"Come on, Carnes, we're going to follow that globe. Take the front cockpit alone, Maynard; Carnes and I will get in the rear pit with the spec and guide you. You can take off your gas mask at an elevation of a thousand feet. You have pack 'chutes, haven't you?" "In the rear pit, Doctor." "Put one on, Carnes, and climb in. I've got to get this spec set up before he gets too high." The Douglass equipped with the Bird silencer, took the air noiselessly and rapidly gained elevation under the urging of the pilot. Dr. Bird clamped the gas-detecting spectroscope on the front of his cockpit and peered through it. "Southwest, at about a thousand more elevation," he directed. "Right!" replied the pilot as he turned the nose of his plane in the indicated direction and began to climb. For an hour and a half the plane flew noiselessly through the night. "Bald Mountain," said the pilot, pointing. "The Canadian Border is only a few miles away." "If they've crossed the Border, we're sunk," replied the doctor. "The trail leads straight ahead." * * * * * For a few minutes they continued their flight toward the Canadian Border and then Dr. Bird spoke. "Swing south," he directed, "and drop a thousand feet and come back." The pilot executed the maneuver and Dr. Bird peered over the edge of the plane and directed the spectroscope toward the ground. "Half a mile east," he said, "and drop another thousand. Carnes, get ready to jump when I give the word." "Oh, Lord!" groaned Carnes as he fumbled for the rip cord of his parachute, "suppose this thing doesn't open?" "They'll slide you between two barn doors for a coffin and bury you that way," said Dr. Bird grimly. "You know your orders, Maynard?" "Yes, sir. When you drop, I am to land at the nearest town--it will be Lowell--and get in touch with the Commandant of the Portsmouth Navy Yard if possible. If I get him, I am to tell him my location and wait for the arrival of reenforcements. If I fail to get him on the telephone, I am to deliver a sealed packet which I carry to the nearest United States Marshal. When reenforcements arrive, either from the Navy Yard or from the Marshal, I am to guide them toward the spot where I dropped you and remain, as nearly as I can judge, two miles away until I get a further signal or orders from you." "That is right. We'll be over the edge in another minute. Are you ready, Carnes?" "Oh, yes, I'm ready, Doctor, if I have to risk my precious life in this contraption." "Then jump!" * * * * *