Sir Hiram Maxim also introduced fore and aft superposed
surfaces in his wondrous flying machine of 1893,
but he relied chiefly for the lift upon his main large surface
and this necessitated so many guys, to prevent distortion,
as greatly to increase the head resistance and
this, together with the unstable equilibrium, made it
evident that the design of the machine would have to
be changed.

How Lilienthal Was Killed.

In 1895, Otto Lilienthal, the father of modern aviation,
the man to whose method of experimenting almost all
present successes are due, after making something like
two thousand glides with monoplanes, added a superposed
surface to his apparatus and found the control of
it much improved. The two surfaces were kept apart
by two struts or vertical posts with a few guy wires, but
the connecting joints were weak and there was nothing
like trussing. This eventually cost his most useful life.
Two weeks before that distressing loss to science, Herr
Wilhelm Kress, the distinguished and veteran aviator
of Vienna, witnessed a number of glides by Lilienthal
with his double-decked apparatus. He noticed that it
was much wracked and wobbly and wrote to me after
the accident: "The connection of the wings and the
steering arrangement were very bad and unreliable. I
warned Herr Lilienthal very seriously. He promised
me that he would soon put it in order, but I fear that he