Once Jack experienced a sudden sinking in the region of his heart.  There was a strange movement to the plane that made him fear the motor had been struck.  He also missed the cheery hum at the same time, and felt a sickening sensation of falling.

But immediately he realized that Tom was only executing his pet drop, the nose-dive.  One of the Huns followed them down, just as a hawk-might pursue its prey.  When the American plane came out of the dive at the new level Jack saw that the Hun was closer than ever, and once again starting to bombard them.

At least they now had only a single adversary to deal with, which could be reckoned a point gained.  Most of the fighting was going on above them, but Jack believed the bombers must be somewhere near by, possibly at a still lower level.

Again the maneuvering, or jockeying, for position commenced.  In this air duel the pilot who knew his business best was going to come out ahead.  It might be they were opposed by some celebrated German ace with a long list of victories to his credit, which would render their chances smaller.

Tom, however, seemed to be keeping up his end wonderfully well.  The hissing missiles cut through the canvas of their wings, beat upon the side of the fuselage, and even nipped the Air Service Boys more than once as they stormed past.  Neither of the boys knew whether they were seriously wounded or not; all they could do was to fight on and on, until something definite had been achieved on one side or the other.

Once Jack felt something blinding him, and putting up a hand discovered that it was wet; yet he was not conscious of having been struck in the head by a passing bullet.  Dashing his sleeve across his eyes he shut his jaws still tighter together, and continued to play his gun as the opportunity arose.

They were coming to closer quarters, and the issue of the battle, however dreadful the result, could not be much longer delayed, Jack knew.

Then it happened, coming like a flash of lightning from the storm cloud!

CHAPTER VIII

BOMBING THE BRIDGE

“Tom, we’ve done it!” Jack shrieked, when he saw the enemy Gotha plane take a sudden significant dip and flutter downward like a stricken bird.

Evidently a shot more fortunate than any that had preceded it had struck a vital part of the rival craft, putting the motor suddenly out of repair.

When he felt his plane begin to crumple up under him the Hun pilot had commenced to strive frantically to recover control.  Jack, horror-stricken by what was happening, leaned over and watched his struggle, which he knew was well nigh hopeless from the beginning.

Still the German ace made a valiant effort to avoid his fate.  He could be seen working madly to keep from overturning, but apparently his hour had struck, for the last Jack saw of the beaten Gotha it was turning topsy-turvy, falling like a shooting star attracted to the earth by the law of gravitation.