Chanute, who spent a great deal of time closely observing sea gulls in California, distinguished between “gliding,” which involved loss of altitude, and “sailing,” which did not. He used the terms sailing and soaring interchangeably, though at times I think by soaring he implied a gain of altitude — all this, of course, without wing beats. It was, in reality, a distinction without a difference. The Nobel-winning physicist John Strutt, Lord Rayleigh, in Chanute’s words “the highest scientific authority in Great Britain,” had written in 1883 that if a soaring bird appeared to gather energy from the air, it could come from only three possible sources: sacrificing its own speed, vertical movement of the air or differences of wind speed in closely neighboring air masses. This was correct; all other opinions, however painstakingly reasoned and documented by Chanute, were nonsense.