In a moment the boys were hauling in the rope and Ned was back in the cabin after a new bulb which he secured and attached in the dark.
"Now give her a swing," he said as Bob again lowered the rope. "It will make it harder to hit."
When Bob announced that all the rope was paid out Ned snapped the switch again. In spite of the gravity of the situation all the boys were tempted to laugh. A brilliant green glow shot down. An emerald circle of light flooded the ground beneath.
"If anyone sees that they'll sure think it's a drug store," suggested Bob.
"'Or a sign of the Great Spirit, perhaps," added Ned soberly, "it may help us in more ways than one, if Indians are—"
"Look," hoarsely shouted Alan, "there, over there!"
But his words were superfluous. The three boys saw the same thing. And then as the wide swaying of the bulb swept the gnome-like picture in green from view Ned threw himself over and shut off the engine.
Not a hundred feet beneath the brilliant bulb the precipitous bank of the river had again shot into the circle of light. At the very edge of the cliff stood the big freight wagon. Behind it, between the wagon and the steep river bank, stood two horses. At one end two more lay prostrate on the ground. In front a light barrier of boxes and barrels rose a few feet from the ground. And there, a rifle at his shoulder, knelt Elmer Grissom, their friend and servant. Buck was nowhere in sight.
Their worst fears were realized.
As the dramatic picture flashed from view each boy knew that it was time to act.
"What's to be done?" exclaimed Alan, his voice choking.
"There can't be many of them," answered Ned finally, as if thinking, "or they would pushed their attack. If we could locate them the rest would be easy. Let Bob take the wheel and try to get over the wagon again; I have an idea."
The Cibola again answered the rudder and circled, Ned flashing the bulb until the river came beneath them. This required but a few moments, but, before the craft had gathered momentum on the way back, there were four shots almost together about three hundred yards to the right of where they supposed the wagon stood, and a quick reply from the river bank.
"Our light did it," exclaimed Alan, "they are rushing the barricade."
"Indians don't rush together, if it is Indians," replied Ned. "Keep on up the bank, Bob. It's risky for Elmer," he added with a husky voice, "but we've got to take chances."
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.
"I guess I can come a little nearer finding out," exclaimed Ned finally to the others in a whisper.
Alan did not know what he meant, but he resumed his place at the wheel. Ned had disappeared in the dark.
"Where are you, Ned?" asked Alan anxiously at last.
The answer came from beneath the car.
"Only down here, but I'm going lower," Ned replied, again in a whisper. "Be ready with that ballast."
A perspiration of fear broke out on Alan's body. He sprang to the open trap door.
Just discernible in the darkness was Ned's slowly retreating form.
He was climbing down the twenty-five-foot rope landing ladder with only his own strong grip and the spruce rungs to save him from death.
There was nothing to be said or done. Bob did not know what was going on below, but he knew that he had a task set for him, and in the long silence that followed while the Cibola settled lower and lower and drifted on and on in the dark he stood, knife in hand, at the ballast bags.
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