of its two predecessors, and was
fitted with a fixed vertical fin at the rear in addition to the movable
elevator in front. According to Mr Griffith Brewer,[*] this third glider
contained 305 square feet of surface; though there may possibly be a
mistake here, as he states[**] the surface of the previous year's glider
to have been only 290 square feet, whereas Wilbur Wright himself[***]
states it to have been 308 square feet. The matter is not, perhaps, save
historically, of much importance, except that the gliders are believed
to have been progressively larger, and therefore if we accept Wilbur
Wright's own figure of the surface of the second glider, the third
must have had a greater area than that given by Mr Griffith Brewer.
Unfortunately, no evidence of the Wright Brothers themselves on this
point is available.

[*] Fourth Wilbur Wright Memorial Lecture, Aeronautical Journal, Vol.
XX, No. 79, page 75.

[**] Ibid. page 73.

[***] Ibid. pp. 91 and 102.

The first glide of the 1902, season was made on September 17th of that
year, and the new machine at once showed itself an improvement on its
predecessors, though subsequent trials showed that the difficulty
of lateral balance had not been entirely overcome. It was decided,
therefore, to turn the vertical fin at the rear into a rudder by making
it movable. At the same time it was realised that there was a definite
relation between lateral balance and directional control, and the rudder
controls and wing-warping wires were accordingly connected This ended
the pioneer gliding experiments of Wilbur and Orville Wright--though
further glides were made in subsequent years--as the following year,
1903, saw the first power-driven machine leave the ground.

To recapitulate--in the course of these original experiments the Wrights
confirmed Lilienthal's theory of the reversal of the centre of pressure
on cambered surfaces at small angles of incidence: they confirmed the
importance of high aspect ratio in respect to lift: they had evolved new
and more accurate tables of lift and pressure on cambered surfaces:
they were the first to use a movable horizontal elevator for controlling
height: they were the first to adjust the wings to different angles of
incidence to maintain lateral balance: and they were the first to use
the movable rudder and adjustable wings in combination.

They now considered that they had gone far enough to justify them in
building a power-driven 'flier,'