depart further and further from the conventional ideas concerning water-borne craft. It is impossible to prophesy at present what form the great passenger-carrying air ships of the future will take, but it is certain that their hulls or the closed-in portion carrying the machinery and passengers will be very short, snubbed-nose affairs. The world will be obliged to change its mind as to what constitutes a speedy-looking craft. Man has learned to fly. More than 1,000 aeroplanes have been built which have successfully risen above the earth. It is estimated that these aeroplanes have flown in all more than 250,000 miles, or a distance equal to ten times the circumference of the earth. But no machine has yet been made which will fly alone, without the skilful manipulation of planes and rudders. The model aeroplane which soars gracefully aloft, suiting itself to the varying air conditions, perhaps comes nearest to the automatic flying machine. A great advance will be made in aviation with the appearance of some practical contrivance for securing automatic stability. The aeroplane as it stands to-day shows a wonderful advance in the improvement of its general lines, and the mechanical perfection of its parts, but the question of stability remains practically the same as it was when the Wright Brothers made their first flights. The machine has been brought under a remarkable control, but only as it is directed by the practised hand of the sky pilot. Let him take his hand even for a moment from the levers, which control the planes and rudders, and there is danger of a bad spill, perhaps a fatal accident. Practically nothing has been accomplished in building machines which will fly unaided. It has been pointed out, elsewhere in this volume, that the experiments with the model aeroplanes are certain to have an important influence upon the development of aeronautics as a whole, because they address themselves particularly to this problem of stability. It is believed by many aviators that the problem of automatic stability will be solved by some form of the gyroscope. A great many experiments are being made with various forms of the gyroscope, although no machine has as yet been actually fitted and flown with such a device. The general principle of the gyroscope is very simple. It consists of a wheel which is made to revolve at very high speed. When such a wheel turns fast enough it will remain in a fixed position. Every one is familiar for instance with the gyroscope top. You wind it up and place it at any angle, and it will support itself and retain the position until it has run down.