On the banks of the Scheldt River in northeastern France lay a small town called Cambrai, c-a-m-b-r-a-i, not c-a-m-b-r-a-y. It had been a battlefield between Britain and Germany during World War I. Both sides had committed large numbers of tanks to the fighting, and planes had flown low overhead.
Who knew whether those who dreamed of flying like birds and went on to invent all manner of flying machines had ever imagined such a day would come? According to Leonardo da Vinci's early dissections of bird wings and his studies of feather structures, birds' wings were covered in thick networks of tendons. Such formidable strength allowed them to exert far more force than they normally used for flight, whether to seize prey or evade pursuit. In theory, it could increase their flying speed twofold or even threefold.
Yet when birds hovered in the air, their wings did not flap. Instead, they used them to maintain balance. When an eagle prepared to catch a wild hare on the ground, it tucked in its wings to increase the speed of its dive. When it neared its target or the ground, it spread its wings again and seized the rabbit with its talons.
Another animal, the bat, could fly as well. It needed to flap its wings constantly to remain airborne, but bats flew nowhere near as high as birds. Once they reached a certain altitude, they too stopped flapping and glided with their membranous wings spread wide.
Bird feathers were soft yet resilient, and they allowed air to pass through them. Bat wings, on the other hand, were completely airtight.
Yet upon closer observation, agile birds such as hummingbirds had almost no tail feathers, and bats likewise had no tails. The nocturnal creatures they hunted always tried to escape pursuit through chaotic