The human fascination with flight is older than recorded history. An ancient Chinese legend tells of a prince who builds a wind-powered flying chariot, and in the famed Greek myth, Daedalus devises wings of feathers and wax so he and his son Icarus can escape their island prison. Icarus flies too close to the sun, his wings melt, and he plunges to his death.

Early history records a number of other failed attempts at imitating the flight of birds. Over nine hundred years ago, in what surely must have been a leap of faith, an English monk with a wing attached to each arm jumped off a church roof; somewhat remarkably, he suffered only two broken legs. A Frenchman attempting a similar feat some four centuries later was not so lucky; he fell to his death from a high church steeple. Around 1500, Leonardo da Vinci was busily observing...