"Gollyation!" he bawled. "Dem fellers is suah tryin' ter punctuate us!"
Through the blackness of the night a distant voice hailed the pilot of the Snowbird.
"Ahoy! ahoy! Who goes there?" was the cry, and it was repeated twice.
CHAPTER V
BETWEEN TWO PERILS
Mark Sampson, having all the mechanism of the flying machine under his immediate control, had it in his power to increase speed and seek to escape the second airship. And Jack wondered why his chum did not immediately send the Snowbird flying at increased speed over the top of Mt. Katahdin and so seek to escape the menace below.
But the young fellow at the controls of the Snowbird had an advantage over his companions that Jack had forgotten. He could hear sounds at a much greater distance than they, and much clearer.
This was because of an invention of Professor Henderson—a small instrument similar to part of the ordinary telephone. The sensitive disk was a form of radio receiver which could be attached to any aviator's helmet, and was being put into general use by pilots. The two boys always adjusted this whenever they were strapped upon the pilot's seat.
Thus, although the report of the gun had sounded but faintly to the other members of the party, to Mark it seemed as though the explosion was within a hundred yards. The voice hailing them likewise seemed to ring in his ears very plainly; and beyond the words somewhat distinguished by his companions the young operator of the Snowbird could make out a further phrase spoken by the person who hailed from the other air-craft.
"Halt in the name of the law!"