ace consists of a
surface or pair of wings mounted above another surface or pair of wings.

=Bay=--The space enclosed by two struts and whatever they are fixed to.

=Boom=--A term usually applied to the long spars joining the tail of a
"pusher" aeroplane to its main lifting surface. [4]

=Bracing=--A system of struts and tie wires to transfer a force from one
point to another.

=Canard=--Literally "duck." The name which was given to a type of
aeroplane of which the longitudinal stabilizing surface (_empennage_)
was mounted in front of the main lifting surface. Sometimes termed
"tail-first" aeroplanes, but such term is erroneous, as in such a design
the main lifting surface acts as, and is, the _empennage_.

=Cabre=--To fly or glide at an excessive angle of incidence; tail down.

=Camber=--Curvature.

=Chord=--Usually taken to be a straight line between the trailing and
leading edges of a surface.

=Cell=--The whole of the lower surface, that part of the upper surface
directly over it, together with the struts and wires holding them
together.

=Centre (Line) of Pressure=--A line running from wing-tip to wing-tip,
and through which all the air forces acting upon the surface may be
said to act, or about which they may be said to balance.

=Centre (Line) of Pressure, Resultant=--A line transverse to the
longitudinal axis, and the position of which is the resultant of the
centres of pressure of two or more surfaces.

=Centre of Gravity=--The centre of weight.

=Cabane=--A combination of two pylons, situated over the fuselage, and
from which the anti-lift wires are suspended. [5]

=Cloche=--Literally "bell." Is applied to the bell-shaped construction
which forms the lower part of the pilot's control lever in a Bleriot
monoplane, and to which the control cables are attached.

=Centrifugal Force=--Every body which moves in a curved path is urged
outwards from the centre of the curve by a force termed "centrifugal."

=Control Lever=--A lever by means of which the controlling surfaces are
operated. It usually operates the ailerons and elevator. The
"joy-stick." [6]

=Cavitation, Propeller=--The tendency to produce a cavity in the air.

=Distance Piece=--A long, thin piece of wood (sometimes tape) passing
through and attached to all the ribs in order to prevent them from
rolling over sideways. [7]

=Displacement=--Change of position.

=Drift= (_of an aeroplane as distinct from the propeller_)--The horizontal