Again the light flashed. Ned and Alan hurried to the bridge.

Within its circle and almost together, sealing the seamed and hard bank of the river, were five dark figures. As the powerful light encircled them the crouching figures sprang backwards. But they were not quicker than the alert and prepared Ned Napier. A small round object shot downward from his hands. The glare of flame as the missile struck true and the thunderous roar that hurled the big bag of the Cibola sideways told that the cordite bomb had done its work well.

Bob was speechless. Ned and Alan were already in hurried consultation. They could not count on fortunately finding the other besiegers all together, "'and there are at least four more," said Ned. The rescue of the lone besieged lad was not an easy problem. The boys believed themselves now just above the wagon again, but they were afraid to draw possible fire to the barricade by showing another light.

The hurling of the bomb overboard had shot the Cibola heavenward like a bird. Before they realized it the aeronauts had mounted up at least two thousand feet. They then began maneuvering to regain their position. But this was not so easy. A flash of the suspended searchlight gave them not a trace of their bearings and it was plainly apparent they would have to use time and patience in recovering the location of the besieged wagon. Using their best judgment, they put the aeroplanes to work, and, circling slowly, the Cibola gradually came nearer and nearer to the ground. After ten minutes or more the car gave a sharp bound upward.

"The drag has touched the ground," exclaimed Ned.

The aeroplanes were righted, the engine was stopped, and again the balloon was drifting. There was not a sound to guide the aeronauts. The contact with the ground had broken the bulb and it was not replaced. For aught the rescuers knew they might be again directly over the wagon. Not a shot had been fired since the roar of the explosion, but there was no reason to believe that the yet living besiegers had withdrawn.

"More likely planning a final attack," suggested Alan.

Again a council was held.

"We've got to take the risk," said Ned at last in desperation; "we can't do anything up here."

And then, with Alan's approval, the propeller was set turning again, but so slowly that the big balloon was just moving under control. The aeroplanes were also set to bring the craft nearer the ground and, as a precaution, Bob was sent onto the bridge with an open knife to cut away ballast if sudden ascent were needed. The drag rope had been brought in. There were no means of knowing how near the car might be to the earth and the suspense was decidedly trying.