Although, under favourable conditions, a modern machine requires little control, and though he meets with few difficulties when he is learning to fly, a pupil must remember always that no liberties can be taken while he is in the air; every instant he is aloft he needs caution. The greatest of the world’s airmen--the Wrights, say, or Bleriot or Farman--never lost for one moment what may be termed their respect for the air. A man who is haphazard or careless should not turn to aviation; he is a danger to himself, and to others also. After making turns to the left, until he can accomplish them with ease, the novice attempts a similar manœuvre to the right; but he needs to remember, while at this stage of his tuition, that a turn must never be attempted while a machine is ascending. If this mistake is made, and a craft is swung sideways while its planes are inclined at a steep angle to the air, it may lose its forward speed and slide tail-first towards the ground. When turning to the right, as soon as he attempts this manœuvre, the pupil finds that his craft has a tendency to rise: this is due to the gyroscopic effect of engine and propeller, which are revolving in the opposite direction to the turn. To counteract the influence, however, which is slight, the pilot should move his elevator so that it is in the position for a descent. The machine, if he does this, will resist the gyroscopic motion and maintain an even keel. In early days, when little was known about this gyroscopic influence, a turn to the right was considered difficult and even dangerous, and there were men who would not attempt it if they could avoid doing so. But nowadays, thanks to greater knowledge and experience, the right-hand turn proves as easy almost as a similar movement to the left. Reaching the stage when he can turn with facility either right or left, the pupil combines these manœuvres in a single flight, and learns also to stop his motor while in the air and descend in a glide. The point to be remembered in making a _vol-plané_ is that, when its motor is stopped, the only force which keeps an aeroplane moving is that of gravity. If it stands still in the air its planes are inoperative, and it falls. So, as he switches off the motor, the airman must push forward his elevating lever, tilt down the front of his machine, and set it gliding earthward; and, if the speed of his glide is maintained, the craft is perfectly controllable. The actual landing is a matter of skill. Just before his craft touches ground, the novice must tilt back his elevating plane; this checks the glide, raises the front of the machine, and brings his wheels into a smooth contact with the ground. Should such a checking movement not be made--and some nervous pupils have been known to forget it--a machine may strike ground sharply, at an awkward angle, and damage its chassis. The landing-gear of a school biplane is, however, made specially strong, and will resist a heavy shock.