manner hereinbefore described as to present different
angles of incidence to the atmosphere, that side presenting the largest
angle of incidence, although being lifted or moved upward in the manner
already described, at the same time meets with an increased resistance
to its forward motion, while at the same time the other side of the
machine, presenting a smaller angle of incidence, meets with less
resistance to its forward motion and tends to move forward more rapidly
than the retarded side. This gives the machine a tendency to turn around
its vertical axis, and this tendency if not properly met will not only
change the direction of the front of the machine, but will ultimately
permit one side thereof to drop into a position vertically below the
other side with the aero planes in vertical position, thus causing the
machine to fall. The movement of the rudder, hereinbefore described,
prevents this action, since it exerts a retarding influence on that side
of the machine which tends to move forward too rapidly and keeps the
machine with its front properly presented to the direction of flight and
with its body properly balanced around its central longitudinal axis.
The pivoting of the supports 23 so as to permit them to swing upward
prevents injury to the rudder and its supports in case the machine
alights at such an angle as to cause the rudder to strike the ground
first, the parts yielding upward, as indicated in dotted lines in Fig.
3, and thus preventing injury or breakage. We wish it to be understood,
however, that we do not limit ourselves to the particular description of
rudder set forth, the essential being that the rudder shall be vertical
and shall be so moved as to present its resisting surface on that side
of the machine which offers the least resistance to the atmosphere, so
as to counteract the tendency of the machine to turn around a vertical
axis when the two sides thereof offer different resistances to the air.

From the central portion of the front of the machine struts 28 extend
horizontally forward from the lower aeroplane, and struts 29 extend
downward and forward from the central portion of the upper aeroplane,
their front ends being united to the struts 28, the forward extremities
of which are turned up, as indicated at 30. These struts 28 and 29 form
truss-skids projecting in front of the whole frame of the machine
and serving to prevent the machine from rolling over forward when it
alights. The s