Further concerning Dr. Bernoulli he was I think more correct than incorrect, other than of course for planes moving at supersonc speeds, space craft etc.... to quote David Kennett's link concerning the longer path explanation (ie: top surface of the wing or sail)... "The Longer Path explanation is correct in more than one way. First, the air on the top surface of the wing actually does move faster than the air on the bottom -- in fact, it is moving faster than the speed required for the top and bottom air particles to reunite, as many people suggest. Second, the overall pressure on the top of a lift-producing wing is lower than that on the bottom of the wing, and it is this net pressure difference that creates the lifting force" Ron Barr