Tam said nothing and presently began whistling softly.
He walked to his book-shelf, took down a thin, paper-covered volume and sank back on the bed.
"That will do, Angus," he said presently; "ca' me at five."
The barriers were up all around—they had been erected in the course of a short week. They penned him to his class, confined him to certain narrow roads from whence he might see all that was desirable but forbidden.
He was so silent the next morning, when he joined the big squadron that was assembling on the flying field, that Blackie did not know he was there.
"Where's Tam? Oh, here you are. You know your position in the formation? Right point to cover the right of the American bombing squad. Mr. Sutton before you and Mr. Benson behind. You will get turning signals from me. Altitude twelve thousand—that will be two thousand feet above the bombers—no need to tell you anything. The objective is Bapaume and Achiet junctions—"
Tam answered shortly and climbed into his fuselage.
The squadron went up in twos, the fighting machines first, the heavier bombing airplanes last. For twenty minutes they maneuvered for position, and presently the leader's machine spluttered little balls of colored lights and the squadron moved eastward—a great diamond-shaped flock, filling the air and the earth with a tremulous roar of sound.