Bob shook his head. "Well doesn't that beat all," he exclaimed.
As night fell and the air grew heavier, the barometer showed that the Cibola had a tendency to rise. The aeroplanes were readjusted and then for an hour the craft sped on untouched. At eight o'clock Ned said:
"We haven't traveled over eighteen miles in an hour and we've been afloat four hours. If we are still over the Chusco and Elmer and Buck are at the appointed place we may be within ten or twelve miles of them."
"They are going to burn three small camp fires set in a triangle, you remember," remarked Bob.
"Therefore," suggested. Ned, "all keep a sharp lookout."
At half past eight Ned showed some concern. No lights had been sighted and the reckoning showed that they must be within two or three miles of the probable location of the camp. Another fifteen minutes went by, and yet no signal fires were seen. They had now passed over the junction of the two rivers, if their calculations were right, and Ned and Alan were in a quandary.
"It's no use to go on," commented Ned; "so we'll just make a wide circle and see what we can find."
It was also useless to look below. In the darkness there was no sight of either river or desert.
"It we don't pick them up in that way," continued Ned, "we'll descend and tie up for the night."
Both Ned and Alan went below, and with the engine shut down to half speed the Cibola was turned on her course in a wide sweep. Bob alone watched with anxious eyes, until he was joined in a short time by Ned. There was no sound but the soft chug-chug of the engine, and for some time neither spoke. The breeze of the early evening had died and there was not a breath of air. Alan in the dark cabin below held the wheel and Ned and Bob alone, hanging over the side net, watched and listened in vain.