A descent from the skies with engine shut off and the machine at its own gliding angle is the familiar ' vol plane.' To assume the angle is not difficult, for the well-designed aeroplane, if its nose is tilted down, will find it of its own accord. A descent at a steeper angle is a ' nose dive ' or ' vol pique.' An aviator will often execute this to pick up speed if he has lost way in the air, or if he is forced to descend on a particular space. To land a swift machine in a small area is test of the highest skill on the part of a pilot; but in our tidily kept island, where fields are small and fences many, it proves, over and over again, the only way to avert disaster.

Of possible accidents aloft there are a soul-satisfying variety. Some are due to atmospheric causes, of which wind naturally counts as chief. Nevertheless it is astonishing how wind has lost its terrors for the aviator, and how few accidents can be laid to its account. Five years ago Wilbur Wright refused to stir from his shed if the smoke of a cigarette did not rise straight upwards. A year later the whole world went wild with enthusiasm because Latham, at Blackpool, flew in a 40-mile wind. It was indeed a marvellous feat for those days, but now aviators will fly in almost any wind that blows; well aware that their properly balanced craft, although it will pitch and roll and wallow in the aerial waves, may yet be trusted, like a well-found ship, to recover its equilibrium.

Almost more disconcerting, because unexpected, are the perils of a hot, windless day—those suddenly encountered ascending and descending vertical currents known respectively as 'air pockets' and 1 holes in the wind.' On entering one of these unseen perils all air resistance suddenly seems to cease, and the planes lose their support. As one famous aviator expresses it, it is 1 like suddenly treading into a bog after walking on firm ground.' It may be an alarming experience, yet if the pilot is at a safe height, and keeps his head while his machine drops 50 feet or so, all is well, for he will then recover speed. The little eddies known as 'remous' are more entertaining than annoying, and are affectionately nick-named in the flying grounds where they resort. Increased speed and stability have shorn the atmosphere of most of its terrors.

Accidents due to faulty construction tend to become ever rarer with increased knowledge and care. There remain accidents due to the errors of the pilots themselves, and these, of course—human nature being what it is—can never be wholly eliminated. Nevertheless the inherently stable machine that looks after itself will go far towards achieving the impossible, as also the practice of flying high. In olden days aviators feared to do more than flutter along a few feet from the earth; now they know that their safety lies in height. High aloft they can do what they like with their aeroplanes—roll them over, fly upside down, slide down on their tails, upset them in every direction—confident that they have sufficient time to recover before reaching the ground. One of the most awkward things to occur in the air is a bad 'side-slip '—an expressive term which means that the aeroplane starts to fall sideways. A side-slip most frequently occurs when a pilot' stalls ' his machine—that is, attempts to make it climb at too steep an angle, or in other ways do more than it has power for. An overpressed machine flies 'cabre' or tail down, and as it loses its speed tends also to lose its lateral balance.

In a bad side-slip the machine may turn over so far that the elevator becomes upright and the rudder horizontal, so that their functions are reversed. Even then if the pilot but keeps his head all will be well, provided always he is flying high. Left alone, the properly designed craft will right itself; and one the side-slip has become a nose-dive, the flyer shoul be able to resume command. 'Trust your machine ' is one of the maxims drilled into a beginner. ' Don't switch off your engine in a tight corner.' 'Don't try to rise when making a turn.' ' Always land facing the wind.' 'If the engine begins to fail, tilt the nose down immediately.' All these are golden rules. It is reckoned that an average pupil learns to fly in about eight hours in the air. His tuition, however, is spread out over several weeks, because he is only allowed to practice for a few minutes at a time. Should he attempt more, he will infallibly get tired and muddled, and retrograde rather than progress. As one authority puts it—' Flying has to become instinctive, and you must give a new instinct time to grow.'

As to the cost of aviation. The price of an aeroplane —which may be made also to include a course of tuition upon it—can be anything from £400 to £1500. A good part of the price depends upon the engine. A single-seater machine with a 50 horsepower Gnome may be bought for about £7oo; a two-seater with 80 horse-power engine for £1000. The wages of a mechanic, cost of housing, insurance and repairs must all be considered, as well as the expense of fuel and oil, which, for a motor of 80 horse-power, would be about £1 for every hour of flight—averaging 70 miles. At present aviation is undoubtedly a costly sport, but every year now will see its expense lessen and its popularity increase.

