nes. On either, if he has an inclination, a
pupil can undergo his instruction, and do so usually with success. But
explanation is rendered more easy, and there is less likelihood of a
dispersal of interest, if one machine is selected for illustration;
and our reasons for the choice of a "pusher" biplane, regarded from
the point of view of tuition, have been explained already.

First, therefore, one may deal with raising the craft into the air,
and causing it to descend. In the photograph of the school machine
shown facing this page, it will be seen that the control surfaces are
indicated by lettering. In front of the biplane, on outriggers, is the
plane "A." This surface (aided in its action by a rear plane) governs
the rise or descent of the machine. When the motor is started, and the
propeller drives the biplane across the ground on its chassis B, the
machine would, if this lifting plane was held in a negative position,
continue to move forward on the earth and would make no attempt to
rise. In order to leave the ground, when the speed of the machine is
sufficient for its main-planes (C.C.) to become operative, and bear
its weight through the air, the pilot draws back slightly towards him
a lever, which is placed just to the right of his driving-seat and is
held with the right hand. A photograph which shows this lever, and the
other controls, appears facing page 36, the lever to which we are
referring being indicated by the figure 1. The effect on the aircraft
when the pilot draws back this lever--the motion being slight and made
gently--is to tilt up the elevating plane A, and this in its turn,
owing to the pressure of air upon it, raises the front of the machine.
The result of this alteration in the angle of the craft is that it
presents its main-planes at a steeper angle to the air. Their lifting
influence is increased, with the result that--at an angle governed by
the pilot with his movement of the elevating plane--they bear the
machine from the ground into the air.

[Illustration: GRAHAME-WHITE SCHOOL BIPLANE (TYPE XV.) _Photo by
Topical Press Agency._

A.--The front elevating plane, which acts in conjunction with the
rear-plane marked A1; B.--The landing-chassis; C.C.--The main-planes;
D.D.--The ailerons; E.E.--The rudders; F.--Engine (a 60-h.p. Le Rhone)
and propeller.]

A reverse movement of the elevator reduces the lift of the main-planes;
hence, when an aviator wishes to descend, he tilts dow