After supper everybody sat around the stove in the portable house, for the nights were still chilly, till about ten o’clock. They had all made as much noise as possible early in the evening with the ultimate motive of accentuating the quietness later on.
Frank and Harry stood at the door of the portable house as Schultz and Le Blanc started for the aerodrome and shouted out “good-night” till the echoes rang back from the hills. Then one by one the lights in the two houses went out and all was quiet. That is, all seemed so to two watchers concealed in a thick mass of brush up on the hill, but in reality no sooner had the houses been plunged in darkness than the boys and Ben Stubbs had crept quietly into the aerodrome and sat down to wait for the crisis they felt sure was coming.
Harry and Billy each carried a long thin package that might have contained anything from dynamite to a pistol. Ben Stubbs, with a grim expression on his rugged face, grasped a stout club he had cut that afternoon. It was pitchy dark in the aerodrome and as they waited, in the absolute silence Frank had enjoined, the watchers could hear one another breathing. Upstairs only the rhythmic snores of Schultz and Le Blanc, who were not in the secret, disturbed the silence.
Frank sat with his hand on the switch that would shoot a current of 500 volts through the copper wires surrounding the aerodrome when he connected it. A hole, bored earlier in the afternoon in the wooden wall of the aerodrome gave the boy a command of the view outside in the direction of the woods. So dark was it, however, that even his keen eyes could detect little in the black murk. He saw they would have to judge of their enemies’ whereabouts solely by sound.
They must have sat there in the darkness for an hour or more, with no sound being borne to their ears but the unmelodious snoring of the two mechanics in the loft when, suddenly, and without any further warning there came a sharp “crack” from up on the hillside as a branch snapped under a heavy foot.
“Here they come,” whispered Frank to the boys, whom he knew were there; but couldn’t see any more than if they were in the antipodes.
“Get outside now, you fellows, and when I give the word, let go!”
Silently as cats Billy Barnes, Harry and Ben Stubbs slipped off their shoes and tiptoed out through the door of the aerodrome, which had been left open to allow for the noiseless exit. Frank was left alone in the barn-like aerodrome save for the two sleepers upstairs. The tension in the silence grew painful. When would the persons who had crackled the broken branch on the hillside recover their courage enough to make a further advance?
All at once, close at hand, Frank heard a loud whisper of:
“Well, they are all asleep, evidently.”