They found that a slight curve or camber in the wing section would cause the moving air to travel farther over the top of the wing surface than along the under side. This made the air pressure greater under the wing, gave a suction effect above the wing, and caused it to rise, creating lift. They discovered that a wing section of the proper camber would counteract the weight of gravity. Thus, a wing must be so designed that, with a certain amount of air flowing around it, it would lift a certain weight. They also discovered that air flow against any surface attached to the wing would cause a resistance or drag. Hundreds of experiments in their wind tunnel with various types of wing shapes gave the Wrights a series of tables from which to design a wing that would create the lift for a designed weight.