"Artillery," he said in a whisper.
"Beyond a doubt," said Karnes. "It means that the Mexicans have crossed the river—there's a ford two or three hundred yards above—and mean to attack us. It was your good ear, Ned, that gave us the first warning."
Ned flushed with pleasure at the compliment, but, a moment or two later, they saw dark figures rising out of the prairie and advancing toward them.
"Mexicans!" cried Karnes, and instantly fired at a dusky outline. The figures flitted away in the dusk, but the camp of Bowie was aroused at once. Inside of a minute every man was on his feet, rifle in hand, facing the open place in the horseshoe. They knew that they could not be attacked from the river. Bowie came to the side of Ned and Karnes.
"What is it?" he asked.
"Ned heard a sound," Karnes replied, "and when we put our ears to the earth we knew that it was made by artillery. Then I saw their scouts and skirmishers and fired upon them. They must have crossed the river in strong force, Colonel."
"Very likely," said Bowie. "Well, we shall be ready for them. Henry, you and Smith and the Ring Tailed Panther scout across the prairie there, and see what has become of them."
"Can't I go, too?" asked Ned.
Bowie patted him on the shoulder.
"You young fire eater!" he replied. "Haven't you done enough for one night? You gave us the first warning that the Mexicans were at hand. I think you'd better rest now, and let these old boys do this job."