Take a large sheet of paper, and after climbing up on to a chair or table let it fall to the ground. If the paper remains flat, you can see how it receives considerable support from the air; the paper will not fall as a heavy book does, but will glide down gently to the floor. This is a very simple experiment, but it may help you to realise the kind of support that an aeroplane with its outstretched wings or planes does receive from the air.

An old-fashioned paper kite shows us how an object which is heavier than air can float about in the ocean of air. You remember that when you ran along holding the string of the kite it soared away up into the air. You chose a day when there was some wind. Why? Because the ocean of air was running past you, and that saved you running so fast through the air. More than that, if there had been no wind you would have had to keep running all the time in order to keep a kite up in the air; when the air kept running past you, you could then stand still.

When men began experimenting with gliders (aeroplanes without engines) they always set out against a gentle breeze for the same reason as you face the wind with your kite. But when it became possible to drive an aeroplane through the air by means of an engine, then flying machines became independent of the wind.

I remember attending the first Aviation Meeting in Scotland. We had to go some thirty miles into the country. The trains were so crowded that passengers having third-class tickets did not hesitate to get into the first-class carriages, and many having first-class tickets were glad to squeeze into the third-class compartments. Each train carried a full load, even all the available standing room being crowded. Few of the passengers had ever seen a flying machine as yet. A vast crowd had gathered at the ground, and there was great interest centred in the aeroplanes. After a little, one became used to the sight; it began to appear less dangerous.

Some hours later I noticed what appeared to be a large bird in the distance. I suggested to some friends that this was a flying machine coming across country; they laughed at the idea as absurd. A little later it became evident that it was an aeroplane flying at a great height. It came nearer and nearer, then, circling round the grounds, it alighted exactly like a great bird. The applause was very great. This was a much more daring deed than flying round the grounds.

We were very patient in those days; for several hours we had to wait until the wind died down, as at that time flying machines could not venture up except in calm weather. Now all that has been changed. Just as we speak of ships being seaworthy, we may say that the modern aeroplane is very airworthy. An aeroplane can now fly through a gale, and even face a storm in which the air is flying past at the rate of 60 miles an hour. The change has been brought about by building larger and more powerful machines and altering the design according to experience gained in flying.

In 1909 the world marvelled when an aeroplane succeeded in remaining in the air for one hour. In 1916 little attention was paid to the announcement that an aeroplane remained in the air for sixteen hours.

In 1909 the world was amazed when Louis Bleriot flew across the Channel from France to England. Year by year great improvements were made, and by 1914, when the Great European War broke out, the aeroplane was in a position to render much assistance. At first we thought of the flying machine only as a scout, and it was not difficult to realise what a great deal of assistance these air-scouts would be able to render.

Before the advent of air-scouts the Commander of an army was dependent for information regarding the enemy upon small patrols of men on horseback or on foot. These outposts tried to pierce the opposing outposts, and see what the enemy were doing, to find where they were gathering for an attack, or where their artillery was stationed, or how strong was the enemy force that the Commander had to face. What a tremendous advantage to be able to soar in the air above the enemy, and get a bird's-eye view of all that was going on, and so we began to build larger numbers of aeroplanes to act as war-scouts. The French were foremost in this matter, and by means of their manœuvres, or what you would call sham fights, they found that the air-scouts entirely altered the conditions of warfare. A squadron of aeroplanes could go out and bring back in an hour a complete report of where the enemy were and what they were doing.

The Commander who was planning an attack would be at a great disadvantage, for the enemy air-scouts would warn their Commander of every movement. Therefore these enemy aeroplanes must be destroyed if possible. The simplest way seemed to be to provide the army with guns which could shoot right up into the air, and thus bring these great enemy birds down. Some experiments with early anti-aircraft guns did not prove very satisfactory; it seemed as though the aircraft would be able to keep out of range of these guns by flying high and by darting about in a zigzag course. Why not have some aeroplanes—aerial destroyers—with guns mounted on them?

When making a kite you have to be careful that you do not make it too heavy or it will not fly. The same thing is to be watched in connection with aeroplanes; they can only carry a definite weight, according to their size and shape. Calculations and experiments showed that an aeroplane of moderate size could carry a quick-firing machine-gun, and such war-planes or battle-planes had been invented before the outbreak of the Great European War.

Seeing that the air-scouts were to face the enemy aerial destroyers, it became necessary for the outgoing air-scouts either to carry guns or to be accompanied by aerial destroyers of their own. And so it became apparent that there would be war in the air, for the enemy would not suffer our air-scouts to come and go at will, and our scouts would not be driven off without a stiff fight. That is the real meaning of war in the air, and you see how it came about.

In the illustration facing page 240 we see a British war-plane attacking a German machine. The artist has drawn this picture to represent a fight which took place on Sunday, 20th June 1915. While at a height of 4000 feet our war-plane was attacked by the German machine. You can easily distinguish the machines by their marks. You see the black crosses on the German machine, and the eye-like mark on the British war-plane. The German machine at first circled round ours, shooting at it with a machine-gun, but did not succeed in doing any real damage. One of our officers navigated the British war-plane into a good position, bringing it within 200 yards of the German machine, thus enabling his brother officer to use the machine-gun with great effect. In the illustration you can see how the British war-plane is in a position from which it can attack the enemy, while the enemy cannot bring his gun to bear on the British machine. The British war-plane poured forth a stream of bullets upon the enemy war-plane, which commenced to waver. Another round of the machine-gun and the engines were put out of action. As already stated, the fight took place at a height of 4000 feet: three quarters of a mile from the ground. The British officers succeeded in crippling the enemy craft, which dived down 2000 feet, and then made for the ground in a very erratic fashion.

