Larkin grinned. Rarely did they go into the air together but what they engaged in mimic warfare--dog-fighting--before their wheels again touched the ground. It was the airman's game of tag, the winner being that one who could get on the other's tail and stay there. It was a thunderous, strut singing game wherein the pursued threw his plane into fantastic gyrations in a frenzied, wild effort to shake off the pursuer and get on his tail. It was a game in which McGee excelled. Although Larkin recognized this fact, he was always the first to start the dog fight and had never found McGee unwilling to play. As for contour chasing--well, they had broken regulations times without number, and to date had paid no penalty. McGee, knowing what thoughts lurked behind Larkin's grin, wagged a prudent finger under his nose. "Mind your step, Buzz," he warned. "We are supposed to be sedate, dignified, instruction-keeping instructors. Fly northwest to Auxerre, then follow the railroad toward Sens and on to Melun. Then swing straight north and come into Le Bourget from the east." "All right. All set?" "Yes. You lead off and I'll follow. Wait! On second thought I think I'll lead and pick my own altitude. And if you start any funny business, I'll leave you flat!" They climbed into the waiting planes, whose motors were still warming idly. Members of the ground crew took up their stations at the wing tips. McGee was on the point of nodding to the crew to remove the wheel chocks when he remembered that for the first time in his experience as a pilot he had climbed into the cockpit without first casting an appraising eye over braces, struts and turn buckles. He promptly cut the motor and climbed from the plane, saying, half aloud; "I must be getting balmy. It's the weather, I guess." "How's that, sir?" asked the air mechanic. "I say, it's balmy weather we're having." "Oh! Yes, sir." "You've checked her all over, Wilson?" "Yes, sir. And fueled her according to Lieutenant Larkin's instructions." "Hum." McGee slowly walked around the plane, giving every functional detail a critical look, nor was he the least hurried by the fact that Larkin was displaying impatience. Satisfied at last, he climbed back into the plane. A member of the ground crew took his place at the propeller. "Petrol off, sir?" "Petrol off." Whish! Whish! went the prop as the helper began pulling it over against compression. "Contact, sir!" "Contact." The motor caught, coughed, caught again and the prop whirled into an indistinct blur. The sudden blast of wind sent clouds of dust eddying toward the hangar, but ahead lay the cool, fresh, dew-washed green of the field. McGee turned to look once more at the wind sock which, for want of a breeze, hung limp along its staff. He nodded to the men at the wheel chocks, waved his hand to Larkin and gave her the gun.