nal evolutions. Having mastered the
left-hand turn, he proceeds to make one to the right. It used to be
the contention--a contention that is now disputed--that in this
movement, if the pupil employed his rudder-bar only, he would find the
biplane showed an inclination to rise; a tendency due to the
gyroscopic influence of the engine and propeller which--assuming a
rotary engine is used--are now revolving in the opposite direction to
that on which the machine is turned. What the pupil was recommended to
do, in order to counteract this rising movement, was to tilt down his
elevator a little, as he would in making a descent.

When right-hand turns can be made with the same facility as those to
the left, the pupil begins to combine the two without descending,
making left turns and right turns, and so achieving in the air a
series of figures of eight. He learns also to fly a little higher,
thus preparing himself for one of his certificate tests.

There are now certain very important rules which, in the navigation of
his craft, he must accustom himself to bear constantly in mind. Should
the engine of his machine, for example, betray any signs of failing,
he must tilt down his elevator very promptly, and place his craft in a
position for a descent. If he does not do this, and should the motor
stop before he has his biplane at an angle for descent, the machine
may lose speed so quickly, and its tail-planes show such a tendency to
droop--owing to the lessening of pressure on their surfaces,
consequent upon the failure of the motor--that there is a risk of the
craft coming to a standstill in the air and then either falling
tail-first, or beginning a side-slip that may bring it crashing to the
ground.

The pupil must learn also, and this again is important, not to force
his machine round on a turn while it is climbing. If he does so the
power absorbed in the ascent, combined with the resistance of the turn,
may so reduce the speed of the machine that it threatens to become
"stalled," or reach a standstill in the air, with the result that it
either side-slips or falls tail-first. The procedure the pupil is
taught to follow is this: when he leaves the ground he climbs a little,
then he allows his machine to move straight ahead; then he proceeds
to ascend again for a spell, repeating afterwards the horizontal
flight. In this way he ascends by a series of steps, like climbing a
succession of hills in a car; and his turns should be