A quick comparison between these two sets of photographs demonstrates some important advances made by the Wrights from their most significant predecessor, Otto Lilienthal.

At first glance, there are many similarities: both are launching unpowered gliders from hills. Both display the machines in controlled flight. However, the fact that Lilienthal's legs are visible underneath his machines is, in terms of control, a major difference and represents a significant advance made by the Wrights. Lilienthal controlled his machine by throwing his weight fore and aft and left and right, changing the center of gravity of the glider as it descended. In the images of the Wright glider, Wilbur's position on the machine is virtually unchanged. Using the forward elevator and wing warping controls, the pilot controlled his descent by changing the aerodynamic shape of the machine itself.

Image credits: Library of Congress, Archive Otto-Lilienthal-Museum / www.lilienthal-museum.de