During the fight our war-plane was hit by one of the enemy anti-aircraft guns fired from the ground, and unfortunately this set the British war-plane on fire. Although the officers were both severely burnt, they managed to land in the British lines. They both recovered, and it was not long before they were ready for another combat in the air.

The foregoing gives us a very good idea of what is meant by war in the air. Some people have the idea that future battles will be fought chiefly in the air, but there does not seem to be much evidence to suggest this. War in the air has been brought about as a means of preventing the air-scouts of the enemy getting information as to the movements and plans of the opposing armies.

In the Great War, aeroplanes were put to another use. It was evident that while perched up in the air over the heads of the enemy they could drop explosive bombs and do considerable damage. We heard of many daring raids made by our air squadrons upon the Zeppelin sheds, railway stations, munition stores and other possessions of the enemy. The world was stirred by the daring attack made by a light-racing aeroplane upon a great Zeppelin. Soaring above the huge enemy air-ship, the British aeroplane swept down like a hawk and threw a bomb right on to the Zeppelin. There was a terrific explosion, which nearly caught the attacking aeroplane. The back of the Zeppelin was broken, its gas-bags burst, and down it went to certain death.

Then there was the case of an aviator following a German submarine as a hawk follows its prey, and at the right moment swooping down, dropped an explosive right on board the submarine, which was completely wrecked.

In such incidents as the two just cited, we see the aeroplane no longer confined to scouting. Yet its greatest use is to act as the eye of the Army and Navy. The scouting aeroplane may carry a wireless telegraphic apparatus, by means of which messages could be sent to Headquarters, while the aeroplane is still in the air over the enemy's head. It is not difficult to realise how useful the aeroplane is in searching out the enemy's hidden guns. When the flying man sights a battery of guns, he comes down to a certain pre-arranged height, and while immediately over the guns he signals to his own gunners. Two officers take observations of the position of the aeroplane, and the range-finder determines the actual distance. The guns are then set, and the aeroplane flies to and fro, watching the shells fall, reporting each time whether short or beyond the unseen battery at which they are firing. Then when he reports that the shells are landing true, the gunners, knowing their range is right, lose no time in making things very hot for the enemy.

At one time it was thought that aeroplanes would be of very little use to the Navy, as the deck of a battleship was not a convenient place on which to land, nor would it be easy to set off from the deck. Someone tried to get over this difficulty by inventing an arrangement of wires from which the aeroplane might soar into the air, but the real solution of the difficulty was to make the aeroplane like a sea-bird, giving it floats instead of wheels. Floating on the surface of the sea, it could start its air propeller and skim along the water until it had sufficient way on to lift it into the air. Then the sea gives a grand landing-place.

At first there was great confusion as to what to call these new sea-birds; some called them hydro-aeroplanes, but others confused that with hydroplanes, which are boats that skim along the surface of the sea at a great speed, but never leave the water. There is no confusion now, as we call the aeroplane which can alight on the water a sea-plane or water-plane.

One boy asks: What chance of escape has an aviator if his engine breaks down while he is high up over the enemy's lines? Here the simple experiment with which we began this chapter will help us to realise that under such circumstances the flying man is not hopelessly lost. In falling, the sheet of paper may glide along to quite a distance before reaching the floor. The aeroplane, with its engine stopped, can do very much better than the sheet of paper. It may make a long, slow glide, and turn its face homewards, and it may continue in this way for a long time, coming down to a lower level very gradually. Of course if the aviator is not high in the air he may be forced to come down in the enemy's lines. However, if he is even at the height of 1500 feet he may glide to a distance of nearly two miles. If he is 5000 feet up he can do very much better, and so in the Great War we heard of many aeroplanes getting into difficulties while over the enemy and yet returning safely to their own lines.

In these pages we have considered inventions for waging war on land, on sea, under sea, and in air. There are many other inventions, such as the telephone, the line telegraph, wireless telegraphs, electric searchlights, X-ray apparatus to aid the surgeons, motor vehicles, and such like, all of which are of great assistance in war, but these are not primarily war inventions.

The Great European War has been called a "War of Machinery," signifying the very important part played by war inventions, and I have heard some people say that we had no right to make such machines of war. It goes without saying that the more destructive we can make our weapons, the more chance we have of saving the lives of our men. However, the conclusion of the whole matter is that with the dreadful experience of the Great War all nations may agree to combine together in a real endeavour to make further wars impossible. The poet Longfellow has dealt with the material side in the following lines;

"Were half the power that fills the world with terror, Were half the wealth bestow'd on camps and courts, Given to redeem the human mind from error, There were no need for arsenals nor forts."

The material side is of little consequence compared with the terrible loss of valuable human lives, but we are confident that our children's children will agree that we did the right thing in taking part in the Great War. All the so-called arguments of the pacifist who would have peace on any terms, and the conscientious objectors who refuse to fight, are worthless.

When this subject was before the public in connection with the Great War, the Rev. A. J. Gossip, of Glasgow, when preaching a sermon upon "The Conscientious Objector," used the parable of the Good Samaritan with reference to Belgium in the following words:

"A certain little nation fell among thieves, who stripped it and wounded it, and left it half dead. And by chance a certain pacifist came down that way, who, when he saw it lying in its blood, passed by on the other side. Likewise a conscientious objector, when he was at the place, came and looked at it, and passed by on the other side. But a certain boy as he journeyed through life, came to where it was, and when he saw it, he had compassion on it, and leaving home and everything, risking life and limb, bearing much grievous discomfort and sore pain, did what he could to right it. Tell me, therefore, which of these three was neighbour unto that little nation that fell among thieves?"