In our army, and indeed in all others, applicants for appointment to the aviation corps were subjected to scientific tests of their nerves, and their mental and physical alertness. How they would react to the sudden explosion of a shell near their ears, how long it took the candidate to respond to a sudden call for action, how swiftly he reacted to a sensation of touch were all tested and measured by delicate electric apparatus. A standard was fixed, failing to attain which, the applicant was rejected. The practical effect might be to determine how long after suddenly discovering a masked machine gun a given candidate would take before taking the action necessary to avoid its fire. Or how quickly would he pull the lever necessary to guard against a sudden gust of wind. To the layman it would appear that problems of this sort could only be solved in the presence of the actual attack, but science, which enables artillerists to destroy a little village beyond the hills which they never see, was able to devise instruments to answer these questions in the quiet of the laboratory.
One of the best known flying schools of the French army was at Pau, where on broad level plains were, in 1917, four separate camps for aviators, each with its group of hangars for the machines, its repair shops, and with a tall wireless tower upstanding in the midst for the daily war news from Paris. On these plains the Wright Brothers had made some of their earliest French flights. A little red barn which they had made their workshop was still standing there when war suddenly turned the spot into a flying school often with as many as five thousand pupils in attendance. "To-day that little red barn," writes Carroll Dana Winslow, one of the Americans who went to fly for France, "stands as a monument to American stupidity, for when we allowed the Wrights to go abroad to perfect their ideas instead of aiding them to carry on their work at home we lost a golden opportunity. Now the United States which gave to the world the first practical airplane is the least advanced in this all-important science."
Arrived at the school the tyro studies the fundamentals of flying in the classroom and on the field for two months before he is allowed to go up--to receive as they express it, his baptême de l'air. He picks motors to pieces, and puts them together, he learns the principles of airplane construction, and can discourse on such topics as the angle of attack of the cellule, the incidence of the wings, and the carrying power of the tail-plane. More than any other science aviation has a vocabulary of its own, and a peculiarly cosmopolitan one drawn from all tongues, but with the French predominating. America gave the airplane to France, but France has given the science its terminology.
The maps of the battlefields of this war are the marvels of military science. Made from the air they show every road and watercourse, every ditch and gully, every patch of woodland, every farmhouse, church, or stonewall. Much of the early work of the aviator is in learning to make such maps, both by sketches and by the employment of the camera. It is no easy task. From an airplane one thousand feet up the earth seems to be all a dead level. Slight hills, gentle elevations, offer no contrast to the general plain. A road is not easy to tell from a trench. All these things the aviator must first learn to see with accuracy, and then to depict on his map with precision. He must learn furthermore to read the maps of his fellows--a task presupposing some knowledge of how they had been made. He must learn to fly by a map, to recognize objects by the technical signs upon it, to estimate his drift before the wind because of which the machine moves sidewise en crabe--or like a crab as the French phrase it.