It is not the place of this little work—actually passing through the press as the Great War broke out—to enlarge upon the mighty events which have shaken the world and altered the perspective of mankind. The part which aviation has played in the tremendous campaign is beyond all present estimate and cannot yet be fully gauged. The task of attempting to do so must be left to later days and wider knowledge. Meantime we can but attempt to summarize, in briefest words, some outstanding lessons Which have already been taught.

Flying machines have been used, since the commencement of hostilities, with the most prodigious effects, one of which, it is claimed, has been the prolonging of the action ; since with the practical elimination of the ' fog of war,' owing to the fact that all movements of the enemy are now immediately known, the day of surprises and sudden concealed strokes is over, and war, as has been said, becomes less kriegspiel than a game of chess. This is one terrific and unlooked-for result. Of scarcely less far-reaching importance has been the immense assistance of the military aeroplanes in directing artillery fire, and the naval machines in detecting mines at sea. The effect, both moral and actual, of our aerial raids is hard to estimate —or possibly to over-estimate—even though they have demonstrated that it is as hard to aim correctly with a bomb from above as it is to hit a high-flying and swiftly moving machine with an anti-aircraft gun from below.

Many literally hair-breadth escapes from bullets and pom-pom shells, many actual duels in the air, have emphasized the supreme importance of speed and quick climbing in a war machine; qualities which appear to take precedence of all other advantages, even of stability and ease of control. This is understandable enough when we reflect that an aeroplane is within rifle and machine-gun range at 8000 feet altitude, and that machines have been riddled with bullets at 6500 feet. The armour-plating of aeroplanes does not appear to have been widely adopted, no doubt because it interferes with the two above-mentioned all-essential qualifications ; but a protective sheet of steel is frequently placed in the pilot's seat as a very wise and well-proved precaution. The dropping of the deadly little steel arrows or ' flechettes' from aeroplanes is a natural retaliation from aloft for unpleasant attentions from below.

The extraordinary immunity from accident of our naval and military pilots is one of the wonders of the War. Notwithstanding the vast amount of flying done, the dangerous conditions and the fact that flights are made in every sort of weather, it yet actually appears that an aviator on active service runs less risk of injury or death than an officer in any other branch of the service, except those on lines of communication. In explanation it has been brought forward that flying on the Continent is far safer than it is in Great Britain; and that an English pilot, educated to the treacherous gusts and air-pockets, and the hedges and walls of our wind-swept and tidy island, finds the uniform conditions and the wide obstacle-less plains of France and Belgium mere child's play to negotiate.

Nevertheless when all possible explanations are brought forward, the fact remains that good fortune has undoubtedly favoured us in our aerial endeavours ; and this is the more remarkable when we reflect how badly we were equipped at the commencement of the War. According to expert calculation Germany opened hostilities with an aeroplane fleet of 1300 machines, doubtless all of her very best; France had about 800, many very ineffective; and Great Britain a scratch team of 100 or so. But how short a time did Germany enjoy her superiority. In sea-planes we have, of course, all along been facile princeps.

From the beginning the tractor biplanes have obtained and kept the lead over every other form of aerial craft, while the fast air-scouts are claimed as the salvation of our army. Monoplanes, though extremely useful for their special tasks, have not been so widely employed as biplanes, while vertical engines have rather gained the ascendancy over the rotaries as being more easy to silence.

The day has not yet dawned, as we write, for the revealing of many lessons that the Great War has taught. With the coming of Peace much will be made clear, and vastly increased knowledge and experience brought to bear in directions that will add materially to the welfare of mankind. Lessons learned on the battle-field will bear fruit in peace time, and the hour is surely very near when mails, and light merchandise, and travellers in a hurry, are borne by air from town to town and from country to country.

It is easy to speculate about the future of flight— as easy as it was to scoff at it ten years ago. Times change rapidly, and we have to cultivate short memories if only to forget our own false prophecies. This much at least is certain, that in subduing another element to himself man has accomplished a feat as great as when he pushed his first rude raft into the waves in prehistoric days, or set his earliest sail to explore the realms of the great unknown.

Printed by T. and A. Constable, Printers to His Majesty at the Edinburgh University Press.