That affair being over, Jack, breathing hard, now allowed himself to pay some attention to what was going on in other quarters.  At the same time he proceeded to introduce a fresh belt of cartridges into the hungry maw of the machine gun, in case they were forced into another engagement.

Above them the battle still raged, though of course Jack could not decide which side might be getting the better of it.  His interest focused chiefly on the bombing machines, which he found were now far away, moving along in erratic courses as their pilots strove to get in exact position for a successful blowing up of the bridge.

Jack could count only three of them.  Unless the fourth had wandered far afield it looked as though disaster had overtaken its crew.  No matter, even such a catastrophe must not deter those remaining from seeking by every means in their power to reach their objective.

Even as he stared downward Jack saw another of those brilliant flashes that proclaimed the bursting of a bomb.  He felt a sense of chagrin steal over him, because so far no explosive seemed to have succeeded in attaining the great end sought.  The bridge still stood intact, if deserted, for he could catch glimpses of it when the smoke clouds were drifted aside by the night breeze.

Fires were now burning in several quarters, started undoubtedly by some of the bombs that had missed their intended objective.  These lighted up the scene and gave it a weird, almost terrifying aspect as witnessed from far above.

All at once Jack saw some bulky object pass between their machine and the ground below.  It must be the missing bomber, he concluded, though the realization of the fact made him thrill all over in admiration of the nerve of those who could accept such terrible chances.

Yes, despairing of getting in a telling blow at such a height, the reckless crew of the big Yankee plane had actually dropped down until they could not be more than a thousand feet from the earth.  And now they were speeding forward, meaning to test their skill at such close quarters.

Not being able to make Tom hear his voice, Jack gave the other a tug, and so managed to call his attention to what was passing below.  Just in time did Tom look, for at that very moment there came another of those amazing brilliant illuminations, and the dull roar greeted their ears a few seconds afterwards.

They saw with staring eyes the air filled with the material that had once constituted the wonderful bridge, across which day and night the retreating Huns were taking their valuable guns and stores.  A brief space of time did the scene bear the aspect of chaos, and then, when the smoke cleared sufficiently for them to see, they looked upon a void where the bridge had stood.

Jack fell back appalled, yet quivering with deepest satisfaction.  Their raid would be one of triumph, since the main object had now been achieved.