The magnitude of the Dihedral angles, from which radiate three and occasionally four walls, depends on the position of the hypertonic poles of diffusion.
"The Mechanism of Life"
Stéphane Leduc
A more satisfactory system, especially for lateral balance, was that of arranging the wings in the shape of a broad V, to form a Dihedral angle, with the center low and the wing-tips elevated.
"The Early History of the Airplane The Wright Brothers' Aeroplane, How We Made the First Flight & Some Aeronautical Experiments"
Orville Wright Wilbur Wright
After considering the practical effect of the Dihedral principle, we reached the conclusion that a flyer founded upon it might be of interest from a scientific point of view, but could be of no value in a practical way.
"The Early History of the Airplane The Wright Brothers' Aeroplane, How We Made the First Flight & Some Aeronautical Experiments"
Orville Wright Wilbur Wright